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Sample records for high rate deformation

  1. High strain rate deformation of layered nanocomposites.

    Science.gov (United States)

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A; Thomas, Edwin L

    2012-01-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  2. High strain rate deformation of layered nanocomposites

    Science.gov (United States)

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P.; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A.; Thomas, Edwin L.

    2012-11-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  3. Twinning in copper deformed at high strain rates

    Indian Academy of Sciences (India)

    Abstract. Copper samples having varying microstructures were deformed at high strain rates using a split-. Hopkinson pressure bar. Transmission electron microscopy results show deformation twins present in samples that were both annealed and strained, whereas samples that were annealed and left unstrained, as well ...

  4. Dynamic tensile behaviour and deformational mechanism of C5191 phosphor bronze under high strain rates deformation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Dao-chun [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Mechanical and Electrical Engineering, Taizhou Vocational & Technical College, Taizhou 318000 (China); Chen, Ming-he, E-mail: meemhchen@nuaa.edu.cn [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Lei; Cheng, Hu [College of Mechanical Engineering, Taizhou University, Taizhou 318000 (China)

    2016-01-01

    High speed stamping process is used to high strength and high electrical conductivity phosphor bronze with extremely high strain rates more than 10{sup 3} s{sup −1}. This study on the dynamic tensile behaviour and deformational mechanism is to optimise the high speed stamping processes and improve geometrical precision in finished products. Thus, the tensile properties and deformation behaviour of C5191 phosphor bronze under quasi-static tensile condition at a strain rate of 0.001 s{sup −1} by electronic universal testing machine, and dynamic tensile condition at strain rate of 500, 1000 and 1500 s{sup −1} by split Hopkinson tensile bar (SHTB) apparatus were studied. The effects of strain rate and the deformation mechanism were investigated by means of SEM and TEM. The results showed that the yield strength and tensile strength of C5191 phosphor bronze under high strain rates deformation increased by 32.77% and 11.07% respectively compared with quasi-static condition, the strain hardening index increases from 0.075 to 0.251, and the strength of the material strain rates sensitivity index change from 0.005 to 0.022, which presented a clear sensitive to strain rates. Therefore, it is claimed that the dominant deformation mechanism was changed by the dislocation motion under different strain rates, and the ability of plastic deformation of C5191 phosphor bronze increased due to the number of movable dislocations increased significantly, started multi-line slip, and the soft effect of adiabatic temperature rise at the strain rate ranging from 500 to 1500 s{sup −1}.

  5. High Strain Rate and Shock-Induced Deformation in Metals

    Science.gov (United States)

    Ravelo, Ramon

    2012-02-01

    Large-scale non-equilibrium molecular Dynamics (MD) simulations are now commonly used to study material deformation at high strain rates (10^9-10^12 s-1). They can provide detailed information-- such as defect morphology, dislocation densities, and temperature and stress profiles, unavailable or hard to measure experimentally. Computational studies of shock-induced plasticity and melting in fcc and bcc single, mono-crystal metals, exhibit generic characteristics: high elastic limits, large directional anisotropies in the yield stress and pre-melting much below the equilibrium melt temperature for shock wave propagation along specific crystallographic directions. These generic features in the response of single crystals subjected to high strain rates of deformation can be explained from the changes in the energy landscape of the uniaxially compressed crystal lattice. For time scales relevant to dynamic shock loading, the directional-dependence of the yield strength in single crystals is shown to be due to the onset of instabilities in elastic-wave propagation velocities. The elastic-plastic transition threshold can accurately be predicted by a wave-propagation stability analysis. These strain-induced instabilities create incipient defect structures, which can be quite different from the ones, which characterize the long-time, asymptotic state of the compressed solid. With increase compression and strain rate, plastic deformation via extended defects gives way to amorphization associated with the loss in shear rigidity along specific deformation paths. The hot amorphous or (super-cooled liquid) metal re-crystallizes at rates, which depend on the temperature difference between the amorphous solid and the equilibrium melt line. This plastic-amorphous transition threshold can be computed from shear-waves stability analyses. Examples from selected fcc and bcc metals will be presented employing semi-empirical potentials of the embedded atom method (EAM) type as well as

  6. High rate deformation of metallic liner and its dislocation description

    International Nuclear Information System (INIS)

    Prut, V.V.; Shybaev, S.A.

    1996-01-01

    The dynamics of deformation in cylindrical liners are studied experimentally and theoretically in Z-pinch geometry, where the cylinders are deformed by a magnetic field created by a current flowing along the axis. This method allows one to obtain one-dimensional deformation and a reliable recording of magnetic field and cylinder deformation. The experiments are performed with a current amplitude of 0.8-3 MA and a current rise time of 2.5-4 μs. Aluminium and copper tubes, from 4 to 6 mm in diameter and 0.25-1 mm wall thick, are compressed. The deformation rates under study are in the range of 10 5 -10 6 s -1 . The time dependence of the radii of the copper and aluminium tubes are measured with a streak camera and by the pulsed x-ray technique. The time resolution of the streak and x-ray photographs is 10-15 ns, their spatial resolution is 10-15 μm. A rheological model describing the dynamics of compression is developed. The model includes the description of the metal as a plastic medium with moving dislocations in the solid state, and as a viscous medium in the liquid state. The one-dimensional solution to magneto-hydrodynamical equations of the liner dynamics is compared with the experimental results and thus the following rheological parameters of the metal are obtained: β, the probability of dislocation generation in plastic deformation; and σ d , the drag stress, the parameter which characterizes a drag force acting on the dislocation. (Author)

  7. High Rate Plastic Deformation and Failure of Tungsten-Sintered Metals

    National Research Council Canada - National Science Library

    Bjerke, Todd

    2004-01-01

    The competition between plastic deformation and brittle fracture during high rate loading of a tungsten-sintered metal is examined through impact experiments, post-experiment microscopy, and numerical simulation...

  8. Effects of strain rate and temperature on deformation behaviour of IN 718 during high temperature deformation

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, L X [Dept. of Metallurgy and Engineering Materials, Univ. of Strathclyde, Glasgow (United Kingdom); Baker, T N [Dept. of Metallurgy and Engineering Materials, Univ. of Strathclyde, Glasgow (United Kingdom)

    1994-04-15

    The hot deformation characteristics of a wrought IN 718 alloy were investigated by compression testing at constant strain rates in the range of 0.1 to 5 x 10[sup -3] s[sup -1], and testing temperatures in the range of 950 to 1100 C using a 200 ton capacity microprocessor controlled Fielding hydraulic press. Examination of the microstructures was carried out by optical microscopy and TEM. The flow stress of the compression tests showed a single peak in the flow stress-strain curves, and indicated that a dynamic recrystallization transition took place during the hot compression. The relationship between the peak stresses ([sigma][sub p]) and the Zener-Hollomon parameter (z) can be expressed by [sigma][sub p] = 0.5 Z[sup 0.17]. Necklace'' microstructures were observed at testing temperatures below 1050 C, for strain of 0.7. The fraction of recrystallized grains increased with the increasing temperature and strain, and decreasing strain rate. Fully recrystallized microstructures were observed at temperatures 1050 C or greater, with a strain of 0.7. (orig.)

  9. The High Strain Rate Deformation Behavior of High Purity Magnesium and AZ31B Magnesium Alloy

    Science.gov (United States)

    Livescu, Veronica; Cady, Carl M.; Cerreta, Ellen K.; Henrie, Benjamin L.; Gray, George T.

    The deformation in compression of pure magnesium and AZ31B magnesium alloy, both with a strong basal pole texture, has been investigated as a function of temperature, strain rate, and specimen orientation. The mechanical response of both metals is highly dependent upon the orientation of loading direction with respect to the basal pole. Specimens compressed along the basal pole direction have a high sensitivity to strain rate and temperature and display a concave down work hardening behavior. Specimens loaded perpendicularly to the basal pole have a yield stress that is relatively insensitive to strain rate and temperature and a work hardening behavior that is parabolic and then linearly upwards. Both specimen orientations display a mechanical response that is sensitive to temperature and strain rate. Post mortem characterization of the pure magnesium was conducted on a subset of specimens to determine the microstructural and textural evolution during deformation and these results are correlated with the observed work hardening behavior and strain rate sensitivities were calculated.

  10. Analytical Modeling of the High Strain Rate Deformation of Polymer Matrix Composites

    Science.gov (United States)

    Goldberg, Robert K.; Roberts, Gary D.; Gilat, Amos

    2003-01-01

    The results presented here are part of an ongoing research program to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. State variable constitutive equations originally developed for metals have been modified in order to model the nonlinear, strain rate dependent deformation of polymeric matrix materials. To account for the effects of hydrostatic stresses, which are significant in polymers, the classical 5 plasticity theory definitions of effective stress and effective plastic strain are modified by applying variations of the Drucker-Prager yield criterion. To verify the revised formulation, the shear and tensile deformation of a representative toughened epoxy is analyzed across a wide range of strain rates (from quasi-static to high strain rates) and the results are compared to experimentally obtained values. For the analyzed polymers, both the tensile and shear stress-strain curves computed using the analytical model correlate well with values obtained through experimental tests. The polymer constitutive equations are implemented within a strength of materials based micromechanics method to predict the nonlinear, strain rate dependent deformation of polymer matrix composites. In the micromechanics, the unit cell is divided up into a number of independently analyzed slices, and laminate theory is then applied to obtain the effective deformation of the unit cell. The composite mechanics are verified by analyzing the deformation of a representative polymer matrix composite (composed using the representative polymer analyzed for the correlation of the polymer constitutive equations) for several fiber orientation angles across a variety of strain rates. The computed values compare favorably to experimentally obtained results.

  11. Effect of Strain Rate on Microscopic Deformation Behavior of High-density Polyethylene under Uniaxial Stretching

    Directory of Open Access Journals (Sweden)

    Kida Takumitsu

    2017-01-01

    Full Text Available The microscopic deformation behaviors such as the load sharing and the molecular orientation of high-density polyethylene under uniaxial stretching at various strain rates were investigated by using in-situ Raman spectroscopy. The chains within crystalline phase began to orient toward the stretching direction beyond the yielding region and the orientation behavior was not affected by the strain rate. While the stretching stress along the crystalline chains was also not affected by the strain rate, the peak shifts of the Raman bands at 1130, 1418, 1440 and 1460 cm-1, which are sensitive to the interchain interactions obviously, depended on the strain rate; the higher strain rates lead to the stronger stretching stress or negative pressure on the crystalline and amorphous chains. These effects of the strain rate on the microscopic deformation was associated with the cavitation and the void formation leading to the release of the internal pressure.

  12. Some contributions to the high strain rate deformation of solids and the thermally activated deformation of wood

    International Nuclear Information System (INIS)

    Ferguson, W George

    2009-01-01

    The behaviour of metals as a function of rate of loading, strain rate, and temperature is discussed in terms of previous work by the author. Strain rates range from 10 -3 s -1 , obtained in a standard tensile testing machine, to 10 2 s -1 obtained in a hydraulic piston driven machine and up to 10 4 s -1 , very high strain rates with a Kolsky split Hopkinson bar using shear type loading. At rates less 10 3 s -1 the strength is a function of strain rate and temperature, is thermally activated and governed by the stress-assisted thermal activation of dislocations across short-range barriers in the crystal. At very high strain rates however the behaviour is controlled by interaction of dislocations with either phonons or electrons, giving a strength proportional to strain rate. The compressive strength of small clear samples of wood, Pinus radiata and Kahikatea, determined over the strain rate range 10 -3 s -1 to 10 3 s -1 as a function of strain rate, temperature and moisture content shows the behaviour to again be thermally activated with the strength a function of stain rate, temperature and moisture content. A rate theory of deformation is developed where the yield behaviour of wood is assumed to result from the stress-assisted thermally activated motion of elementary fibrils over short-range barriers. The moisture is assumed to affect the bond energy between elementary fibrils and the barrier energy is taken to be a linear decreasing function of increasing moisture content and the moisture to act like a plasticiser in separating the elementary fibrils. The theory more than adequately explains the observed behaviour.

  13. High-rate deformation and fracture of steel 09G2S

    Science.gov (United States)

    Balandin, Vl. Vas.; Balandin, Vl. Vl.; Bragov, A. M.; Igumnov, L. A.; Konstantinov, A. Yu.; Lomunov, A. K.

    2014-11-01

    The results of experimental and theoretical studies of steel 09G2S deformation and fracture laws in a wide range of strain rates and temperature variations are given. The dynamic deformation curves and the ultimate characteristics of plasticity in high-rate strain were determined by the Kolsky method in compression, extension, and shear tests. The elastoplastic properties and spall strength were studied by using the gaseous gun of calibre 57 mm and the interferometer VISAR according to the plane-wave experiment technique. The data obtained by the Kolsky method were used to determine the parameters of the Johnson-Cook model which, in the framework of the theory of flow, describes how the yield surface radius depends on the strain, strain rate, and temperature.

  14. Integrated experimental and computational studies of deformation of single crystal copper at high strain rates

    Science.gov (United States)

    Rawat, S.; Chandra, S.; Chavan, V. M.; Sharma, S.; Warrier, M.; Chaturvedi, S.; Patel, R. J.

    2014-12-01

    Quasi-static (0.0033 s-1) and dynamic (103 s-1) compression experiments were performed on single crystal copper along ⟨100⟩ and ⟨110⟩ directions and best-fit parameters for the Johnson-Cook (JC) material model, which is an important input to hydrodynamic simulations for shock induced fracture, have been obtained. The deformation of single crystal copper along the ⟨110⟩ direction showed high yield strength, more strain hardening, and less strain rate sensitivity as compared to the ⟨100⟩ direction. Although the JC model at the macro-scale is easy to apply and describes a general response of material deformation, it lacks physical mechanisms that describe the influence of texture and initial orientation on the material response. Hence, a crystal plasticity model based on the theory of thermally activated motion of dislocations was used at the meso-scale, in which the evolution equations permit one to study and quantify the influence of initial orientation on the material response. Hardening parameters of the crystal plasticity model show less strain rate sensitivity along the ⟨110⟩ orientation as compared to the ⟨100⟩ orientation, as also shown by the JC model. Since the deformation process is inherently multiscale in nature, the shape changes observed in the experiments due to loading along ⟨100⟩ and ⟨110⟩ directions are also validated by molecular dynamics simulations at the nano-scale.

  15. Dislocation-drag contribution to high-rate plastic deformation in shock-loaded tantalum

    International Nuclear Information System (INIS)

    Tonks, D.L.; Hixson, R.S.; Johnson, J.N.; Gray, G.T. III

    1994-01-01

    Time-resolved plastic waves in plate-impact experiments give information on the relationship between applied shear stress and plastic strain rate at low plastic strain. This information is essentially different from that obtained at intermediate strain rates using Hopkins on bar techniques, because in the former case the material deformation state is driven briefly into the regime dominated by dislocation drag rather than thermal activation. Two VISAR records of the particle velocity at the tantalum/sapphire (window) interface are obtained for symmetric impact producing peak in situ longitudinal stresses of approximately 75 kbar and 111 kbar. The risetimes of the plastic waves are about 100 ns and 60 ns, respectively, with peak strain rates of about 2x10 5 /s and 1x10 6 /s, respectively, as determined by weak-shock analysis [Wallace, Phys. Rev. B 22, 1487 (1980), and Tonks, Los Alamos DataShoP Report LA-12068-MS (1991)]. These data show a much stronger dependence of plastic strain rate on applied shear stress than previously predicted by linear viscous drag models in combination with thermal activation through a large Peierls barrier. The data also show complex evolution of the mobile dislocation density during early stages of high-rate plastic flow. This measurement and analysis aid significantly in establishing the fundamental picture of dynamic deformation of BCC metals and the evolution of the internal material state at early times following shock compression. copyright 1994 American Institute of Physics

  16. A model of high-rate indentation of a cylindrical striking pin into a deformable body

    Science.gov (United States)

    Zalazinskaya, E. A.; Zalazinsky, A. G.

    2017-12-01

    Mathematical modeling of an impact and high-rate indentation to a significant depth of a flat-faced hard cylindrical striking pin into a massive deformable target body is carried out. With the application of the kinematic extreme theorem of the plasticity theory and the kinetic energy variation theorem, the phase trajectories of the striking pin are calculated, the initial velocity of the striking pin in the body, the limit values of the inlet duct length, and the depth of striking pin penetration into the target are determined.

  17. Noise Characteristics of High-Rate Multi-GNSS for Subdaily Crustal Deformation Monitoring

    Science.gov (United States)

    Geng, Jianghui; Pan, Yuanxin; Li, Xiaotao; Guo, Jiang; Liu, Jingnan; Chen, Xianchun; Zhang, Yong

    2018-02-01

    High-rate GPS (Global Positioning System) has the potential to record crustal motions on a wide subdaily timescale from seconds to hours but usually fails to capture subtle deformations which are often overwhelmed by the centimeter noise of epoch-wise GPS displacements. We hence investigated high-rate multi-GNSS (Global Navigation Satellite System) by processing 1 Hz GPS/GLONASS/BeiDou data at 15 static stations over 24 days and also those from the 8 August 2017 Jiuzhaigou Mw 6.5 earthquake. In contrast to high-rate GPS, its further integration with GLONASS/BeiDou reduces near uniformly the power spectral densities (PSDs) of 1 Hz displacement noise by 4-6 dB over the periods from a few seconds to half of a day, and orbital repeat time (ORT) filtering on all GNSS further again leads to a 2 more decibel decline of the PSDs over the periods of a few tens of seconds to minutes. BeiDou ORT filtering, however, takes effect mainly on the periods of over 2,000 s due to the high altitudes of Inclined Geosynchronous Satellite Orbiters/Geosynchronous Earth Orbiters. Multi-GNSS integration is on average as effective as GPS ORT filtering in reducing PSDs for the periods of a few tens of seconds to minutes while desirably can further decrease the PSDs on almost all other periods by 3-4 dB thanks to the enhanced satellite geometry. We conclude that the introduction of more GNSS into high-rate solutions and its augmentation by ORT filtering benefit the discrimination of slight deformations over a broad subdaily frequency band.

  18. Three-dimensional modeling for deformation of austenitic NiTi shape memory alloys under high strain rate

    Science.gov (United States)

    Yu, Hao; Young, Marcus L.

    2018-01-01

    A three-dimensional model for phase transformation of shape memory alloys (SMAs) during high strain rate deformation is developed and is then calibrated based on experimental results from an austenitic NiTi SMA. Stress, strain, and martensitic volume fraction distribution during high strain rate deformation are simulated using finite element analysis software ABAQUS/standard. For the first time, this paper presents a theoretical study of the microscopic band structure during high strain rate compressive deformation. The microscopic transformation band is generated by the phase front and leads to minor fluctuations in sample deformation. The strain rate effect on phase transformation is studied using the model. Both the starting stress for transformation and the slope of the stress-strain curve during phase transformation increase with increasing strain rate.

  19. TRP 9904 - Constitutive Behavior of High Strength Multiphase Sheel Steel Under High Strain Rate Deformation

    Energy Technology Data Exchange (ETDEWEB)

    David Matlock; John Speer

    2005-03-31

    The focus of the research project was to systematically assess the strain rate dependence of strengthening mechanisms in new advanced high strength sheet steels. Data were obtained on specially designed and produced Duel Phase and TRIP steels and compared to the properties of automotive steels currently in use.

  20. Evaluation of Dynamic Deformation Behaviors in Metallic Materials under High Strain-Rates Using Taylor Bar Impact Test

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Kyung Oh; Shin, Hyung Seop [Andong National Univ., Andong (Korea, Republic of)

    2016-09-15

    To ensure the reliability and safety of various mechanical systems in accordance with their high-speed usage, it is necessary to evaluate the dynamic deformation behavior of structural materials under impact load. However, it is not easy to understand the dynamic deformation behavior of the structural materials using experimental methods in the high strain-rate range exceeding 10{sup 4} s{sup -1}. In this study, the Taylor bar impact test was conducted to investigate the dynamic deformation behavior of metallic materials in the high strain-rate region, using a high-speed photography system. Numerical analysis of the Taylor bar impact test was performed using AUTODYN S/W. The results of the analysis were compared with the experimental results, and the material behavior in the high strain-rate region was discussed.

  1. High Strain Rate Deformation Mechanisms of Body Centered Cubic Material Subjected to Impact Loading

    Science.gov (United States)

    Visser, William

    Low carbon steel is the most common grade of structural steel used; it has carbon content of 0.05% to 0.25% and very low content of alloying elements. It is produced in great quantities and provides material properties that are acceptable for many engineering applications, particularly in the construction industry in which low carbon steel is widely used as the strengthening phase in civil structures. The overall goal of this dissertation was to investigate the deformation response of A572 grade 50 steel when subjected to impact loading. This steel has a 0.23% by weight carbon content and has less than 2% additional alloying elements. The deformation mechanisms of this steel under shock loading conditions include both dislocation motion and twin formation. The goal of this work was achieved by performing experimental, analytical and numerical research in three integrated tasks. The first is to determine the relationship between the evolution of deformation twins and the impact pressure. Secondly, a stress criterion for twin nucleation during high strain rate loading was developed which can account for the strain history or initial dislocation density. Lastly, a method was applied for separating the effects of dislocations and twins generated by shock loading in order to determine their role in controlling the flow stress of the material. In this regard, the contents of this work have been categorically organized. First, the active mechanisms in body centered cubic (BCC) low carbon steel during shock loading have been determined as being a composed of the competing mechanisms of dislocations and deformation twins. This has been determined through a series of shock loading tests of the as-received steel. The shock loading tests were done by plate impact experiments at several impact pressures ranging from 2GPa up to 13GPa using a single stage light gas gun. A relationship between twin volume fraction and impact pressure was determined and an analytical model was

  2. Deformation twinning: Influence of strain rate

    Energy Technology Data Exchange (ETDEWEB)

    Gray, G.T. III

    1993-11-01

    Twins in most crystal structures, including advanced materials such as intermetallics, form more readily as the temperature of deformation is decreased or the rate of deformation is increased. Both parameters lead to the suppression of thermally-activated dislocation processes which can result in stresses high enough to nucleate and grow deformation twins. Under high-strain rate or shock-loading/impact conditions deformation twinning is observed to be promoted even in high stacking fault energy FCC metals and alloys, composites, and ordered intermetallics which normally do not readily deform via twinning. Under such conditions and in particular under the extreme loading rates typical of shock wave deformation the competition between slip and deformation twinning can be examined in detail. In this paper, examples of deformation twinning in the intermetallics TiAl, Ti-48Al-lV and Ni{sub 3}A as well in the cermet Al-B{sub 4}C as a function of strain rate will be presented. Discussion includes: (1) the microstructural and experimental variables influencing twin formation in these systems and twinning topics related to high-strain-rate loading, (2) the high velocity of twin formation, and (3) the influence of deformation twinning on the constitutive response of advanced materials.

  3. Microstructure and mechanical properties of precipitation hardened aluminum under high rate deformation

    International Nuclear Information System (INIS)

    Grady, D.E.; Asav, J.R.; Rohde, R.W.; Wise, J.L.

    1983-01-01

    This chapter attempts to correlate the shock compression and quasistatic deformation of 6061-T6 aluminium. Examines recovered specimens which have been shock loaded, and compares results with both static and dynamic mechanical property measurements. Discusses experimental procedures (reshock and unloading experiments, shock recovery techniques, metallographic techniques and coldwork experiments); dynamic strength and wave-profile properties (strength and shear-stress states on the Hugoniot, steady-wave risetime and viscosity); quasistatic and shock metallography studies (metallography of quasistatically deformed material; metallography of shock deformed specimens; comparison of static and shock deformation; correlation of hardness and dynamic strength measurements); and thermal trapping calculations in shocked aluminium (heterogeneous deformation and adiabatic heating in shock-wave loading; energy and risetime relations under steadywave shock compression; heterogeneous temperature calculations in aluminium). Concludes that heterogeneous shear deformation appears to play a role in the dynamic deformation process

  4. Hydrostatic Stress Effects Incorporated Into the Analysis of the High-Strain-Rate Deformation of Polymer Matrix Composites

    Science.gov (United States)

    Goldberg, Robert K.; Roberts, Gary D.

    2003-01-01

    Procedures for modeling the effect of high strain rate on composite materials are needed for designing reliable composite engine cases that are lighter than the metal cases in current use. The types of polymer matrix composites that are likely to be used in such an application have a deformation response that is nonlinear and that varies with strain rate. The nonlinearity and strain rate dependence of the composite response is primarily due to the matrix constituent. Therefore, in developing material models to be used in the design of impact-resistant composite engine cases, the deformation of the polymer matrix must be correctly analyzed. However, unlike in metals, the nonlinear response of polymers depends on the hydrostatic stresses, which must be accounted for within an analytical model. An experimental program has been carried out through a university grant with the Ohio State University to obtain tensile and shear deformation data for a representative polymer for strain rates ranging from quasi-static to high rates of several hundred per second. This information has been used at the NASA Glenn Research Center to develop, characterize, and correlate a material model in which the strain rate dependence and nonlinearity (including hydrostatic stress effects) of the polymer are correctly analyzed. To obtain the material data, Glenn s researchers designed and fabricated test specimens of a representative toughened epoxy resin. Quasi-static tests at low strain rates and split Hopkinson bar tests at high strain rates were then conducted at the Ohio State University. The experimental data confirmed the strong effects of strain rate on both the tensile and shear deformation of the polymer. For the analytical model, Glenn researchers modified state variable constitutive equations previously used for the viscoplastic analysis of metals to allow for the analysis of the nonlinear, strain-rate-dependent polymer deformation. Specifically, we accounted for the effects of

  5. A Model for High-Strain-Rate Deformation of Uranium-Niobium Alloys

    Energy Technology Data Exchange (ETDEWEB)

    F.L.Addessio; Q.H.Zuo; T.A.Mason; L.C.Brinson

    2003-05-01

    A thermodynamic approach is used to develop a framework for modeling uranium-niobium alloys under the conditions of high strain rate. Using this framework, a three-dimensional phenomenological model, which includes nonlinear elasticity (equation of state), phase transformation, crystal reorientation, rate-dependent plasticity, and porosity growth is presented. An implicit numerical technique is used to solve the evolution equations for the material state. Comparisons are made between the model and data for low-strain-rate loading and unloading as well as for heating and cooling experiments. Comparisons of the model and data also are made for low- and high-strain-rate uniaxial stress and uniaxial strain experiments. A uranium-6 weight percent niobium alloy is used in the comparisons of model and experiment.

  6. Effects of cooling rate, austenitizing temperature and austenite deformation on the transformation behavior of high-strength boron steel

    International Nuclear Information System (INIS)

    Mun, Dong Jun; Shin, Eun Joo; Choi, Young Won; Lee, Jae Sang; Koo, Yang Mo

    2012-01-01

    Highlights: ► Non-equilibrium segregation of B in steel depends strongly on the cooling rate. ► A higher austenitization temperature reduced the B hardenability effect. ► An increase in B concentration at γ grain boundaries accelerates the B precipitation. ► The loss of B hardenability effect is due to intragranular borocarbide precipitation. ► The controlled cooling after hot deformation increased the B hardenability effect. - Abstract: The phase transformation behavior of high-strength boron steel was studied considering the segregation and precipitation behavior of boron (B). The effects of cooling rate, austenitizing temperature and austenite deformation on the transformation behavior of B-bearing steel as compared with B-free steel were investigated by using dilatometry, microstructural observations and analysis of B distribution. The effects of these variables on hardenability were discussed in terms of non-equilibrium segregation mechanism and precipitation behavior of B. The retardation of austenite-to-ferrite transformation by B addition depends strongly on cooling rate (CR); this is mainly due to the phenomenon of non-equilibrium grain boundary segregation of B. The hardenability effect of B-bearing steel decreased at higher austenitizing temperature due to the precipitation of borocarbide along austenite grain boundaries. Analysis of B distribution by second ion mass spectroscopy confirmed that the grain boundary segregation of B occurred at low austenitizing temperature of 900 °C, whereas B precipitates were observed along austenite grain boundaries at high austenitizing temperature of 1200 °C. The significant increase in B concentration at austenite grain boundaries due to grain coarsening and a non-equilibrium segregation mechanism may lead to the B precipitation. In contrast, solute B segregated to austenite grain boundaries during cooling after heavy deformation became more stable because the increase in boundary area by grain

  7. Deformation induced dynamic recrystallization and precipitation strengthening in an Mg−Zn−Mn alloy processed by high strain rate rolling

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jimiao; Song, Min [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Yan, Hongge [School of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Yang, Chao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Ni, Song, E-mail: song.ni@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

    2016-11-15

    The microstructure of a high strain-rate rolled Mg−Zn−Mn alloy was investigated by transmission electron microscopy to understand the relationship between the microstructure and mechanical properties. The results indicate that: (1) a bimodal microstructure consisting of the fine dynamic recrystallized grains and the largely deformed grains was formed; (2) a large number of dynamic precipitates including plate-like MgZn{sub 2} phase, spherical MgZn{sub 2} phase and spherical Mn particles distribute uniformly in the grains; (3) the major facets of many plate-like MgZn{sub 2} precipitates deviated several to tens of degrees (3°–30°) from the matrix basal plane. It has been shown that the high strength of the alloy is attributed to the formation of the bimodal microstructure, dynamic precipitation, and the interaction between the dislocations and the dynamic precipitates. - Highlights: •A bimodal microstructure was formed in a high strain-rate rolled Mg−Zn−Mn alloy. •Plate-like MgZn{sub 2}, spherical MgZn{sub 2} and spherical Mn phases were observed. •The major facet of the plate-like MgZn{sub 2} deviated from the matrix basal plane.

  8. Influence of deformation rate on plasticity of metals under pressure

    International Nuclear Information System (INIS)

    Churbaev, R.V.; Dobromyslov, A.V.; Kolmogorov, V.L.; Taluts, G.G.

    1990-01-01

    Change of polycrystalline molybdenum (BCC) and titanium (HCP) plasticity under pressure depeding on the deformation rate at the room temperature is studied. It is shown that the reduction of molybdenum and titanium deformation rate leads to a substantial growth of their plastic properties with the effect being increased with pressure growth. Production of several necks testifying to the transition to a superplastic state is observed at high pressures and low deformation rates. A functional dependence of plasticity change on the deformation rate under pressure is ascertained

  9. Microstructural characteristics of adiabatic shear localization in a metastable beta titanium alloy deformed at high strain rate and elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zhan, Hongyi, E-mail: h.zhan@uq.edu.au [Centre for Advanced Materials Processing and Manufacture, School of Mechanical and Mining Engineering, The University of Queensland, St Lucia, Queensland 4072 (Australia); Zeng, Weidong [State Key Laboratory of Solidification Processing, School of Materials, Northwestern Polytechnical University, Xi' an 710072 (China); Wang, Gui [Centre for Advanced Materials Processing and Manufacture, School of Mechanical and Mining Engineering, The University of Queensland, St Lucia, Queensland 4072 (Australia); Defence Material Technology Centre, Level 2, 24 Wakefield St, Hawthorn, VIC 3122 (Australia); Kent, Damon [School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland 4575 (Australia); Dargusch, Matthew [Centre for Advanced Materials Processing and Manufacture, School of Mechanical and Mining Engineering, The University of Queensland, St Lucia, Queensland 4072 (Australia); Defence Material Technology Centre, Level 2, 24 Wakefield St, Hawthorn, VIC 3122 (Australia)

    2015-04-15

    The microstructural evolution and grain refinement within adiabatic shear bands in the Ti6554 alloy deformed at high strain rates and elevated temperatures have been characterized using transmission electron microscopy. No stress drops were observed in the corresponding stress–strain curve, indicating that the initiation of adiabatic shear bands does not lead to the loss of load capacity for the Ti6554 alloy. The outer region of the shear bands mainly consists of cell structures bounded by dislocation clusters. Equiaxed subgrains in the core area of the shear band can be evolved from the subdivision of cell structures or reconstruction and transverse segmentation of dislocation clusters. It is proposed that dislocation activity dominates the grain refinement process. The rotational recrystallization mechanism may operate as the kinetic requirements for it are fulfilled. The coexistence of different substructures across the shear bands implies that the microstructural evolution inside the shear bands is not homogeneous and different grain refinement mechanisms may operate simultaneously to refine the structure. - Graphical abstract: Display Omitted - Highlights: • The microstructure within the adiabatic shear band was characterized by TEM. • No stress drops were observed in the corresponding stress–strain curve. • Dislocation activity dominated the grain refinement process. • The kinetic requirements for rotational recrystallization mechanism were fulfilled. • Different grain refinement mechanisms operated simultaneously to refine the structure.

  10. Localization in inelastic rate dependent shearing deformations

    KAUST Repository

    Katsaounis, Theodoros

    2016-09-18

    Metals deformed at high strain rates can exhibit failure through formation of shear bands, a phenomenon often attributed to Hadamard instability and localization of the strain into an emerging coherent structure. We verify formation of shear bands for a nonlinear model exhibiting strain softening and strain rate sensitivity. The effects of strain softening and strain rate sensitivity are first assessed by linearized analysis, indicating that the combined effect leads to Turing instability. For the nonlinear model a class of self-similar solutions is constructed, that depicts a coherent localizing structure and the formation of a shear band. This solution is associated to a heteroclinic orbit of a dynamical system. The orbit is constructed numerically and yields explicit shear localizing solutions. © 2016 Elsevier Ltd

  11. Localization in inelastic rate dependent shearing deformations

    KAUST Repository

    Katsaounis, Theodoros; Lee, Min-Gi; Tzavaras, Athanasios

    2016-01-01

    Metals deformed at high strain rates can exhibit failure through formation of shear bands, a phenomenon often attributed to Hadamard instability and localization of the strain into an emerging coherent structure. We verify formation of shear bands for a nonlinear model exhibiting strain softening and strain rate sensitivity. The effects of strain softening and strain rate sensitivity are first assessed by linearized analysis, indicating that the combined effect leads to Turing instability. For the nonlinear model a class of self-similar solutions is constructed, that depicts a coherent localizing structure and the formation of a shear band. This solution is associated to a heteroclinic orbit of a dynamical system. The orbit is constructed numerically and yields explicit shear localizing solutions. © 2016 Elsevier Ltd

  12. Dynamic behavior and microstructural evolution during moderate to high strain rate hot deformation of a Fe–Ni–Cr alloy (alloy 800H)

    International Nuclear Information System (INIS)

    Cao, Yu; Di, Hongshuang; Zhang, Jiecen; Yang, Yaohua

    2015-01-01

    The objective of the study is to fundamentally understand the dynamic behavior of alloy 800H at moderate to high strain rate using hot compression tests and propose nucleation mechanism associated with dynamic crystallization (DRX). We firstly investigated the dynamic behavior of alloy 800H with industrial scale strain rates using hot compression tests and adiabatic correction was performed to correct as-measured flow curves. Secondly, a Johnson–Cook model was established by using the corrected data and could give a precise prediction of elevated temperature flow stress for the studied alloy. Finally, the nucleation mechanism of DRX grains at high strain rates was studied. The results showed that the predominant nucleation mechanism for DRX is the formation of “bulge” at parent grain boundary. Additionally, the fragmentation of original grain at low deformation temperatures and the twinning near the bulged regions at high deformation temperatures also accelerate the DRX process

  13. Dynamic behavior and microstructural evolution during moderate to high strain rate hot deformation of a Fe-Ni-Cr alloy (alloy 800H)

    Science.gov (United States)

    Cao, Yu; Di, Hongshuang; Zhang, Jiecen; Yang, Yaohua

    2015-01-01

    The objective of the study is to fundamentally understand the dynamic behavior of alloy 800H at moderate to high strain rate using hot compression tests and propose nucleation mechanism associated with dynamic crystallization (DRX). We firstly investigated the dynamic behavior of alloy 800H with industrial scale strain rates using hot compression tests and adiabatic correction was performed to correct as-measured flow curves. Secondly, a Johnson-Cook model was established by using the corrected data and could give a precise prediction of elevated temperature flow stress for the studied alloy. Finally, the nucleation mechanism of DRX grains at high strain rates was studied. The results showed that the predominant nucleation mechanism for DRX is the formation of "bulge" at parent grain boundary. Additionally, the fragmentation of original grain at low deformation temperatures and the twinning near the bulged regions at high deformation temperatures also accelerate the DRX process.

  14. High strain rate deformation and fracture of the magnesium alloy Ma2-1 under shock wave loading

    Science.gov (United States)

    Garkushin, G. V.; Kanel', G. I.; Razorenov, S. V.

    2012-05-01

    This paper presents the results of measurements of the dynamic elastic limit and spall strength under shock wave loading of specimens of the magnesium alloy Ma2-1 with a thickness ranging from 0.25 to 10 mm at normal and elevated (to 550°C) temperatures. From the results of measurements of the decay of the elastic precursor of a shock compression wave, it has been found that the plastic strain rate behind the front of the elastic precursor decreases from 2 × 105 s-1 at a distance of 0.25 mm to 103 s-1 at a distance of 10 mm. The plastic strain rate in a shock wave is one order of magnitude higher than that in the elastic precursor at the same value of the shear stress. The spall strength of the alloy decreases as the solidus temperature is approached.

  15. Final Report: Multi-Scale Analysis of Deformation and Failure in Polycrystalline Titanium Alloys Under High Strain-Rates

    Science.gov (United States)

    2015-12-28

    element simulations of polycrystalline Tita - nium alloys. Jour. Mech. Phys. Solids, 59(10):2157–2176, 2011. 5. S. Ghosh and M. Anahid. Homogenized...2013) 111 – 124. [72] P. Shade, Private communication. [73] H. Ogi, S. Kai, H. Ledbetter, R. Tarumi, M. Hirao, K. Takashima, Tita - niums high-temperature

  16. Deformation of high-temperature superconductors

    International Nuclear Information System (INIS)

    Goretta, K.C.; Routbort, J.L.; Miller, D.J.; Chen, N.; Dominguez-Rodriguez, A.; Jimenez-Melendo, M.; De Arellano-Lopez, A.R.

    1994-08-01

    Of the many families of high-temperature superconductors, only the properties of those discovered prior to 1989 - Y-Ba-Cu-O, Tl-Ba(Sr)-Ca-Cu-O, and Bi(Pb)-Sr-Ca-Cu-O - have been studied extensively. Deformation tests have been performed on YBa 2 Cu 3 O x (Y-123), YBa 2 Cu 4 O x (Y-124), TlBa 2 Ca 2 Cu 3 O x (Bi-2223). The tests have revealed that plasticity is generally limited in these compounds and that the rate-controlling diffusional kinetics for creep are very slow. Nevertheless, hot forming has proved to be quite successful for fabrication of bulk high-temperature superconductors, so long as deformation rates are low or large hydrostatic stresses are applied. Steady-state creep data have proved to be useful in designing optimal heat treatments for superconductors and in support of more-fundamental diffusion experiments. The high-temperature superconductors are highly complex oxides, and it is a challenge to understand their deformation responses. In this paper, results of interest and operant creep mechanisms will be reviewed

  17. The role of strain rate during deposition of CAP on Ti6Al4V by superplastic deformation-like method using high-temperature compression test machine

    International Nuclear Information System (INIS)

    Ramdan, R.D.; Jauhari, I.; Hasan, R.; Masdek, N.R. Nik

    2008-01-01

    This paper describes an implementation of superplastic deformation method for the deposition of carbonated-apatite (CAP) on the well-know titanium alloy, Ti6Al4V. This deposition process was carried out using high-temperature compression test machine, at temperature of 775 deg. C, different strain rates, and conducted along the elastic region of the sample. Before the process, titanium substrate was cryogenically treated in order to approach superplastic characteristic during the process. After the process, thin film of CAP was created on the substrate with the thickness from 0.71 μm to 1.42 μm. The resulted film has a high density of CAP that covered completely the surface of the substrate. From the stress-strain relation chart, it can be observed that as the strain rate decreases, the area under stress-strain chart also decreases. This condition influences the density of CAP layer on the substrate that as this area decreases, the density of CAP layer also decreases as also confirmed by X-ray diffraction characterization. In addition, since the resulting layer of CAP is in the form of thin film, this layer did not alter the hardness of the substrate as measured by Vickers hardness test method. On the other hand, the resulting films also show a good bonding strength properties as the layer remain exist after friction test against polishing clothes for 1 h

  18. Effect of structural factors on mechanical properties of the magnesium alloy Ma2-1 under quasi-static and high strain rate deformation conditions

    Science.gov (United States)

    Garkushin, G. V.; Razorenov, S. V.; Krasnoveikin, V. A.; Kozulin, A. A.; Skripnyak, V. A.

    2015-02-01

    The elastic limit and tensile strength of deformed magnesium alloys Ma2-1 with different structures and textures were measured with the aim of finding a correlation between the spectrum of defects in the material and the resistance to deformation and fracture under quasi-static and dynamic loading conditions. The studies were performed using specimens in the as-received state after high-temperature annealing and specimens subjected to equal-channel angular pressing at a temperature of 250°C. The anisotropy of strength characteristics of the material after shock compression with respect to the direction of rolling of the original alloy was investigated. It was shown that, in contrast to the quasi-static loading conditions, under the shock wave loading conditions, the elastic limit and tensile strength of the magnesium alloy Ma2-1 after equal-channel angular pressing decrease as compared to the specimens in the as-received state.

  19. Brittleness and elastic limit of iron-aluminium 40 at high strain rates; Fragilite et limite elastique du fer-aluminium 40 aux grandes vitesses de deformation

    Energy Technology Data Exchange (ETDEWEB)

    Cottu, J P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-07-01

    Iron-aluminium 40 - a B2 ordered solid solution - was tensile tested to provide information on the brittleness of this alloy and its dependence on strain rate and temperature. For slow strain rates (0.34 per cent s{sup -1}) cleaved fracture prevails when temperature is kept below 400 deg. C, while a ductile rupture is observed, with an almost 100 per cent necking at higher temperatures. In this case, recrystallization occurs during the deformation. For higher strain rates - 335 per cent s{sup -1}), a ductility reduction - owed to intergranular fracture - precedes the brittle-ductile transition. This property may be bound to the peak on the yield stress temperature curve, which is itself connected to the ordered structure of this alloy. (author) [French] Les essais de traction que nous avons effectues sur le fer-aluminium 40, solution solide ordonnee de type B2, ont pour but de preciser l'influence de la vitesse de deformation et de la temperature sur la fragilite de l'alliage. Pour les faibles vitesses (0,34 pour cent s{sup -1}), la rupture est surtout clivee si la temperature est inferieure a 400 deg. C, puis ductile avec une striction voisine de 100 pour cent aux temperatures superieures; la recristallisation intervient alors ou cours meme de la deformation. Aux vitesses elevees (335 pour cent s{sup -1}) la transition fragile-ductile est precedee d'une chute de ductilite liee a une decohesion intergranulaire. Nous avons associe cette derniere propriete a la presence d'un pic de limite elastique apparaissant a chaud, a vitesse elevee et pouvant etre relie au caractere ordonne de l'alliage. (auteur)

  20. Highly deformable bones: unusual deformation mechanisms of seahorse armor.

    Science.gov (United States)

    Porter, Michael M; Novitskaya, Ekaterina; Castro-Ceseña, Ana Bertha; Meyers, Marc A; McKittrick, Joanna

    2013-06-01

    Multifunctional materials and devices found in nature serve as inspiration for advanced synthetic materials, structures and robotics. Here, we elucidate the architecture and unusual deformation mechanisms of seahorse tails that provide prehension as well as protection against predators. The seahorse tail is composed of subdermal bony plates arranged in articulating ring-like segments that overlap for controlled ventral bending and twisting. The bony plates are highly deformable materials designed to slide past one another and buckle when compressed. This complex plate and segment motion, along with the unique hardness distribution and structural hierarchy of each plate, provide seahorses with joint flexibility while shielding them against impact and crushing. Mimicking seahorse armor may lead to novel bio-inspired technologies, such as flexible armor, fracture-resistant structures or prehensile robotics. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. High temperature deformation of silicon steel

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Calvillo, Pablo, E-mail: pablo.rodriguez@ctm.com.es [CTM - Technologic Centre, Materials Technology Area, Manresa, Cataluna (Spain); Department of Materials Science and Metallurgical Engineering, Universidad Politecnica de Cataluna, Barcelona (Spain); Houbaert, Yvan, E-mail: Yvan.Houbaert@UGent.be [Department of Materials Science and Engineering, University of Ghent (Belgium); Petrov, Roumen, E-mail: Roumen.Petrov@ugent.be [Department of Materials Science and Engineering, University of Ghent (Belgium); Kestens, Leo, E-mail: Leo.kestens@ugent.be [Department of Materials Science and Engineering, University of Ghent (Belgium); Colas, Rafael, E-mail: rafael.colas@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico)

    2012-10-15

    The microstructure and texture development during high temperature plane strain compression of 2% in weight silicon steel was studied. The tests were carried out at a constant strain rate of 5 s{sup -1} with reductions of 25, 35 and 75% at temperatures varying from 800 to 1100 Degree-Sign C. The changes in microstructure and texture were studied by means of scanning electron microscopy and electron backscattered diffraction. The microstructure close to the surface of the samples was equiaxed, which is attributed to the shear caused by friction, whereas that at the centre of the specimens was made of a mixture of elongated and fine equiaxed grains, the last ones attributed to the action of dynamic recovery followed by recrystallization. It was found that the volume fraction of these equiaxed grains augmented as reduction and temperature increased; a 0.7 volume fraction was accomplished with a 75% reduction at 1100 Degree-Sign C. The texture of the equiaxed and elongated grains was found to vary with the increase of deformation and temperature, as the {gamma}-fibre tends to disappear and the {alpha}-fibre to increase towards the higher temperature range. -- Highlights: Black-Right-Pointing-Pointer The plastic deformation of a silicon containing steel is studied by plane strain compression. Black-Right-Pointing-Pointer Equiaxed and elongated grains develop in different regions of the sample due to recrystallization. Black-Right-Pointing-Pointer Texture, by EBSD, is revealed to be similar in either type of grains.

  2. High temperature deformation of silicon steel

    International Nuclear Information System (INIS)

    Rodríguez-Calvillo, Pablo; Houbaert, Yvan; Petrov, Roumen; Kestens, Leo; Colás, Rafael

    2012-01-01

    The microstructure and texture development during high temperature plane strain compression of 2% in weight silicon steel was studied. The tests were carried out at a constant strain rate of 5 s −1 with reductions of 25, 35 and 75% at temperatures varying from 800 to 1100 °C. The changes in microstructure and texture were studied by means of scanning electron microscopy and electron backscattered diffraction. The microstructure close to the surface of the samples was equiaxed, which is attributed to the shear caused by friction, whereas that at the centre of the specimens was made of a mixture of elongated and fine equiaxed grains, the last ones attributed to the action of dynamic recovery followed by recrystallization. It was found that the volume fraction of these equiaxed grains augmented as reduction and temperature increased; a 0.7 volume fraction was accomplished with a 75% reduction at 1100 °C. The texture of the equiaxed and elongated grains was found to vary with the increase of deformation and temperature, as the γ-fibre tends to disappear and the α-fibre to increase towards the higher temperature range. -- Highlights: ► The plastic deformation of a silicon containing steel is studied by plane strain compression. ► Equiaxed and elongated grains develop in different regions of the sample due to recrystallization. ► Texture, by EBSD, is revealed to be similar in either type of grains.

  3. Grain boundary engineering of highly deformable ceramics

    International Nuclear Information System (INIS)

    Mecartney, M.L.

    2000-01-01

    Highly deformable ceramics can be created with the addition of intergranular silicate phases. These amorphous intergranular phases can assist in superplastic deformation by relieving stress concentrations and minimizing grain growth if the appropriate intergranular compositions are selected. Examples from 3Y-TZP and 8Y-CSZ ceramics are discussed. The grain boundary chemistry is analyzed by high resolution analytical TEM is found to have a strong influence on the cohesion of the grains both at high temperature and at room temperature. Intergranular phases with a high ionic character and containing large ions with a relatively weak bond strength appear to cause premature failure. In contrast, intergranular phases with a high degree of covalent character and similar or smaller ions than the ceramic and a high ionic bond strength are the best for grain boundary adhesion and prevention of both cavitation at high temperatures and intergranular fracture at room temperature

  4. Influence of temperature and rate of deformation on mechanical properties of a low alloyed niobium alloy

    International Nuclear Information System (INIS)

    Borisenko, V.A.; Krashchenko, V.P.; Statsenko, V.E.; Kharchenko, V.K.

    1979-01-01

    The technique for indirect temperature measurements of wire samples is suggested and justified. Temperature dependences are investigated of strength and plasticity characteristics of niobium alloy alloyed with zirconium in the range of 20-1100 deg C at two deformation rates: 1.1x10 -3 and 5.3x10 -3 sec -1 . Deformation aging at both deformation rates in the temperature range of 0.25-0.42 Tsub(m) takes place in the form of the increase of σsub(B) and σsub(0.2) strength characteristics and discontinuous yield. The σsub(B) and σsub(0.2) level in this interval is higher for a lesser deformation rate, than for a higher one. Maxima on temperature strength dependence curves move to the side of high temperatures. In the 20-900 deg C temperature range rate alterations slightly affect plasticity characteristics

  5. Microstructural Analysis of Orientation-Dependent Recovery and Recrystallization in a Modified 9Cr-1Mo Steel Deformed by Compression at a High Strain Rate

    DEFF Research Database (Denmark)

    Zhang, Zhenbo; Zhang, Yubin; Mishin, Oleg

    2016-01-01

    energies in 〈111〉- and 〈100〉-oriented regions in deformed and annealed samples, as well as investigations of the growth of recrystallizing grains, are used to analyze the annealing behavior. It is concluded that recrystallization in the given material occurs by a combination of oriented nucleation...

  6. Transformation of deformation martensite into austenite in stainless steels at various heating rates

    International Nuclear Information System (INIS)

    Gojkhenberg, Yu.N.; Shtejnberg, M.M.

    1978-01-01

    Under isothermal conditions and with continuous preheating at defferent rates, the inverse transformation of deformation martensite that is obtained through reductions to small, medium and great degrees, has been studied. It has been established that depending on the preheat rate, the temperature of the end α → ν of rebuilding varies according to a curve having a maximum. The ascending branch of that curve is connected with the diffusion-controlled shear transformation, whereas the descending branch with the transition to the martensite reaction of austenite formation. As the deformation degree increases, the temperature of the end of the inverse transformation decreases. As a result, recrystallization of austenite proceeds only after completing α → ν transition, when heating the steels deformed to the medium degree at rates of at least 25 deg/sec and after high reductions at rates of at least 0.8 deg/sec

  7. Modeling of dislocation generation and interaction during high-speed deformation of metals

    DEFF Research Database (Denmark)

    Schiøtz, J.; Leffers, T.; Singh, B.N.

    2002-01-01

    Recent experiments by Kiritani et al. [1] have revealed a surprisingly high rate of vacancy production during highspeed deformation of thin foils of fcc metals. Virtually no dislocations are seen after the deformation. This is interpreted as evidence for a dislocation-free deformation mechanism...... at very high strain rates. We have used molecular-dynamics simulations to investigate high-speed deformation of copper crystals. Even though no pre-existing dislocation sources are present in the initial system, dislocations are quickly nucleated and a very high dislocation density is reached during...... the deformation. Due to the high density of dislocations, many inelastic interactions occur between dislocations, resulting in the generation of vacancies. After the deformation, a very high density of vacancies is observed, in agreement with the experimental observations. The processes responsible...

  8. Effects of strain rate and confining pressure on the deformation and failure of shale

    Energy Technology Data Exchange (ETDEWEB)

    Cook, J.M. (Schlumberger Cambridge Research (GB)); Sheppard, M.C. (Anadrill/Schlumberger (US)); Houwen, O.H. (Sedco Forex (FR))

    1991-06-01

    Previous work on shale mechanical properties has focused on the slow deformation rates appropriate to wellbore deformation. Deformation of shale under a drill bit occurs at a very high rate, and the failure properties of the rock under these conditions are crucial in determining bit performance and in extracting lithology and pore-pressure information from drilling parameters. Triaxial tests were performed on two nonswelling shales under a wide range of strain rates and confining and pore pressures. At low strain rates, when fluid is relatively free to move within the shale, shale deformation and failure are governed by effective stress or pressure (i.e., total confining pressure minus pore pressure), as is the case for ordinary rock. If the pore pressure in the shale is high, increasing the strain rate beyond about 0.1%/sec causes large increases in the strength and ductility of the shale. Total pressure begins to influence the strength. At high stain rates, the influence of effective pressure decreases, except when it is very low (i.e., when pore pressure is very high); ductility then rises rapidly. This behavior is opposite that expected in ordinary rocks. This paper briefly discusses the reasons for these phenomena and their impact on wellbore and drilling problems.

  9. First indications of high slip rates on active reverse faults NW of Damascus, Syria, from observations of deformed Quaternary sediments: Implications for the partitioning of crustal deformation in the Middle Eastern region

    Science.gov (United States)

    Abou Romieh, Mohammad; Westaway, Rob; Daoud, Mohamad; Bridgland, David R.

    2012-05-01

    Recent research on rates of crustal shortening within the Palmyra Fold Belt (PFB) in Syria has drawn attention to the possibility that reverse faults near the city of Damascus, which adjoins the SW PFB, have significant slip rates. We infer that the Damascus Fault, directly adjacent to the city, has developed a throw of ~ 2500 m and report the discovery of the en echelon Bassimeh Fault, with a throw of ~ 1000 m, this fault being revealed by warping of the local bedrock and of a terrace, of inferred Late Pleistocene age, of the River Barada. We estimate that this set of faults became active circa 0.9 Ma, synchronous with changes to the pattern of faulting previously reported farther southwest in the northern Jordan Valley. Vertical slip rates on the Bassimeh and Damascus faults of ~ 1.1 and ~ 2.8 mm a- 1, respectively, are thus estimated. We also infer that large historical earthquakes, previously attributed to left-lateral faulting farther west on the Dead Sea Fault Zone (DSFZ), probably occurred on this set of reverse faults; these faults thus represent a significant hazard to the city of Damascus. Our observations indicate that as much as half of the northward motion of the Arabian plate, relative to the African plate, may be 'absorbed' by crustal shortening within the PFB, potentially explaining the low slip rate recently measured geodetically on the northern DSFZ in western Syria.

  10. Theoretical and experimental study of high strain, high strain rate materials viscoplastic behaviour. Application to Mars 190 steel and tantalum; Etude theorique et experimentale du comportement viscoplastique des materiaux aux grandes deformations et grandes vitesses de deformations. Application a l'acier mars 190 et au tantale

    Energy Technology Data Exchange (ETDEWEB)

    Juanicotena, A

    1998-07-01

    This work enters in the general framework of the study and modelling of metallic materials viscoplastic behaviour in the area of high strain and high strain rate, from 10{sup 4} to 10{sup 5} s{sup -1}. We define a methodology allowing to describe the behaviour of armor steel Mars 190 and tantalum in the initial area. In a first time, the study of visco-plasticity physical mechanisms shows the necessity to take into account some fundamental processes of the plastic deformation. Then, the examination of various constitutive relations allows to select the Preston-Tonks-Wallace model, that notably reproduce the physical phenomenon of the flow stress saturation. In a second part, a mechanical characterization integrating loading direction, strain rate and temperature effects is conducted on the two materials. Moreover, these experimental results allow to calculate associated constants to Preston-Tonks-Wallace, Zerilli-Armstrong and Johnson-Cook models for each material. In a third time, in order to evaluate and to validate these constitutive laws, we conceive and develop an experimental device open to reach the area of study: the expanding spherical shell test. It concerns to impose a free radial expanding to a thin spherical shell by means a shock wave generated by an explosive. By the radial expanding velocity measure, we can determine stress, strain rate and strain applied on the spherical shell at each time. In a four and last part, we evaluate constitutive models out of their optimization area's. This validation is undertaken by comparisons 'experimental results/calculations' with the help of global experiences like expanding spherical shell test and Taylor test. (author)

  11. The Microstructure Evolution of Dual-Phase Pipeline Steel with Plastic Deformation at Different Strain Rates

    Science.gov (United States)

    Ji, L. K.; Xu, T.; Zhang, J. M.; Wang, H. T.; Tong, M. X.; Zhu, R. H.; Zhou, G. S.

    2017-07-01

    Tensile properties of the high-deformability dual-phase ferrite-bainite X70 pipeline steel have been investigated at room temperature under the strain rates of 2.5 × 10-5, 1.25 × 10-4, 2.5 × 10-3, and 1.25 × 10-2 s-1. The microstructures at different amount of plastic deformation were examined by using scanning and transmission electron microscopy. Generally, the ductility of typical body-centered cubic steels is reduced when its stain rate increases. However, we observed a different ductility dependence on strain rates in the dual-phase X70 pipeline steel. The uniform elongation (UEL%) and elongation to fracture (EL%) at the strain rate of 2.5 × 10-3 s-1 increase about 54 and 74%, respectively, compared to those at 2.5 × 10-5 s-1. The UEL% and EL% reach to their maximum at the strain rate of 2.5 × 10-3 s-1. This phenomenon was explained by the observed grain structures and dislocation configurations. Whether or not the ductility can be enhanced with increasing strain rates depends on the competition between the homogenization of plastic deformation among the microconstituents (ultra-fine ferrite grains, relatively coarse ferrite grains as well as bainite) and the progress of cracks formed as a consequence of localized inconsistent plastic deformation.

  12. Microstructure and properties of 700 MPa grade HSLA steel during high temperature deformation

    International Nuclear Information System (INIS)

    Chen, Xizhang; Huang, Yuming; Lei, Yucheng

    2015-01-01

    Highlights: • Hot deformation behavior of 700 MPa HSLA steel above 1200 °C in was detailed studied. • Uniform and granular bainite is formed when the deformation amount is 40%. • Deformation resistance value under steady-equilibrium state is about 56 MPa. - Abstract: A high temperature deformation experiment was conducted on a high strength low alloy (HSLA) steel Q690 using Thermecmastor-Z thermal/physical simulator. During the experiment, the specimens were heated from room temperature to 1200 °C with the heating rate of 10 °C/s and 50 °C/s, respectively. The deformation temperature was 1200 °C and the deformation amounts were 0%, 10% and 40%, respectively. The microstructures, stress–strain diagram and hardness were obtained. The results revealed that the microstructure transformation of deformed austenite was quite different from that of the normal situation. With the increasing of deformation amount, more lath-shaped microstructure and less granulous microstructure were observed. The compressive deformation effectively prevented the precipitation of carbides. Larger deformation amount or lower heating rate was conducive to the atomic diffusion, which led to the microstructure uniformity and hardness decreasing. The maximum stress was 68.4 MPa and the steady stress was about 56 MPa

  13. 'Static' octupole deformation at high spin

    International Nuclear Information System (INIS)

    Nazarewicz, W.

    1985-01-01

    Rotational bands characterized by spin states of alternating parity p=(-1) I connected by enhanced E1 transitions have recently been observed in several nuclei from the Ra-Th region. They can be interpreted by means of a reflection asymmetric mean field theory. The interplay between octupole deformation and rotation is briefly discussed. For nuclei with ground state octupole deformation a transition to a reflection symmetric shape is expected around I=22. (orig.)

  14. Rates and style of Cenozoic deformation around the Gonghe Basin, northeastern Tibetan Plateau

    Science.gov (United States)

    Craddock, William H.; Kirby, Eric; Zhang, Huiping; Clark, Marin K.; Champagnac, Jean-Daniel; Yuan, Daoyang

    2014-01-01

    The northeastern Tibetan Plateau constitutes a transitional region between the low-relief physiographic plateau to the south and the high-relief ranges of the Qilian Shan to the north. Cenozoic deformation across this margin of the plateau is associated with localized growth of fault-cored mountain ranges and associated basins. Herein, we combine detailed structural analysis of the geometry of range-bounding faults and deformation of foreland basin strata with geomorphic and exhumational records of erosion in hanging-wall ranges in order to investigate the magnitude, timing, and style of deformation along the two primary fault systems, the Qinghai Nan Shan and the Gonghe Nan Shan. Structural mapping shows that both ranges have developed above imbricate fans of listric thrust faults, which sole into décollements in the middle crust. Restoration of shortening along balanced cross sections suggests a minimum of 0.8–2.2 km and 5.1–6.9 km of shortening, respectively. Growth strata in the associated foreland basin record the onset of deformation on the two fault systems at ca. 6–10 Ma and ca. 7–10 Ma, respectively, and thus our analysis suggests late Cenozoic shortening rates of 0.2 +0.2/–0.1 km/m.y. and 0.7 +0.3/–0.2 km/m.y. along the north and south sides of Gonghe Basin. Along the Qinghai Nan Shan, these rates are similar to late Pleistocene slip rates of ∼0.10 ± 0.04 mm/yr, derived from restoration and dating of a deformed alluvial-fan surface. Collectively, our results imply that deformation along both flanks of the doubly vergent Qilian Shan–Nan Shan initiated by ca. 10 Ma and that subsequent shortening has been relatively steady since that time.

  15. Large inelastic deformation analysis of steel pressure vessels at high temperature

    International Nuclear Information System (INIS)

    Ikonen, K.

    2001-01-01

    This publication describes the calculation methodology developed for a large inelastic deformation analysis of pressure vessels at high temperature. Continuum mechanical formulation related to a large deformation analysis is presented. Application of the constitutive equations is simplified when the evolution of stress and deformation state of an infinitesimal material element is considered in the directions of principal strains determined by the deformation during a finite time increment. A quantitative modelling of time dependent inelastic deformation is applied for reactor pressure vessel steels. Experimental data of uniaxial tensile, relaxation and creep tests performed at different laboratories for reactor pressure vessel steels are investigated and processed. An inelastic deformation rate model of strain hardening type is adopted. The model simulates well the axial tensile, relaxation and creep tests from room temperature to high temperature with only a few fitting parameters. The measurement data refined for the inelastic deformation rate model show useful information about inelastic deformation phenomena of reactor pressure vessel steels over a wide temperature range. The methodology and calculation process are validated by comparing the calculated results with measurements from experiments on small scale pressure vessels. A reasonably good agreement, when taking several uncertainties into account, is obtained between the measured and calculated results concerning deformation rate and failure location. (orig.)

  16. High population increase rates.

    Science.gov (United States)

    1991-09-01

    In addition to its economic and ethnic difficulties, the USSR faces several pressing demographic problems, including high population increase rates in several of its constituent republics. It has now become clear that although the country's rigid centralized planning succeeded in covering the basic needs of people, it did not lead to welfare growth. Since the 1970s, the Soviet economy has remained sluggish, which as led to increase in the death and birth rates. Furthermore, the ideology that held that demography could be entirely controlled by the country's political and economic system is contradicted by current Soviet reality, which shows that religion and ethnicity also play a significant role in demographic dynamics. Currently, Soviet republics fall under 2 categories--areas with high or low natural population increase rates. Republics with low rates consist of Christian populations (Armenia, Moldavia, Georgia, Byelorussia, Russia, Lithuania, Estonia, Latvia, Ukraine), while republics with high rates are Muslim (Tadzhikistan, Uzbekistan, Turkmenistan, Kirgizia, Azerbaijan Kazakhstan). The later group has natural increase rates as high as 3.3%. Although the USSR as a whole is not considered a developing country, the later group of republics fit the description of the UNFPA's priority list. Another serious demographic issue facing the USSR is its extremely high rate of abortion. This is especially true in the republics of low birth rates, where up to 60% of all pregnancies are terminated by induced abortions. Up to 1/5 of the USSR's annual health care budget is spent on clinical abortions -- money which could be better spent on the production of contraceptives. Along with the recent political and economic changes, the USSR is now eager to deal with its demographic problems.

  17. Measuring High Speed Deformation for Space Applications

    Science.gov (United States)

    Wentzel, Daniel

    2014-01-01

    PDV (Photonic Doppler Velocimetry) has proven to be a reliable and versatile technique to observe rapid deformation of frangible joints. It will be a valuable technique in order to understand the physics of two-stage light gas guns and the material response to hypervelocity impact.

  18. Highly Deformable Origami Paper Photodetector Arrays

    KAUST Repository

    Lin, Chun-Ho

    2017-09-25

    Flexible electronics will form the basis of many next-generation technologies, such as wearable devices, biomedical sensors, the Internet of things, and more. However, most flexible devices can bear strains of less than 300% as a result of stretching. In this work, we demonstrate a simple and low-cost paper-based photodetector array featuring superior deformability using printable ZnO nanowires, carbon electrodes, and origami-based techniques. With a folded Miura structure, the paper photodetector array can be oriented in four different directions via tessellated parallelograms to provide the device with excellent omnidirectional light harvesting capabilities. Additionally, we demonstrate that the device can be repeatedly stretched (up to 1000% strain), bent (bending angle ±30°), and twisted (up to 360°) without degrading performance as a result of the paper folding technique, which enables the ZnO nanowire layers to remain rigid even as the device is deformed. The origami-based strategy described herein suggests avenues for the development of next-generation deformable optoelectronic applications.

  19. Current deformation rates and extrusion of the northwestern Okhotsk plate, northeast Russia

    Science.gov (United States)

    Hindle, D.; Fujita, K.; Mackey, K.

    2006-01-01

    Northeast Asia is a region of broad deformation resulting from the convergence of the Eurasian (EU) and North American (NA) plates. Part of this convergence has been suggested to be relieved by the extrusion and deformation of the Okhotsk plate (OK). Three models for the deformation of the seismically active northwestern corner of the Okhotsk plate, based on different modes of deformation partitioning, are calculated and compared to observations from GPS, seismicity, and geology. The results suggest that this region is being extruded southeastward and deforming internally by a mixture of pure contraction, ``smooth'' extrusion, and ``rigid'' extrusion. Calculated extrusion rates are ~3-5.5 mm/yr, comparable to estimates from geologic data, and internal deformation rates are ~3.0 × 10-9 yr -1. Internal deformation may be only partially accommodated by seismicity, but the short time span of seismic data leaves this subject to large uncertainty.

  20. Two Back Stress Hardening Models in Rate Independent Rigid Plastic Deformation

    Science.gov (United States)

    Yun, Su-Jin

    In the present work, the constitutive relations based on the combination of two back stresses are developed using the Armstrong-Frederick, Phillips and Ziegler’s type hardening rules. Various evolutions of the kinematic hardening parameter can be obtained by means of a simple combination of back stress rate using the rule of mixtures. Thus, a wide range of plastic deformation behavior can be depicted depending on the dominant back stress evolution. The ultimate back stress is also determined for the present combined kinematic hardening models. Since a kinematic hardening rule is assumed in the finite deformation regime, the stress rate is co-rotated with respect to the spin of substructure obtained by incorporating the plastic spin concept. A comparison of the various co-rotational rates is also included. Assuming rigid plasticity, the continuum body consists of the elastic deformation zone and the plastic deformation zone to form a hybrid finite element formulation. Then, the plastic deformation behavior is investigated under various loading conditions with an assumption of the J2 deformation theory. The plastic deformation localization turns out to be strongly dependent on the description of back stress evolution and its associated hardening parameters. The analysis for the shear deformation with fixed boundaries is carried out to examine the deformation localization behavior and the evolution of state variables.

  1. Deformation of superplastic alloys at relatively low strain rates

    International Nuclear Information System (INIS)

    Grivas, D.

    1978-02-01

    The superplastic and sub-superplastic creep properties of Pb-Sn eutectic and Al-Zn eutectoid alloys were studied. Various thermomechanical treatments we tested to check the possibilities of whether the subsuperplastic deformation mechanism is affected by these treatments. All thermomechanical histories were found to reveal the same stress exponent, which is believed to be indicative of the predominant mechanism. The mechanical data in the low stress region lead us to suggest that dislocation glide is the predominant mechanism in this region. At higher stresses extensive grain boundary sliding takes place and the dislocation movement is directed to relieve the stress concentration developed by the grain movement

  2. Rating of intra-operative neuro-monitoring results in operative correction of the spinal deformities

    Directory of Open Access Journals (Sweden)

    A. A. Skripnikov

    2015-01-01

    Full Text Available Purpose of the work was filing the electrophysiological phenomena observed in the process of intra-operative neuromonitoring followed by development of the results’ scale of intra-operative neuro-physiological testing of the pyramidal tract. Materials and мethods. The selection for evaluation included data of 147 protocols of intra-operative neuromonitoring in 135 patients (53 males, 82 females, aged from 1 y. 5 m. to 52 years (14,1±0,7 years with spinal deformities of different etiology who underwent instrumentation spinal correction followed by fixation of thoracic / thoracolumbar spine segments using various variants of internal systems of trans-pedicular fixation. Intra-operative neuro-monitoring was performed using system «ISIS IOM» (Inomed Medizintechnik GmbH, Germany. The changes of motor evoked potentials were evaluated according to this scale. Results. Five types of pyramidal system reaction to operative invasion were revealed. According to neurophysiological criteria three grades of the risk of neurological disorders development during operative spinal deformity correction and, correspondingly, three levels of anxiety for the surgeon were defined. Conclusion. Intra-operative neurophysiological monitoring is the effective highly technological instrument to prevent neurological disorders in the spinal deformity. Offered rating scale of the risk of neurological complications gives the possibility to highlight three levels of anxiety during operative invasion.

  3. High resolution, large deformation 3D traction force microscopy.

    Directory of Open Access Journals (Sweden)

    Jennet Toyjanova

    Full Text Available Traction Force Microscopy (TFM is a powerful approach for quantifying cell-material interactions that over the last two decades has contributed significantly to our understanding of cellular mechanosensing and mechanotransduction. In addition, recent advances in three-dimensional (3D imaging and traction force analysis (3D TFM have highlighted the significance of the third dimension in influencing various cellular processes. Yet irrespective of dimensionality, almost all TFM approaches have relied on a linear elastic theory framework to calculate cell surface tractions. Here we present a new high resolution 3D TFM algorithm which utilizes a large deformation formulation to quantify cellular displacement fields with unprecedented resolution. The results feature some of the first experimental evidence that cells are indeed capable of exerting large material deformations, which require the formulation of a new theoretical TFM framework to accurately calculate the traction forces. Based on our previous 3D TFM technique, we reformulate our approach to accurately account for large material deformation and quantitatively contrast and compare both linear and large deformation frameworks as a function of the applied cell deformation. Particular attention is paid in estimating the accuracy penalty associated with utilizing a traditional linear elastic approach in the presence of large deformation gradients.

  4. High-Resolution Reciprocal Space Mapping for Characterizing Deformation Structures

    DEFF Research Database (Denmark)

    Pantleon, Wolfgang; Wejdemann, Christian; Jakobsen, Bo

    2014-01-01

    With high-angular resolution three-dimensional X-ray diffraction (3DXRD), quantitative information is gained about dislocation structures in individual grains in the bulk of a macroscopic specimen by acquiring reciprocal space maps. In high-resolution 3D reciprocal space maps of tensile......-deformed copper, individual, almost dislocation-free subgrains are identified from high-intensity peaks and distinguished by their unique combination of orientation and elastic strain; dislocation walls manifest themselves as a smooth cloud of lower intensity. The elastic strain shows only minor variations within...... dynamics is followed in situ during varying loading conditions by reciprocal space mapping: during uninterrupted tensile deformation, formation of subgrains is observed concurrently with broadening of Bragg reflections shortly after the onset of plastic deformation. When the traction is terminated, stress...

  5. High performance deformable image registration algorithms for manycore processors

    CERN Document Server

    Shackleford, James; Sharp, Gregory

    2013-01-01

    High Performance Deformable Image Registration Algorithms for Manycore Processors develops highly data-parallel image registration algorithms suitable for use on modern multi-core architectures, including graphics processing units (GPUs). Focusing on deformable registration, we show how to develop data-parallel versions of the registration algorithm suitable for execution on the GPU. Image registration is the process of aligning two or more images into a common coordinate frame and is a fundamental step to be able to compare or fuse data obtained from different sensor measurements. E

  6. Application of SAR interferometry to low-rate crustal deformation fields

    Science.gov (United States)

    Vincent, Paul

    Differential SAR interferometry is applied to the study of low-rate interseismic crustal deformation fields along three regions of the San Adreas fault system: Salton Sea (southernmost region), Pinto Mountain fault (south-central region), and San Francisco Bay (northern region). New techniques are developed to analyze and model these low-rate deformation fields including constrained horizontal-vertical component deconvolution, deformation phase pattern analysis and strain field evolution modeling. Several new active faults were discovered as well as unmeasured activity on existing faults in the process of this SAR interferometry study. The feasibility and limitations of InSAR as a tool to study low-rate deformation fields is also addressed.

  7. Characteristics of permanent deformation rate of warm mix asphalt with additives variation (BNA-R and zeolite)

    Science.gov (United States)

    Wahjuningsih, Nurul; Hadiwardoyo, Sigit Pranowo; Sumabrata, R. Jachrizal

    2017-06-01

    Permanent deformation is one of the criteria of failure on asphalt concrete mixture. The nature of the bitumen melt at high temperatures, this condition causes the asphalt concrete mixture tends to soften due to an increase in temperature of the road surface. The increase in surface temperature and the load wheel that has repeated itself on the same trajectory causes deformation groove has formed. Conditions rutting due to permanent deformation has resulted in inconvenience to the passengers and can lead to high costs of road maintenance. On the road planning process required a prediction of the rate of the permanent deformation of asphalt concrete mixtures. It is important to know early on the road surface damage due to vehicle load and surface temperature during service life. Asphalt has been mixed with the additive BNA-R and Zeolite intended to make variations in the characteristics of bitumen in this study. This variation is further combined with variations in the composition of aggregate in order to obtain a combination of asphalt-aggregate mixture. This mixture using warm mix, and to determine the permanent deformation of asphalt mix with material combinations was performed through the wheel tracking test machine with 3,780 cycles or 7,560 tracks for 3 hours. Another analysis to determine the characteristics of asphalt concrete mixtures have also been carried out changes in the surface temperature at the time of the test track. From the results of the test track to nearly 8 thousand passes has seen permanent deformation characteristics of asphalt concrete mixture with a variation of the characteristics of bitumen and aggregate variation. Groove of deformation due to a wheel load from the initial until the last passes shows that there are influence of compaction temperature on the variation of bitumen and aggregate composition to the relationship of permanent deformation of the wheel groove, especially on the road surface temperature changes.

  8. A survey of rate and causes of deformity in boys and girls youngsters in Lorestan province

    Directory of Open Access Journals (Sweden)

    mostafa Bahrami

    2007-01-01

    Materials and methods: The statistical community of the research included all the youngsters in Lorestan Province. The subjects in this study were 400 boys and 450 girls (11-15 years old that collected randomly. Data collection was done by questionnaires and physical examination (posture screen, tape-measure, Scales and…. The results were analyzed by SPSS software Results: In general, the results of this study indicated that abnormal posture in male was 57.67% and in female was 68.89%. additionally, there was a significant relationship between the level of kyphosis and lordosis and sleep habit, between shoulder dropping and briefcase carriage, between Bow leg and sitting between Hallux Valgus and high heel shoes of subjects ( P<0.05 . Conclusion: Considering the generated results, the level and rate of deformity among youngsters is very high. So, it seems that there is a need to plan an especial program by managers to reduce the burden of this abnormality.

  9. Effects of high-order deformation on high-K isomers in superheavy nuclei

    International Nuclear Information System (INIS)

    Liu, H. L.; Bertulani, C. A.; Xu, F. R.; Walker, P. M.

    2011-01-01

    Using, for the first time, configuration-constrained potential-energy-surface calculations with the inclusion of β 6 deformation, we find remarkable effects of the high-order deformation on the high-K isomers in 254 No, the focus of recent spectroscopy experiments on superheavy nuclei. For shapes with multipolarity six, the isomers are more tightly bound and, microscopically, have enhanced deformed shell gaps at N=152 and Z=100. The inclusion of β 6 deformation significantly improves the description of the very heavy high-K isomers.

  10. High temperature deformation behavior and microstructural evolutions of a high Zr containing WE magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Asqardoust, Sh.; Zarei-Hanzaki, A. [School of Metallurgical & Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Fatemi, S.M., E-mail: mfatemi@ut.ac.ir [Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of); Moradjoy-Hamedani, M. [School of Metallurgical & Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2016-06-05

    Magnesium alloys containing RE elements (WE grade) are considered as potential materials for high temperature structural applications. To this end, it is crucial to study the flow behavior and the microstructural evolution of these alloys at high temperatures. In present work, the hot compression testing was employed to investigate the deformation behavior of a rolled WE54 magnesium alloy at elevated temperatures. The experimental material failed to deform to target strain of 0.6 at 250 and 300 °C, while the straining was successfully performed at 350 °C. A flow softening was observed at 350 °C, which was related to the depletion of RE strengthener elements, particularly Y atoms, from the solid solution and dynamic precipitation of β phases. It was suggested that the Zener pinning effect of the latter precipitates might retard the occurrence of dynamic recrystallization. As the temperature increased to 450 and 500 °C, the RE elements dissolved in the matrix and thus dynamic recrystallization could considerably progress in the microstructure. The comparative study of specimens cut along transverse ad normal direction (TD and ND specimens) implied that the presence of RE elements might effectively reduce the yield anisotropy in WE54 rolled alloy. Microstructural observations indicated a higher fraction of dynamically-recrystallized grains for the ND specimens. This was discussed relying on the different shares of deformation mechanism during compressing the TD and ND specimens. - Highlights: • Deformation behavior of a high Zr WE alloy was addressed at low strain rate. • Dynamic precipitation was realized at 350 °C. • The occurrence of DRX was retarded due to Zener pinning effect. • A higher DRX fraction was obtained in ND specimens comparing with TD ones.

  11. Flow rate-pressure drop relation for deformable shallow microfluidic channels

    Science.gov (United States)

    Christov, Ivan C.; Cognet, Vincent; Shidhore, Tanmay C.; Stone, Howard A.

    2018-04-01

    Laminar flow in devices fabricated from soft materials causes deformation of the passage geometry, which affects the flow rate--pressure drop relation. For a given pressure drop, in channels with narrow rectangular cross-section, the flow rate varies as the cube of the channel height, so deformation can produce significant quantitative effects, including nonlinear dependence on the pressure drop [{Gervais, T., El-Ali, J., G\\"unther, A. \\& Jensen, K.\\ F.}\\ 2006 Flow-induced deformation of shallow microfluidic channels.\\ \\textit{Lab Chip} \\textbf{6}, 500--507]. Gervais et. al. proposed a successful model of the deformation-induced change in the flow rate by heuristically coupling a Hookean elastic response with the lubrication approximation for Stokes flow. However, their model contains a fitting parameter that must be found for each channel shape by performing an experiment. We present a perturbation approach for the flow rate--pressure drop relation in a shallow deformable microchannel using the theory of isotropic quasi-static plate bending and the Stokes equations under a lubrication approximation (specifically, the ratio of the channel's height to its width and of the channel's height to its length are both assumed small). Our result contains no free parameters and confirms Gervais et. al.'s observation that the flow rate is a quartic polynomial of the pressure drop. The derived flow rate--pressure drop relation compares favorably with experimental measurements.

  12. High-temperature deformation and processing maps of Zr-4 metal matrix with dispersed coated surrogate nuclear fuel particles

    Science.gov (United States)

    Chen, Jing; Liu, Huiqun; Zhang, Ruiqian; Li, Gang; Yi, Danqing; Lin, Gaoyong; Guo, Zhen; Liu, Shaoqiang

    2018-06-01

    High-temperature compression deformation of a Zr-4 metal matrix with dispersed coated surrogate nuclear fuel particles was investigated at 750 °C-950 °C with a strain rate of 0.01-1.0 s-1 and height reduction of 20%. Scanning electron microscopy was utilized to investigate the influence of the deformation conditions on the microstructure of the composite and damage to the coated surrogate fuel particles. The results indicated that the flow stress of the composite increased with increasing strain rate and decreasing temperature. The true stress-strain curves showed obvious serrated oscillation characteristics. There were stable deformation ranges at the initial deformation stage with low true strain at strain rate 0.01 s-1 for all measured temperatures. Additionally, the coating on the surface of the surrogate nuclear fuel particles was damaged when the Zr-4 matrix was deformed at conditions of high strain rate and low temperature. The deformation stability was obtained from the processing maps and microstructural characterization. The high-temperature deformation activation energy was 354.22, 407.68, and 433.81 kJ/mol at true strains of 0.02, 0.08, and 0.15, respectively. The optimum deformation parameters for the composite were 900-950 °C and 0.01 s-1. These results are expected to provide guidance for subsequent determination of possible hot working processes for this composite.

  13. Modelling plastic deformation of metals over a wide range of strain rates using irreversible thermodynamics

    International Nuclear Information System (INIS)

    Huang Mingxin; Rivera-Diaz-del-Castillo, Pedro E J; Zwaag, Sybrand van der; Bouaziz, Olivier

    2009-01-01

    Based on the theory of irreversible thermodynamics, the present work proposes a dislocation-based model to describe the plastic deformation of FCC metals over wide ranges of strain rates. The stress-strain behaviour and the evolution of the average dislocation density are derived. It is found that there is a transitional strain rate (∼ 10 4 s -1 ) over which the phonon drag effects appear, resulting in a significant increase in the flow stress and the average dislocation density. The model is applied to pure Cu deformed at room temperature and at strain rates ranging from 10 -5 to 10 6 s -1 showing good agreement with experimental results.

  14. Effect of cold working and aging on high temperature deformation of high Mn stainless steel

    International Nuclear Information System (INIS)

    Yoshikawa, M.; Habara, Y.; Matsuki, R.; Aoyama, H.

    1999-01-01

    By the addition of N, the strength of high Mn stainless steel can be increased. Cold rolling and aging are effective to increase its strength further, and with those treatments this grade is often used for high temperature applications. In this study, creep deformation behavior and high temperature strength of the high Mn stainless steel in cold rolled and aged conditions are discussed as compared to Type 304 stainless steel. It has been revealed that as-rolled specimens show instant elongation at the beginning of creep tests and its amount is larger in the high Mn grade than in Type 304. Also, the creep rate of the high Mn stainless steel is smaller than that of Type 304. These facts may be related to the change in microstructure. (orig.)

  15. Towards high velocity deformation characterisation of metals and composites using Digital Image Correlation

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Normann Wilken; Berggreen, Christian; Boyd, S.W

    2010-01-01

    images and then extracting deformation data using Digital Image Correlation (DIC) from tensile testing in the intermediate strain rate regime available with the test machines. Three different materials, aluminium alloy 1050, S235 steel and glass fibre reinforced plastic (GFRP) were tested at different......Characterisation of materials subject to high velocity deformation is necessary as many materials behave differently under such conditions. It is particularly important for accurate numerical simulation of high strain rate events. High velocity servo-hydraulic test machines have enabled material...... testing in the strain rate regime from 1 – 500 ε/s. The range is much lower than that experienced under ballistic, shock or impact loads, nevertheless it is a useful starting point for the application of optical techniques. The present study examines the possibility of using high speed cameras to capture...

  16. High incidence of deformity in aquatic turtles in the John Heinz National Wildlife Refuge

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Barbara [Department of Bioscience and Biotechnology, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Spotila, James R [Department of Bioscience and Biotechnology, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Congdon, Justin [Savannah River Ecology Laboratory, University of Georgia, Drawer E., Aiken, SC (United States)

    2006-08-15

    The John Heinz National Wildlife Refuge is subject to pollution from multiple sources. We studied development of snapping turtle (Chelydra serpentina) and painted turtle (Chrysemys picta) embryos from the refuge from 2000 through 2003. Mean annual deformity rate of pooled painted turtle clutches over four years ranged from 45 to 71%, while that of snapping turtle clutches ranged from 13 to 19%. Lethal deformities were more common than minor or moderate deformities in embryos of both species. Adult painted turtles had a higher deformity rate than adult snapping turtles. Snapping turtles at JHNWR had high levels of PAH contamination in their fat. This suggests that PAHs are involved in the high level of deformities. Other contaminants may also play a role. Although the refuge offers many advantages to resident turtle populations, pollution appears to place a developmental burden on the life history of these turtles. - This paper presents findings on the prevalence of developmental abnormalities in turtles at a national wildlife refuge that have direct relevance to studies on the effects of contamination on development and morphology of vertebrates.

  17. High incidence of deformity in aquatic turtles in the John Heinz National Wildlife Refuge

    International Nuclear Information System (INIS)

    Bell, Barbara; Spotila, James R.; Congdon, Justin

    2006-01-01

    The John Heinz National Wildlife Refuge is subject to pollution from multiple sources. We studied development of snapping turtle (Chelydra serpentina) and painted turtle (Chrysemys picta) embryos from the refuge from 2000 through 2003. Mean annual deformity rate of pooled painted turtle clutches over four years ranged from 45 to 71%, while that of snapping turtle clutches ranged from 13 to 19%. Lethal deformities were more common than minor or moderate deformities in embryos of both species. Adult painted turtles had a higher deformity rate than adult snapping turtles. Snapping turtles at JHNWR had high levels of PAH contamination in their fat. This suggests that PAHs are involved in the high level of deformities. Other contaminants may also play a role. Although the refuge offers many advantages to resident turtle populations, pollution appears to place a developmental burden on the life history of these turtles. - This paper presents findings on the prevalence of developmental abnormalities in turtles at a national wildlife refuge that have direct relevance to studies on the effects of contamination on development and morphology of vertebrates

  18. NORA-2, a model for creep deformation and rupture of zircaloy at high temperatures

    International Nuclear Information System (INIS)

    Raff, S.; Meyder, R.

    1983-01-01

    A model has been developed to describe Zircaloy cladding behaviour under LOCA and small leak conditions within specified temperature range and strain rates. The deformation model consists of a strain rate equation with two components representing strain rate controlled contributions from different deformation mechanisms. Transition from one mechanism to the other produces the strain rate dependence of the stress exponent of steady state creep. During transient creep the change of creep mechanisms produces a flow softening behaviour which induces unstable creep. Together with a strain hardening model, the strain history can be described for low and high strain values. The influence of oxidation is taken into account by modelling hardening due to solid solution of oxygen, cracking of the brittle oxide and oxygen stabilised α-phase layers, and by an oxidation-induced creep component in steam atmosphere. The rupture criterion is based on a strain fraction rule whose variables are temperature, strain rate or applied stress, and oxygen content. (author)

  19. Study of resistance to deformation dependence on temperature and strain degree during working with different rates for ABM-1 alloy

    International Nuclear Information System (INIS)

    Kharlamov, V.V.; Dvinskij, V.M.; Vashlyaev, Eh.V.; Dyblenko, Z.A.; Khamatov, R.I.; Zverev, K.P.

    1981-01-01

    On the basis of approximation of the experimental curves partial differential equations relating ABM-1 alloy deformation resistance to the deformation parameters are obtained. Using statistical processing of the experimental data the regression equations of the dependence of the deformation resistance on temperature rate and relative reduction of the samples are found. In the 2.1-23.6 1/c deformation rate range hardening and weakening rates of the AMB-1 alloy increases with the increase of the latter. The data obtained permit to calculate the deformation parameters of the studied alloy for different processes of metal plastic working in the studied temperature range [ru

  20. Deformation behavior of large, high-pressure vessel flanges

    International Nuclear Information System (INIS)

    Spaas, H.A.C.M.; Latzko, D.G.H.

    1975-01-01

    The analysis of the deformation behavior of large high-pressure vessel flanges poses a much more difficult problem than for low-pressure flanges due to their particular geometry. For a particularly narrow flange geometry (typical of PWR flanges) a finite-element analysis (MARC-IBM-program, eight-node, isoparametric ring elements) was used to predict the behavior of the flange rings. The nonlinear elastic problem resulting from the local closing and/or opening of the partial gap between the gasket faces was solved by an incremental technique using gap elements. The resulting deformation behavior of the flange system has been compared to that obtained from an analysis using the refined rigid ring concept for both bolt-tightening and hydro-testing conditions. The elasto-plastic analysis was solved by the same finite element program system as mentioned above. The incremental steps describing the nonlinear material behavior are allowed to be larger than those for the gap-closure mechanism. Besides a comparison with the former elastic analyses an interpretation will be given of the local plasticity effects, which result in a shift in location of the gasket reaction. Experimental data on local gasket face deformation was obtained by a specially developed laser beam apparatus, with the leak detection channel of the flange serving as a beam hole. Additionally strain gauges were used on flanges and bolts, in combination with special sensing pins for the determination of relative flange rotations. Results obtained so far indicate that for high-pressure flanges of the narrow design investigated here the deformation behavior is best described by an elasto-plastic finite element analysis

  1. Development of a Rotation Drickamer Apparatus for Deformation Studies Under High Pressure and High Temperature: Applications to magnesiowustite and Wadsleyite

    Science.gov (United States)

    Xu, Y.; Karato, S.

    2002-12-01

    Well-controlled high-pressure deformation experiments are critical for understanding the dynamics of Earth's interior. Most of the previous works on ultrahigh-pressure (P>10 GPa) deformation experiments have two limitations. (1) The mode of deformation is "stress-relaxation", in which stress changes with time in a given experiment, and (2) the magnitude of stress is limited (press combined with a rotation actuator involving an ac servo-motor. After the desired pressure and temperature are reached, torsional stress can be applied to a sample with a constant rotation rate. The advantage of this design is that the direction of shear deformation is normal to that of compression and therefore compression and deformation can be separated. A sample (typically ~1.8 mm diameter and ~0.2 mm thickness) is sandwiched between two zirconia plates and two heater plates made of TiC + diamond. Thin foils of W3%Re and W25%Re are inserted between two halves of samples which act as a thermocouple as well as strain markers. We have conducted a preliminary test on MgO at ~12 GPa and ~1470 K to the strain up to ~3. Deformation experiments on wadsleyite are underway to investigate the fabric development and rheology in this mineral.

  2. Monitoring the Deformation of High-Rise Buildings in Shanghai Luijiazui Zone by Tomo-Psinsar

    Science.gov (United States)

    Zhou, L. F.; Ma, P. F.; Xia, Y.; Xie, C. H.

    2018-05-01

    In this study, we utilize a Tomography-based Persistent Scatterers Interferometry (Tomo-PSInSAR) approach for monitoring the deformation performances of high-rise buildings, i.e. SWFC and Jin Mao Tower, in Shanghai Lujiazui Zone. For the purpose of this study, we use 31 Stripmap acquisitions from TerraSAR-X missions, spanning from December 2009 to February 2013. Considering thermal expansion, creep and shrinkage are two long-term movements that occur in high-rise buildings with concrete structures, we use an extended 4-D SAR phase model, and three parameters (height, deformation velocity, and thermal amplitude) are estimated simultaneously. Moreover, we apply a two-tier network strategy to detect single and double PSs with no need for preliminary removal of the atmospheric phase screen (APS) in the study area, avoiding possible error caused by the uncertainty in spatiotemporal filtering. Thermal expansion is illustrated in the thermal amplitude map, and deformation due to creep and shrinkage is revealed in the linear deformation velocity map. The thermal amplitude map demonstrates that the derived thermal amplitude of the two high-rise buildings both dilate and contract periodically, which is highly related to the building height due to the upward accumulative effect of thermal expansion. The linear deformation velocity map reveals that SWFC is subject to deformation during the new built period due to creep and shrinkage, which is height-dependent movements in the linear velocity map. It is worth mention that creep and shrinkage induces movements that increase with the increasing height in the downward direction. In addition, the deformation rates caused by creep and shrinkage are largest at the beginning and gradually decrease, and at last achieve a steady state as time goes infinity. On the contrary, the linear deformation velocity map shows that Jin Mao Tower is almost stable, and the reason is that it is an old built building, which is not influenced by creep

  3. MONITORING THE DEFORMATION OF HIGH-RISE BUILDINGS IN SHANGHAI LUIJIAZUI ZONE BY TOMO-PSINSAR

    Directory of Open Access Journals (Sweden)

    L. F. Zhou

    2018-05-01

    Full Text Available In this study, we utilize a Tomography-based Persistent Scatterers Interferometry (Tomo-PSInSAR approach for monitoring the deformation performances of high-rise buildings, i.e. SWFC and Jin Mao Tower, in Shanghai Lujiazui Zone. For the purpose of this study, we use 31 Stripmap acquisitions from TerraSAR-X missions, spanning from December 2009 to February 2013. Considering thermal expansion, creep and shrinkage are two long-term movements that occur in high-rise buildings with concrete structures, we use an extended 4-D SAR phase model, and three parameters (height, deformation velocity, and thermal amplitude are estimated simultaneously. Moreover, we apply a two-tier network strategy to detect single and double PSs with no need for preliminary removal of the atmospheric phase screen (APS in the study area, avoiding possible error caused by the uncertainty in spatiotemporal filtering. Thermal expansion is illustrated in the thermal amplitude map, and deformation due to creep and shrinkage is revealed in the linear deformation velocity map. The thermal amplitude map demonstrates that the derived thermal amplitude of the two high-rise buildings both dilate and contract periodically, which is highly related to the building height due to the upward accumulative effect of thermal expansion. The linear deformation velocity map reveals that SWFC is subject to deformation during the new built period due to creep and shrinkage, which is height-dependent movements in the linear velocity map. It is worth mention that creep and shrinkage induces movements that increase with the increasing height in the downward direction. In addition, the deformation rates caused by creep and shrinkage are largest at the beginning and gradually decrease, and at last achieve a steady state as time goes infinity. On the contrary, the linear deformation velocity map shows that Jin Mao Tower is almost stable, and the reason is that it is an old built building, which is not

  4. Extension of an anisotropic creep model to general high temperature deformation of a single crystal superalloy

    International Nuclear Information System (INIS)

    Pan, L.M.; Ghosh, R.N.; McLean, M.

    1993-01-01

    A physics based model has been developed that accounts for the principal features of anisotropic creep deformation of single crystal superalloys. The present paper extends this model to simulate other types of high temperature deformation under strain controlled test conditions, such as stress relaxation and tension tests at constant strain rate in single crystals subject to axial loading along an arbitrary crystal direction. The approach is applied to the SRR99 single crystal superalloy where a model parameter database is available, determined via analysis of a database of constant stress creep curves. A software package has been generated to simulate the deformation behaviour under complex stress-strain conditions taking into account anisotropic elasticity. (orig.)

  5. A novel multitemporal insar model for joint estimation of deformation rates and orbital errors

    KAUST Repository

    Zhang, Lei; Ding, Xiaoli; Lu, Zhong; Jung, Hyungsup; Hu, Jun; Feng, Guangcai

    2014-01-01

    be corrected efficiently and reliably. We propose a novel model that is able to jointly estimate deformation rates and orbital errors based on the different spatialoral characteristics of the two types of signals. The proposed model is able to isolate a long

  6. Anisotropic deformation of Zr–2.5Nb pressure tube material at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Fong, R.W.L., E-mail: fongr@aecl.ca [Fuel and Fuel Channel Safety Branch, Atomic Energy of Canada Limited, Chalk River Nuclear Laboratories, Chalk River, Ontario (Canada)

    2013-09-15

    Zr–2.5Nb alloy is used for the pressure tubes in CANDU® reactor fuel channels. In reactor, the pressure tube normally operates at 300 °C and experiences a primary coolant fluid internal pressure of approximately 10 MPa. Manufacturing and processing procedures generate an anisotropic state in the pressure tube which makes the tube stronger in the hoop (transverse) direction than in the axial (longitudinal) direction. This anisotropy condition is present for temperatures less than 500 °C. During postulated accident conditions where the material temperature could reach 1000 °C, it might be assumed that the high temperature and subsequent phase change would reduce the inherent anisotropy, and thus affect the deformation behaviour (ballooning) of the pressure tube. From constant-load, rapid-temperature-ramp, uniaxial deformation tests, the deformation rate in the longitudinal direction of the tube behaves differently than the deformation rate in the transverse direction of the tube. This anisotropic mechanical behaviour appears to persist at temperatures up to 1000 °C. This paper presents the results of high-temperature deformation tests using longitudinal and transverse specimens taken from as-received Zr–2.5Nb pressure tubes. It is shown that the anisotropic deformation behaviour observed at high temperatures is largely due to the stable crystallographic texture of the α-Zr phase constituent in the material that was previously observed by neutron diffraction measurements during heating at temperatures up to 1050 °C. The deformation behaviour is also influenced by the phase transformation occurring at high temperatures during heating. The effects of texture and phase transformation on the anisotropic deformation of as-received Zr–2.5Nb pressure tube material are discussed in the context of the tube ballooning behaviour. Because of the high temperatures in postulated accident scenarios, any irradiation damage will be annealed from the pressure tube material

  7. The effect of coarse second-phase particles on the rate of grain refinement during severe deformation processing

    DEFF Research Database (Denmark)

    Apps, P.J.; Bowen, Jacob R.; Prangnell, P.B.

    2003-01-01

    The effect of second-phase particles on the rate of grain refinement during severe deformation processing has been investigated, by comparing the microstructure evolution in an AA8079 aluminium alloy, containing 2.5 vol.% of ~2 μm particles, with that in a high purity, single-phase, Al-0.13% Mg a...... by an effective strain of only five in the particle-containing alloy, compared to ten in the single-phase material. The mechanisms that contribute to this acceleration of the grain refinement process are discussed.......The effect of second-phase particles on the rate of grain refinement during severe deformation processing has been investigated, by comparing the microstructure evolution in an AA8079 aluminium alloy, containing 2.5 vol.% of ~2 μm particles, with that in a high purity, single-phase, Al-0.13% Mg...... alloy, deformed identically by ECAE to an effective strain of ten. The materials were analysed by high-resolution EBSD orientation mapping, which revealed that grain refinement occurred at a dramatically higher rate in the particle-containing alloy. A submicron grain structure could be achieved...

  8. Slow strain rate stress corrosion cracking under multiaxial deformation conditions: technique and application to admiralty brass

    International Nuclear Information System (INIS)

    Blanchard, W.K.; Heldt, L.A.; Koss, D.

    1984-01-01

    A set of straightforward experimental techniques are described for the examination of slow strain rate stress corrosion cracking (SCC) of sheet deforming under nearly all multiaxial deformation conditions which result in sheet thinning. Based on local fracture strain as a failure criterion, the results contrast stress corrosion susceptibility in uniaxial tension with those in both plane strain and balanced biaxial tension. These results indicate that the loss of ductility of the brass increases as the stress state changes from uniaxial toward balanced biaxial tension

  9. On the role of high multipolarity interactions in deformed nuclei

    International Nuclear Information System (INIS)

    Solov'ev, V.G.; Sushkov, A.V.

    1989-01-01

    The influence of interactions with the multipolarity λ=5,6,7 and 9 is studied on the mixing of two-quasineutron and two-quasineutron states with large K in doubly even deformed nuclei. The mixing of the two-quasineutron and two-quasiproton states with the same values of K π , caused by a high multipolarity interaction, is shown to be large in the case of proximity of their energies. Qualitatively correct description of experimental data on the mixing of two-quasineutron and two-quasiproton configurations in 178,176 Hf, 174 Yb, 168 Er and 158 Gd is obtained. 20 refs.; 1 tab

  10. High Rate Digital Demodulator ASIC

    Science.gov (United States)

    Ghuman, Parminder; Sheikh, Salman; Koubek, Steve; Hoy, Scott; Gray, Andrew

    1998-01-01

    The architecture of High Rate (600 Mega-bits per second) Digital Demodulator (HRDD) ASIC capable of demodulating BPSK and QPSK modulated data is presented in this paper. The advantages of all-digital processing include increased flexibility and reliability with reduced reproduction costs. Conventional serial digital processing would require high processing rates necessitating a hardware implementation in other than CMOS technology such as Gallium Arsenide (GaAs) which has high cost and power requirements. It is more desirable to use CMOS technology with its lower power requirements and higher gate density. However, digital demodulation of high data rates in CMOS requires parallel algorithms to process the sampled data at a rate lower than the data rate. The parallel processing algorithms described here were developed jointly by NASA's Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory (JPL). The resulting all-digital receiver has the capability to demodulate BPSK, QPSK, OQPSK, and DQPSK at data rates in excess of 300 Mega-bits per second (Mbps) per channel. This paper will provide an overview of the parallel architecture and features of the HRDR ASIC. In addition, this paper will provide an over-view of the implementation of the hardware architectures used to create flexibility over conventional high rate analog or hybrid receivers. This flexibility includes a wide range of data rates, modulation schemes, and operating environments. In conclusion it will be shown how this high rate digital demodulator can be used with an off-the-shelf A/D and a flexible analog front end, both of which are numerically computer controlled, to produce a very flexible, low cost high rate digital receiver.

  11. Measuring Local Strain Rates In Ductile Shear Zones: A New Approach From Deformed Syntectonic Dykes

    Science.gov (United States)

    Sassier, C.; Leloup, P.; Rubatto, D.; Galland, O.; Yue, Y.; Ding, L.

    2006-12-01

    At the Earth surface, deformation is mostly localized in fault zones in between tectonic plates. In the upper crust, the deformation is brittle and the faults are narrow and produce earthquakes. In contrast, deformation in the lower ductile crust results in larger shear zones. While it is relatively easy to measure in situ deformation rates at the surface using for example GPS data, it is more difficult to determinate in situ values of strain rate in the ductile crust. Such strain rates can only be estimated in paleo-shear zones. Various methods have been used to assess paleo-strain rates in paleo-shear zones. For instance, cooling and/or decompression rates associated with assumptions on geothermic gradients and shear zone geometry can lead to such estimates. Another way to estimate strain rates is the integration of paleo-stress measurements in a power flow law. But these methods are indirect and imply strong assumptions. Dating of helicitic garnets or syntectonic fibres are more direct estimates. However these last techniques have been only applied in zones of low deformation and not in major shear zones. We propose a new direct method to measure local strain rates in major ductile shear zones from syntectonic dykes by coupling quantification of deformation and geochronology. We test our method in a major shear zone in a well constrained tectonic setting: the Ailao-Shan - Red River Shear Zone (ASRRsz) located in SE Asia. For this 10 km wide shear zone, large-scale fault rates, determined in three independent ways, imply strain rates between 1.17×10^{-13 s-1 and 1.52×10^{-13 s-1 between 35 and 16 Ma. Our study focused on one outcrop where different generations of syntectonic dykes are observed. First, we quantified the minimum shear strain γ for each dyke using several methods: (1) by measuring the stretching of dykes with a surface restoration method (2) by measuring the final angle of the dykes with respect to the shear direction and (3) by combining the two

  12. Thermodynamic dislocation theory of high-temperature deformation in aluminum and steel

    Energy Technology Data Exchange (ETDEWEB)

    Le, K. C. [Ruhr-Univ Bochum, Bochum (Germany). Lehrstuhl fur Mechanik-Materialtheorie; Tran, T. M. [Ruhr-Univ Bochum, Bochum (Germany). Lehrstuhl fur Mechanik-Materialtheorie; Langer, J. S. [Univ. of California, Santa Barbara, CA (United States). Dept. of Physics

    2017-07-12

    The statistical-thermodynamic dislocation theory developed in previous papers is used here in an analysis of high-temperature deformation of aluminum and steel. Using physics-based parameters that we expect theoretically to be independent of strain rate and temperature, we are able to fit experimental stress-strain curves for three different strain rates and three different temperatures for each of these two materials. Here, our theoretical curves include yielding transitions at zero strain in agreement with experiment. We find that thermal softening effects are important even at the lowest temperatures and smallest strain rates.

  13. Towards the determination of deformation rates - pinch-and-swell structures as a natural and simulated paleo-strain rate gage

    Science.gov (United States)

    Peters, Max; Poulet, Thomas; Karrech, Ali; Regenauer-Lieb, Klaus; Herwegh, Marco

    2014-05-01

    Layered rocks deformed under viscous deformation conditions frequently show boudinage, a phenomenon that results from differences in effective viscosity between the involved layers. In the case of continuous necking of a mechanically stiffer layer embedded in a weaker matrix, symmetric boudins are interpreted as the result of dominant visco-plastic deformation (Goscombe et al., 2004). However, information on the physical conditions, material properties and deformation processes are yet unknown. Natural samples deformed under low-grade (TAustin and Evans (2007) combined with the thermodynamic approach of Regenauer-Lieb and Yuen (2004). Depending on the dissipated energy, grain sizes in these domains vary substantially in space and time. While low strain rates (low stresses) in the swells favor grain growth and GSI dominated deformation, high strain rates in the pinches provoke dramatic grain size reduction with an increasing contribution of GSS as a function of decreasing grain size. The development of symmetric necks observed in nature thus seems to coincide with the transition from dislocation to diffusion creep dominated flow with continuous grain size reduction and growth from swell to neck at relatively high extensional strains. REFERENCES Austin, N. and Evans, B. (2007). Paleowattmeters: A scaling relation for dynamically recrystallized grain size. Geology, 35. Goscombe, B.D., Passchier, C.W. and Hand, M. (2004). Boudinage classification: End-member boudin types and modified boudin structures, Journal of Structural Geology, 26. Herwegh, M., Poulet, T., Karrech, A. and Regenauer-Lieb, K. (in press). From transient to steady state deformation and grain size: A thermodynamic approach using elasto-visco-plastic numerical modeling. Journal of Geophysical Research. Karrech, A., Regenauer-Lieb, K. and Poulet, T. (2011a). A Damaged visco-plasticity model for pressure and temperature sensitive geomaterials. Journal of Engineering Science 49. Regenauer-Lieb, K. and Yuen

  14. High temperature deformation behavior of gradually pressurized zircaloy-4 tubes

    International Nuclear Information System (INIS)

    Suzuki, Motoye

    1982-03-01

    In order to obtain preliminary perspectives on fuel cladding deformation behavior under changing temperature and pressure conditions in a hypothetical loss-of-coolant accident of PWR, a Zircaloy-4 tube burst test was conducted in both air and 99.97% Ar atomospheres. The tubes were directly heated by AC-current and maintained at various temperatures, and pressurized gradually until rupture occurred. Rupture circumferential strains were generally larger in Ar gas than in air and attained a maximum around 1100 K in both atmospheres. Some tube tested in air produced axially-extended long balloons, which proved not to be explained by such properties or ideas as effect of cooling on strain rate, superplasticity, geometrical plastic instability and stresses generated by surface oxide layer. A cause of the long balloon may be obtained in the anisotropy of the material structure. But even a qualitative analysis based on this property can not be made due to insufficient data of the anisotropy. (author)

  15. Strain rate dependent deformation and failure behavior of laser welded DP780 steel joint under dynamic tensile loading

    International Nuclear Information System (INIS)

    Liu, Yang; Dong, Danyang; Wang, Lei; Chu, Xi; Wang, Pengfei; Jin, Mengmeng

    2015-01-01

    Laser welded DP steel joints are used widely in the automotive industry for weight reduction. Understanding the deformation and fracture behavior of the base metal (BM) and its welded joint (WJ), especially at high strain rates, is critical for the design of vehicle structures. This paper is concerned with the effects of strain rate on the tensile properties, deformation and fracture behavior of the laser welded DP780 steel joint. Quasi-static and dynamic tensile tests were performed on the WJ and BM of the DP780 steel using an electromechanical universal testing machine and a high-speed tensile testing machine over a wide range of strain rate (0.0001–1142 s −1 ). The microstructure change and microhardness distribution of the DP780 steel after laser welding were examined. Digital image correlation (DIC) and high-speed photography were employed for the strain measurement of the DP780 WJ during dynamic tensile tests. The DP780 WJ is a heterogeneous structure with hardening in fusion zone (FZ) and inner heat-affected zone (HAZ), and softening in outer HAZ. The DP780 BM and WJ exhibit positive strain rate dependence on the YS and UTS, which is smaller at lower strain rates and becomes larger with increasing strain rate, while ductility in terms of total elongation (TE) tends to increase under dynamic loading. Laser welding leads to an overall reduction in the ductility of the DP780 steel. However, the WJ exhibits a similar changing trend of the ductility to that of the BM with respect to the strain rate over the whole strain rate range. As for the DP780 WJ, the distance of tensile failure location from the weld centerline decreases with increasing strain rate. The typical ductile failure characteristics of the DP780 BM and WJ do not change with increasing strain rate. DIC measurements reveal that the strain localization starts even before the maximum load is attained in the DP780 WJ and gradual transition from uniform strains to severely localized strains occurs

  16. Strain rate dependent deformation and failure behavior of laser welded DP780 steel joint under dynamic tensile loading

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yang, E-mail: liuyang@mail.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China); Dong, Danyang, E-mail: dongdanyang@mail.neu.edu.cn [College of Science, Northeastern University, Shenyang 110819 (China); Wang, Lei, E-mail: wanglei@mail.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China); Chu, Xi, E-mail: chuxi.ok@163.com [College of Science, Northeastern University, Shenyang 110819 (China); Wang, Pengfei, E-mail: wpf1963871400@163.com [College of Science, Northeastern University, Shenyang 110819 (China); Jin, Mengmeng, E-mail: 24401878@163.com [College of Science, Northeastern University, Shenyang 110819 (China)

    2015-03-11

    Laser welded DP steel joints are used widely in the automotive industry for weight reduction. Understanding the deformation and fracture behavior of the base metal (BM) and its welded joint (WJ), especially at high strain rates, is critical for the design of vehicle structures. This paper is concerned with the effects of strain rate on the tensile properties, deformation and fracture behavior of the laser welded DP780 steel joint. Quasi-static and dynamic tensile tests were performed on the WJ and BM of the DP780 steel using an electromechanical universal testing machine and a high-speed tensile testing machine over a wide range of strain rate (0.0001–1142 s{sup −1}). The microstructure change and microhardness distribution of the DP780 steel after laser welding were examined. Digital image correlation (DIC) and high-speed photography were employed for the strain measurement of the DP780 WJ during dynamic tensile tests. The DP780 WJ is a heterogeneous structure with hardening in fusion zone (FZ) and inner heat-affected zone (HAZ), and softening in outer HAZ. The DP780 BM and WJ exhibit positive strain rate dependence on the YS and UTS, which is smaller at lower strain rates and becomes larger with increasing strain rate, while ductility in terms of total elongation (TE) tends to increase under dynamic loading. Laser welding leads to an overall reduction in the ductility of the DP780 steel. However, the WJ exhibits a similar changing trend of the ductility to that of the BM with respect to the strain rate over the whole strain rate range. As for the DP780 WJ, the distance of tensile failure location from the weld centerline decreases with increasing strain rate. The typical ductile failure characteristics of the DP780 BM and WJ do not change with increasing strain rate. DIC measurements reveal that the strain localization starts even before the maximum load is attained in the DP780 WJ and gradual transition from uniform strains to severely localized strains

  17. High-carbon chromium steel resistance to small plastic deformation

    International Nuclear Information System (INIS)

    Gajduchenya, V.F.; Madyanov, S.A.; Apaev, B.A.; Kirillov, Yu.V.; Sokolov, L.D.

    1978-01-01

    The phase composition of a steel with 1.08% C and 2.1% Cr, and the variation in the level of microstresses in the matrix as related to the annealing temperature in the range of 400-600 deg C and in the applied compression stress were investigated. To study the phase composition, and chromium content in the α-solution and the carbide phases, magnetic, chemical, and X-ray spectrum analyses were carried out. The change in the level of microstresses was determined roentgenographically. During the stress relaxation test at temperatures of 20-180 deg C, the mechanism of plastic deformation near the yield point was investigated. It is shown that three dislocation mechanisms operate in high-carbon chromium steel under the conditions at hand: overcoming the Pierls-Nabarro barriers by the dislocations, overcoming the stress fields of coherent carbide particles by dislocations, and circumvention of second-phase particles by dislocations. The dependence of the realization of the different plastic deformation mechanisms on the number of carbide particles and the chromium concentration in the matrix was established. The thermally activated nature of the motion of the dislocations under conditions of stress relaxation at an elevated temperature is noted

  18. High strain rate studies in rock

    International Nuclear Information System (INIS)

    Grady, D.

    1977-01-01

    Dynamic compression studies using high velocity impact are usually considered to involve a catastrophic process of indeterminate loading rate by which a material is brough to a shock compressed state. Although this is frequently the case, methods are also available to control the rate of strain during the shock compression process. One of the most accurate of these methods makes use of the anomalous nonlinear elastic property of glass to transform an initial shock or step wave input into a ramp wave of known amplitude and duration. Fused silica is the most carefully calibrated material for this purpose and, when placed between the test specimen and the impact projectile, can provide loading strain rates in the range of 10 4 /s to 10 6 /s for final stress states of approximately 3.9 GPa or less.Ramp wave compression experiments have been conducted on dolomite at strain rates of 3 x 10 4 /s. Both initial yielding and subsequent deformation at this strain rate agrees well with previous shock wave studies (epsilon-dotapprox.10 6 /s) and differs substantially from quasi-static measurements (epsilon-dotapprox.10 -4 /s). The ramp wave studies have also uncovered a pressure-induced phase transition in dolomite initiating at 4.0 GPa

  19. An improved evaluation of the seismic/geodetic deformation-rate ratio for the Zagros Fold-and-Thrust collisional belt

    Science.gov (United States)

    Palano, Mimmo; Imprescia, Paola; Agnon, Amotz; Gresta, Stefano

    2018-04-01

    We present an improved picture of the ongoing crustal deformation field for the Zagros Fold-and-Thrust Belt continental collision zone by using an extensive combination of both novel and published GPS observations. The main results define the significant amount of oblique Arabia-Eurasia convergence currently being absorbed within the Zagros: right-lateral shear along the NW trending Main Recent fault in NW Zagros and accommodated between fold-and-thrust structures and NS right-lateral strike-slip faults on Southern Zagros. In addition, taking into account the 1909-2016 instrumental seismic catalogue, we provide a statistical evaluation of the seismic/geodetic deformation-rate ratio for the area. On Northern Zagros and on the Turkish-Iranian Plateau, a moderate to large fraction (˜49 and >60 per cent, respectively) of the crustal deformation occurs seismically. On the Sanandaj-Sirjan zone, the seismic/geodetic deformation-rate ratio suggests that a small to moderate fraction (<40 per cent) of crustal deformation occurs seismically; locally, the occurrence of large historic earthquakes (M ≥ 6) coupled with the high geodetic deformation, could indicate overdue M ≥ 6 earthquakes. On Southern Zagros, aseismic strain dominates crustal deformation (the ratio ranges in the 15-33 per cent interval). Such aseismic deformation is probably related to the presence of the weak evaporitic Hormuz Formation which allows the occurrence of large aseismic motion on both subhorizontal faults and surfaces of décollement. These results, framed into the seismotectonic framework of the investigated region, confirm that the fold-and-thrust-dominated deformation is driven by buoyancy forces; by contrast, the shear-dominated deformation is primary driven by plate stresses.

  20. Interaction of heat production, strain rate and stress power in a plastically deforming body under tensile test

    Science.gov (United States)

    Paglietti, A.

    1982-01-01

    At high strain rates the heat produced by plastic deformation can give rise to a rate dependent response even if the material has rate independent constitutive equations. This effect has to be evaluated when interpreting a material test, or else it could erroneously be ascribed to viscosity. A general thermodynamic theory of tensile testing of elastic-plastic materials is given in this paper; it is valid for large strain at finite strain rates. It enables discovery of the parameters governing the thermodynamic strain rate effect, provides a method for proper interpretation of the results of the tests of dynamic plasticity, and suggests a way of planning experiments in order to detect the real contribution of viscosity.

  1. Strength and Deformation Rate of Plate Boundaries: The Rheological Effects of Grain Size Reduction, Structure, and Serpentinization.

    Science.gov (United States)

    Montesi, L.; Gueydan, F.

    2016-12-01

    Global strain rate maps reveal 1000-fold contrasts between plate interiors, oceanic or continental diffuse plate boundaries and narrow plate boundaries. Here, we show that rheological models based on the concepts of shear zone localization and the evolution of rock structure upon strain can explain these strain rate contrasts. Ductile shear zones constitute a mechanical paradox in the lithosphere. As every plastic deformation mechanism is strain-rate-hardening, ductile rocks are expected to deform at low strain rate and low stress (broad zone of deformation). Localized ductile shear zones require either a localized forcing (locally high stress) or a thermal or structural anomaly in the shear zone; either can be inherited or develop progressively as rocks deform. We previously identified the most effective process at each depth level of the lithosphere. In the upper crust and middle crust, rocks fabric controls localization. Grain size reduction is the most efficient mechanism in the uppermost mantle. This analysis can be generalized to consider a complete lithospheric section. We assume strain rate does not vary with depth and that the depth-integrated strength of the lithospheric does not change over time, as the total force is controlled by external process such as mantle convection and plate and slab buoyancy. Reducing grain size from a coarse value typical of undeformed peridotite to a value in agreement with the stress level (piezometer) while letting that stress vary from depth to depth (the integrated stress remains the same) increases the lithospheric strain rate by about a factor of 1000. This can explain the development of diffuse plate boundaries. The slightly higher strain rate of continental plate boundary may reflect development of a layered rock fabric in the middle crust. Narrow plate boundaries require additional weakening process. The high heat flux near mid-ocean ridge implies a thin lithosphere, which enhances stress (for constant integrated

  2. High-temperature deformation of B2 NiAl-base alloys

    International Nuclear Information System (INIS)

    Lee, I.G.; Ghosh, A.K.

    1994-01-01

    The high-temperature deformation behavior of three rapidly solidified and processed NiAl-base alloys--NiAl, NiAl containing 2 pct TiB 2 , and NiAl containing 4 pct HfC--have been studied and their microstructural and textural changes during deformation characterized. Compressions tests were conducted at 1,300 and 1,447 K at strain rates ranging from 10 -6 to 10 -2 s -1 . HfC-containing material showed dispersion strengthening as well as some degree of grain refinement over NiAl, while TiB 2 dispersoid-containing material showed grain refinement as well as secondary recrystallization and did not improve high-temperature strength. Hot-pack rolling was also performed to develop thin sheet materials (1.27-mm thick) and from these alloys. Without dispersoids, NiAl rolled easily at 1,223 K and showed low flow stress and good ductility during the hot-rolling operation. Rolling of dispersoid-containing alloys was difficult due to strain localization and edge-cracking effects, resulting partly from the high flow stress at the higher strain rate during the rolling operation. Sheet rolling initially produced a {111} texture, which eventually broke into multiple-texture components with severe deformation

  3. Charged particle beam scanning using deformed high gradient insulator

    Science.gov (United States)

    Chen, Yu -Jiuan

    2015-10-06

    Devices and methods are provided to allow rapid deflection of a charged particle beam. The disclosed devices can, for example, be used as part of a hadron therapy system to allow scanning of a target area within a patient's body. The disclosed charged particle beam deflectors include a dielectric wall accelerator (DWA) with a hollow center and a dielectric wall that is substantially parallel to a z-axis that runs through the hollow center. The dielectric wall includes one or more deformed high gradient insulators (HGIs) that are configured to produce an electric field with an component in a direction perpendicular to the z-axis. A control component is also provided to establish the electric field component in the direction perpendicular to the z-axis and to control deflection of a charged particle beam in the direction perpendicular to the z-axis as the charged particle beam travels through the hollow center of the DWA.

  4. Deformation of high-speed meteor bodies by the atmosphere

    International Nuclear Information System (INIS)

    Maslov, I V; Gorshkov, A V

    2012-01-01

    We model the deformation that a meteorite can undergo during its passage through the atmosphere. First, the pressure distribution around a solid body in a flow was measured in a wind tunnel. Second, the deformation of molten tin droplets with different temperatures dropped into water was observed. Finally, a mathematical model of the fall was constructed to determine what pressure the meteorite experiences in the atmosphere and whether it is enough to deform it. (paper)

  5. Quantification of the microstructures of high purity nickel subjected to dynamic plastic deformation

    DEFF Research Database (Denmark)

    Luo, Z.P.; Zhang, H.W.; Hansen, Niels

    2012-01-01

    and the misorientation angle across dislocation boundaries and high angle boundaries. These boundaries subdivide the structure on a finer and finer scale towards saturation at the highest strain. The structural evolution follows a hierarchical pattern from the formation of cells and cell blocks to a characteristic...... and high angle boundaries. Shear bands and twins have not been observed. In order to underpin the structural analysis, the mechanical properties as a function of strain have been determined by tensile and hardness tests. The flow stress is 850 MPa, showing that high strain rate deformation has potential...

  6. Style and rate of quaternary deformation of the Hosgri Fault Zone, offshore south-central coastal California

    Science.gov (United States)

    Hanson, Kathryn L.; Lettis, William R.; McLaren, Marcia; Savage, William U.; Hall, N. Timothy; Keller, Mararget A.

    2004-01-01

    The Hosgri Fault Zone is the southernmost component of a complex system of right-slip faults in south-central coastal California that includes the San Gregorio, Sur, and San Simeon Faults. We have characterized the contemporary style of faulting along the zone on the basis of an integrated analysis of a broad spectrum of data, including shallow high-resolution and deep penetration seismic reflection data; geologic and geomorphic data along the Hosgri and San Simeon Fault Zones and the intervening San Simeon/Hosgri pull-apart basin; the distribution and nature of near-coast seismicity; regional tectonic kinematics; and comparison of the Hosgri Fault Zone with worldwide strike-slip, oblique-slip, and reverse-slip fault zones. These data show that the modern Hosgri Fault Zone is a convergent right-slip (transpressional) fault having a late Quaternary slip rate of 1 to 3 mm/yr. Evidence supporting predominantly strike-slip deformation includes (1) a long, narrow, linear zone of faulting and associated deformation; (2) the presence of asymmetric flower structures; (3) kinematically consistent localized extensional and compressional deformation at releasing and restraining bends or steps, respectively, in the fault zone; (4) changes in the sense and magnitude of vertical separation both along trend of the fault zone and vertically within the fault zone; (5) strike-slip focal mechanisms along the fault trace; (6) a distribution of seismicity that delineates a high-angle fault extending through the seismogenic crust; (7) high ratios of lateral to vertical slip along the fault zone; and (8) the separation by the fault of two tectonic domains (offshore Santa Maria Basin, onshore Los Osos domain) that are undergoing contrasting styles of deformation and orientations of crustal shortening. The convergent component of slip is evidenced by the deformation of the early-late Pliocene unconformity. In characterizing the style of faulting along the Hosgri Fault Zone, we assessed

  7. Advanced Actuator Concepts for High Precision Deformable Mirrors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes to develop a variety of single crystal actuators for adaptive optics deformable mirrors. Single crystal piezoelectric actuators are...

  8. A STUDY OF THE PRESSURE SOLUTION AND DEFORMATION OF QUARTZ CRYSTALS AT HIGH pH AND UNDER HIGH STRESS

    Directory of Open Access Journals (Sweden)

    JUNG-HAE CHOI

    2013-02-01

    Full Text Available Bentonite is generally used as a buffer material in high-level radioactive waste disposal facilities and consists of 50% quartz by weight. Quartz strongly affects the behavior of bentonite over very long periods. For this reason, quartz dissolution experiment was performed under high-pressure and high-alkalinity conditions based on the conditions found in a high-level radioactive waste disposal facility located deep underground. In this study, two quartz dissolution experiments were conducted on 1 quartz beads under low-pressure and high-alkalinity conditions and 2 a single quartz crystal under high-pressure and high-alkalinity conditions. Following the experiments, a confocal laser scanning microscope (CLSM was used to observe the surfaces of experimental samples. Numerical analyses using the finite element method (FEM were also performed to quantify the deformation of contact area. Quartz dissolution was observed in both experiments. This deformation was due to a concentrated compressive stress field, as indicated by the quartz deformation of the contact area through the FEM analysis. According to the numerical results, a high compressive stress field acted upon the neighboring contact area, which showed a rapid dissolution rate compared to other areas of the sample.

  9. Deformation rates in northern Cascadia consistent with slow updip propagation of deep interseismic creep

    Science.gov (United States)

    Bruhat, Lucile; Segall, Paul

    2017-10-01

    Interpretations of interseismic slip deficit on the northern Cascadia megathrust are complicated by an enigmatic `gap' between the downdip limit of the locked region, inferred from kinematic inversions of deformation rates, and the top of the episodic tremor and slip (ETS) zone. Recent inversions of global positioning system (GPS) and tide gauge/leveling data for shear stress rates acting on the megathrust found a ˜21 km locking depth with a steep slip-rate gradient at its base is required to fit the data. Previous studies have assumed the depth distribution of interseismic slip rate to be time invariant; however, steep slip-rate gradients could also result from the updip propagation of slip into the locked region. This study explores models where interseismic slip penetrates up into the locked zone. We consider the creeping region, corresponding to the gap and the ETS zone, as a quasi-static crack driven by the plate velocity at its downdip end. We derive a simple model that allows for crack propagation over time, and provides analytical expressions for stress drop within the crack, slip and slip rate on the fault. It is convenient to expand the non-singular slip-rate distribution in a sum of Chebyshev polynomials. Estimation of the polynomial coefficients is underdetermined, yet provides a useful way of testing particular solutions and provides bounds on the updip propagation rate. When applied to the deformation rates in northern Cascadia, best-fitting models reveal that a very slow updip propagation, between 30 and 120 m yr-1 along the fault, could explain the steep slip-rate profile, needed to fit the data. This work provides a new tool for estimating interseismic slip rates, between purely kinematic inversions and full physics-based modeling, allowing for the possibility for updip expansion of the creeping zone.

  10. Microcrack Evolution and Associated Deformation and Strength Properties of Sandstone Samples Subjected to Various Strain Rates

    Directory of Open Access Journals (Sweden)

    Chong-Feng Chen

    2018-05-01

    Full Text Available The evolution of micro-cracks in rocks under different strain rates is of great importance for a better understanding of the mechanical properties of rocks under complex stress states. In the present study, a series of tests were carried out under various strain rates, ranging from creep tests to intermediate strain rate tests, so as to observe the evolution of micro-cracks in rock and to investigate the influence of the strain rate on the deformation and strength properties of rocks. Thin sections from rock samples at pre- and post-failure were compared and analyzed at the microscale using an optical microscope. The results demonstrate that the main crack propagation in the rock is intergranular at a creep strain rate and transgranular at a higher strain rate. However, intergranular cracks appear mainly around the quartz and most of the punctured grains are quartz. Furthermore, the intergranular and transgranular cracks exhibit large differences in the different loading directions. In addition, uniaxial compressive tests were conducted on the unbroken rock samples in the creep tests. A comparison of the stress–strain curves of the creep tests and the intermediate strain rate tests indicate that Young’s modulus and the peak strength increase with the strain rate. In addition, more deformation energy is released by the generation of the transgranular cracks than the generation of the intergranular cracks. This study illustrates that the conspicuous crack evolution under different strain rates helps to understand the crack development on a microscale, and explains the relationship between the micro- and macro-behaviors of rock before the collapse under different strain rates.

  11. The effect of dispersoids on the grain refinement mechanisms during deformation of aluminium alloys to ultra-high strains

    International Nuclear Information System (INIS)

    Apps, P.J.; Berta, M.; Prangnell, P.B.

    2005-01-01

    The effect of fine dispersoids on the mechanisms and rate of grain refinement has been investigated during the severe deformation of a model aluminium alloy. A binary Al-0.2Sc alloy, containing coherent Al 3 Sc dispersoids, of ∼20 nm in diameter and ∼100 nm spacing, has been deformed by equal channel angular extrusion to an effective strain of ten. The resulting deformation structures were quantitatively analysed using high-resolution electron backscattered diffraction orientation mapping, and the results have been compared to those obtained from a single-phase Al-0.13Mg alloy, deformed under identical conditions. The presence of fine, non-shearable, dispersoids has been found to homogenise slip, retard the formation of a cellular substructure and inhibit the formation of microshear bands during deformation. These factors combine to reduce the rate of high-angle grain boundary generation at low to medium strains and, hence, retard the formation of a submicron grain structure to higher strains during severe deformation

  12. Intrinsic And Extrinsic Controls On Unsteady Deformation Rates, Northern Apennine Mountains, Italy

    Science.gov (United States)

    Anastasio, D. J.; Gunderson, K. L.; Pazzaglia, F. J.; Kodama, K. P.

    2017-12-01

    The slip rates of faults in the Northern Apennine Mountains were unsteady at 104-105 year timescales during the Neogene and Quaternary. Fault slip rates were recovered from growth strata and uplifted fluvial terraces associated with the Salsomaggiore, Quatto Castella, and Castevetro fault-related folds, sampled along the Stirone, Enza, and Panaro Rivers, respectively. The forelimb stratigraphy of each anticline was dated using rock magnetic-based cyclostratigraphy, which varies with Milankovitch periodicity, multispecies biostratigraphy, magnetostratigraphy, OSL luminescence dating, TCN burial dating, and radiocarbon dating of uplifted and folded fluvial terraces. Fault slip magnitudes were constrained with trishear forward models. We observed decoupled deformation and sediment accumulation rates at each structure. From 3.5Ma deformation of a thick and thin-skinned thrusts was temporally variable and controlled by intrinsic rock processes, whereas, the more regional Pede-Apenninic thrust fault, a thick-skinned thrust underlying the mountain front, was likely activated because of extrinsic forcing from foreland basin sedimentation rate accelerations since 1.4Ma. We found that reconstructed slip rate variability increased as the time resolution increased. The reconstructed slip history of the thin-skinned thrust faults was characterized relatively long, slow fold growth and associated fault slip, punctuated by shorter, more rapid periods limb rotation, and slip on the underlying thrust fault timed asynchronously. Thrust fault slip rates slip rates were ≤ 0.1 to 6 mm/yr at these intermediate timescales. The variability of slip rates on the thrusts is likely related to strain partitioning neighboring faults within the orogenic wedge. The studied structures slowed down at 1Ma when there was a switch to slower synchronous fault slip coincident with orogenic wedge thickening due to the emplacement of the out of sequence Pene-Apenninic thrust fault that was emplaced at 1

  13. Numerical Modelling of Metal-Elastomer Spring Nonlinear Response for Low-Rate Deformations

    Directory of Open Access Journals (Sweden)

    Sikora Wojciech

    2018-03-01

    Full Text Available Advanced knowledge of mechanical characteristics of metal-elastomer springs is useful in their design process and selection. It can also be used in simulating dynamics of machine where such elements are utilized. Therefore this paper presents a procedure for preparing and executing FEM modelling of a single metal-elastomer spring, also called Neidhart’s spring, for low-rate deformations. Elastomer elements were made of SBR rubber of two hardness values: 50°Sh and 70°Sh. For the description of material behaviour the Bergström-Boyce model has been used.

  14. Deformation of high performance concrete plate under humid tropical weather

    Science.gov (United States)

    Niken, C.; Elly, T.; Supartono, FX; Laksmi, I.

    2018-03-01

    This paper presents the relationship between surrounding relative humidity and temperature on deformation behavior of one sample concrete plate with compressive strength of 60MPa. This research was done in Indonesia that is in humid tropical weather. A specimens measuring 3000 mm × 1600 mm × 150 mm were used. The behavior was obtained by using four embedded vibrating wire strain gauges (VWESG). As a result there is a very strong relationship between humidity and deformation at the age range of 7 until 21 days. The largest deformation occurs in the corner and the fluctuation of deformation in side position is larger than in the corner and in the middle. The peaks of surrounding relative humidity were fully followed by the deepest valley of deformation on time in the corner, while in another position the range delay time was 8 - 11 hours. There is a strong relationship between surrounding temperature and deformation at the range of 7 until 14 days. The influenced of surrounding relative humidity to concrete behavior is faster and longer than surrounding temperature. The influence of surrounding temperature in humid tropical weather was shorter than in non-humid tropical weather.

  15. Microstructure and Strain Rate-Dependent Tensile Deformation Behavior of Fiber Laser-Welded Butt Joints of Dual-Phase Steels

    Science.gov (United States)

    Liu, Yang; Dong, Danyang; Han, Zhiqiang; Yang, Zhibin; Wang, Lu; Dong, Qingwei

    2018-05-01

    The microstructure and tensile deformation behavior of the fiber laser-welded similar and dissimilar dual-phase (DP) steel joints over a wide range of strain rates from 10-3 to 103 s-1 were investigated for the further applications on the lightweight design of vehicles. The high strain rate dynamic tensile deformation process and full-field strain distribution of the base metals and welded joints were examined using the digital image correlation method and high-speed photography. The strain rate effects on the stress-strain responses, tensile properties, deformation, and fracture behavior of the investigated materials were analyzed. The yield stress (YS) and ultimate tensile strength (UTS) of the dissimilar DP780/DP980 welded joints were lying in-between those of the DP780 and DP980 base metals, and all materials exhibited positive strain rate dependence on the YS and UTS. Owing to the microstructure heterogeneity, the welded joints showed relatively lower ductility in terms of total elongation (TE) than those of the corresponding base metals. The strain localization started before the maximum load was reached, and the strain localization occurred earlier during the whole deformation process with increasing strain rate. As for the dissimilar welded joint, the strain localization tended to occur in the vicinity of the lowest hardness value across the welded joint, which was in the subcritical HAZ at the DP780 side. As the strain rate increased, the typical ductile failure characteristic of the investigated materials did not change.

  16. Microstructure and Strain Rate-Dependent Tensile Deformation Behavior of Fiber Laser-Welded Butt Joints of Dual-Phase Steels

    Science.gov (United States)

    Liu, Yang; Dong, Danyang; Han, Zhiqiang; Yang, Zhibin; Wang, Lu; Dong, Qingwei

    2018-04-01

    The microstructure and tensile deformation behavior of the fiber laser-welded similar and dissimilar dual-phase (DP) steel joints over a wide range of strain rates from 10-3 to 103 s-1 were investigated for the further applications on the lightweight design of vehicles. The high strain rate dynamic tensile deformation process and full-field strain distribution of the base metals and welded joints were examined using the digital image correlation method and high-speed photography. The strain rate effects on the stress-strain responses, tensile properties, deformation, and fracture behavior of the investigated materials were analyzed. The yield stress (YS) and ultimate tensile strength (UTS) of the dissimilar DP780/DP980 welded joints were lying in-between those of the DP780 and DP980 base metals, and all materials exhibited positive strain rate dependence on the YS and UTS. Owing to the microstructure heterogeneity, the welded joints showed relatively lower ductility in terms of total elongation (TE) than those of the corresponding base metals. The strain localization started before the maximum load was reached, and the strain localization occurred earlier during the whole deformation process with increasing strain rate. As for the dissimilar welded joint, the strain localization tended to occur in the vicinity of the lowest hardness value across the welded joint, which was in the subcritical HAZ at the DP780 side. As the strain rate increased, the typical ductile failure characteristic of the investigated materials did not change.

  17. Nuclear structure at high-spin and large-deformation

    International Nuclear Information System (INIS)

    Shimizu, Yoshifumi R.

    2000-01-01

    Atomic nucleus is a finite quantal system and shows various marvelous features. One of the purposes of the nuclear structure study is to understand such features from a microscopic viewpoint of nuclear many-body problem. Recently, it is becoming possible to explore nuclear states under 'extreme conditions', which are far different from the usual ground states of stable nuclei, and new aspects of such unstable nuclei attract our interests. In this lecture, I would like to discuss the nuclear structure in the limit of rapid rotation, or the extreme states with very large angular momenta, which became accessible by recent advent of large arrays of gamma-ray detecting system; these devices are extremely useful to measure coincident multiple γ-rays following heavy-ion fusion reactions. Including such experimental aspects as how to detect the nuclear rotational states, I review physics of high-spin states starting from the elementary subjects of nuclear structure study. In would like also to discuss the extreme states with very large nuclear deformation, which are easily realized in rapidly rotating nuclei. (author)

  18. Correlations between deformations, surface state and leak rate in metal to metal contact; Correlations entre deformations, etat de surface et debit de fuite au contact metal-metal

    Energy Technology Data Exchange (ETDEWEB)

    Armand, G; Lapujoulade, J; Paigne, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The study of metal to metal contact from the stand-point of the leak rate has been carried on a copper ring located between two hard-steel flanges. The analysis of the results confirms the hysteresis phenomenon already seen. Some curves (leak rate versus force and leak rate versus true deformation) in semi-logarithmic coordinates are straight lines. Likewise some curves (electrical contact resistance versus force) in bi-logarithmic coordinates are straight lines. All these results can be understood by looking at the conductance introduced by the deformations of the micro-geometry of the surfaces in contact. Some tests carried out in rising the temperature confirm these hypothesis. (authors) [French] L'etude du contact metal-metal du point de vue debit de fuite a ete poursuivie en utilisant un anneau de cuivre place entre brides d'acier dur. L'analyse des resultats confirme le phenomene d'hysteresis deja constate, montre l'influence de l'etat de surface des brides et du joint. Certaines courbes (debit de fuite/force et debit de fuite/deformation rationnelle), en coordonnees semi-logarithmiques, sont des droites. De meme, certaines courbes (resistance de contact/force) en coordonnees bi-logarithmiques, sont des droites. Ces resultats s'interpretent en considerant la conductance produite par la deformation des microgeometries des surfaces en contact. Quelques essais d'elevation de temperature confirment ces resultats. (auteurs)

  19. Large-strain time-temperature equivalence in high density polyethylene for prediction of extreme deformation and damage

    Directory of Open Access Journals (Sweden)

    Gray G.T.

    2012-08-01

    Full Text Available Time-temperature equivalence is a widely recognized property of many time-dependent material systems, where there is a clear predictive link relating the deformation response at a nominal temperature and a high strain-rate to an equivalent response at a depressed temperature and nominal strain-rate. It has been found that high-density polyethylene (HDPE obeys a linear empirical formulation relating test temperature and strain-rate. This observation was extended to continuous stress-strain curves, such that material response measured in a load frame at large strains and low strain-rates (at depressed temperatures could be translated into a temperature-dependent response at high strain-rates and validated against Taylor impact results. Time-temperature equivalence was used in conjuction with jump-rate compression tests to investigate isothermal response at high strain-rate while exluding adiabatic heating. The validated constitutive response was then applied to the analysis of Dynamic-Tensile-Extrusion of HDPE, a tensile analog to Taylor impact developed at LANL. The Dyn-Ten-Ext test results and FEA found that HDPE deformed smoothly after exiting the die, and after substantial drawing appeared to undergo a pressure-dependent shear damage mechanism at intermediate velocities, while it fragmented at high velocities. Dynamic-Tensile-Extrusion, properly coupled with a validated constitutive model, can successfully probe extreme tensile deformation and damage of polymers.

  20. Microstructure Deformation and Fracture Mechanism of Highly Filled Polymer Composites under Large Tensile Deformation

    International Nuclear Information System (INIS)

    Tao Zhangjiang; Ping Songdan; Mei Zhang; Cheng Zhaipeng

    2013-01-01

    The microstructure deformation and fracture mechanisms of particulate-filled polymer composites were studied based on microstructure observations in this paper. By using in-situ tensile test system under scanning electron microscopy, three different composites composed of polymer binder filled by three different types of particles, namely Al particles, AP particles and HMX particles, with the same total filler content were tested. The roles of initial microstructure damage and particle type on the microstructure deformation and damage are highlighted. The results show that microstructure damage starts with the growth of the initial microvoids within the binders or along the binder/particle interfaces. With the increase of strain, the microstructure damages including debonding at the particle/binder interface and tearing of the binder lead to microvoid coalescence, and finally cause an abrupt fracture of the samples. Coarse particles lead to an increase of debonding at the particle/binder interface both in the initial state and during the loading process, and angular particles promote interface debonding during the loading process.

  1. Biomolecular Origin of The Rate-Dependent Deformation of Prismatic Enamel

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J; Hsiung, L

    2006-07-05

    Penetration deformation of columnar prismatic enamel was investigated using instrumented nanoindentation testing, carried out at three constant strain rates (0.05 s{sup -1}, 0.005 s{sup -1}, and 0.0005 s{sup -1}). Enamel demonstrated better resistance to penetration deformation and greater elastic modulus values were measured at higher strain rates. The origin of the rate-dependent deformation was rationalized to be the shear deformation of nanoscale protein matrix surrounding each hydroxyapatite crystal rods. And the shear modulus of protein matrix was shown to depend on strain rate in a format: G{sub p} = 0.213 + 0.021 ln {dot {var_epsilon}}. Most biological composites compromise reinforcement mineral components and an organic matrix. They are generally partitioned into multi-level to form hierarchical structures that have supreme resistance to crack growth [1]. The molecular mechanistic origin of toughness is associated with the 'sacrificial chains' between the individual sub-domains in a protein molecule [2]. As the protein molecule is stretched, these 'sacrificial chains' break to protect its backbone and dissipate energy [3]. Such fresh insights are providing new momentum toward updating our understanding of biological materials [4]. Prismatic enamel in teeth is one such material. Prismatic microstructure is frequently observed in the surface layers of many biological materials, as exemplified in mollusk shells [5] and teeth [6]. It is a naturally optimized microstructure to bear impact loading and penetration deformation. In teeth, the columnar prismatic enamel provides mechanical and chemical protection for the relatively soft dentin layer. Its mechanical behavior and reliability are extremely important to ensure normal tooth function and human health. Since enamel generally contains up to 95% hydroxyapatite (HAP) crystals and less than 5% protein matrix, it is commonly believed to be a weak and brittle material with little resistance to

  2. Linking bedrock exhumation, fluvial terraces, and geomorphic indices to constrain deformation rates at multiple timescales across the Himalayan deformation front in the Kashmir Himalaya, northwest India.

    Science.gov (United States)

    Gavillot, Y. G.

    2017-12-01

    In Kashmir, the Himalayan Frontal thrust (HFT) is blind, characterized by a broad fold, the Suruin-Mastargh anticline, and displays no major emergent faults cutting either limb. A lack of knowledge of the rate of shortening and structural framework of the Suruin-Mastargh anticline hampers quantifying the earthquake potential for the deformation front. Our study combines bedrock exhumation, folded fluvial terraces, long-river profiles and river incision (specific stream power) analyses across the deformation front. At the core of the frontal fold, Apatite (U-Th)/He (AHe) cooling ages of detrital grains from the Siwalik foreland sediments indicate significant resetting. AHe data and thermal modeling reveal rapid cooling and exhumation initiated ca. 4 Ma for the deformation front, at least 3 Ma earlier than is indicated from previously available data. Exhumation rates over the last 1 m.y. and 4 m.y. range from 0.5 - 2.4 mm/yr, and 0.5 - 1 mm/yr, respectively. Four fluvial terraces yield multiple OSL and depth profiles Be10 TCN ages between 53 ka and 0.4 ka. Vector fold restoration of long terrace profiles, calculated specific stream power values, bedrock dip data, and stratigraphic thickness indicate a deformation pattern controlled by a duplex structure emplaced at depth along the basal décollement, folding the overlying roof thrust and foreland strata into a detachment-like fold. Dated terraces across the frontal fold yield rock uplift and shortening rates that range between 1.8-2.5 mm/yr, and 3.8-5.4 mm/yr, respectively, since 53 ka. Similarly, a balanced cross section yields a long-term shortening rate of 5mm mm/yr since 4 Ma. Geodetic data indicate that an 11-12 mm/yr arc-normal shortening rate characterizes the interseismic strain accumulation across the plate boundary due to India-Tibet convergence. These data combined with rates of other active internal faults in the Kashmir Himalaya indicate that shortening occurs roughly at an equal rate between folding at

  3. A test case of the deformation rate analysis (DRA) stress measurement method

    Energy Technology Data Exchange (ETDEWEB)

    Dight, P.; Hsieh, A. [Australian Centre for Geomechanics, Univ. of WA, Crawley (Australia); Johansson, E. [Saanio and Riekkola Oy, Helsinki (Finland); Hudson, J.A. [Rock Engineering Consultants (United Kingdom); Kemppainen, K.

    2012-01-15

    As part of Posiva's site and ONKALO investigations, the in situ rock stress has been measured by a variety of techniques, including hydraulic fracturing, overcoring, and convergence measurements. All these techniques involve direct measurements in a drillhole or at the rock surface. An alternative method is to test drillhole core in a way that enables estimation of the magnitudes and orientations of the in situ rock stress. The Kaiser Effect (KE) and Deformation Rate Analysis (DRA) are two ways to do this. In the work reported here, a 'blind' DRA test was conducted on core obtained from the POSE (Posiva's Olkiluoto Spalling Experiment) niche in the ONKALO. The term 'blind' means that the two first authors of this report, who conducted the tests at the Australian Centre for Geomechanics, did not know the depths below surface at which the cores had been obtained. The results of this DRA Test Case are presented, together with an explanation of the DRA procedure. Also, additional information that would help in such DRA testing and associated analysis is explained. One of the problems in comparing the DRA results with the known Olkiluoto stress field is that the latter is highly variable across the site, as experienced by the previous in situ stress measurements and as predicted by numerical analysis. The variability is mainly caused by the presence of the large brittle deformation zones which perturb the local stress state. However, this variability reduces with depth and the stress field becomes more stable at the {approx} 350 m at which the drillhole cores were obtained. Another compounding difficulty is that the stress quantity, being a second order tensor, requires six independent components for its specification. In other words, comparison of the DRA results and the known stress field requires comparison of six different quantities. In terms of the major principal stress orientation, the DRA results predict an orientation completely

  4. A test case of the deformation rate analysis (DRA) stress measurement method

    International Nuclear Information System (INIS)

    Dight, P.; Hsieh, A.; Johansson, E.; Hudson, J.A.; Kemppainen, K.

    2012-01-01

    As part of Posiva's site and ONKALO investigations, the in situ rock stress has been measured by a variety of techniques, including hydraulic fracturing, overcoring, and convergence measurements. All these techniques involve direct measurements in a drillhole or at the rock surface. An alternative method is to test drillhole core in a way that enables estimation of the magnitudes and orientations of the in situ rock stress. The Kaiser Effect (KE) and Deformation Rate Analysis (DRA) are two ways to do this. In the work reported here, a 'blind' DRA test was conducted on core obtained from the POSE (Posiva's Olkiluoto Spalling Experiment) niche in the ONKALO. The term 'blind' means that the two first authors of this report, who conducted the tests at the Australian Centre for Geomechanics, did not know the depths below surface at which the cores had been obtained. The results of this DRA Test Case are presented, together with an explanation of the DRA procedure. Also, additional information that would help in such DRA testing and associated analysis is explained. One of the problems in comparing the DRA results with the known Olkiluoto stress field is that the latter is highly variable across the site, as experienced by the previous in situ stress measurements and as predicted by numerical analysis. The variability is mainly caused by the presence of the large brittle deformation zones which perturb the local stress state. However, this variability reduces with depth and the stress field becomes more stable at the ∼ 350 m at which the drillhole cores were obtained. Another compounding difficulty is that the stress quantity, being a second order tensor, requires six independent components for its specification. In other words, comparison of the DRA results and the known stress field requires comparison of six different quantities. In terms of the major principal stress orientation, the DRA results predict an orientation completely different to the NW-SE regional

  5. Creep of crystals: High-temperature deformation processes in metals, ceramics and minerals

    Science.gov (United States)

    Poirier, J. P.

    An introductory text describing high-temperature deformation processes in metals, ceramics, and minerals is presented. Among the specific topics discussed are: the mechanical aspects of crystal deformation; lattice defects; and phenomenological and thermodynamical analysis of quasi-steady-state creep. Consideration is also given to: dislocation creep models; the effect of hydrostatic pressure on deformation; creep polygonization; and dynamic recrystallization. The status of experimental techniques for the study of transformation plasticity in crystals is also discussed.

  6. Monitoring microstructural evolution in-situ during cyclic deformation by high resolution reciprocal space mapping

    DEFF Research Database (Denmark)

    Diederichs, Annika Martina; Thiel, Felix; Fischer, Torben

    2017-01-01

    The recently developed synchrotron technique High Resolution Reciprocal Space Mapping (HRRSM) is used to characterize the deformation structures evolving during cyclic deformation of commercially pure, polycrystalline aluminium AA1050. Insight into the structural reorganization within single grains...... is gained by in-situ monitoring of the microstructural evolution during cyclic deformation. By HRRSM, a large number of individual subgrains can be resolved within individual grains in the bulk of polycrystalline specimens and their fate, their individual orientation and elastic stresses, tracked during...

  7. New Developments in Deformation Experiments at High Pressure

    International Nuclear Information System (INIS)

    Durham, W B; Weidner, D J; Karato, S; Wang, Y

    2004-01-01

    Although the importance of rheological properties in controlling the dynamics and evolution of the whole mantle of Earth is well-recognized, experimental studies of rheological properties and deformation-induced microstructures have mostly been limited to low-pressure conditions. This is mainly a result of technical limitations in conducting quantitative rheological experiments under high-pressure conditions. A combination of factors is changing this situation. Increased resolution of composition and configuration of Earth's interior has created a greater demand for well-resolved laboratory measurement of the effects of pressure on the behavior of materials. Higher-strength materials have become readily available for containing high-pressure research devices, and new analytical capabilities--in particular very bright synchrotron X-ray sources--are now readily available to high-pressure researchers. One of the biggest issues in global geodynamics is the style of mantle convection and the nature of chemical differentiation associated with convectional mass transport. Although evidence for deep mantle circulation has recently been found through seismic tomography (e.g., van der Hilst et al. (1997)), complications in convection style have also been noted. They include (1) significant modifications of flow geometry across the mantle transition zone as seen from high resolution tomographic studies (Fukao et al. 1992; Masters et al. 2000; van der Hilst et al. 1991) and (2) complicated patterns of flow in the deep lower mantle (∼1500-2500 km), perhaps caused by chemical heterogeneity (Kellogg et al. 1999; van der Hilst and Karason 1999). These studies indicate that while large-scale circulation involving the whole mantle no doubt occurs, significant deviations from simple flow geometry are also present. Two mineral properties have strong influence on convection: (1) density and (2) viscosity (rheology) contrasts. In the past, the effects of density contrast have been

  8. High temperature transient deformation of mixed oxide fuels

    International Nuclear Information System (INIS)

    Slagle, O.D.

    1986-01-01

    The purpose of this paper is to present recent experimental results on fuel creep under transient conditions at high temperatures. The effect of temperature, stress, heating rate, density and grain size were considered. An empirical formulation is derived for the relationship between strain, stress, temperature and heating rate. This relationship provides a means for incorporating stress relief into the analysis of fuel-cladding interaction during an overpower transient. The effect of sample density and initial grain size is considered by varying the sample parameters. Previously derived steady-state creep relationships for the high temperature creep of mixed oxide fuel were combined with the time dependency of creep found for UO 2 to calculate a transient creep relationship for mixed oxide fuel. These calculated results were found to be in good agreement with the measured high temperature transient creep results

  9. A novel multitemporal insar model for joint estimation of deformation rates and orbital errors

    KAUST Repository

    Zhang, Lei

    2014-06-01

    Orbital errors, characterized typically as longwavelength artifacts, commonly exist in interferometric synthetic aperture radar (InSAR) imagery as a result of inaccurate determination of the sensor state vector. Orbital errors degrade the precision of multitemporal InSAR products (i.e., ground deformation). Although research on orbital error reduction has been ongoing for nearly two decades and several algorithms for reducing the effect of the errors are already in existence, the errors cannot always be corrected efficiently and reliably. We propose a novel model that is able to jointly estimate deformation rates and orbital errors based on the different spatialoral characteristics of the two types of signals. The proposed model is able to isolate a long-wavelength ground motion signal from the orbital error even when the two types of signals exhibit similar spatial patterns. The proposed algorithm is efficient and requires no ground control points. In addition, the method is built upon wrapped phases of interferograms, eliminating the need of phase unwrapping. The performance of the proposed model is validated using both simulated and real data sets. The demo codes of the proposed model are also provided for reference. © 2013 IEEE.

  10. A new dynamic recrystallisation model of an extruded Al-Cu-Li alloy during high-temperature deformation

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Bo; Deng, Lei; Wang, Xinyun, E-mail: wangxy_hust@163.com

    2015-02-11

    The high-temperature deformation behaviour and microstructure evolution of an extruded Al-Cu-Li alloy were investigated by compression tests conducted at various temperatures (613, 673 and 733 K) with various strain rates (0.001, 0.01, and 0.1 s{sup -1}). The results indicated that the deformation activation energy increased from 208.7 kJ/mol to 255.7 kJ/mol with an increase in strain from 0.1 to 0.7. The electron backscatter diffraction maps indicated that a dynamic recrystallisation occurred during the high-temperature deformation. Two types of recrystallisation mechanisms, grain boundary bulging and a grain boundary transformation from low misorientation to high misorientation, were considered as the mechanisms for controlling the formation of the recrystallised grains. A new dynamic recrystallisation model containing these two mechanisms was proposed to describe the microstructure evolution of the extruded Al-Cu-Li alloy. At the early stage of the deformation, the recrystallised grains were formed by grain boundary bulging along the original grain boundaries. With increasing strain, recrystallised grains were gradually generated in the deformed grains due to the transformation from low angle boundaries to high angle boundaries.

  11. Effect of cold deformation on latent energy value and high-temperature mechanical properties of 12Cr18Ni10Ti steel

    International Nuclear Information System (INIS)

    Maksimkin, O.P.; Shiganakov, Sh.B.; Gusev, M.N.

    1997-01-01

    Energetic and magnetic characteristics and also the high-temperature mechanical properties depending on the preliminary cold deformation of 12Cr18Ni10Ti steel are presented. It is shown that the value of storage energy in the steel has being grown with increase of the deformation. The rate of its growth has been increased after beginning of martensitic γ→α'- transformation when value of comparative storage energy at first decreased and then has been stay practically constant. Level of mechanical properties of the steel at 1073 K has been determined not only by value of cold deformation but and structural reconstruction corresponding to deformations 35-45% and accompanying with α'-phase martensite formation and change of energy accumulating rate. Preliminary cold deformation (40-60 %) does not improve high- temperature plasticity of steel samples implanted by helium. refs. 7, figs. 2

  12. Tensile deformation behavior and deformation twinning of an equimolar CoCrFeMnNi high-entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Joo, S.-H.; Kato, H. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Jang, M.J.; Moon, J. [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of); Tsai, C.W.; Yeh, J.W. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Kim, H.S., E-mail: hskim@postech.ac.kr [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of); Center for High Entropy Alloys, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of)

    2017-03-24

    The tensile deformation and strain hardening behaviors of an equimolar CoCrFeMnNi high-entropy alloy (HEA) were investigated and compared with low and medium entropy equiatomic alloys (LEA and MEA). The HEA had a lower yield strength than the MEA because the addition of Mn weakens solid solution hardening in the HEA. However, deformation twinning induced the multiple stage strain hardening behavior of the HEA and enhanced strength and elongation. Using tensile-interrupted electron backscatter diffraction analysis, geometrically necessary dislocations were observed as plume-shaped features in grain interior, and a considerable texture was characterized, which is typical of face centered cubic metals. Moreover, the relationship between favorably oriented grains and twinning in the HEA bore a clear resemblance to the same tendency in TWIP steels. The thickness of the twin bundles was less than 100 nm. A high density of stacking defects was found in the nanotwins. Nano twinning and stacking faults were found to contribute to the remarkable mechanical properties. Deformation induced twinning not only demonstrated the dynamic Hall-Petch effect but also changed dislocation cell substructures into microband structures.

  13. Deformation and degradation of polymers in ultra-high-pressure liquid chromatography.

    Science.gov (United States)

    Uliyanchenko, Elena; van der Wal, Sjoerd; Schoenmakers, Peter J

    2011-09-28

    Ultra-high-pressure liquid chromatography (UHPLC) using columns packed with sub-2 μm particles has great potential for separations of many types of complex samples, including polymers. However, the application of UHPLC for the analysis of polymers meets some fundamental obstacles. Small particles and narrow bore tubing in combination with high pressures generate significant shear and extensional forces in UHPLC systems, which may affect polymer chains. At high stress conditions flexible macromolecules may become extended and eventually the chemical bonds in the molecules can break. Deformation and degradation of macromolecules will affect the peak retention and the peak shape in the chromatogram, which may cause errors in the obtained results (e.g. the calculated molecular-weight distributions). In the present work we explored the limitations of UHPLC for the analysis of polymers. Degradation and deformation of macromolecules were studied by collecting and re-injecting polymer peaks and by off-line two-dimensional liquid chromatography. Polystyrene standards with molecular weight of 4 MDa and larger were found to degrade at UHPLC conditions. However, for most polymers degradation could be avoided by using low linear velocities. No degradation of 3-MDa PS (and smaller) was observed at linear velocities up to 7 mm/s. The column frits were implicated as the main sources of polymer degradation. The extent of degradation was found to depend on the type of the column and on the column history. At high flow rates degradation was observed without a column being installed. We demonstrated that polymer deformation preceded degradation. Stretched polymers eluted from the column in slalom chromatography mode (elution order opposite to that in SEC or HDC). Under certain conditions we observed co-elution of large and small PS molecules though a convolution of slalom chromatography and hydrodynamic chromatography. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Variation of low temperature internal friction of microplastic deformation of high purity molybdenum single crystals

    International Nuclear Information System (INIS)

    Pal-Val, P.P.; Kaufmann, H.J.

    1984-01-01

    Amplitude and temperature spectra of ultrasound absorption in weakly deformed high purity molybdenum single crystals of different orientations were measured. The results were discussed in terms of parameter changes related to quasiparticle or dislocation oscillations, respectively, dislocation point defect interactions as well as defect generation at microplastic deformation. (author)

  15. Recrystallization textures and microstructures of Al-0.3%Cu alloy after deformation to high strains

    DEFF Research Database (Denmark)

    Li, X.R.; Wakeel, A.; Huang, T.L.

    2015-01-01

    An Al-0.3%Cu alloy was deformed to high strains by cold rolling. The as-deformed samples were annealed at different temperatures until complete recrystallization. The cold rolling textures were determined by X-ray diffraction while the recrystallization textures and microstructures were...

  16. Variation of low temperature internal friction of microplastic deformation of high purity molybdenum single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Pal-Val, P.P. (AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst. Nizkikh Temperatur); Kaufmann, H.J. (Akademie der Wissenschaften der DDR, Berlin)

    1984-08-01

    Amplitude and temperature spectra of ultrasound absorption in weakly deformed high purity molybdenum single crystals of different orientations were measured. The results were discussed in terms of parameter changes related to quasiparticle or dislocation oscillations, respectively, dislocation point defect interactions as well as defect generation at microplastic deformation.

  17. Mathematical modeling of phenomena of dynamic recrystallization during hot plastic deformation in high-carbon bainitic steel

    Directory of Open Access Journals (Sweden)

    T. Dembiczak

    2017-01-01

    Full Text Available Based on the research results, coefficients were determined in constitutive equations, describing the kinetics of dynamic recrystallization in high-carbon bainitic steel during hot deformation. The developed mathematical model takes into account the dependence of changing kinetics in the size evolution of the initial austenite grains, the value of strain, strain rate, temperature and time. Physical simulations were carried out on rectangular specimens measuring 10 × 15 × 20 mm. Compression tests with a plane state of deformation were carried out using a Gleeble 3800.

  18. Mechanism for microstructural evolution induced by high temperature deformation in Zr-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Cheng, Sirui; Wang, Chunju; Ma, Mingzhen; Shan, Debin; Guo, Bin

    2016-01-01

    In the Zr_4_1_._2Ti_1_3_._8Cu_1_2_._5Ni_1_0Be_2_2_._5 (Vit1) alloy undergoing high temperature deformation, its thermal properties and microstructure are quite different from those in the annealing alloy. In order to research the coupled effect of temperature and plastic strain on microstructural evolution of Zr-based amorphous, uniaxial compression test of Vit1 alloy with good amorphous nature has been performed, and then the structural state and thermal properties of Vit1 alloy after thermal deformation and isothermal annealing in the supercooled liquid region were investigated. It is revealed that the deformed specimens possess higher characteristic temperature and lower enthalpy change of microstructural relaxation. In addition, the smaller inter-atomic distance and higher order degree of atomic arrangement can be observed in those deformed Vit1 alloy. That can be deduced that thermal deformation is in favor of the microstructural evolution from a metastable amorphous state to stable crystallization state, because plastic strain promotes the annihilation of free volume and provide excess driving force of atomic diffusion. However, upon increasing the ambient temperature, the influence of plastic deformation on microstructure gradually decreased owing to the decreasing proportion of the plastic deformation-induced annihilation of free volume during the whole thermal deformation process. - Highlights: • The deformed specimens possess closer microstructure and higher characteristic temperatures. • The order degree of microstructures in deformed specimens is higher than that in annealed specimens. • Thermal deformation accelerates the microstructural evolution of Zr-based BMGs. • The influence of thermal deformation on microstructure decreases with the temperature increasing.

  19. Mechanism for microstructural evolution induced by high temperature deformation in Zr-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Sirui [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Chunju [Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education, Harbin Institute of Technology, Harbin 150080 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Mingzhen [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Shan, Debin, E-mail: shandebin@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education, Harbin Institute of Technology, Harbin 150080 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Guo, Bin [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2016-08-15

    In the Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} (Vit1) alloy undergoing high temperature deformation, its thermal properties and microstructure are quite different from those in the annealing alloy. In order to research the coupled effect of temperature and plastic strain on microstructural evolution of Zr-based amorphous, uniaxial compression test of Vit1 alloy with good amorphous nature has been performed, and then the structural state and thermal properties of Vit1 alloy after thermal deformation and isothermal annealing in the supercooled liquid region were investigated. It is revealed that the deformed specimens possess higher characteristic temperature and lower enthalpy change of microstructural relaxation. In addition, the smaller inter-atomic distance and higher order degree of atomic arrangement can be observed in those deformed Vit1 alloy. That can be deduced that thermal deformation is in favor of the microstructural evolution from a metastable amorphous state to stable crystallization state, because plastic strain promotes the annihilation of free volume and provide excess driving force of atomic diffusion. However, upon increasing the ambient temperature, the influence of plastic deformation on microstructure gradually decreased owing to the decreasing proportion of the plastic deformation-induced annihilation of free volume during the whole thermal deformation process. - Highlights: • The deformed specimens possess closer microstructure and higher characteristic temperatures. • The order degree of microstructures in deformed specimens is higher than that in annealed specimens. • Thermal deformation accelerates the microstructural evolution of Zr-based BMGs. • The influence of thermal deformation on microstructure decreases with the temperature increasing.

  20. Preliminary investigation on the deformation rates of the Nazimiye Fault (Eastern Turkey)

    Science.gov (United States)

    Sançar, Taylan

    2016-04-01

    The complex tectonic setting of the eastern Mediterranean is mainly shaped by the interaction between three major plates, Eurasian, African, and Arabian plates, with additional involvement from the smaller Anatolian Scholle. The internal deformation of the Anatolian Scholle is mainly accommodated along NW-striking dextral and NE-striking sinistral faults, which are explained by the Prandtl Cell model by Şengör (1979). Although some of these strike-slip faults, such as Tuzgölü, Ecemiş and Malatya-Ovacık faults, have long been documented, the Nazimiye Fault (NF) is only presented in very recent studies (Kara et al. 2013; Emre et al. 2012). The aim of the study is to understand intra-plate deformation of the Anatolian Scholle, by studying the morphotectonic structures along the NF. The study area located close to the eastern boundary of Anatolia, roughly on the wedge that is delimited by the North and East Anatolian shear zones and the Malatya-Ovacık Fault Zone. After the preliminary remote sensing analyses and field observations, I mapped the locations of the different terrace treads along the Pülümür River, which is strongly deflected by the activity of the NF. This dextral strike-slip fault, is not only characterized with the deformation of the Pülümür River, but also it shows many beheaded streams, pressure ridges, hot springs and travertines along its course. I sampled one of the alluvial fans for cosmogenic dating at the eastern section of the NF, where about 20 m of dextral offset was measured at the margins of the incised stream. Moreover, additional sampling was performed from different terrace levels along the Pülümür River, in order not only to estimate the min. horizontal rate, but also to quantify the vertical deformation. Moreover, I applied morphometric indices to understand the tectonic control on the local morphology along the NF. Transverse Topographic Symmetry Factor was used to show the relative degree of tectonic activity along the

  1. High quality transmission Kikuchi diffraction analysis of deformed alloys - Case study

    International Nuclear Information System (INIS)

    Tokarski, Tomasz; Cios, Grzegorz; Kula, Anna; Bała, Piotr

    2016-01-01

    Modern scanning electron microscopes (SEM) equipped with thermally assisted field emission guns (Schottky FEG) are capable of imaging with a resolution in the range of several nanometers or better. Simultaneously, the high electron beam current can be used, which enables fast chemical and crystallographic analysis with a higher resolution than is normally offered by SEM with a tungsten cathode. The current resolution that limits the EDS and EBSD analysis is related to materials' physics, particularly to the electron-specimen interaction volume. The application of thin, electron-transparent specimens, instead of bulk samples, improves the resolution and allows for the detailed analysis of very fine microstructural features. Beside the typical imaging mode, it is possible to use a standard EBSD camera in such a configuration that only transmitted and scattered electrons are detected. This modern approach was successfully applied to various materials giving rise to significant resolution improvement, especially for the light element magnesium based alloys. This paper presents an insight into the application of the transmission Kikuchi diffraction (TKD) technique applied to the most troublesome, heavily-deformed materials. In particular, the values of the highest possible acquisition rates for high resolution and high quality mapping were estimated within typical imaging conditions of stainless steel and magnesium-yttrium alloy. - Highlights: •Monte Carlo simulations were used to simulate EBSD camera intensity for various measuring conditions. •Transmission Kikuchi diffraction parameters were evaluated for highly deformed, light and heavy elements based alloys. •High quality maps with 20 nm spatial resolution were acquired for Mg and Fe based alloys. •High speed TKD measurements were performed at acquisition rates comparable to the reflection EBSD.

  2. Prediction of hot deformation behavior of high phosphorus steel using artificial neural network

    Science.gov (United States)

    Singh, Kanchan; Rajput, S. K.; Soota, T.; Verma, Vijay; Singh, Dharmendra

    2018-03-01

    To predict the hot deformation behavior of high phosphorus steel, the hot compression experiments were performed with the help of thermo-mechanical simulator Gleeble® 3800 in the temperatures ranging from 750 °C to 1050 °C and strain rates of 0.001 s-1, 0.01 s-1, 0.1 s-1, 0.5 s-1, 1.0 s-1 and 10 s-1. The experimental stress-strain data are employed to develop artificial neural network (ANN) model and their predictability. Using different combination of temperature, strain and strain rate as a input parameter and obtained experimental stress as a target, a multi-layer ANN model based on feed-forward back-propagation algorithm is trained, to predict the flow stress for a given processing condition. The relative error between predicted and experimental stress are in the range of ±3.5%, whereas the correlation coefficient (R2) of training and testing data are 0.99986 and 0.99999 respectively. This shows that a well-trained ANN model has excellent capability to predict the hot deformation behavior of materials. Comparative study shows quite good agreement of predicted and experimental values.

  3. High-temperature deformation of SiC-whisker-reinforced MgO-PSZ/mullite composites

    International Nuclear Information System (INIS)

    Parthasarathy, T.A.; Hay, R.S.; Ruh, R.

    1996-01-01

    The effect of 33.5 vol% SiC whisker loading on high-temperature deformation of 1 wt% MgO-38.5 wt% zirconia-mullite composites was studied between 1,300 and 1,400 C. At strain rates of 10 -6 to 5 x 10 -4 /s the creep resistance of zirconia-mullite composites without SiC reinforcement was inferior to monolithic mullite of similar grain size. Analysis of the results suggested that the decreased creep resistance of mullite-zirconia composites compared to pure mullite could be at least partially explained by mechanical effects of the weaker zirconia phase, increased effective diffusivity of mullite by zirconia addition, and to the differences in mullite grain morphology. With SiC whisker reinforcement, the deformation rate at high stress was nearly the same as that of the unreinforced material, but at low stress the creep rates of the SiC-reinforced material were significantly lowered. The stress dependence of the creep rate of unreinforced material suggested that diffusional creep was the operative mechanism, while the reinforced material behaved as if a threshold stress for creep existed. The threshold stress could be rationalized based on a whisker network model. This was supported by data on other whisker-containing materials; however, the threshold stress had a temperature dependence that was orders of magnitude higher than the elastic constants, leaving the physical model incomplete. The effects of residual stresses and amorphous phases at whisker/matrix interfaces are invoked to help complete the physical model for creep threshold stress

  4. Cytocompatibility evaluation and surface characterization of TiNi deformed by high-pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Awang Shri, Dayangku Noorfazidah, E-mail: AWANGSHRI.Dayangku@nims.go.jp [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Structural Materials Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Tsuchiya, Koichi [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Structural Materials Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Yamamoto, Akiko [Biomaterials Unit, International Center for Material Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-10-01

    Effect of high-pressure torsion (HPT) deformation on biocompatibility and surface chemistry of TiNi was systematically investigated. Ti–50 mol% Ni was subjected to HPT straining for different numbers of turns, N = 0.25, 0.5, 1, 5 and 10 at a rotation speed of 1 rpm. X-ray photoelectron spectroscopy observations after 7 days of cell culture revealed the changes in the surface oxide composition, enrichment of Ti and detection of nitrogen derived from organic molecules in the culture medium. Plating efficiency of L929 cells was slightly increased by HPT deformation though no significant difference was observed. Albumin adsorption was higher in HPT-deformed samples, while vitronectin adsorption was peaked at N = 1. HPT deformation was also found to effectively suppress the Ni ion release from the TiNi samples into the cell culture medium even after the low degree of deformation at N = 0.25. - Highlights: • Nanostructured Ti–50 mol%Ni alloy was produced using high-pressure torsion. • HPT deformation improved L929 growth on TiNi samples. • Changes in surface chemistry were observed in HPT deformed samples. • Protein adsorption behavior was influenced by the surface chemistry. • Ni ion release was suppressed in HPT deformed samples.

  5. Variability of sea ice deformation rates in the Arctic and their relationship with basin-scale wind forcing

    Directory of Open Access Journals (Sweden)

    A. Herman

    2012-12-01

    Full Text Available The temporal variability of the moments of probability distribution functions (pdfs of total sea ice deformation rates in the Arctic is analyzed in the context of the basin-scale wind forcing acting on the ice. The pdfs are estimated for 594 satellite-derived sea ice deformation maps from 11 winter seasons between 1996/1997 and 2007/2008, provided by the RADARSAT Geophysical Processor System. The temporal scale analyzed equals 3 days. The moments of the pdfs, calculated for a range of spatial scales (12.5–900 km, have two dominating components of variability: a seasonal cycle, with deformation rates decreasing throughout winter towards a minimum in March; and a short-term, synoptic variability, strongly correlated with the area-averaged magnitude of the wind stress over the Arctic, estimated based on the NCEP-DOE Reanalysis-2 data (correlation coefficient of 0.71 for the mean deformation rate. Due to scaling properties of the moments, logarithms of higher moments are strongly correlated with the wind stress as well. Exceptions are observed only at small spatial scales, as a result of extreme deformation events, not directly associated with large-scale wind forcing. By repeating the analysis within regions of different sizes and locations, we show that the wind–ice deformation correlation is largest at the basin scale and decreases with decreasing size of the area of study. Finally, we suggest that a positive trend in seasonally averaged correlation between sea ice deformation rates and the wind forcing, present in the analyzed data, may be related to an observed decrease in the multi-year ice area in the Arctic, indicating possibly even stronger correlations in the future.

  6. Stretching of red blood cells at high strain rates

    Science.gov (United States)

    Mancuso, J. E.; Ristenpart, W. D.

    2017-10-01

    Most work on the mechanical behavior of red blood cells (RBCs) in flow has focused on simple shear flows. Relatively little work has examined RBC deformations in the physiologically important extensional flow that occurs at the entrance to a constriction. In particular, previous work suggests that RBCs rapidly stretch out and then retract upon entering the constriction, but to date no model predicts this behavior for the extremely high strain rates typically experienced there. In this Rapid Communication, we use high speed video to perform systematic measurements of the dynamic stretching behavior of RBCs as they enter a microfluidic constriction. We demonstrate that both the Kelvin-Voigt and Skalak viscoelastic models capture the observed stretching dynamics, up to strain rates as high as 2000 s-1. The results indicate that the effective elastic modulus of the RBC membrane at these strain rates is an order of magnitude larger than moduli measured by micropipette aspiration or other low strain rate techniques.

  7. Magneto-induced large deformation and high-damping performance of a magnetorheological plastomer

    International Nuclear Information System (INIS)

    Liu, Taixiang; Gong, Xinglong; Xu, Yangguang; Pang, Haoming; Xuan, Shouhu

    2014-01-01

    A magnetorheological plastomer (MRP) is a new kind of soft magneto-sensitive polymeric composite. This work reports on the large magneto-deforming effect and high magneto-damping performance of MRPs under a quasi-statical shearing condition. We demonstrate that an MRP possesses a magnetically sensitive malleability, and its magneto-mechanical behavior can be analytically described by the magneto-enhanced Bingham fluid-like model. The magneto-induced axial stress, which drives the deformation of the MRP with 70 wt % carbonyl iron powder, can be tuned in a large range from nearly 0.0 kPa to 55.4 kPa by an external 662.6 kA m −1 magnetic field. The damping performance of an MRP has a significant correlation with the magnetic strength, shear rate, carbonyl iron content and shear strain amplitude. For an MRP with 60 wt % carbonyl iron powder, the relative magneto-enhanced damping effect can reach as high as 716.2% under a quasi-statically shearing condition. Furthermore, the related physical mechanism is proposed, and we reveal that the magneto-induced, particle-assembled microstructure directs the magneto-mechanical behavior of the MRP. (paper)

  8. High Strain Rate Tensile Testing of Silver Nanowires: Rate-Dependent Brittle-to-Ductile Transition.

    Science.gov (United States)

    Ramachandramoorthy, Rajaprakash; Gao, Wei; Bernal, Rodrigo; Espinosa, Horacio

    2016-01-13

    The characterization of nanomaterials under high strain rates is critical to understand their suitability for dynamic applications such as nanoresonators and nanoswitches. It is also of great theoretical importance to explore nanomechanics with dynamic and rate effects. Here, we report in situ scanning electron microscope (SEM) tensile testing of bicrystalline silver nanowires at strain rates up to 2/s, which is 2 orders of magnitude higher than previously reported in the literature. The experiments are enabled by a microelectromechanical system (MEMS) with fast response time. It was identified that the nanowire plastic deformation has a small activation volume (ductile failure mode transition was observed at a threshold strain rate of 0.2/s. Transmission electron microscopy (TEM) revealed that along the nanowire, dislocation density and spatial distribution of plastic regions increase with increasing strain rate. Furthermore, molecular dynamic (MD) simulations show that deformation mechanisms such as grain boundary migration and dislocation interactions are responsible for such ductility. Finally, the MD and experimental results were interpreted using dislocation nucleation theory. The predicted yield stress values are in agreement with the experimental results for strain rates above 0.2/s when ductility is pronounced. At low strain rates, random imperfections on the nanowire surface trigger localized plasticity, leading to a brittle-like failure.

  9. Electric anisotropy in high density polyethylene + carbon black composites induced by mechanical deformation

    Energy Technology Data Exchange (ETDEWEB)

    Vigueras-Santiago, E; Hernandez-Lopez, S; Camacho-Lopez, M A; Lara-Sanjuan, O, E-mail: eviguerass@uaemex.m [Laboratorio de Investigacion y Desarrollo de Materiales Avanzados (LIDMA), Facultad de Quimica, UAEM. Paseo Colon esq. con Paseo Tollocan, s/n. C.P. 50000, Toluca (Mexico)

    2009-05-01

    High density polyethylene + carbon black composites with electrical anisotropy was studied. Electrical anisotropy was induced by uniaxial mechanical deformation and injection moulding. We show that anisotropy depends on the carbon black concentration and percentage deformation. Resistivity had the highest anisotropy resistivity around the percolation threshold. Perpendicular resistivity showed two magnitude orders higher than parallel resistivity for injected samples, whereas resistivity showed an inverse behaviour for 100% tensile samples. Both directions were set respect to the deformation axe. Anisotropy could be explained in terms of the molecular deformation (alignment) of the polymer chains as a response of the deformation process originating a redistribution of the carbon black particles in both directions. Alignment of the polymer chains was evidenced by polarized Raman spectroscopy.

  10. TEMPERATURE-DEFORMATION CRITERION OF OPTIMIZATION OF FINE DRAWING HIGH CARBON WIRE ROUTE

    Directory of Open Access Journals (Sweden)

    Y. L. Bobarikin

    2012-01-01

    Full Text Available The temperature-deformation criterion of assessment and optimization of routes of the thin high-carbon wire drawing enabling to increase plastic properties of wire at retaining of its durability is offered.

  11. Microstructure characteristic for high temperature deformation of powder metallurgy Ti–47Al–2Cr–0.2Mo alloy

    International Nuclear Information System (INIS)

    Zhang, Dan-yang; Li, Hui-zhong; Liang, Xiao-peng; Wei, Zhong-wei; Liu, Yong

    2014-01-01

    Highlights: • With temperature increasing and strain rate decreasing, the β phase decreases. • With temperature increasing and strain rate decreasing, DRX grains increase. • The high temperature deformation mechanism of TiAl alloy was clearly. - Abstract: Hot compression tests of a powder metallurgy (P/M) Ti–47Al–2Cr–0.2Mo (at. pct) alloy were carried out on a Gleeble-3500 simulator at the temperatures ranging from 1000 °C to 1150 °C with low strain rates ranging from 1 × 10 −3 s −1 to 1 s −1 . Electron back scattered diffraction (EBSD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were employed to investigate the microstructure characteristic and nucleation mechanisms of dynamic recrystallization. The stress–strain curves show the typical characteristic of working hardening and flow softening. The working hardening is attributed to the dislocation movement. The flow softening is attributed to the dynamic recrystallization (DRX). The number of β phase decreases with increasing of deformation temperature and decreasing of strain rate. The ratio of dynamic recrystallization grain increases with the increasing of temperature and decreasing of strain rate. High temperature deformation mechanism of powder metallurgy Ti–47Al–2Cr–0.2Mo alloy mainly refers to twinning, dislocations motion, bending and reorientation of lamellae

  12. Effect of initial grain size on inhomogeneous plastic deformation and twinning behavior in high manganese austenitic steel with a polycrystalline microstructure

    Science.gov (United States)

    Ueji, R.; Tsuchida, N.; Harada, K.; Takaki, K.; Fujii, H.

    2015-08-01

    The grain size effect on the deformation twinning in a high manganese austenitic steel which is so-called TWIP (twining induced plastic deformation) steel was studied in order to understand how to control deformation twinning. The 31wt%Mn-3%Al-3% Si steel was cold rolled and annealed at various temperatures to obtain fully recrystallized structures with different mean grain sizes. These annealed sheets were examined by room temperature tensile tests at a strain rate of 10-4/s. The coarse grained sample (grain size: 49.6μm) showed many deformation twins and the deformation twinning was preferentially found in the grains in which the tensile axis is parallel near to [111]. On the other hand, the sample with finer grains (1.8 μm) had few grains with twinning even after the tensile deformation. The electron back scattering diffraction (EB SD) measurements clarified the relationship between the anisotropy of deformation twinning and that of inhomogeneous plastic deformation. Based on the EBSD analysis, the mechanism of the suppression of deformation twinning by grain refinement was discussed with the concept of the slip pattern competition between the slip system governed by a grain boundary and that activated by the macroscopic load.

  13. Physical nature of strain rate sensitivity of metals and alloys at high strain rates

    Science.gov (United States)

    Borodin, E. N.; Gruzdkov, A. A.; Mayer, A. E.; Selyutina, N. S.

    2018-04-01

    The role of instabilities of plastic flow at plastic deformation of various materials is one of the important cross-disciplinary problems which is equally important in physics, mechanics and material science. The strain rate sensitivities under slow and high strain rate conditions of loading have different physical nature. In the case of low strain rate, the sensitivity arising from the inertness of the defect structures evolution can be expressed by a single parameter characterizing the plasticity mechanism. In our approach, this is the value of the characteristic relaxation time. In the dynamic case, there are additional effects of “high-speed sensitivity” associated with the micro-localization of the plastic flow near the stress concentrators. In the frames of mechanical description, this requires to introduce additional strain rate sensitivity parameters, which is realized in numerous modifications of Johnson–Cook and Zerilli–Armstrong models. The consideration of both these factors is fundamental for an adequate description of the problems of dynamic deformation of highly inhomogeneous metallic materials such as steels and alloys. The measurement of the dispersion of particle velocities on the free surface of a shock-loaded material can be regarded as an experimental expression of the effect of micro-localization. This is also confirmed by our results of numerical simulation of the propagation of shock waves in a two-dimensional formulation and analytical estimations.

  14. Coal Matrix Deformation and Pore Structure Change in High-Pressure Nitrogen Replacement of Methane

    Directory of Open Access Journals (Sweden)

    Xiaofeng Ji

    2018-01-01

    Full Text Available Coal matrix deformation is one of the main controlling factors for coal reservoir permeability changes in nitrogen foam fracturing. The characteristics and mechanism of coal matrix deformation during the process of adsorption/desorption were studied by isothermal adsorption/desorption experiments with methane and nitrogen. Based on the free-energy theories, the Langmuir equation, and elastic mechanics, mathematical models of coal matrix deformation were developed and the deformation characteristics in adsorption/desorption processes were examined. From the study, we deduced that the coal matrix swelling, caused by methane adsorption, was a Langmuir-type relationship with the gas pressure, and exponentially increased as the adsorption quantity increased. Then, the deformation rate and amplitude of the coal matrix decreased gradually with the increase of the pressure. At the following stage, where nitrogen replaces methane, the coal matrix swelling continued but the deformation amplitude decreased, which was only 19.60% of the methane adsorption stage. At the mixed gas desorption stage, the coal matrix shrank with the reduction of pressure and the shrinkage amount changed logarithmically with the pressure, which had the hysteresis effect when compared with the swelling in adsorption. The mechanism of coal matrix deformation was discussed through a comparison of the change of micropores, mesopores, and also part macropores in the adsorption process.

  15. Plastic deformation of Al13Fe4 particles in Al-Al13Fe4 by high-speed compression

    International Nuclear Information System (INIS)

    Yoneyama, N.; Mizoguchi, K.; Kumai, S.; Sato, A.; Kiritani, M.

    2003-01-01

    Spray-formed Al-Fe alloys having undergone high-speed deformation were examined under a high-voltage electron microscope. Two types of specimens were examined; one containing fine Al 13 Fe 4 particles, and the other containing large particles. In the former specimen, deformation is found to proceed in three patterns, depending on specimen thickness and strain rate: (1) without deformation of the Al 13 Fe 4 ; (2) breaking of the Al 13 Fe 4 ; or (3) melting of the Al 13 Fe 4 . Local melting is found to alter some of the Al 13 Fe 4 particles, to impart five-fold symmetry in diffraction or an amorphous structure. In the latter specimen, introduction of glide dislocations enabled us to determine a shear system in the mc102 monoclinic c2/m crystal of Al 13 Fe 4 . On the bases of these observations, the mechanism of high-speed deformation is discussed while taking into account the highly stressed and/or heated states of Al 13 Fe 4 embedded in Al matrix

  16. High prevalence of morphometric vertebral deformities in patients with inflammatory bowel disease.

    Science.gov (United States)

    Heijckmann, Anna Caroline; Huijberts, Maya S P; Schoon, Erik J; Geusens, Piet; de Vries, Jolanda; Menheere, Paul P C A; van der Veer, Eveline; Wolffenbuttel, Bruce H R; Stockbrugger, Reinhold W; Dumitrescu, Bianca; Nieuwenhuijzen Kruseman, Arie C

    2008-08-01

    Earlier studies have documented that the prevalence of decreased bone mineral density (BMD) is elevated in patients with inflammatory bowel disease. The objective of this study was to investigate the prevalence of vertebral deformities in inflammatory bowel disease patients and their relation with BMD and bone turnover. One hundred and nine patients with Crohn's disease (CD) and 72 with ulcerative colitis (UC) (age 44.5+/-14.2 years) were studied. BMD of the hip (by dual X-ray absorptiometry) was measured and a lateral single energy densitometry of the spine for assessment of vertebral deformities was performed. Serum markers of bone resorption (carboxy-terminal cross-linked telopeptide of type I collagen) and formation (procollagen type I amino-terminal propeptide) were measured, and determinants of prevalent vertebral deformities were assessed using logistic regression analysis. Vertebral deformities were found in 25% of both CD and UC patients. Comparing patients with and without vertebral deformities, no significant difference was found between Z-scores and T-scores of BMD, or levels of serum carboxy-terminal cross-linked telopeptide of type I collagen and serum procollagen type I amino-terminal propeptide. Using logistic regression analysis the only determinant of any morphometric vertebral deformity was sex. The presence of multiple vertebral deformities was associated with older age and glucocorticoid use. The prevalence of morphometric vertebral deformities is high in CD and UC. Male sex, but neither disease activity, bone turnover markers, clinical risk factors, nor BMD predicted their presence. The determinants for having more than one vertebral deformity were age and glucocorticoid use. This implies that in addition to screening for low BMD, morphometric assessment of vertebral deformities is warranted in CD and UC.

  17. High temperature deformation of polycrystalline NiO and CoO

    International Nuclear Information System (INIS)

    Krishnamachari, V.; Notis, M.R.

    1977-01-01

    High temperature creep of polycrystalline NiO appears to be controlled by oxygen lattice diffusion at temperatures between 1273 and 1373 K and at stress levels from 34.5 to 79.8 MPa (5 to 11 ksi). Experimentally observed creep rates agree well with predictions obtained from deformation maps based on self-diffusion data. TEM examination indicates that dislocations present in crept NiO specimens are predominantly glide-type rather than climb-type dislocations as found in CoO. The difference in creep behavior of these materials is believed to be due to the difference in stacking fault energies and the nature of charge associated with lattice defects. 2 tables. 7 figs., 34 references

  18. Rate controlling mechanisms during hot deformation of Mg–3Gd–1Zn magnesium alloy: Dislocation glide and climb, dynamic recrystallization, and mechanical twinning

    International Nuclear Information System (INIS)

    Mirzadeh, H.; Roostaei, M.; Parsa, M.H.; Mahmudi, R.

    2015-01-01

    Highlights: • Hot deformation behavior and dynamic recrystallization of GZ31 magnesium alloy. • Deducing the operative deformation mechanisms by constitutive analysis. • Viscous glide as the rate controlling step during hot working of GZ31 alloy. • Characterization of the effect of mechanical twinning on constitutive relations. - Abstract: The flow behavior of the Mg–3Gd–1Zn (GZ31) magnesium alloy during hot working was critically analyzed and dislocation glide in the form of a viscous drag process (viscous glide) was identified as the rate controlling mechanism due to interaction of rare earth Gd atoms with the moving dislocations. Mechanical twinning was shown to significantly affect the level of flow stress at high Zener–Hollomon parameters, i.e. low forming temperatures and high strain rates. Moreover, dynamic recrystallization (DRX) was found to be another responsible phenomenon for deviation of constitutive equations from the theoretical ones, namely the deformation activation energy based on diffusivity and the pre-defined Garofalo’s type hyperbolic sine power, during high-temperature thermomechanical processing of this creep resistant light alloy

  19. Alloy-dependent deformation behavior of highly ductile nanocrystalline AuCu thin films

    International Nuclear Information System (INIS)

    Lohmiller, Jochen; Spolenak, Ralph; Gruber, Patric A.

    2014-01-01

    Nanocrystalline thin films on compliant substrates become increasingly important for the development of flexible electronic devices. In this study, nanocrystalline AuCu thin films on polyimide substrate were tested in tension while using a synchrotron-based in situ testing technique. Analysis of X-ray diffraction profiles allowed identifying the underlying deformation mechanisms. Initially, elastic and microplastic deformation is observed, followed by dislocation-mediated shear band formation, and eventually macroscopic crack formation. Particularly the influence of alloy composition, heat-treatment, and test temperature were investigated. Generally, a highly ductile behavior is observed. However, high Cu concentrations, annealing, and/or large plastic strains lead to localized deformation and hence reduced ductility. On the other hand, enhanced test temperature allows for a delocalized deformation and extended ductility

  20. Alloy-dependent deformation behavior of highly ductile nanocrystalline AuCu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lohmiller, Jochen [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, 76021 Karlsruhe (Germany); Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich (Switzerland); Spolenak, Ralph [Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich (Switzerland); Gruber, Patric A., E-mail: patric.gruber@kit.edu [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, 76021 Karlsruhe (Germany)

    2014-02-10

    Nanocrystalline thin films on compliant substrates become increasingly important for the development of flexible electronic devices. In this study, nanocrystalline AuCu thin films on polyimide substrate were tested in tension while using a synchrotron-based in situ testing technique. Analysis of X-ray diffraction profiles allowed identifying the underlying deformation mechanisms. Initially, elastic and microplastic deformation is observed, followed by dislocation-mediated shear band formation, and eventually macroscopic crack formation. Particularly the influence of alloy composition, heat-treatment, and test temperature were investigated. Generally, a highly ductile behavior is observed. However, high Cu concentrations, annealing, and/or large plastic strains lead to localized deformation and hence reduced ductility. On the other hand, enhanced test temperature allows for a delocalized deformation and extended ductility.

  1. Strain Rate Effect on Tensile Behavior for a High Specific Strength Steel: From Quasi-Static to Intermediate Strain Rates

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2017-12-01

    Full Text Available The strain rate effect on the tensile behaviors of a high specific strength steel (HSSS with dual-phase microstructure has been investigated. The yield strength, the ultimate strength and the tensile toughness were all observed to increase with increasing strain rates at the range of 0.0006 to 56/s, rendering this HSSS as an excellent candidate for an energy absorber in the automobile industry, since vehicle crushing often happens at intermediate strain rates. Back stress hardening has been found to play an important role for this HSSS due to load transfer and strain partitioning between two phases, and a higher strain rate could cause even higher strain partitioning in the softer austenite grains, delaying the deformation instability. Deformation twins are observed in the austenite grains at all strain rates to facilitate the uniform tensile deformation. The B2 phase (FeAl intermetallic compound is less deformable at higher strain rates, resulting in easier brittle fracture in B2 particles, smaller dimple size and a higher density of phase interfaces in final fracture surfaces. Thus, more energy need be consumed during the final fracture for the experiments conducted at higher strain rates, resulting in better tensile toughness.

  2. High-temperature behavior of a deformed Fermi gas obeying interpolating statistics.

    Science.gov (United States)

    Algin, Abdullah; Senay, Mustafa

    2012-04-01

    An outstanding idea originally introduced by Greenberg is to investigate whether there is equivalence between intermediate statistics, which may be different from anyonic statistics, and q-deformed particle algebra. Also, a model to be studied for addressing such an idea could possibly provide us some new consequences about the interactions of particles as well as their internal structures. Motivated mainly by this idea, in this work, we consider a q-deformed Fermi gas model whose statistical properties enable us to effectively study interpolating statistics. Starting with a generalized Fermi-Dirac distribution function, we derive several thermostatistical functions of a gas of these deformed fermions in the thermodynamical limit. We study the high-temperature behavior of the system by analyzing the effects of q deformation on the most important thermostatistical characteristics of the system such as the entropy, specific heat, and equation of state. It is shown that such a deformed fermion model in two and three spatial dimensions exhibits the interpolating statistics in a specific interval of the model deformation parameter 0 < q < 1. In particular, for two and three spatial dimensions, it is found from the behavior of the third virial coefficient of the model that the deformation parameter q interpolates completely between attractive and repulsive systems, including the free boson and fermion cases. From the results obtained in this work, we conclude that such a model could provide much physical insight into some interacting theories of fermions, and could be useful to further study the particle systems with intermediate statistics.

  3. Understanding High Rate Behavior Through Low Rate Analog

    Science.gov (United States)

    2014-04-28

    challenges in high rate character- isation of polymers. The most important is that, owing to their low stress wavespeed, the structural response of...box’ tool, to provide supporting date for the rate dependent mechanical character- isation . Experiments were performed on a TA instruments Q800

  4. Deformation limits of polymer coated metal sheets

    NARCIS (Netherlands)

    Van Den Bosch, M.J.W.J.P.; Schreurs, P.J.G; Geers, M.G.D.

    2005-01-01

    Polymer coated metals are increasingly used by the packaging and automotive industry. During industrial deformation processes (drawing, roll-forming, bending etc.) the polymer-metal laminate is highly deformed at high deformation rates. These forming conditions can affect the mechanical integrity

  5. Paediatric lower limb deformity correction using the Ilizarov technique: a statistical analysis of factors affecting the complication rate.

    Science.gov (United States)

    Oostenbroek, Hubert J; Brand, Ronald; van Roermund, Peter M; Castelein, René M

    2014-01-01

    Limb length discrepancy (LLD) and other patient factors are thought to influence the complication rate in (paediatric) limb deformity correction. In the literature, information is conflicting. This study was performed to identify clinical factors that affect the complication rate in paediatric lower-limb lengthening. A consecutive group of 37 children was analysed. The median proportionate LLD was 15 (4-42)%. An analysis was carried out on several patient factors that may complicate the treatment or end result using logistic regression in a polytomous logistic regression model. The factors analysed were proportionate LLD, cause of deformity, location of corrected bone, and the classification of the deformity according to an overall classification that includes the LLD and all concomitant deformity factors. The median age at the start of the treatment was 11 (6-17) years. The median lengthening index was 1.5 (0.8-3.8) months per centimetre lengthening. The obstacle and complication rate was 69% per lengthened bone. Proportionate LLD was the only statistically significant predictor for the occurrence of complications. Concomitant deformities did not influence the complication rate. From these data we constructed a simple graph that shows the relationship between proportionate LLD and risk for complications. This study shows that only relative LLD is a predictor of the risk for complications. The additional value of this analysis is the production of a simple graph. Construction of this graph using data of a patient group (for example, your own) may allow a more realistic comparison with results in the literature than has been possible before.

  6. Deformation mechanisms in a fine-grained Udimet 720LI nickel-base superalloy with high volume fractions of γ′ phases

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiayu, E-mail: chenjiayu975@126.com; Dong, Jianxin; Zhang, Maicang; Yao, Zhihao

    2016-09-15

    Hot-deformation behaviors and mechanisms below γ′ solvus of U720LI with fine-grained microstructure and high volume fractions of γ′ phases were studied. MTS hot-compressed samples under hot-deformation parameters (Temperatures of 1040 °C, 1070 °C, 1100 °C, 1130 °C, strain rates of 0.01 s{sup −1}, 0.1 s{sup −1}, 0.5 s{sup −1} and strains of 0.11, 0.36, 0.69 and 1.2) were investigated by using multiple microstructural analysis methods, such as transmission electron microscopy (TEM), electron channeling contrast image (ECCI), et al.. Rare recovery and recrystallization were observed indicating that other deformation mechanisms might be enhanced during the deformation process. Except for the pinning effect, deformation happened within γ′ phases and also γ′ phase promoted the deformation of the matrix. When the slipping was inhibited by γ′ phases, twinning acted as a deformation mechanism in fine-grained U720LI. Due to the retardation effect of γ′ phases in the early stage of the deformation process, local grain boundary migration took effect. Once grain boundaries crossed γ′ phases, it made recrystallization by strain induced boundary motion(SIBM) easier.

  7. High temperature deformation mechanisms of L12-containing Co-based superalloys

    Science.gov (United States)

    Titus, Michael Shaw

    Ni-based superalloys have been used as the structural material of choice for high temperature applications in gas turbine engines since the 1940s, but their operating temperature is becoming limited by their melting temperature (Tm =1300degrees C). Despite decades of research, no viable alternatives to Ni-based superalloys have been discovered and developed. However, in 2006, a ternary gamma' phase was discovered in the Co-Al-W system that enabled a new class of Co-based superalloys to be developed. These new Co-based superalloys possess a gamma-gamma' microstructure that is nearly identical to Ni-based superalloys, which enables these superalloys to achieve extraordinary high temperature mechanical properties. Furthermore, Co-based alloys possess the added benefit of exhibiting a melting temperature of at least 100degrees C higher than commercial Ni-based superalloys. Superalloys used as the structural materials in high pressure turbine blades must withstand large thermomechanical stresses imparted from the rotating disk and hot, corrosive gases present. These stresses induce time-dependent plastic deformation, which is commonly known as creep, and new superalloys must possess adequate creep resistance over a broad range of temperature in order to be used as the structural materials for high pressure turbine blades. For these reasons, this research focuses on quantifying high temperature creep properties of new gamma'-containing Co-based superalloys and identifying the high temperature creep deformation mechanisms. The high temperature creep properties of new Co- and CoNi-based alloys were found to be comparable to Ni-based superalloys with respect to minimum creep rates and creep-rupture lives at 900degrees C up to the solvus temperature of the gamma' phase. Co-based alloys exhibited a propensity for extended superlattice stacking fault formation in the gamma' precipitates resulting from dislocation shearing events. When Ni was added to the Co-based compositions

  8. Characterization of low-mass deformable mirrors and ASIC drivers for high-contrast imaging

    Science.gov (United States)

    Mejia Prada, Camilo; Yao, Li; Wu, Yuqian; Roberts, Lewis C.; Shelton, Chris; Wu, Xingtao

    2017-09-01

    The development of compact, high performance Deformable Mirrors (DMs) is one of the most important technological challenges for high-contrast imaging on space missions. Microscale Inc. has fabricated and characterized piezoelectric stack actuator deformable mirrors (PZT-DMs) and Application-Specific Integrated Circuit (ASIC) drivers for direct integration. The DM-ASIC system is designed to eliminate almost all cables, enabling a very compact optical system with low mass and low power consumption. We report on the optical tests used to evaluate the performance of the DM and ASIC units. We also compare the results to the requirements for space-based high-contrast imaging of exoplanets.

  9. Sustained high basal motion of the Greenland ice sheet revealed by borehole deformation

    DEFF Research Database (Denmark)

    Ryser, Claudia; Luethi, Martin P.; Andrews, Lauren C.

    2014-01-01

    amount of basal motion contribution to surface velocity of 44-73% in winter, and up to 90% in summer. Measured ice deformation rates show an unexpected variation with depth that can be explained with the help of an ice-flow model as a consequence of stress transfer from slippery to sticky areas...

  10. Investigation on coupling error characteristics in angular rate matching based ship deformation measurement approach

    Science.gov (United States)

    Yang, Shuai; Wu, Wei; Wang, Xingshu; Xu, Zhiguang

    2018-01-01

    The coupling error in the measurement of ship hull deformation can significantly influence the attitude accuracy of the shipborne weapons and equipments. It is therefore important to study the characteristics of the coupling error. In this paper, an comprehensive investigation on the coupling error is reported, which has a potential of deducting the coupling error in the future. Firstly, the causes and characteristics of the coupling error are analyzed theoretically based on the basic theory of measuring ship deformation. Then, simulations are conducted for verifying the correctness of the theoretical analysis. Simulation results show that the cross-correlation between dynamic flexure and ship angular motion leads to the coupling error in measuring ship deformation, and coupling error increases with the correlation value between them. All the simulation results coincide with the theoretical analysis.

  11. Expressway deformation mapping using high-resolution TerraSAR-X images

    KAUST Repository

    Shi, Xuguo

    2014-01-27

    Monitoring deformation of linear infrastructures such as expressway and railway caused by natural processes or anthropogenic activities is a vital task to ensure the safety of human lives and properties. Interferometric Synthetic Aperture Radar (InSAR) has been widely recognized as an effective technology to carry out large-area surface deformation mapping. However, its application in linear infrastructure deformation monitoring has not been intensively studied till now. In this article, a modified Small BAseline Subset (SBAS) method is proposed to retrieve the deformation patterns of the expressway. In our method, only the point-like targets identified on the expressway were kept in our analysis, and two complementary subsets of interferograms were formed to better separate the signals of height error and deformation from inteferometric phase observations. We successfully applied this method with multitemporal high-resolution TerraSAR-X images to retrieve the spatialoral pattern of surface deformation along the Beian-Heihe expressway that is located in island-permafrost areas and threatened by geohazards. © 2014 Taylor & Francis.

  12. Expressway deformation mapping using high-resolution TerraSAR-X images

    KAUST Repository

    Shi, Xuguo; Liao, Mingsheng; Wang, Teng; Zhang, Lu; Shan, Wei; Wang, Chunjiao

    2014-01-01

    Monitoring deformation of linear infrastructures such as expressway and railway caused by natural processes or anthropogenic activities is a vital task to ensure the safety of human lives and properties. Interferometric Synthetic Aperture Radar (InSAR) has been widely recognized as an effective technology to carry out large-area surface deformation mapping. However, its application in linear infrastructure deformation monitoring has not been intensively studied till now. In this article, a modified Small BAseline Subset (SBAS) method is proposed to retrieve the deformation patterns of the expressway. In our method, only the point-like targets identified on the expressway were kept in our analysis, and two complementary subsets of interferograms were formed to better separate the signals of height error and deformation from inteferometric phase observations. We successfully applied this method with multitemporal high-resolution TerraSAR-X images to retrieve the spatialoral pattern of surface deformation along the Beian-Heihe expressway that is located in island-permafrost areas and threatened by geohazards. © 2014 Taylor & Francis.

  13. Investigation of inhomogeneous deformation in band amorphous alloys at constant heating rate

    Science.gov (United States)

    Fedorov, Victor; Berezner, Arseniy; Pluzhnikova, Tatiana; Beskrovnyi, Anatolyi

    2017-11-01

    The present paper contains investigations of the creep process in the cobalt-based amorphous metallic alloy within the temperature range from 300 up to 1023 K. In all the curves of deformation there were observed jumps and dying oscillations. It is noted that the creep of the sample ribbons is unstable and results in the thinning of ribbons with tightening and crimping. There is suggested the mechanism of inhomogeneous deformation, which takes place in course of the process of creep under intermittent heating. For the evaluation of amorphism in the treated samples there have been carried out neutron-graphical and X-ray diffraction investigations, as well as thermal analysis.

  14. InSAR deformation monitoring of high risk landslides

    Science.gov (United States)

    Singhroy, V.; Li, J.

    2013-05-01

    During the past year there were at least twenty five media reports of landslides and seismic activities some fatal, occurring in various areas in Canada. These high risk geohazards sites requires high resolution monitoring both spatially and temporally for mitigation purposes, since they are near populated areas and energy, transportation and communication corridors. High resolution air photos, lidar and satellite images are quite common in areas where the landslides can be fatal. Radar interferometry (InSAR) techniques using images from several radar satellites are increasingly being used in slope stability assessment. This presentation provides examples of using high-resolution (1-3m) frequent revisits InSAR techniques from RADARSAT 2 and TerraSAR X to monitor several types of high-risk landslides affecting transportation and energy corridors and populated areas. We have analyses over 200 high resolution InSAR images over a three year period on geologically different landslides. The high-resolution InSAR images are effective in characterizing differential motion within these low velocity landslides. The low velocity landslides become high risk during the active wet spring periods. The wet soils are poor coherent targets and corner reflectors provide an effective means of InSAR monitoring the slope activities.

  15. Multi-quasiparticle high-K isomeric states in deformed nuclei

    Directory of Open Access Journals (Sweden)

    Xu F. R.

    2016-01-01

    Full Text Available In the past years, we have made many theoretical investigations on multi-quasiparticle high-K isomeric states. A deformation-pairing-configuration self-consistent calculation has been developed by calculating a configuration-constrained multi-quasiparticle potential energy surface (PES. The specific single-particle orbits that define the high-K configuration are identified and tracked (adiabatically blocked by calculating the average Nilsson numbers. The deformed Woods-Saxon potential was taken to give single-particle orbits. The configuration-constrained PES takes into account the shape polarization effect. Such calculations give good results on excitation energies, deformations and other structure information about multi-quasiparticle high-K isomeric states. Many different mass regions have been investigated.

  16. High-Temperature Creep Behaviour and Positive Effect on Straightening Deformation of Q345c Continuous Casting Slab

    Science.gov (United States)

    Guo, Long; Zhang, Xingzhong

    2018-03-01

    Mechanical and creep properties of Q345c continuous casting slab subjected to uniaxial tensile tests at high temperature were considered in this paper. The minimum creep strain rate and creep rupture life equations whose parameters are calculated by inverse-estimation using the regression analysis were derived based on experimental data. The minimum creep strain rate under constant stress increases with the increase of the temperature from 1000 °C to 1200 °C. A new casting machine curve with the aim of fully using high-temperature creep behaviour is proposed in this paper. The basic arc segment is cancelled in the new curve so that length of the straightening area can be extended and time of creep behaviour can be increased significantly. For the new casting machine curve, the maximum straightening strain rate at the slab surface is less than the minimum creep strain rate. So slab straightening deformation based on the steel creep behaviour at high temperature can be carried out in the process of Q345c steel continuous casting. The effect of creep property at high temperature on slab straightening deformation is positive. It is helpful for the design of new casting machine and improvement of old casting machine.

  17. Effect of borides on hot deformation behavior and microstructure evolution of powder metallurgy high borated stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xuan [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Mingjia, E-mail: mingjiawangysu@126.com [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Fu, Yifeng [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Zixi; Li, Yanmei [Yanming Alloy Roll Co. Ltd, Qinhuangdao 066004 (China); Yang, Shunkai; Zhao, Hongchang; Li, Hangbo [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2017-02-15

    To investigate borides effect on the hot deformation behavior and microstructure evolution of powder metallurgy high borated stainless steel, hot compression tests at the temperatures of 950– 1150 °C and the strain rates of 0.01– 10 s{sup −1} were performed. Flow stress curves indicated that borides increased the material's stress level at low temperature but the strength was sacrificed at temperatures above 1100 °C. A hyperbolic-sine equation was used to characterize the dependence of the flow stress on the deformation temperature and strain rate. The hot deformation activation energy and stress exponent were determined to be 355 kJ/mol and 3.2, respectively. The main factors leading to activation energy and stress exponent of studied steel lower than those of commercial 304 stainless steel were discussed. Processing maps at the strains of 0.1, 0.3, 0.5, and 0.7 showed that flow instability mainly concentrated at 950– 1150 °C and strain rate higher than 0.6 s{sup −1}. Results of microstructure illustrated that dynamic recrystallization was fully completed at both high temperature-low strain rate and low temperature-high strain rate. In the instability region cracks were generated in addition to cavities. Interestingly, borides maintained a preferential orientation resulting from particle rotation during compression. - Highlights: •The decrement of activation energy was affected by boride and boron solution. •The decrease of stress exponent was influenced by composition and Cottrell atmosphere. •Boride represented a preferential orientation caused by particle rotation.

  18. On the High Temperature Deformation Behaviour of 2507 Super Duplex Stainless Steel

    Science.gov (United States)

    Mishra, M. K.; Balasundar, I.; Rao, A. G.; Kashyap, B. P.; Prabhu, N.

    2017-02-01

    High temperature deformation behaviour of 2507 super duplex stainless steel was investigated by conducting isothermal hot compression tests. The dominant restoration processes in ferrite and austenite phases present in the material were found to be distinct. The possible causes for these differences are discussed. Based on the dynamic materials model, processing map was developed to identify the optimum processing parameters. The microstructural mechanisms operating in the material were identified. A unified strain-compensated constitutive equation was established to describe the high temperature deformation behaviour of the material under the identified processing conditions. Standard statistical parameter such as correlation coefficient has been used to validate the established equation.

  19. Spinal deformities after high-energy radiotherapy for nephroblastoma in children. Report of 82 cases

    Energy Technology Data Exchange (ETDEWEB)

    Zollner, G.; Pfeil, J.; Scheibel, P.

    1987-01-01

    Study of spinal deformities in 82 cases of nephroblastoma treated surgically or by chemotherapy and high-energy radiotherapy. This paper stresses the high incidence of radiation induced scoliosis which was observed in all patients who had reached adulthood. On the basis of a detailed analysis of the relations between the height of the vertebral body and of the intervertebral space, the authors propose a theory of a compensation of the reduction in vertebral height by displacement the nucleus pulposus towards the irradiated side. This phenomenon prevents the development of scoliosis in subjects under the age of 11 years, despite an already well established deformity of the vertebral bodies. The compensation decreases with increasing age and the degree od scoliosis. This explains partly the increased degree of scoliotic deformity during puberty. Orthopaedic treatment therefore needs to be started relatively early.

  20. Thermally induced processes in mixtures of aluminum with organic acids after plastic deformations under high pressure

    Science.gov (United States)

    Zhorin, V. A.; Kiselev, M. R.; Roldugin, V. I.

    2017-11-01

    DSC is used to measure the thermal effects of processes in mixtures of solid organic dibasic acids with powdered aluminum, subjected to plastic deformation under pressures in the range of 0.5-4.0 GPa using an anvil-type high-pressure setup. Analysis of thermograms obtained for the samples after plastic deformation suggests a correlation between the exothermal peaks observed around the temperatures of degradation of the acids and the thermally induced chemical reactions between products of acid degradation and freshly formed surfaces of aluminum particles. The release of heat in the mixtures begins at 30-40°C. The thermal effects in the mixtures of different acids change according to the order of acid reactivity in solutions. The extreme baric dependences of enthalpies of thermal effects are associated with the rearrangement of the electron subsystem of aluminum upon plastic deformation at high pressures.

  1. Effect of microplastic deformation on the electron ultrasonic absorption in high-purity molybdenum monocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Pal' -Val' , P.P.; Kaufmann, Kh.J.

    1983-03-01

    The low temperature (100-6 K) linear absorption of ultrasound (88 kHz) by high purity molybdenum single crystals have been studied. Both unstrained samples and samples sub ected to microplastic deformation (epsilon<=0.45%) were used. Unstrained samples displayed at T<30 K a rapid increase in the absorption with lowering temperature which is interpreted as an indication of electron viscosity due to electron-phonon collisions. After deformation this part of absorption disappeared. This seems to suggest that microplastic deformation brings about in the crystal a sufficiently large number of defects that can compete with phonons in restricting the electron mean free path. A low temperature dynamic annealing has been revealed in strained samples, that is almost complete recovery of the absorption nature under irradiation with high amplitude sound, epsilon/sub 0/ approximately 10/sup -4/, during 10 min, at 6 K. A new relaxation peak of absorption at 10 K has been found in strained samples.

  2. Transient deformational properties of high temperature alloys used in solid oxide fuel cell stacks

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Kwok, Kawai; Frandsen, Henrik Lund

    2017-01-01

    Stresses and probability of failure during operation of solid oxide fuel cells (SOFCs) is affected by the deformational properties of the different components of the SOFC stack. Though the overall stress relaxes with time during steady state operation, large stresses would normally appear through...... to describe the high temperature inelastic deformational behaviors of Crofer 22 APU used for metallic interconnects in SOFC stacks.......Stresses and probability of failure during operation of solid oxide fuel cells (SOFCs) is affected by the deformational properties of the different components of the SOFC stack. Though the overall stress relaxes with time during steady state operation, large stresses would normally appear through...... transients in operation including temporary shut downs. These stresses are highly affected by the transient creep behavior of metallic components in the SOFC stack. This study investigates whether a variation of the so-called Chaboche's unified power law together with isotropic hardening can represent...

  3. The effect of the cooling rate during quenching, electron bombardment and plastic deformation on the kinetics of a solid solution disintegration in iron-copper alloys

    International Nuclear Information System (INIS)

    Fedorov, G.B.; Zhukov, V.P.; Braun, A.G.; Smirnov, E.A.

    1974-01-01

    From the electroresistivity variation at 77 0 K, the influence of nonequilibrium point defect density and of complexes and dislocations on the decay process of the iron-copper solid solution is determined. Owing to high quenching rate of thin foils, isochrones of their electroconductivity curves appear shifted by about 200 0 C to lower temperatures. For quenched and irradiated specimens at 200-250 0 C a sharp retardation of electroconductivity decline is observed due to a zone stage. The plastic deformation (15%) leads to a partial suppression of that stage. Both irradiation and deformation initiate the process of copper separation from the solid solution, the latter being the stronger, the more copper is in the solid solution

  4. High-temperature deformation of dispersion-strengthened Cu-Zr-Ti-C alloys

    International Nuclear Information System (INIS)

    Palma, Rodrigo H.; Sepulveda, Aquiles; Espinoza, Rodrigo; Dianez, M. Jesus; Criado, Jose M.; Sayagues, M. Jesus

    2005-01-01

    The hot mechanical behaviour and microstructure of Cu-5 vol.% TiC, Cu-5 vol.% ZrO 2 and Cu-2.5 vol.% TiC-2.5 vol.% ZrO 2 alloys prepared by reaction milling were studied. After a test of 1 h annealing at 1173 K, the Cu-5 vol.% ZrO 2 alloy presented the lower softening resistance to annealing, while the other two ones kept their initial room-temperature hardness (about 2 GPa). Hot-compression tests at 773 and 1123 K, at initial true strain rates of 0.85 x 10 -3 and 0.85 x 10 -4 s -1 were performed. The Cu-2.5 vol.% TiC-2.5 vol.% ZrO 2 and the Cu-5 vol.% ZrO 2 alloys were the strongest and softest materials, respectively. Moreover, by electron microscopy, nanometric TiC and micrometric particles were detected in the Cu-5 vol.% TiC and Cu-5 vol.% ZrO 2 alloys, respectively. A possible explanation for the observed behaviour of these materials is proposed. In the compression tests, it was also found that strain rate has a low effect on flow stress, as it has been previously observed by various authors in dispersion-strengthened alloys deformed at high temperatures

  5. Deformation and failure in extreme regimes by high-energy pulsed lasers: A review

    Energy Technology Data Exchange (ETDEWEB)

    Remington, Tane P. [The University of California, San Diego, La Jolla, CA 92093 (United States); Remington, Bruce A. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Hahn, Eric N. [The University of California, San Diego, La Jolla, CA 92093 (United States); Meyers, Marc A., E-mail: mameyers@ucsd.edu [The University of California, San Diego, La Jolla, CA 92093 (United States)

    2017-03-14

    The use of high-power pulsed lasers to probe the response of materials at pressures of hundreds of GPa up to several TPa, time durations of nanoseconds, and strain rates of 10{sup 6}–10{sup 1}° s{sup −1} is revealing novel mechanisms of plastic deformation, phase transformations, and even amorphization. This unique experimental tool, aided by advanced diagnostics, analysis, and characterization, allows us to explore these new regimes that simulate those encountered in the interiors of planets. Fundamental Materials Science questions such as dislocation velocity regimes, the transition between thermally-activated and phonon drag regimes, the slip-twinning transition, the ultimate tensile strength of metals, the dislocation mechanisms of void growth are being answered through this powerful tool. In parallel with experiments, molecular dynamics simulations provide modeling and visualization at comparable strain rates (10{sup 8}–10{sup 10} s{sup −1}) and time durations (hundreds of picoseconds). This powerful synergy is illustrated in our past and current work, using representative face-centered cubic (fcc) copper, body-centered cubic (bcc) tantalum and diamond cubic silicon as model structures.

  6. The results of high tibial open wedge osteotomy in patients with varus deformity

    Directory of Open Access Journals (Sweden)

    Mahmood Jabalameli

    2013-07-01

    Full Text Available Background: High tibial open wedg osteotomy is one of the most important modality for treatment of varus deformity in order to correct deformity and improving signs and symptoms of patients with primary degenerative osteoarthritis. The aim of this study was to investigate the results of high tibial open wedge osteotomy in patients with varus deformities.Methods: This retrospective study conducted on twenty nine patients (36 knees undergone proximal tibial osteotomy operation in Shafa Yahyaian University Hospital from 2004 to 2010. Inclusion criteria were: age less than 60 years, high physical activity, varus deformity and involvement of medical compartment of knee. Patients with obesity, smoking, patelofemoral pain, lateral compartment lesion, deformity degree more than 20 degree, extension limitation and range of motion less than 90 degree were excluded. The clinical and radiologic characteristics were measured before and after operation.Results: Fourteen patients were females. All of them were younger than 50 years, with mean (±SD 27.64 (±10.88. The mean (±SD of follow up time was 4.33 (±1.7. All the patients were satisfied with the results of operation. Tenderness and pain decreased in all of them. In all patients autologus bone graft were used, in 15 cases (42.5% casting and in the rest T.Buttress plate were used for fixation of fractures. In both groups of primary and double varus the International knee documentation committee (IKDC and modified Larson indices were improved after operation, but there was no significant difference between two groups.Conclusion: High tibial open wedge osteotomy can have satisfying results in clinical signs and symptoms of patients with primary medial joint degenerative osteoarthritis. This procedure also may correct the deformity and improves the radiologic parameters of the patients.

  7. Influence of sulphur and phosphorus on the hot deformation of Fe-Cr 13% high purity steel

    International Nuclear Information System (INIS)

    Lahreche, M.; Bouzabata, B.; Kobylanski, A.

    1995-01-01

    A series of Fe-Cr13%-C high purity steels containing increasing volume fractions of Sulphur (30, 60 and 100ppm) and Phosphorus (30, 60 and 100ppm) were prepared in order to study their hot deformation properties by tensile tests at various strain rates (10 -1 s -1 to 10 -4 s -1 ) and at temperatures from 700 C to 1100 C. It is observed that the hot ductility is lowered at 1000 C with the addition of sulphur. However, this decrease is relatively small (about 30% for 100ppm of sulphur) and quite similar for all additions of sulphur. When phosphorus is added, the embrittlement is along the whole deformed specimen. The usual criteria of ductility by parameter Z do not seem to be sufficient to describe this embrittlement. (orig.)

  8. Late Quaternary uplift rate inferred from marine terraces, Muroto Peninsula, southwest Japan: Forearc deformation in an oblique subduction zone

    Science.gov (United States)

    Matsu'ura, Tabito

    2015-04-01

    Tectonic uplift rates across the Muroto Peninsula, in the southwest Japan forearc (the overriding plate in the southwest Japan oblique subduction zone), were estimated by mapping the elevations of the inner edges of marine terrace surfaces. The uplift rates inferred from marine terraces M1 and M2, which were correlated by tephrochronology with marine isotope stages (MIS) 5e and 5c, respectively, include some vertical offset by local faults but generally decrease northwestward from 1.2-1.6 m ky- 1 on Cape Muroto to 0.3-0.7 m ky- 1 in the Kochi Plain. The vertical deformation of the Muroto Peninsula since MIS 5e and 5c was interpreted as a combination of regional uplift and folding related to the arc-normal offshore Muroto-Misaki fault. A regional uplift rate of 0.46 m ky- 1 was estimated from terraces on the Muroto Peninsula, and the residual deformation of these terraces was attributed to fault-related folding. A mass-balance calculation yielded a shortening rate of 0.71-0.77 m ky- 1 for the Muroto Peninsula, with the Muroto-Misaki fault accounting for 0.60-0.71 m ky- 1, but these rates may be overestimated by as much as 10% given variations of several meters in the elevation difference between the buried shoreline angles and terrace inner edges in the study area. A thrust fault model with flat (5-10° dip) and ramp (60° dip) components is proposed to explain the shortening rate and uplift rate of the Muroto-Misaki fault since MIS 5e. Bedrock deformation also indicates that the northern extension of this fault corresponds to the older Muroto Flexure.

  9. High temperature deformation behavior, thermal stability and irradiation performance in Grade 92 steel

    Science.gov (United States)

    Alsagabi, Sultan

    The 9Cr-2W ferritic-martensitic steel (i.e. Grade 92 steel) possesses excellent mechanical and thermophysical properties; therefore, it has been considered to suit more challenging applications where high temperature strength and creep-rupture properties are required. The high temperature deformation mechanism was investigated through a set of tensile testing at elevated temperatures. Hence, the threshold stress concept was applied to elucidate the operating high temperature deformation mechanism. It was identified as the high temperature climb of edge dislocations due to the particle-dislocation interactions and the appropriate constitutive equation was developed. In addition, the microstructural evolution at room and elevated temperatures was investigated. For instance, the microstructural evolution under loading was more pronounced and carbide precipitation showed more coarsening tendency. The growth of these carbide precipitates, by removing W and Mo from matrix, significantly deteriorates the solid solution strengthening. The MX type carbonitrides exhibited better coarsening resistance. To better understand the thermal microstructural stability, long tempering schedules up to 1000 hours was conducted at 560, 660 and 760°C after normalizing the steel. Still, the coarsening rate of M23C 6 carbides was higher than the MX-type particles. Moreover, the Laves phase particles were detected after tempering the steel for long periods before they dissolve back into the matrix at high temperature (i.e. 720°C). The influence of the tempering temperature and time was studied for Grade 92 steel via Hollomon-Jaffe parameter. Finally, the irradiation performance of Grade 92 steel was evaluated to examine the feasibility of its eventual reactor use. To that end, Grade 92 steel was irradiated with iron (Fe2+) ions to 10, 50 and 100 dpa at 30 and 500°C. Overall, the irradiated samples showed some irradiation-induced hardening which was more noticeable at 30°C. Additionally

  10. Constitutive relationships for 22MnB5 boron steel deformed isothermally at high temperatures

    International Nuclear Information System (INIS)

    Naderi, M.; Durrenberger, L.; Molinari, A.; Bleck, W.

    2008-01-01

    The strain, strain rate and temperature dependency of a boron steel, which was isothermally deformed under uniaxial compression tests, has been investigated at temperatures between 600 and 900 o C, and at strain rates of 0.1, 1.0 and 10.0 s -1 . Two constitutive models were used to correlate the plastic behavior: the Voce constitutive relation in combination with the kinetic model proposed by Kocks and the phenomenological model proposed by Molinari-Ravichandran. The Kocks model has been introduced in the Voce formulation to describe the temperature and the strain rate dependency of the saturation stress and of the yield stress. The Molinari-Ravichandran model is based on a single internal variable that can be viewed as being related to a characteristic length scale of the microstructure that develops during deformation. It has been shown that the plastic behavior of the boron steel can be well described using these two models

  11. Strain-rate effect on initial crush stress of irregular honeycomb under dynamic loading and its deformation mechanism

    Science.gov (United States)

    Wang, Peng; Zheng, Zhijun; Liao, Shenfei; Yu, Jilin

    2018-02-01

    The seemingly contradictory understandings of the initial crush stress of cellular materials under dynamic loadings exist in the literature, and a comprehensive analysis of this issue is carried out with using direct information of local stress and strain. Local stress/strain calculation methods are applied to determine the initial crush stresses and the strain rates at initial crush from a cell-based finite element model of irregular honeycomb under dynamic loadings. The initial crush stress under constant-velocity compression is identical to the quasi-static one, but less than the one under direct impact, i.e. the initial crush stresses under different dynamic loadings could be very different even though there is no strain-rate effect of matrix material. A power-law relation between the initial crush stress and the strain rate is explored to describe the strain-rate effect on the initial crush stress of irregular honeycomb when the local strain rate exceeds a critical value, below which there is no strain-rate effect of irregular honeycomb. Deformation mechanisms of the initial crush behavior under dynamic loadings are also explored. The deformation modes of the initial crush region in the front of plastic compaction wave are different under different dynamic loadings.

  12. 3D High Resolution Mesh Deformation Based on Multi Library Wavelet Neural Network Architecture

    Science.gov (United States)

    Dhibi, Naziha; Elkefi, Akram; Bellil, Wajdi; Amar, Chokri Ben

    2016-12-01

    This paper deals with the features of a novel technique for large Laplacian boundary deformations using estimated rotations. The proposed method is based on a Multi Library Wavelet Neural Network structure founded on several mother wavelet families (MLWNN). The objective is to align features of mesh and minimize distortion with a fixed feature that minimizes the sum of the distances between all corresponding vertices. New mesh deformation method worked in the domain of Region of Interest (ROI). Our approach computes deformed ROI, updates and optimizes it to align features of mesh based on MLWNN and spherical parameterization configuration. This structure has the advantage of constructing the network by several mother wavelets to solve high dimensions problem using the best wavelet mother that models the signal better. The simulation test achieved the robustness and speed considerations when developing deformation methodologies. The Mean-Square Error and the ratio of deformation are low compared to other works from the state of the art. Our approach minimizes distortions with fixed features to have a well reconstructed object.

  13. Simulation of microdamage in ceramics deformed under high confinement

    International Nuclear Information System (INIS)

    Zhang Dongmei; Feng Ruqiang

    2004-01-01

    A polycrystalline ceramic may display high strength under dynamic compression but fails catastrophically during load reversal to tension. One plausible mechanism is that heterogeneous plasticity in some of the crystals under compression induces microdamage during load reversal. To examine this possibility quantitatively, we developed a computational method, in which the polycrystalline microstructure is realistically simulated using Voronoi crystals having grain boundary layer. Both anisotropic elasticity and plastic slip in limited crystallographic planes are considered in crystal modeling. The grain boundary material is treated as an isotropic glassy solid, which has pressure-dependent shear strength under compression and fractures in Mode I when the threshold is reached. The structural and material models have been implemented into ABAQUS/Explicit code. Model simulations have been performed to analyze the intragranular microplasticity, intergranular microdamage, and their interactions in polycrystalline α-6H silicon carbide subjected to dynamic unaxial-strain compression and then load reversal to tension. It is found that microplasticity is more favorable than intergranular shear damage during compression. However, both the microplasticity-induced heterogeneity and the grain boundary damage affect strongly microcracking during load reversal, which leads to fragmentation or spallation depending on the level of compression. The significance of these findings is discussed

  14. High Temperature Deformation Mechanisms in a DLD Nickel Superalloy

    Directory of Open Access Journals (Sweden)

    Sean Davies

    2017-04-01

    Full Text Available The realisation of employing Additive Layer Manufacturing (ALM technologies to produce components in the aerospace industry is significantly increasing. This can be attributed to their ability to offer the near-net shape fabrication of fully dense components with a high potential for geometrical optimisation, all of which contribute to subsequent reductions in material wastage and component weight. However, the influence of this manufacturing route on the properties of aerospace alloys must first be fully understood before being actively applied in-service. Specimens from the nickel superalloy C263 have been manufactured using Powder Bed Direct Laser Deposition (PB-DLD, each with unique post-processing conditions. These variables include two build orientations, vertical and horizontal, and two different heat treatments. The effects of build orientation and post-process heat treatments on the materials’ mechanical properties have been assessed with the Small Punch Tensile (SPT test technique, a practical test method given the limited availability of PB-DLD consolidated material. SPT testing was also conducted on a cast C263 variant to compare with PB-DLD derivatives. At both room and elevated temperature conditions, differences in mechanical performances arose between each material variant. This was found to be instigated by microstructural variations exposed through microscopic and Energy Dispersive X-ray Spectroscopy (EDS analysis. SPT results were also compared with available uniaxial tensile data in terms of SPT peak and yield load against uniaxial ultimate tensile and yield strength.

  15. Thermal deformation analysis and test of electron gun for high power klystron

    International Nuclear Information System (INIS)

    Zhou Zusheng; Chinese Academy of Sciences, Beijing; Dong Dong

    2006-01-01

    A 120 MW pulsed electron gun has been developed for 50 MW China-made klystron. It has a Pierce type dispenser cathode and it scans with a diameter of 85 mm. This paper describes the temperature field distribution in the gun and the gun deformation caused by this distribution by using ANSYS. According to the real complex structure and the energy conversion inside the electron gun, the authors took the thermal conduction as the main energy conversion form and got the temperature field. The coincidence between the temperature field and the structural deformation is also described. The beam optics simulated by EGUN with and without considering deformation is discussed, and the valuable results have been obtained. The high power test results and simulation results are analyzed and compared. (authors)

  16. High Resolution Transmission Electron Microscope Observation of Zero-Strain Deformation Twinning Mechanisms in Ag

    Science.gov (United States)

    Liu, L.; Wang, J.; Gong, S. K.; Mao, S. X.

    2011-04-01

    We have observed a new deformation-twinning mechanism using the high resolution transmission electron microscope in polycrystalline Ag films, zero-strain twinning via nucleation, and the migration of a Σ3{112} incoherent twin boundary (ITB). This twinning mechanism produces a near zero macroscopic strain because the net Burgers vectors either equal zero or are equivalent to a Shockley partial dislocation. This observation provides new insight into the understanding of deformation twinning and confirms a previous hypothesis: detwinning could be accomplished via the nucleation and migration of Σ3{112} ITBs. The zero-strain twinning mechanism may be unique to low staking fault energy metals with implications for their deformation behavior.

  17. Features micro plastic deformation auxetic beryllium irradiated with high-energy electrons

    International Nuclear Information System (INIS)

    Rarans'kij, M.D.; Olyijnich-Lisyuk, A.V.; Tashchuk, O.Yu.

    2016-01-01

    By low-frequency internal friction (LFIF) (1...3 Hz) method, the study of the behavior of the dynamic modulus of torsion (Gef) and by mathematical modeling of dislocation motion studied micro plastic deformation in naturally aged and irradiated with high-energy (18 MeV) electrons auxetic beryllium. With increasing doses of radiation found an increase in IF and speed of movement of dislocations in 2-3 times. Installed stage character micro strain auxetic Be. By mathematical modeling showed that in the irradiated material the deformation occurs due to the accelerated movement of the twin dislocations in the early stages, and anomalous dynamic deceleration of complete dislocations with an increase in the degree of deformation in the second stage. It is shown that theoretically estimated values are in good agreement with the experimentally determined.

  18. In-situ high-P, T X-ray microtomographic imaging during large deformation

    DEFF Research Database (Denmark)

    Wang, Y; Lesher, Charles

    2011-01-01

    We have examined the microstructural evolution of a two-phase composite (olivine + Fe-Ni-S) during large shear deformation, using a newly developed high-pressure X-ray tomography microscope. Two samples were examined: a load-bearing framework–type texture, where the alloy phase (Fe-Ni-S) was pres...

  19. Effect of microplastic deformation on the electron ultrasonic absorption in high-purity molybdenum monocrystals

    International Nuclear Information System (INIS)

    Pal'-Val', P.P.; Kaufmann, Kh.-J.

    1983-01-01

    The low temperature (100-6 K) linear absorption of ultrasound (88 kHz) by high purity molybdenum single crystals have been studied. Both unstrained samples and samples sub ected to microplastic deformation (epsilon 0 approximately 10 -4 , during 10 min, at 6 K. A new relaxation peak of absorption at 10 K has been found in strained samples

  20. Microplastic deformation of TiB2 particles during vihrocrushing and pressing in high pressure chambers

    International Nuclear Information System (INIS)

    Ordan'yan, S.S.; Kravchik, A.E.; Ponomarenko, V.A.; Chunov, V.D.

    1984-01-01

    The character of plastic strain in titanium diboride particles is described. It is shown that during titanium diboride vibrocrushing unlike that of carbide there is practically no microplastic deformation that is observed only when TiB 2 particles are squeezed in high-pressure chambers at pressures not less than 3GPa

  1. Effect of cooling rate on microstructure and deformation behavior of Ti-based metallic glassy/crystalline powders

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.J. [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD 4072 (Australia); Huang, Y.J. [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); Shen, J., E-mail: junshen@hit.edu.cn [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); Wu, Y.Q.; Huang, H. [School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD 4072 (Australia); Zou, J., E-mail: j.zou@uq.edu.au [School of Mechanical and Mining Engineering, University of Queensland, Brisbane, QLD 4072 (Australia); Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, QLD 4072 (Australia)

    2010-08-20

    The microstructures and deformation behavior of Ti-based metallic powders were comprehensively investigated. It has been found that, with increasing the powder size, the phase constituent alters from pure glassy to glassy with crystalline phases (face centered cubic structured NiSnZr and hexagonal structured Ti{sub 3}Sn phases). Our results suggest that the synergetic effect of the thermodynamics and kinetics determines the subsequent characteristics of the crystalline precipitations. Through comparative nanoindentation tests, it was found that the small powders exhibit more pop-in events and a larger pile-up ratio, suggesting that the plastic deformation of the metallic powders is governed by the combined effects of the free volume and the crystallization, which are determined by the cooling rate.

  2. High burn rate solid composite propellants

    Science.gov (United States)

    Manship, Timothy D.

    High burn rate propellants help maintain high levels of thrust without requiring complex, high surface area grain geometries. Utilizing high burn rate propellants allows for simplified grain geometries that not only make production of the grains easier, but the simplified grains tend to have better mechanical strength, which is important in missiles undergoing high-g accelerations. Additionally, high burn rate propellants allow for a higher volumetric loading which reduces the overall missile's size and weight. The purpose of this study is to present methods of achieving a high burn rate propellant and to develop a composite propellant formulation that burns at 1.5 inches per second at 1000 psia. In this study, several means of achieving a high burn rate propellant were presented. In addition, several candidate approaches were evaluated using the Kepner-Tregoe method with hydroxyl terminated polybutadiene (HTPB)-based propellants using burn rate modifiers and dicyclopentadiene (DCPD)-based propellants being selected for further evaluation. Propellants with varying levels of nano-aluminum, nano-iron oxide, FeBTA, and overall solids loading were produced using the HTPB binder and evaluated in order to determine the effect the various ingredients have on the burn rate and to find a formulation that provides the burn rate desired. Experiments were conducted to compare the burn rates of propellants using the binders HTPB and DCPD. The DCPD formulation matched that of the baseline HTPB mix. Finally, GAP-plasticized DCPD gumstock dogbones were attempted to be made for mechanical evaluation. Results from the study show that nano-additives have a substantial effect on propellant burn rate with nano-iron oxide having the largest influence. Of the formulations tested, the highest burn rate was a 84% solids loading mix using nano-aluminum nano-iron oxide, and ammonium perchlorate in a 3:1(20 micron: 200 micron) ratio which achieved a burn rate of 1.2 inches per second at 1000

  3. Highly deformable and highly fluid vesicles as potential drug delivery systems: theoretical and practical considerations

    Directory of Open Access Journals (Sweden)

    Romero EL

    2013-08-01

    Full Text Available Eder Lilia Romero, Maria Jose Morilla Nanomedicine Research Program, Department of Science and Technology, National University of Quilmes, Bernal, Buenos Aires, Argentina Abstract: Vesicles that are specifically designed to overcome the stratum corneum barrier in intact skin provide an efficient transdermal (systemic or local drug delivery system. They can be classified into two main groups according to the mechanisms underlying their skin interaction. The first group comprises those possessing highly deformable bilayers, achieved by incorporating edge activators to the bilayers or by mixing with certain hydrophilic solutes. The vesicles of this group act as drug carriers that penetrate across hydrophilic pathways of the intact skin. The second group comprises those possessing highly fluid bilayers, owing to the presence of permeation enhancers. The vesicles of this group can act as carriers of drugs that permeate the skin after the barrier of the stratum corneum is altered because of synergistic action with the permeation enhancers contained in the vesicle structure. We have included a detailed overview of the different mechanisms of skin interaction and discussed the most promising preclinical applications of the last five years of Transfersomes® (IDEA AG, Munich, Germany, ethosomes, and invasomes as carriers of antitumoral and anti-inflammatory drugs applied by the topical route. Keywords: Transfersomes, ethosomes, antitumoral, anti-inflammatory, topical delivery

  4. Mechanical twinning and texture evolution in severely deformed Ti-6Al-4V at high temperatures

    International Nuclear Information System (INIS)

    Yapici, Guney Guven; Karaman, Ibrahim; Luo Zhiping

    2006-01-01

    We have investigated the deformation behavior and texture evolution of two-phase Ti-6Al-4V subjected to severe plastic deformation using equal channel angular extrusion (ECAE) at a high temperature (∼0.55T m ). Significant deformation twinning activity was observed after one and two ECAE passes in a 90 deg, die at 800 deg. C. Twinning activity at such a high temperature is a first-time observation in this material and is attributed to the high strain and stress levels imposed during ECAE. High stress levels and the stress state can affect the separation of twinning partials considerably. Resolved shear stress magnitudes on twin partials were found to be high during the ECAE process that helps the nucleation of mechanical twinning. The twinning mode was identified as the {101-bar 1} type using electron diffraction patterns which is one of the twinning modes observed in Ti at temperatures above 350 deg. C. Although only one twinning variant was mainly evident after one pass, multiple twin variants of the same mode were observed after the second pass with a significant increase in twin volume fraction. ECAE processing aligned the basal planes of the hexagonal close-packed α phase, initially having a random texture, with the ECAE shear plane. Texture evolution during ECAE was successfully predicted using a viscoplastic self-consistent crystal plasticity framework capturing the effect of the observed twinning mode on texture. Mechanical twins formed during ECAE and grain refinement led to a noteworthy improvement in flow stresses under tension and compression at room temperature. A strong directional anisotropy in yield strengths was also evident which cannot be explained only by crystallographic texture. It was speculated that the asymmetry of critical resolved shear stresses of deformation modes and the processing-induced deformation structure should play a role. With the supporting evidence from our previous works on the severe plastic deformation of other

  5. Interface bonding of SA508-3 steel under deformation and high temperature diffusion

    Science.gov (United States)

    Xu, Bin; Shao, Chunjuan; Sun, Mingyue

    2018-05-01

    There are mainly two parameters affecting high temperature interface bonding: deformation and diffusion. To study these two parameters, interface bonding of SA508-3 bainitic steel at 1100°C are simulated by gleeble3500 thermal simulator. The results show that interface of SA508-3 steel can be bonded under deformation and high temperature. For a specimen pressed at 1100°C without further high temperature diffusion, a reduction ratio of 30% can make the interface begun to bond, but the interface is still part of the grain boundary and small grains exist near the interface. When reduction ratio reaches 50%, the interface can be completely bonded and the microstructure near the interface is the same as that of the base material. When deformation is small, long time diffusion can also help the interface bonding. The results show that when the diffusion time is long enough, the interface under small deformation can also be bonded. For a specimen holding for 24h at 1100°C, only 13% reduction ratio is enough for interface bonding.

  6. High-rate lithium thionyl chloride cells

    Science.gov (United States)

    Goebel, F.

    1982-03-01

    A high-rate C cell with disc electrodes was developed to demonstrate current rates which are comparable to other primary systems. The tests performed established the limits of abuse beyond which the cell becomes hazardous. Tests include: impact, shock, and vibration tests; temperature cycling; and salt water immersion of fresh cells.

  7. Free volume model: High-temperature deformation of a Zr-based bulk metallic glass

    International Nuclear Information System (INIS)

    Bletry, M.; Guyot, P.; Blandin, J.J.; Soubeyroux, J.L.

    2006-01-01

    The homogeneous deformation of a zirconium-based bulk metallic glass is investigated in the glass transition region. Compression tests at different temperatures and strain rates have been conducted. The mechanical behavior is analyzed in the framework of the free volume model, taking into account the dependence of the flow defect concentration on deformation. The activation volume is evaluated and allows one to gather the viscosity data (for the different strain rates and temperatures) on a unique master curve. It is also shown that, due to the relation between flow defect concentration and free volume, it is not possible to deduce the equilibrium flow defect concentration directly from mechanical measurements. However, if this parameter is arbitrarily chosen, mechanical measurements give access to the other parameters of the model, these parameters for the alloy under investigation being of the same order of magnitude as those for other metallic glasses

  8. Lithium thionyl chloride high rate discharge

    Science.gov (United States)

    Klinedinst, K. A.

    1980-04-01

    Improvements in high rate lithium thionyl chloride power technology achieved by varying the electrolyte composition, operating temperature, cathode design, and cathode composition are discussed. Discharge capacities are plotted as a function of current density, cell voltage, and temperature.

  9. Concomitant chemoradiotherapy with high dose rate brachytherapy ...

    African Journals Online (AJOL)

    Concomitant chemoradiotherapy with high dose rate brachytherapy as a definitive treatment modality for locally advanced cervical cancer. T Refaat, A Elsaid, N Lotfy, K Kiel, W Small Jr, P Nickers, E Lartigau ...

  10. High-temperature deformation of YBa2Cu3O7-δ with Ag additions

    International Nuclear Information System (INIS)

    Routbort, J.L.; Goretta, K.C.; Singh, J.P.

    1990-01-01

    The steady-state flow stress of YBa 2 Cu 3 O 7-δ containing 15 to 30 vol.% Ag has been measured in air at nearly constant compressive strain rates between 5 x 10 -6 and 1 x 10 -4 s -1 from 830 to 900 degrees C. Addition of Ag dramatically decreases the flow stress compared to that of the pure superconductor, but the stress exponents and the activation energy for deformation remain unchanged

  11. On the response of rubbers at high strain rates.

    Energy Technology Data Exchange (ETDEWEB)

    Niemczura, Johnathan Greenberg (University of Texas-Austin)

    2010-02-01

    In this report, we examine the propagation of tensile waves of finite deformation in rubbers through experiments and analysis. Attention is focused on the propagation of one-dimensional dispersive and shock waves in strips of latex and nitrile rubber. Tensile wave propagation experiments were conducted at high strain-rates by holding one end fixed and displacing the other end at a constant velocity. A high-speed video camera was used to monitor the motion and to determine the evolution of strain and particle velocity in the rubber strips. Analysis of the response through the theory of finite waves and quantitative matching between the experimental observations and analytical predictions was used to determine an appropriate instantaneous elastic response for the rubbers. This analysis also yields the tensile shock adiabat for rubber. Dispersive waves as well as shock waves are also observed in free-retraction experiments; these are used to quantify hysteretic effects in rubber.

  12. Influence of hot plastic deformation and cooling rate on martensite and bainite start temperatures in 22MnB5 steel

    International Nuclear Information System (INIS)

    Nikravesh, M.; Naderi, M.; Akbari, G.H.

    2012-01-01

    Highlights: ► Reduction of cooling rate, can cause to increase or decrease M s and M f . ► 40% hot plastic deformation hindered the martensitic transformation. ► Hot plastic deformation, caused to decrease M f and M s , while B s increased. ► The critical cooling rate increased 40 °C/s due to apply 40% hot deformation. - Abstract: During hot stamping process, hot forming, cooling and phase transformations are performed in a single step. As a matter of fact, multifunctional phenomena happen and affect each other. Among these phenomena, martensitic and bainitic transformations have the greatest importance. In the current research, the start temperatures of martensite and bainite of 22MnB5 boron steel have been measured in undeformed and 40% deformed conditions, and in various cooling rates from 0.4 °C/s to 100 °C/s by means of deformation dilatometer. It is concluded that, reduction of cooling rate, could bring about an increase or decrease in M s and M f , depending on other phases formation before martensite. Also, hot plastic deformation, hindered the martensitic transformation and decreased M f and M s especially at lower cooling rates, while B s increased. Furthermore, the critical cooling rate, increased about 40 °C/s by applying 40% hot plastic deformation.

  13. Plate rotations, fault slip rates, fault locking, and distributed deformation in northern Central America from 1999-2017 GPS observations

    Science.gov (United States)

    Ellis, A. P.; DeMets, C.; Briole, P.; Cosenza, B.; Flores, O.; Guzman-Speziale, M.; Hernandez, D.; Kostoglodov, V.; La Femina, P. C.; Lord, N. E.; Lasserre, C.; Lyon-Caen, H.; McCaffrey, R.; Molina, E.; Rodriguez, M.; Staller, A.; Rogers, R.

    2017-12-01

    We describe plate rotations, fault slip rates, and fault locking estimated from a new 100-station GPS velocity field at the western end of the Caribbean plate, where the Motagua-Polochic fault zone, Middle America trench, and Central America volcanic arc faults converge. In northern Central America, fifty-one upper-plate earthquakes caused approximately 40,000 fatalities since 1900. The proximity of main population centers to these destructive earthquakes and the resulting loss of human life provide strong motivation for studying the present-day tectonics of Central America. Plate rotations, fault slip rates, and deformation are quantified via a two-stage inversion of daily GPS position time series using TDEFNODE modeling software. In the first stage, transient deformation associated with three M>7 earthquakes in 2009 and 2012 is estimated and removed from the GPS position time series. In Stage 2, linear velocities determined from the corrected GPS time series are inverted to estimate deformation within the western Caribbean plate, slip rates along the Motagua-Polochic faults and faults in the Central America volcanic arc, and the gradient of extension in the Honduras-Guatemala wedge. Major outcomes of the second inversion include the following: (1) Confirmation that slip rates on the Motagua fault decrease from 17-18 mm/yr at its eastern end to 0-5 mm/yr at its western end, in accord with previous results. (2) A transition from moderate subduction zone locking offshore from southern Mexico and parts of southern Guatemala to weak or zero coupling offshore from El Salvador and parts of Nicaragua along the Middle America trench. (3) Evidence for significant east-west extension in southern Guatemala between the Motagua fault and volcanic arc. Our study also shows evidence for creep on the eastern Motagua fault that diminishes westward along the North America-Caribbean plate boundary.

  14. Subgrain and dislocation structure changes in hot-deformed high-temperature Fe-Ni austenitic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ducki, K.J.; Rodak, K.; Hetmanczyk, M.; Kuc, D

    2003-08-28

    The influence of plastic deformation on the substructure of a high-temperature austenitic Fe-Ni alloy has been presented. Hot-torsion tests were executed at constant strain rates of 0.1 and 1.0 s{sup -1}, at testing temperatures in the range 900-1150 deg. C. The examination of the microstructure was carried out, using transmission electron microscopy. Direct measurements on the micrographs allowed the calculation of structural parameters: the average subgrain area, and the mean dislocation density. A detailed investigation has shown that the microstructure is inhomogeneous, consisting of dense dislocation walls, subgrains and recrystallized regions.

  15. Subgrain and dislocation structure changes in hot-deformed high-temperature Fe-Ni austenitic alloy

    International Nuclear Information System (INIS)

    Ducki, K.J.; Rodak, K.; Hetmanczyk, M.; Kuc, D.

    2003-01-01

    The influence of plastic deformation on the substructure of a high-temperature austenitic Fe-Ni alloy has been presented. Hot-torsion tests were executed at constant strain rates of 0.1 and 1.0 s -1 , at testing temperatures in the range 900-1150 deg. C. The examination of the microstructure was carried out, using transmission electron microscopy. Direct measurements on the micrographs allowed the calculation of structural parameters: the average subgrain area, and the mean dislocation density. A detailed investigation has shown that the microstructure is inhomogeneous, consisting of dense dislocation walls, subgrains and recrystallized regions

  16. Deformation of contact surfaces in a vacuum interrupter after high-current interruptions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haoran; Wang, Zhenxing, E-mail: zxwang@xjtu.edu.cn; Zhou, Zhipeng; Jiang, Yanjun; Wang, Jianhua; Geng, Yingsan; Liu, Zhiyuan [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China)

    2016-08-07

    In a high-current interruption, the contact surface in a vacuum interrupter might be severely damaged by constricted vacuum arcs causing a molten area on it. As a result, a protrusion will be initiated by a transient recovery voltage after current zero, enhancing the local electric field and making breakdowns occur easier. The objective of this paper is to simulate the deformation process on the molten area under a high electric field by adopting the finite element method. A time-dependent Electrohydrodynamic model was established, and the liquid-gas interface was tracked by the level-set method. From the results, the liquid metal can be deformed to a Taylor cone if the applied electric field is above a critical value. This value is correlated to the initial geometry of the liquid metal, which increases as the size of the liquid metal decreases. Moreover, the buildup time of a Taylor cone obeys the power law t = k × E{sup −3}, where E is the initial electric field and k is a coefficient related to the material property, indicating a temporal self-similar characteristic. In addition, the influence of temperature has little impact on the deformation but has great impact on electron emission. Finally, the possible reason to initiate a delayed breakdown is associated with the deformation. The breakdown does not occur immediately when the voltage is just applied upon the gap but is postponed to several milliseconds later when the tip is formed on the liquid metal.

  17. Plastic deformation

    NARCIS (Netherlands)

    Sitter, de L.U.

    1937-01-01

    § 1. Plastic deformation of solid matter under high confining pressures has been insufficiently studied. Jeffreys 1) devotes a few paragraphs to deformation of solid matter as a preface to his chapter on the isostasy problem. He distinguishes two properties of solid matter with regard to its

  18. THE CHANGE IN DEFORMATION CHARACTERISTICS OF CONCRETE MONOLITHIC HIGH-RISE BUILDINGS

    Directory of Open Access Journals (Sweden)

    V. V. Punahin

    2009-03-01

    Full Text Available In the article results of studies of deformation features of concrete on actuate cement for monolithic high-altitude buildings are presented. It is shown that in construction of the high-altitude monolithic buildings in a summer period of a year one should take into account the character of changing the concrete elasticity and plasticity in time, which differs from the same indices for the concrete of normal hardening.

  19. Wavelet analysis deformation monitoring data of high-speed railway bridge

    Science.gov (United States)

    Tang, ShiHua; Huang, Qing; Zhou, Conglin; Xu, HongWei; Liu, YinTao; Li, FeiDa

    2015-12-01

    Deformation monitoring data of high-speed railway bridges will inevitably be affected because of noise pollution, A deformation monitoring point of high-speed railway bridge was measurd by using sokkia SDL30 electronic level for a long time,which got a large number of deformation monitoring data. Based on the characteristics of the deformation monitoring data of high-speed railway bridge, which contain lots of noise. Based on the MATLAB software platform, 120 groups of deformation monitoring data were applied to analysis of wavelet denoising.sym6,db6 wavelet basis function were selected to analyze and remove the noise.The original signal was broken into three layers wavelet,which contain high frequency coefficients and low frequency coefficients.However, high frequency coefficient have plenty of noise.Adaptive method of soft and hard threshold were used to handle in the high frequency coefficient.Then,high frequency coefficient that was removed much of noise combined with low frequency coefficient to reconstitute and obtain reconstruction wavelet signal.Root Mean Square Error (RMSE) and Signal-To-Noise Ratio (SNR) were regarded as evaluation index of denoising,The smaller the root mean square error and the greater signal-to-noise ratio indicate that them have a good effect in denoising. We can surely draw some conclusions in the experimental analysis:the db6 wavelet basis function has a good effect in wavelet denoising by using a adaptive soft threshold method,which root mean square error is minimum and signal-to-noise ratio is maximum.Moreover,the reconstructed image are more smooth than original signal denoising after wavelet denoising, which removed noise and useful signal are obtained in the original signal.Compared to the other three methods, this method has a good effect in denoising, which not only retain useful signal in the original signal, but aiso reach the goal of removing noise. So, it has a strong practical value in a actual deformation monitoring

  20. Deformation of cylindrical vessel and the effect of barrel on deformation under inpulsive pressure of high explosive

    International Nuclear Information System (INIS)

    Iikura, Shoichi; Yashizawa, Hiroyasu; Sasanuma, Katsumi.

    1982-01-01

    According to the research performed so far, the result that the amount of deformation due to impulsive pressure was able to be evaluated by the impulse of impulsive pressure waves has been obtained. The analysis treating impulsive pressure waves as plane waves has been made frequently, but the analysis in which impulsive pressure waves must be treated as spherical waves, or the analysis of a vessel with a barrel (internal cylinder) is complex and difficult. In this report, the results of element test, which was carried out in the Oita Works, Asahi Chemical Industry Co., Ltd., in 1973 by the Power Reactor and Nuclear Fuel Development Corp. as the impact resistance test for fast breeder reactors, are rearranged and investigated. The specimens were the cylindrical vessels with upper and lower flanges, and 10 vessels and 9 kinds of barrels were made. Water was used as the pressure medium. The residual deformation and dynamic strain of the vessels and the wave form of pressure waves were measured. The deformation of cylindrical vessels subjected to the impulsive pressure from a point pressure source was able to be evaluated by the impulse distribution in normal direction. The maximum amount of deformation depended on the total plate thickness of barrels. (Kako, I.)

  1. Rate of deformation in the Pasco Basin during the Miocene as determined by distribution of Columbia River basalt flows

    International Nuclear Information System (INIS)

    Reidel, S.P.; Ledgerwood, R.K.; Myers, C.W.; Jones, M.G.; Landon, R.D.

    1980-03-01

    Detailed mapping of over 8000 square kilometers and logs from 20 core holes were used to determine the distribution and thickness of basalt flows and interbeds in the Pasco Basin. The data indicate the high-MgO Grande Ronde Basalt and Wanapum Basalt thicken from the northeast to the southwest. Deformation began in late Frenchman Springs time in the Saddle Mountains along a northwest-southeast trend and in Roza time along an east-west trend. By late Wanapum time, basalt flows were more restricted on the east side. Saddle Mountains Basalt flows spread out in the basin from narrow channels to the east. The Umatilla Member entered from the southeast and is confined to the south-central basin, while the Wilbur Creek, Asotin, Esquatzel, Pomona, and Elephant Mountain Members entered from the east and northeast. The distribution of these members is controlled by flow volume, boundaries of other flows, and developing ridges. The Wilbur Creek, Asotin, and Esquatzel flows exited from the basin in a channel along the northern margin of the Umatilla flow, while the Pomona and Elephant Mountain flows exited between Umtanum Ridge and Wallula Gap. The thickness of sedimentary interbeds and basalt flows indicated subsidence and/or uplift began in post-Grande Ronde time (14.5 million years before present) and continued through Saddle Mountains time (10.5 million years before present). Maximum subsidence occurred 40 kilometers (24 miles) north of Richland, Washington with an approximate rate of 25 meters (81 feet) per million years during the eruption of the basalt. Maximum uplift along the developing ridges was 70 meters (230 feet) per million years

  2. High Strain Rate Characterisation of Composite Materials

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Normann Wilken

    -reinforced polymers, were considered, and it was first shown that the loading history controls equilibrium process. Then the High-speed servo-hydraulic test machine was analysed in terms its ability to create a state of constant strain rate in the specimen. The invertible inertial forces in the load train prevented...... from designing and constructing a high-speed servo-hydraulic test machine and by performing a comprehensive test series. The difficulties encountered in the test work could be addressed with the developed analysis. The conclusion was that the High-speed servo-hydraulic test machine is less suited...... for testing fibre-reinforced polymers due to their elastic behaviour and low strain to failure. This is problematic as the High-speed servo-hydraulic test machine closes the gap between quasi-static tests rates and lower strain rates, which are achievable with the Split Hopkinson Pressure Bar. The Split...

  3. Large-deformation and high-strength amorphous porous carbon nanospheres

    Science.gov (United States)

    Yang, Weizhu; Mao, Shimin; Yang, Jia; Shang, Tao; Song, Hongguang; Mabon, James; Swiech, Wacek; Vance, John R.; Yue, Zhufeng; Dillon, Shen J.; Xu, Hangxun; Xu, Baoxing

    2016-04-01

    Carbon is one of the most important materials extensively used in industry and our daily life. Crystalline carbon materials such as carbon nanotubes and graphene possess ultrahigh strength and toughness. In contrast, amorphous carbon is known to be very brittle and can sustain little compressive deformation. Inspired by biological shells and honeycomb-like cellular structures in nature, we introduce a class of hybrid structural designs and demonstrate that amorphous porous carbon nanospheres with a thin outer shell can simultaneously achieve high strength and sustain large deformation. The amorphous carbon nanospheres were synthesized via a low-cost, scalable and structure-controllable ultrasonic spray pyrolysis approach using energetic carbon precursors. In situ compression experiments on individual nanospheres show that the amorphous carbon nanospheres with an optimized structure can sustain beyond 50% compressive strain. Both experiments and finite element analyses reveal that the buckling deformation of the outer spherical shell dominates the improvement of strength while the collapse of inner nanoscale pores driven by twisting, rotation, buckling and bending of pore walls contributes to the large deformation.

  4. a New Approach for Subway Tunnel Deformation Monitoring: High-Resolution Terrestrial Laser Scanning

    Science.gov (United States)

    Li, J.; Wan, Y.; Gao, X.

    2012-07-01

    With the improvement of the accuracy and efficiency of laser scanning technology, high-resolution terrestrial laser scanning (TLS) technology can obtain high precise points-cloud and density distribution and can be applied to high-precision deformation monitoring of subway tunnels and high-speed railway bridges and other fields. In this paper, a new approach using a points-cloud segmentation method based on vectors of neighbor points and surface fitting method based on moving least squares was proposed and applied to subway tunnel deformation monitoring in Tianjin combined with a new high-resolution terrestrial laser scanner (Riegl VZ-400). There were three main procedures. Firstly, a points-cloud consisted of several scanning was registered by linearized iterative least squares approach to improve the accuracy of registration, and several control points were acquired by total stations (TS) and then adjusted. Secondly, the registered points-cloud was resampled and segmented based on vectors of neighbor points to select suitable points. Thirdly, the selected points were used to fit the subway tunnel surface with moving least squares algorithm. Then a series of parallel sections obtained from temporal series of fitting tunnel surfaces were compared to analysis the deformation. Finally, the results of the approach in z direction were compared with the fiber optical displacement sensor approach and the results in x, y directions were compared with TS respectively, and comparison results showed the accuracy errors of x, y, z directions were respectively about 1.5 mm, 2 mm, 1 mm. Therefore the new approach using high-resolution TLS can meet the demand of subway tunnel deformation monitoring.

  5. A NEW APPROACH FOR SUBWAY TUNNEL DEFORMATION MONITORING: HIGH-RESOLUTION TERRESTRIAL LASER SCANNING

    Directory of Open Access Journals (Sweden)

    J. Li

    2012-07-01

    Full Text Available With the improvement of the accuracy and efficiency of laser scanning technology, high-resolution terrestrial laser scanning (TLS technology can obtain high precise points-cloud and density distribution and can be applied to high-precision deformation monitoring of subway tunnels and high-speed railway bridges and other fields. In this paper, a new approach using a points-cloud segmentation method based on vectors of neighbor points and surface fitting method based on moving least squares was proposed and applied to subway tunnel deformation monitoring in Tianjin combined with a new high-resolution terrestrial laser scanner (Riegl VZ-400. There were three main procedures. Firstly, a points-cloud consisted of several scanning was registered by linearized iterative least squares approach to improve the accuracy of registration, and several control points were acquired by total stations (TS and then adjusted. Secondly, the registered points-cloud was resampled and segmented based on vectors of neighbor points to select suitable points. Thirdly, the selected points were used to fit the subway tunnel surface with moving least squares algorithm. Then a series of parallel sections obtained from temporal series of fitting tunnel surfaces were compared to analysis the deformation. Finally, the results of the approach in z direction were compared with the fiber optical displacement sensor approach and the results in x, y directions were compared with TS respectively, and comparison results showed the accuracy errors of x, y, z directions were respectively about 1.5 mm, 2 mm, 1 mm. Therefore the new approach using high-resolution TLS can meet the demand of subway tunnel deformation monitoring.

  6. Application of viscoelastic, viscoplastic, and rate-and-state friction constitutive laws to the deformation of unconsolidated sands

    Science.gov (United States)

    Hagin, Paul N.

    Laboratory experiments on dry, unconsolidated sands from the Wilmington field, CA, reveal significant viscous creep strain under a variety of loading conditions. In hydrostatic compression tests between 10 and 50 MPa of pressure, the creep strain exceeds the magnitude of the instantaneous strain and follows a power law function of time. Interestingly, the viscous effects only appear when loading a sample beyond its preconsolidation pressure. Cyclic loading tests (at quasi-static frequencies of 10-6 to 10 -2 Hz) show that the bulk modulus increases by a factor of two with increasing frequency while attenuation remains constant. I attempt to fit these observations using three classes of models: linear viscoelastic, viscoplastic, and rate-and-state friction models. For the linear viscoelastic modeling, I investigated two types of models; spring-dashpot (exponential) and power law models. I find that a combined power law-Maxwell solid creep model adequately fits all of the data. Extrapolating the power law-Maxwell creep model out to 30 years (to simulate the lifetime of a reservoir) predicts that the static bulk modulus is 25% of the dynamic modulus, in good agreement with field observations. Laboratory studies also reveal that a large portion of the deformation is permanent, suggesting that an elastic-plastic model is appropriate. However, because the viscous component of deformation is significant, an elastic-viscoplastic model is necessary. An appropriate model for unconsolidated sands is developed by incorporating Perzyna (power law) viscoplasticity theory into the modified Cambridge clay cap model. Hydrostatic compression tests conducted as a function of volumetric strain rate produced values for the required model parameters. As a result, by using an end cap model combined with power law viscoplasticity theory, changes in porosity in both the elastic and viscoplastic regimes can be predicted as a function of both stress path and strain rate. To test whether rate

  7. Thrombus Formation at High Shear Rates.

    Science.gov (United States)

    Casa, Lauren D C; Ku, David N

    2017-06-21

    The final common pathway in myocardial infarction and ischemic stroke is occlusion of blood flow from a thrombus forming under high shear rates in arteries. A high-shear thrombus forms rapidly and is distinct from the slow formation of coagulation that occurs in stagnant blood. Thrombosis at high shear rates depends primarily on the long protein von Willebrand factor (vWF) and platelets, with hemodynamics playing an important role in each stage of thrombus formation, including vWF binding, platelet adhesion, platelet activation, and rapid thrombus growth. The prediction of high-shear thrombosis is a major area of biofluid mechanics in which point-of-care testing and computational modeling are promising future directions for clinically relevant research. Further research in this area will enable identification of patients at high risk for arterial thrombosis, improve prevention and treatment based on shear-dependent biological mechanisms, and improve blood-contacting device design to reduce thrombosis risk.

  8. Non-Deforming, High-Reflectance X-ray Coatings for Lynx and Other Future Missions

    Science.gov (United States)

    Windt, David

    The overarching challenge addressed by this proposal is the development of highreflectance, high-resolution X-ray mirrors, to be used for the construction of lightweight X-ray telescopes for future NASA astronomy missions such as Lynx and others. The proposal's two specific aims are: 1) the development of optimized iridium-based interference coatings for the 0.1–10 keV band; and 2) the development of methods to mitigate coating-stress-induced substrate deformations in thin-shell glass and Si mirror segments. These goals will be achieved by building on established film deposition techniques and metrology infrastructure for X-ray optics that have been developed and advanced by the PI through APRA funding since 1999. Specific Aim #1: Interference Coatings for the 0.1–10 keV Energy Band Telescope effective area can be maximized by using Ir-based reflective coatings that exploit optical interference to provide higher reflectance than Ir alone. However, only preliminary investigations of such coatings have been conducted thus far; more research is required to fully optimize these coatings for maximum performance, to experimentally determine the coating designs that are feasible, and to determine the achievable X-ray reflectance, film stress, surface roughness, and thermal and temporal stability. The first specific aim of this proposal is to reach these very goals through a comprehensive research program. Demonstration of the achievable reflectance, stress, and roughness in stable, optimized coatings will in turn facilitate global telescope design optimization, by identifying the best coating for each mirror shell based on incidence angle, and on telescope effective-area and field-of-view requirements. The research has the potential to greatly increase the effective area of future X-ray telescopes. Specific Aim #2: Mitigation of Coating-Stress-Induced Substrate Deformations High-quality films of Ir and other candidate materials (e.g., B4C) to be investigated for the 0

  9. Behavior of fiber reinforced metal laminates at high strain rate

    Science.gov (United States)

    Newaz, Golam; Sasso, Marco; Amodio, Dario; Mancini, Edoardo

    2018-05-01

    Carbon Fiber Reinforced Aluminum Laminate (CARALL) is a good system for energy absorption through plastic deformation in aluminum and micro-cracking in the composite layers. Moreover, CARALL FMLs also provide excellent impact resistance due to the presence of aluminum layer. The focus of this research is to characterize the CARALL behavior under dynamic conditions. High strain rate tests on sheet laminate samples have been carried out by means of direct Split Hopkinson Tension Bar. The sample geometry and the clamping system were optimized by FEM simulations. The clamping system has been designed and optimized in order reduce impedance disturbance due to the fasteners and to avoid the excessive plastic strain outside the gauge region of the samples.

  10. Effect of prior deformation on microstructural development and Laves phase precipitation in high-chromium stainless steel.

    Science.gov (United States)

    Hsiao, Z-W; Chen, D; Kuo, J-C; Lin, D-Y

    2017-04-01

    This study investigated the influence of deformation on precipitation behaviour and microstructure change during annealing. Here, the prior deformation of high-chromium stainless steel was tensile deformation of 3%, 6% and 10%, and the specimens were then annealed at 700˚C for 10 h. The specimens were subsequently analyzed using backscattered electron image and electron backscattering diffraction measurements with SEM. Compared with the deformation microstructure, the grains revealed no preferred orientation. The precipitates of TiN and NbC were formed homogenously in the grain interior and at grain boundaries after annealing. Fine Laves phase precipitates were observed in grains and along subgrain boundaries as the deformation increased. Furthermore, the volume fraction of Laves phase increased, but the average particle diameter of precipitate was reduced as the deformation increased. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  11. Localized deformation via multiple twinning in a Mg–Gd–Y–Zr alloy processed by high-pressure torsion

    International Nuclear Information System (INIS)

    Tang, Lingling; Zhao, Yonghao; Liang, Ningning; Islamgaliev, R.K.; Valiev, R.Z.; Zhu, Y.T.

    2016-01-01

    Different with common grain refinement dominated by dislocation activities, grain subdivision induced by sequential activation of multiple twinning was observed in a Mg-Gd-Y-Zr magnesium alloy via high-pressure torsion. Deformation bands were evolved from large primary twin bands, which contained refined grains through localized multiple twinning. Nanometer-scaled amorphous bands were also observed within deformation bands in Mg alloys for the first time. These observations indicate that localized deformation via multiple twinning and the consequent formation of deformation bands are potential routes to grain refinement in rare earth-magnesium alloys.

  12. Ultra-high aspect ratio replaceable AFM tips using deformation-suppressed focused ion beam milling

    International Nuclear Information System (INIS)

    Savenko, Alexey; Yildiz, Izzet; Petersen, Dirch Hjorth; Bøggild, Peter; Bartenwerfer, Malte; Krohs, Florian; Oliva, Maria; Harzendorf, Torsten

    2013-01-01

    Fabrication of ultra-high aspect ratio exchangeable and customizable tips for atomic force microscopy (AFM) using lateral focused ion beam (FIB) milling is presented. While on-axis FIB milling does allow high aspect ratio (HAR) AFM tips to be defined, lateral milling gives far better flexibility in terms of defining the shape and size of the tip. Due to beam-induced deformation, it has so far not been possible to define HAR structures using lateral FIB milling. In this work we obtain aspect ratios of up to 45, with tip diameters down to 9 nm, by a deformation-suppressing writing strategy. Several FIB milling strategies for obtaining sharper tips are discussed. Finally, assembly of the HAR tips on a custom-designed probe as well as the first AFM scanning is shown. (paper)

  13. Multiscale modeling of high contrast brinkman equations with applications to deformable porous media

    KAUST Repository

    Brown, Donald

    2013-06-18

    Simulating porous media flows has a wide range of applications. Often, these applications involve many scales and multi-physical processes. A useful tool in the analysis of such problems in that of homogenization as an averaged description is derived circumventing the need for complicated simulation of the fine scale features. In this work, we recall recent developments of homogenization techniques in the application of flows in deformable porous media. In addition, homogenization of media with high-contrast. In particular, we recall the main ideas of the homogenization of slowly varying Stokes flow and summarize the results of [4]. We also present the ideas for extending these techniques to high-contrast deformable media [3]. These ideas are connected by the modeling of multiscale fluid-structure interaction problems. © 2013 American Society of Civil Engineers.

  14. Aluminium. II - A review of deformation properties of high purity aluminium and dilute aluminium alloys.

    Science.gov (United States)

    Reed, R. P.

    1972-01-01

    The elastic and plastic deformation behavior of high-purity aluminum and of dilute aluminum alloys is reviewed. Reliable property data, including elastic moduli, elastic coefficients, tensile, creep, fatigue, hardness, and impact are presented. Single crystal tensile results are discussed. Rather comprehensive reference lists, containing publications of the past 20 years, are included for each of the above categories. Defect structures and mechanisms responsible for mechanical behavior are presented. Strengthening techniques (alloys, cold work, irradiation, quenching, composites) and recovery are briefly reviewed.

  15. High frame rate synthetic aperture duplex imaging

    DEFF Research Database (Denmark)

    Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Pihl, Michael Johannes

    2013-01-01

    aperture flow imaging as demonstrated in this paper. Synthetic aperture, directional beamforming, and cross-correlation are used to produce B-mode and vector velocity images at high frame rates. The frame rate equals the effective pulse repetition frequency of each imaging mode. Emissions for making the B...... estimation is −1.8% and the relative standard deviation 5.4%. The approach can thus estimate both high and low velocities with equal accuracy and thereby makes it possible to present vector flow images with a high dynamic range. Measurements are made using the SARUS research scanner, a linear array......Conventional color flow images are limited in velocity range and can either show the high velocities in systole or be optimized for the lower diastolic velocities. The full dynamics of the flow is, thus, hard to visualize. The dynamic range can be significantly increased by employing synthetic...

  16. A High-Rate, Single-Crystal Model including Phase Transformations, Plastic Slip, and Twinning

    Energy Technology Data Exchange (ETDEWEB)

    Addessio, Francis L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Bronkhorst, Curt Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Bolme, Cynthia Anne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Explosive Science and Shock Physics Division; Brown, Donald William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Cerreta, Ellen Kathleen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Lebensohn, Ricardo A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Lookman, Turab [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Luscher, Darby Jon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Mayeur, Jason Rhea [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Morrow, Benjamin M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Rigg, Paulo A. [Washington State Univ., Pullman, WA (United States). Dept. of Physics. Inst. for Shock Physics

    2016-08-09

    An anisotropic, rate-­dependent, single-­crystal approach for modeling materials under the conditions of high strain rates and pressures is provided. The model includes the effects of large deformations, nonlinear elasticity, phase transformations, and plastic slip and twinning. It is envisioned that the model may be used to examine these coupled effects on the local deformation of materials that are subjected to ballistic impact or explosive loading. The model is formulated using a multiplicative decomposition of the deformation gradient. A plate impact experiment on a multi-­crystal sample of titanium was conducted. The particle velocities at the back surface of three crystal orientations relative to the direction of impact were measured. Molecular dynamics simulations were conducted to investigate the details of the high-­rate deformation and pursue issues related to the phase transformation for titanium. Simulations using the single crystal model were conducted and compared to the high-­rate experimental data for the impact loaded single crystals. The model was found to capture the features of the experiments.

  17. Baltimore District Tackles High Suspension Rates

    Science.gov (United States)

    Maxwell, Lesli A.

    2007-01-01

    This article reports on how the Baltimore District tackles its high suspension rates. Driven by an increasing belief that zero-tolerance disciplinary policies are ineffective, more educators are embracing strategies that do not exclude misbehaving students from school for offenses such as insubordination, disrespect, cutting class, tardiness, and…

  18. Endorectal high dose rate brachytherapy quality assurance

    International Nuclear Information System (INIS)

    Devic, S.; Vuong, T.; Evans, M.; Podgorsak, E.

    2008-01-01

    We describe our quality assurance method for preoperative high dose rate (HDR) brachytherapy of endorectal tumours. Reproduction of the treatment planning dose distribution on a daily basis is crucial for treatment success. Due to the cylindrical symmetry, two types of adjustments are necessary: applicator rotation and dose distribution shift along the applicator axis. (author)

  19. High Temperature Deformation Behavior and Microstructure Evolution of Ti-4Al-4Fe-0.25Si Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Won, Jong Woo; Lee, Yongmoon; Lee, Chong Soo [Pohang University of Science and Technology, Pohang (Korea, Republic of); Yeom, Jong-Taek [Korea Institute of Materials Science, Changwon (Korea, Republic of); Lee, Gi Yeong [KPCM Incorporated, Gyeongsan (Korea, Republic of)

    2016-05-15

    Hot deformation behavior of Ti-4Al-4Fe-0.25Si alloy with martensite microstructure was investigated by compression tests at temperatures of 1023 – 1173 K (α+β phase region) and strain rates of 10{sup -3} – 1 s{sup -1}. By analyzing the deformation behavior, plastic deformation instability parameters including strain rate sensitivity, deformation temperature sensitivity, efficiency of power dissipation, and Ziegler’s instability were evaluated as a function of deformation temperature and strain rate, and they were further examined by drawing deformation processing maps. The microstructure evolution was also studied to determine the deformation conditions under which equiaxed α phase was formed in the microstructure without remnants or kinked α phase platelets and shear bands, these last two of which cause severe cracks during post-forming process. Based on the combined results of the processing maps and the microstructure analysis, the optimum α+β forging conditions for Ti-4Al-4Fe-0.25Si alloy were determined.

  20. Design of a self-calibration high precision micro-angle deformation optical monitoring scheme

    Science.gov (United States)

    Gu, Yingying; Wang, Li; Guo, Shaogang; Wu, Yun; Liu, Da

    2018-03-01

    In order to meet the requirement of high precision and micro-angle measurement on orbit, a self-calibrated optical non-contact real-time monitoring device is designed. Within three meters, the micro-angle variable of target relative to measuring basis can be measured in real-time. The range of angle measurement is +/-50'', the angle measurement accuracy is less than 2''. The equipment can realize high precision real-time monitoring the micro-angle deformation, which caused by high strength vibration and shock of rock launching, sun radiation and heat conduction on orbit and so on.

  1. The unexpected stability of multiwall nanotubes under high pressure and shear deformation

    International Nuclear Information System (INIS)

    Pashkin, E. Y.; Pankov, A. M.; Kulnitskiy, B. A.; Mordkovich, V. Z.; Perezhogin, I. A.; Karaeva, A. R.; Popov, M. Y.; Sorokin, P. B.; Blank, V. D.

    2016-01-01

    The behavior of multiwall carbon nanotubes under a high pressure (up to 55 GPa) combined with shear deformation was studied by experimental and theoretical methods. The unexpectedly high stability of the nanotubes' structure under high stresses was observed. After the pressure was released, we observed that the nanotubes had restored their shapes. Atomistic simulations show that the hydrostatic and shear stresses affect the nanotubes' structure in a different way. It was found that the shear stress load in the multiwall nanotubes' outer walls can induce their connection and formation of an amorphized sp"3-hybridized region but internal core keeps the tubular structure.

  2. The unexpected stability of multiwall nanotubes under high pressure and shear deformation

    Energy Technology Data Exchange (ETDEWEB)

    Pashkin, E. Y.; Pankov, A. M.; Kulnitskiy, B. A.; Mordkovich, V. Z. [Technological Institute for Superhard and Novel Carbon Materials, 7a Centralnaya Street, Troitsk, Moscow 142190 (Russian Federation); Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700 (Russian Federation); Perezhogin, I. A. [Technological Institute for Superhard and Novel Carbon Materials, 7a Centralnaya Street, Troitsk, Moscow 142190 (Russian Federation); Lomonosov Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Karaeva, A. R. [Technological Institute for Superhard and Novel Carbon Materials, 7a Centralnaya Street, Troitsk, Moscow 142190 (Russian Federation); Popov, M. Y.; Sorokin, P. B.; Blank, V. D. [Technological Institute for Superhard and Novel Carbon Materials, 7a Centralnaya Street, Troitsk, Moscow 142190 (Russian Federation); Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny 141700 (Russian Federation); National University of Science and Technology MISiS, 4 Leninskiy Prospekt, Moscow 119049 (Russian Federation)

    2016-08-22

    The behavior of multiwall carbon nanotubes under a high pressure (up to 55 GPa) combined with shear deformation was studied by experimental and theoretical methods. The unexpectedly high stability of the nanotubes' structure under high stresses was observed. After the pressure was released, we observed that the nanotubes had restored their shapes. Atomistic simulations show that the hydrostatic and shear stresses affect the nanotubes' structure in a different way. It was found that the shear stress load in the multiwall nanotubes' outer walls can induce their connection and formation of an amorphized sp{sup 3}-hybridized region but internal core keeps the tubular structure.

  3. Peculiarities of the effect of high temperature deformation on the kinetics of bainite transformation in steels of various compositions

    International Nuclear Information System (INIS)

    Khlestov, V.M.; Gotsulyak, A.A.; Ehntin, R.I.; Konopleva, E.V.; Kogan, L.I.

    1979-01-01

    By the methods of magnetometry and metallography studied is the effect of 25% deformation by rolling at 800 deg C on kinetics and parameters of bainite transformation in steels with different hydrogen contents and types of alloying. The hot deformation decelerates the bainite transformation at temperatures >=400 deg C; while the isoterm temperature increases the decelerating effect of deformation at first decreases and then changes into the accelerating one. The slowing down of the transformation is determined mainly by the decrease in the rate of the bainite crystal growth, whereas the acceleration - by the activation of grain initiation processes in the hot-deformed austenite. A hydrogen content increase and steel alloying with carbide-forming elements increase the stabilization effect of the deformation on kinetics of bainite transformation

  4. Deformability and strength of granite under the influence of stress, temperature, rate of loading and water environment

    International Nuclear Information System (INIS)

    Shivkumar, K.; Nagaraja Rao, G.M.

    1995-01-01

    The design of nuclear waste repository in geological formation is a unique rock mechanics problem for at least two reasons. These are the usually long service life and the relatively high service temperature. These play a major role in rock deformation. Laboratory simulation studies under the anticipated environmental conditions for waste disposal vaults, and the data generated through these investigations will be helpful in designing a theoretical/experimental model for the repository. Towards this end, some efforts were made to understand the mechanical behaviour of granites. (author)

  5. Effect of severe plastic deformation on microstructure and mechanical properties of magnesium and aluminium alloys in wide range of strain rates

    Science.gov (United States)

    Skripnyak, Vladimir; Skripnyak, Evgeniya; Skripnyak, Vladimir; Vaganova, Irina; Skripnyak, Nataliya

    2013-06-01

    Results of researches testify that a grain size have a strong influence on the mechanical behavior of metals and alloys. Ultrafine grained HCP and FCC metal alloys present higher values of the spall strength than a corresponding coarse grained counterparts. In the present study we investigate the effect of grain size distribution on the flow stress and strength under dynamic compression and tension of aluminium and magnesium alloys. Microstructure and grain size distribution in alloys were varied by carrying out severe plastic deformation during the multiple-pass equal channel angular pressing, cyclic constrained groove pressing, and surface mechanical attrition treatment. Tests were performed using a VHS-Instron servo-hydraulic machine. Ultra high speed camera Phantom V710 was used for photo registration of deformation and fracture of specimens in range of strain rates from 0,01 to 1000 1/s. In dynamic regime UFG alloys exhibit a stronger decrease in ductility compared to the coarse grained material. The plastic flow of UFG alloys with a bimodal grain size distribution was highly localized. Shear bands and shear crack nucleation and growth were recorded using high speed photography.

  6. Effect of microplastic deformation on the electron ultrasonic absorption in high-purity molybdenum monocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Pal' -Val' , P.P. (AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst. Nizkikh Temperatur); Kaufmann, Kh.J. (Akademie der Wissenschaften der DDR, Berlin)

    1983-03-01

    The low temperature (100-6 K) linear absorption of ultrasound (88 kHz) by high purity molybdenum single crystals have been studied. Both unstrained samples and samples subjected to microplastic deformation (epsilon<=0.45%) were used. Unstrained samples displayed at T<30 K a rapid increase in the absorption with lowering temperature which is interpreted as an indication of electron viscosity due to electron-phonon collisions. After deformation this part of absorption disappeared. This seems to suggest that microplastic deformation brings about in the crystal a sufficiently large number of defects that can compete with phonons in restricting the electron mean free path. A low temperature ''dynamic annealing'' has been revealed in strained samples, that is, almost complete recovery of the absorption nature under irradiation with high amplitude sound, epsilon/sub 0/ approximately 10/sup -4/, during 10 min, at 6 K. A new relaxation peak of absorption at 10 K has been found in strained samples.

  7. Deformation Monitoring of Geomechanical Model Test and Its Application in Overall Stability Analysis of a High Arch Dam

    Directory of Open Access Journals (Sweden)

    Baoquan Yang

    2015-01-01

    Full Text Available Geomechanical model testing is an important method for studying the overall stability of high arch dams. The main task of a geomechanical model test is deformation monitoring. Currently, many types of deformation instruments are used for deformation monitoring of dam models, which provide valuable information on the deformation characteristics of the prototype dams. However, further investigation is required for assessing the overall stability of high arch dams through analyzing deformation monitoring data. First, a relationship for assessing the stability of dams is established based on the comprehensive model test method. Second, a stability evaluation system is presented based on the deformation monitoring data, together with the relationships between the deformation and overloading coefficient. Finally, the comprehensive model test method is applied to study the overall stability of the Jinping-I high arch dam. A three-dimensional destructive test of the geomechanical model dam is conducted under reinforced foundation conditions. The deformation characteristics and failure mechanisms of the dam abutments and foundation were investigated. The test results indicate that the stability safety factors of the dam abutments and foundation range from 5.2 to 6.0. These research results provide an important scientific insight into the design, construction, and operation stages of this project.

  8. High strain rate behaviour of polypropylene microfoams

    Directory of Open Access Journals (Sweden)

    Martínez A.B.

    2012-08-01

    Full Text Available Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc. or personal safety (helmets, knee-pads, etc.. In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s−1 in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB. Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  9. High strain rate behaviour of polypropylene microfoams

    Science.gov (United States)

    Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.

    2012-08-01

    Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc.) or personal safety (helmets, knee-pads, etc.). In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry) is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  10. High dose rate endobronchial brachytherapy - treatment technique

    International Nuclear Information System (INIS)

    Carvalho, Heloisa de Andrade; Aisen, Salim; Haddad, Cecilia Maria Kalil; Nadalin, Wladimir; Pedreira Junior, Wilson Leite; Chavantes, Maria Cristina

    1998-01-01

    High dose rate endobronchial brachytherapy is efficient in symptom relief due to obstructive endobronchial malignancies. However, it's role in survival improvement for patients with lung cancer is not yet established. The use of this treatment in increasing, specially in the developing countries. The purpose of this paper is to present the treatment technique used in the Radiotherapy Department of the Hospital da Clinicas, University of Sao Paulo, based on an experience of 60 cases treated with 180 procedures. Some practical suggestions and rules adopted in the Department are described. The severe complications rate is 6.7%, demonstrating an adequate patient selection associated with the technique utilized. (author)

  11. Electronics for very high rate tracking detectors

    International Nuclear Information System (INIS)

    Williams, H.H.; Dressnandt, N.; Ekenberg, T.; Gerds, E.J.; Newcomer, F.M.; Tedja, S.; Van Berg, R.; Van der Speigel, J.

    1995-01-01

    Results are presented on a system of electronics designed for very high rate tracking detectors at the SSC and LHC. The primary goal was a system for signal detection, time measurement, and readout for the straw tracker for SDC. An integrated circuit incorporating eight channels of amplifier-shaper-discriminator (including detector tail cancellation), and two different integrated circuits for time measurement are described. The performance of tracking measurements up to counting rates of 8 MHz per wire is reported, as well as preliminary results from a baseline restoration circuit. (orig.)

  12. Holocene deformation offshore Ventura basin, CA, constrained by new high-resolution geophysical data

    Science.gov (United States)

    Perea, H.; Ucarkus, G.; Driscoll, N. W.; Kent, G. M.; Levy, Y.; Rockwell, T. K.

    2017-12-01

    The Transverse Ranges (Southern California, USA) accommodate the contraction resulting from a regional restraining bend in the San Andreas Fault to form a thrust-and-fold belt system. The southern boundary of this system corresponds to the E-W trending Ventura basin, which is filled by more than 5 km of Pleistocene sediment and is shortening at about 10 mm/yr as inferred from geodetic data. Although the different thrust and folds are fairly well known in the onshore areas of the basin, there is still uncertainty about their continuation in the offshore. The analysis of new high-resolution (SIO CHIRP) and existing (USGS sparker and chirp) seismic data has allowed us to characterize better the active geological structures in the offshore. In the dataset, we have identified different latest Quaternary seismostratigraphic units and horizons, with the most regionally recognized being a transgressive surface (LGTS) associated to the Last Glacial maximum and subsequent sea level rise. A series of E-W regional folds related to thrust faults have deformed the LGTS producing highs and depressions. The correlation of these structures between profiles shows that they are elongated and parallel between them and continue to the coastline. In addition, considering their trend and kinematics, we have been able to tie them with the main onshore active thrusts and folds. Above the LGTS we have identified progradational and agradational units that are related to global sea level rise, which exhibit less deformation (folding and faulting) than the lower units and horizons. However, we have recognized some specific fold growth sequences above LGTS associated with the activity of different thrust-related anticlines. Accordingly, we have identified between 3 and 5 tectonic deformation events (e.g., earthquakes) associated to thrust fault activity. These results may help us to determine the deformation history for the offshore Ventura basin and the potentiality of the thrust faults that

  13. Uniaxial Compressive Strength and Fracture Mode of Lake Ice at Moderate Strain Rates Based on a Digital Speckle Correlation Method for Deformation Measurement

    Directory of Open Access Journals (Sweden)

    Jijian Lian

    2017-05-01

    Full Text Available Better understanding of the complex mechanical properties of ice is the foundation to predict the ice fail process and avoid potential ice threats. In the present study, uniaxial compressive strength and fracture mode of natural lake ice are investigated over moderate strain-rate range of 0.4–10 s−1 at −5 °C and −10 °C. The digital speckle correlation method (DSCM is used for deformation measurement through constructing artificial speckle on ice sample surface in advance, and two dynamic load cells are employed to measure the dynamic load for monitoring the equilibrium of two ends’ forces under high-speed loading. The relationships between uniaxial compressive strength and strain-rate, temperature, loading direction, and air porosity are investigated, and the fracture mode of ice at moderate rates is also discussed. The experimental results show that there exists a significant difference between true strain-rate and nominal strain-rate derived from actuator displacement under dynamic loading conditions. Over the employed strain-rate range, the dynamic uniaxial compressive strength of lake ice shows positive strain-rate sensitivity and decreases with increasing temperature. Ice obtains greater strength values when it is with lower air porosity and loaded vertically. The fracture mode of ice seems to be a combination of splitting failure and crushing failure.

  14. Yield strength of molybdenum, tantalum and tungsten at high strain rates and very high temperatures

    International Nuclear Information System (INIS)

    Škoro, G.P.; Bennett, J.R.J.; Edgecock, T.R.; Booth, C.N.

    2012-01-01

    Highlights: ► New experimental data on the yield strength of molybdenum, tantalum and tungsten. ► High strain rate effects at record high temperatures (up to 2700 K). ► Test of the consistency of the Zerilli–Armstrong model at very high temperatures. - Abstract: Recently reported results of the high strain rate, high temperature measurements of the yield strength of tantalum and tungsten have been analyzed along with new experimental results on the yield strength of molybdenum. Thin wires are subjected to high stress by passing a short, fast, high current pulse through a thin wire; the amplitude of the current governs the stress and the repetition rate of the pulses determines the temperature of the wire. The highest temperatures reached in the experiments were 2100 °C (for molybdenum), 2250 °C (for tantalum) and 2450 °C (for tungsten). The strain-rates in the tests were in the range from 500 to 1500 s −1 . The parameters for the constitutive equation developed by Zerilli and Armstrong have been determined from the experimental data and the results have been compared with the data obtained at lower temperatures. An exceptionally good fit is obtained for the deformation of tungsten.

  15. Modeling the Effects of Cu Content and Deformation Variables on the High-Temperature Flow Behavior of Dilute Al-Fe-Si Alloys Using an Artificial Neural Network.

    Science.gov (United States)

    Shakiba, Mohammad; Parson, Nick; Chen, X-Grant

    2016-06-30

    The hot deformation behavior of Al-0.12Fe-0.1Si alloys with varied amounts of Cu (0.002-0.31 wt %) was investigated by uniaxial compression tests conducted at different temperatures (400 °C-550 °C) and strain rates (0.01-10 s -1 ). The results demonstrated that flow stress decreased with increasing deformation temperature and decreasing strain rate, while flow stress increased with increasing Cu content for all deformation conditions studied due to the solute drag effect. Based on the experimental data, an artificial neural network (ANN) model was developed to study the relationship between chemical composition, deformation variables and high-temperature flow behavior. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using the K-fold cross-validation method. The results showed excellent generalization capability of the developed model. Sensitivity analysis indicated that the strain rate is the most important parameter, while the Cu content exhibited a modest but significant influence on the flow stress.

  16. Microstructure and High Temperature Plastic Deformation Behavior of Al-12Si Based Alloy Fabricated by an Electromagnetic Casting and Stirring Process

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Kyung-Soo; Roh, Heung-Ryeol; Kim, Mok-Soon [Inha University, Incheon (Korea, Republic of); Kim, Jong-Ho; Park, Joon-Pyo [Research Institute of Industrial Science and Technology, Pohang (Korea, Republic of)

    2017-06-15

    An as-received EMC/S (electromagnetic casting and stirring)-processed Al-12Si based alloy billet was homogenized to examine its microstructure and high temperature plastic deformation behavior, using compressive tests over the temperature range from 623 to 743 K and a strain rate range from 1.0×10{sup -3} to 1.0×10{sup 0}s{sup -1}. The results were compared with samples processed by the direct chill casting (DC) method. The fraction of equiaxed structure for the as-received EMC/S billet(41%) was much higher than that of the as-received DC billet(6 %). All true stress – true strain curves acquired from the compressive tests exhibited a peak stress at the initial stage of plastic deformation. Flow stress showed a steady state region after the appearance of peak stress with increasing strain. The peak stress decreased with increasing temperature at a given strain rate and a decreasing strain rate at a given temperature. A constitutive equation was made for each alloy, which could be used to predict the peak stress. A recrystallized grain structure was observed in all the deformed specimens, indicating that dynamic recrystallization is the predominant mechanism during high temperature plastic deformation of both the homogenized EMC/S and DC-processed Al-12Si based alloys.

  17. Analysis of High Temperature Deformed Structure and Dynamic Precipitation in W9Mo3Cr4V Steel

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With TEM、SEM, various high-temperature deformed structures inW9Mo3Cr4V steel were investigated. The sub-structures,recrystallized nuclei, as well as the dynamic precipitation were also studied and analyzed. The relationship between recrystallized structures and dynamic precipitation was discussed. The results showed that the deformed structures in W9Mo3Cr4V steel are more complicated than those in low alloy steels. Because W9Mo3Cr4V steel is a high-speed steel, there are a large number of residual carbides on the matrix. Also, much dynamic precipitating carbides will precipitate during deformation at high temperature.

  18. Swelling of uranium dioxide and deformation behavior of the fuel element at high temperature irradiation

    International Nuclear Information System (INIS)

    Gontar, A.S.; Gutnik, V.S.; Nelidov, M.V.; Nikolaev, Yu.V.

    1993-01-01

    As post-reactor investigations showed, significant difference of swelling rates is connected with the fact that swelling of UO 2 with the equiaxial structure is mainly the result of fission gas bubbles accumulation along grain boundaries, and, in the case of the column structure, with formation of fine bubbles inside grains. The data given testify to usefulness of such investigations to predict TFE lifetime. As proven in this study one can see rates of radial deformation of fuel element cladding of a multi-cell TFE as a result of UO 2 swelling. They were calculated using the code SDS. Typical sizes were taken for calculation: cladding diameter--20 mm, cladding temperature at the central section of the fuel element--1,900 K, energy generation rate--145 W/cm 3 . These parameters provide output electric power of the TFE 600 W at the active zone length--400 mm

  19. High magma storage rates before the 1983 eruption of kilauea, hawaii

    Science.gov (United States)

    Cayol; Dieterich; Okamura; Miklius

    2000-06-30

    After a magnitude 7.2 earthquake in 1975 and before the start of the ongoing eruption in 1983, deformation of Kilauea volcano was the most rapid ever recorded. Three-dimensional numerical modeling shows that this deformation is consistent with the dilation of a dike within Kilauea's rift zones coupled with creep over a narrow area of a low-angle fault beneath the south flank. Magma supply is estimated to be 0.18 cubic kilometers per year, twice that of previous estimates. The 1983 eruption may be a direct consequence of the high rates of magma storage within the rift zone that followed the 1975 earthquake.

  20. Processing of high-temperature superconductors at high strain rates

    International Nuclear Information System (INIS)

    Mamalis, A.G.; Pantazsopoulos, G.; Manolakos, D.E.; Szalay, A.

    2000-01-01

    This new book provides, for the first time, a systematic, unified presentation of all steps in the processing of high-temperature superconductor materials, ranging from synthesis of various systems to fabrication and industrial applications. Also covered are characterization techniques and current directions in research and development. The authors are leading specialists who bring to this new book their many years of experience in research, education and industrial engineering work in superconductor materials. This book is primarily focused on the bulk-fabrication techniques of high-temperature ceramic superconducting components, especially on the combination of dynamic powder-consolidation and subsequent deformation processing. The properties of these ceramics, which are difficult-to-form materials by applying conventional techniques, are combined for the net-shape manufacturing of such components for the construction of HTS deviceshor e llipsis. However, very important topics such as superconducting structures, chemical synthesis, film fabrication and characterization techniques are also reviewedhor e llipsis to provide a complete, comprehensive view of superconductors engineering

  1. Timing of isoclinal folds in multiply deformed high metamorphic grade region using FIA succession

    Science.gov (United States)

    Cao, Hui; Cai, Zhihui

    2013-04-01

    Multiply deformed and isoclinally folded interlayered high metamorphic grade gneisses and schists can be very difficult rocks for resolving early formed stratigraphic and structural relationships. When such rocks contain porphyroblasts a new approach is possible because of the way in which porphyroblast growth is affected by crenulation versus reactivation of compositional layering. The asymmetries of the overprinting foliations preserved as inclusion trails that define the FIAs can be used to investigate whether an enigmatic isoclinal fold is an antiform or synform. This approach also reveals when the fold first formed during the tectonic history of the region. Isoclinally folded rocks in the Arkansas River region of Central Colorado contain relics of fold hinges that have been very difficult to ascertain whether they are antiforms or synforms because of younger refolding effects and the locally truncated nature of coarse compositional layering. With the realization that rocks with a schistosity parallel to bedding (S0 parallel S1) have undergone lengthy histories of deformation that predate the obvious first deformation came recognition that large scale regional folds can form early during this process and be preserved throughout orogenesis. This extensive history is lost within the matrix because of reactivational shear on the compositional layering. However, it can be extracted by measuring FIAs. Recent work using this approach has revealed that the trends of axial planes of all map scale folds, when plotted on a rose diagram, strikingly reflect the FIA trends. That is, although it was demonstrated that the largest scale regional folds commonly form early in the total history, other folds can form and be preserved from subsequent destruction in the strain shadows of plutons or through the partitioning of deformation due to heterogeneities at depth.

  2. Microstructural evolution during tensile deformation of polypropylenes

    International Nuclear Information System (INIS)

    Dasari, A.; Rohrmann, J.; Misra, R.D.K.

    2003-01-01

    Tensile deformation processes occurring at varying strain rates in high and low crystallinity polypropylenes and ethylene-propylene di-block copolymers have been investigated by scanning electron microscopy. This is examined for both long and short chain polymeric materials. The deformation processes in different polymeric materials show striking dissimilarities in spite of the common propylene matrix. Additionally, the deformation behavior of long and their respective short chain polymers was different. Deformation mechanisms include crazing/tearing, wedging, ductile ploughing, fibrillation, and brittle fracture. The different modes of deformation are depicted in the form of strain rate-strain diagrams. At a constant strain rate, the strain to fracture follows the sequence: high crystallinity polypropylenes< low crystallinity polypropylenes< ethylene-propylene di-block copolymers, indicative of the trend in resistance to plastic deformation

  3. Deformation patterning driven by rate dependent non-convex strain gradient plasticity

    NARCIS (Netherlands)

    Yalcinkaya, T.; Brekelmans, W.A.M.; Geers, M.G.D.

    2011-01-01

    A rate dependent strain gradient plasticity framework for the description of plastic slip patterning in a system with non-convex energetic hardening is presented. Both the displacement and the plastic slip fields are considered as primary variables. These fields are determined on a global level by

  4. Microstructural evolution at high strain rates in solution-hardened interstitial free steels

    International Nuclear Information System (INIS)

    Uenishi, A.; Teodosiu, C.; Nesterova, E.V.

    2005-01-01

    Comprehensive transmission electron microscopical studies have been conducted for solution-hardened steels deformed at high (1000 s -1 ) and low (0.001 s -1 ) strain rates, in order to clarify the effects of strain rate and a jump in strain rate on the evolution of the microstructure and its connection with the mechanical response. It was revealed that the various types of microstructure, observed even within the same specimen, depend on the corresponding grain orientations and their evolution with progressive deformation depends on these microstructure types. At high strain rates, the dislocation density increases especially at low strains and the onset of dislocation organization is delayed. A jump in strain rate causes an increase of the dislocation density inside an organized structure. These results corroborated the mechanical behaviour at high strain rates after compensation for the cross-sectional reduction and temperature increase. The higher work-hardening rate at high strain rates could be connected to a delay in the dislocation organization. The high work-hardening rate just after a jump could be due to an increase of the density of dislocations distributed uniformly inside an organized structure

  5. Influence of hot plastic deformation and cooling rate on martensite and bainite start temperatures in 22MnB5 steel

    Energy Technology Data Exchange (ETDEWEB)

    Nikravesh, M., E-mail: nikravesh@yahoo.com [Department of Material Science and Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Naderi, M. [Department of Mining and Metallurgy, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Akbari, G.H. [Department of Material Science and Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of)

    2012-04-01

    Highlights: Black-Right-Pointing-Pointer Reduction of cooling rate, can cause to increase or decrease M{sub s} and M{sub f}. Black-Right-Pointing-Pointer 40% hot plastic deformation hindered the martensitic transformation. Black-Right-Pointing-Pointer Hot plastic deformation, caused to decrease M{sub f} and M{sub s}, while B{sub s} increased. Black-Right-Pointing-Pointer The critical cooling rate increased 40 Degree-Sign C/s due to apply 40% hot deformation. - Abstract: During hot stamping process, hot forming, cooling and phase transformations are performed in a single step. As a matter of fact, multifunctional phenomena happen and affect each other. Among these phenomena, martensitic and bainitic transformations have the greatest importance. In the current research, the start temperatures of martensite and bainite of 22MnB5 boron steel have been measured in undeformed and 40% deformed conditions, and in various cooling rates from 0.4 Degree-Sign C/s to 100 Degree-Sign C/s by means of deformation dilatometer. It is concluded that, reduction of cooling rate, could bring about an increase or decrease in M{sub s} and M{sub f}, depending on other phases formation before martensite. Also, hot plastic deformation, hindered the martensitic transformation and decreased M{sub f} and M{sub s} especially at lower cooling rates, while B{sub s} increased. Furthermore, the critical cooling rate, increased about 40 Degree-Sign C/s by applying 40% hot plastic deformation.

  6. Influence of the relative deformation rate on tube processing by ultrasonic vibration drawing

    International Nuclear Information System (INIS)

    Susan, M.; Bujoreanu, L. G.; Galusca, D. G.; Munteanu, C.; Lliescu, V.

    2004-01-01

    After a brief review of the friction reversion mechanism during ultrasonic vibration drawing of tubes (UVD), the paper introduces a method to determine the drawing force based on the theorem of total consumed power, in the case of tube processing. The experiments performed on tubes made from 10TiNiCr180 (AISI321) austenitic stainless steel confirm the superiority of UVD technology regarding the diminution of the drawing force, the increase of the plasticity and the improvement of the safety coefficient, tendencies that are enhanced with the decrease of the relative drawing rate. The best results were obtained for the relative drawing rate of 0.12 for which the drawing force decreased with 33%, plasticity increased with 9% and safety coefficient with 22%, as compared to CT. (Author) 10 refs

  7. High repetition rate intense ion beam source

    International Nuclear Information System (INIS)

    Hammer, D.A.; Glidden, S.C.; Noonan, B.

    1992-01-01

    This final report describes a ≤ 150kV, 40kA, 100ns high repetition rate pulsed power system and intense ion beam source which is now in operation at Cornell University. Operation of the Magnetically-controlled Anode Plasma (MAP) ion diode at > 100Hz (burst mode for up to 10 pulse bursts) provides an initial look at repetition rate limitations of both the ion diode and beam diagnostics. The pulsed power systems are capable of ≥ 1kHz operation (up to 10 pulse bursts), but ion diode operation was limited to ∼100Hz because of diagnostic limitations. By varying MAP diode operating parameters, ion beams can be extracted at a few 10s of keV or at up to 150keV, the corresponding accelerating gap impedance ranging from about 1Ω to about 10Ω. The ability to make hundreds of test pulses per day at an average repetition rate of about 2 pulses per minute permits statistical analysis of diode operation as a function of various parameters. Most diode components have now survived more than 10 4 pulses, and the design and construction of the various pulsed power components of the MAP diode which have enabled us to reach this point are discussed. A high speed data acquisition system and companion analysis software capable of acquiring pulse data at 1ms intervals (in bursts of up to 10 pulses) and processing it in ≤ min is described

  8. High-frame-rate digital radiographic videography

    Science.gov (United States)

    King, Nicholas S. P.; Cverna, Frank H.; Albright, Kevin L.; Jaramillo, Steven A.; Yates, George J.; McDonald, Thomas E.; Flynn, Michael J.; Tashman, Scott

    1994-10-01

    High speed x-ray imaging can be an important tool for observing internal processes in a wide range of applications. In this paper we describe preliminary implementation of a system having the eventual goal of observing the internal dynamics of bone and joint reactions during loading. Two Los Alamos National Laboratory (LANL) gated and image intensified camera systems were used to record images from an x-ray image convertor tube to demonstrate the potential of high frame-rate digital radiographic videography in the analysis of bone and joint dynamics of the human body. Preliminary experiments were done at LANL to test the systems. Initial high frame-rate imaging (from 500 to 1000 frames/s) of a swinging pendulum mounted to the face of an X-ray image convertor tube demonstrated high contrast response and baseline sensitivity. The systems were then evaluated at the Motion Analysis Laboratory of Henry Ford Health Systems Bone and Joint Center. Imaging of a 9 inch acrylic disk with embedded lead markers rotating at approximately 1000 RPM, demonstrated the system response to a high velocity/high contrast target. By gating the P-20 phosphor image from the X-ray image convertor with a second image intensifier (II) and using a 100 microsecond wide optical gate through the second II, enough prompt light decay from the x-ray image convertor phosphor had taken place to achieve reduction of most of the motion blurring. Measurement of the marker velocity was made by using video frames acquired at 500 frames/s. The data obtained from both experiments successfully demonstrated the feasibility of the technique. Several key areas for improvement are discussed along with salient test results and experiment details.

  9. Experimental investigation of bond strength under high loading rates

    Directory of Open Access Journals (Sweden)

    Michal Mathias

    2015-01-01

    Full Text Available The structural behaviour of reinforced concrete is governed significantly by the transmission of forces between steel and concrete. The bond is of special importance for the overlapping joint and anchoring of the reinforcement, where rigid bond is required. It also plays an important role in the rotational capacity of plastic hinges, where a ductile bond behaviour is preferable. Similar to the mechanical properties of concrete and steel also the characteristics of their interaction changes with the velocity of the applied loading. For smooth steel bars with its main bond mechanisms of adhesion and friction, nearly no influence of loading rate is reported in literature. In contrast, a high rate dependence can be found for the nowadays mainly used deformed bars. For mechanical interlock, where ribs of the reinforcing steel are bracing concrete material surrounding the bar, one reason can be assumed to be in direct connection with the increase of concrete compressive strength. For splitting failure of bond, characterized by the concrete tensile strength, an even higher dynamic increase is observed. For the design of Structures exposed to blast or impact loading the knowledge of a rate dependent bond stress-slip relationship is required to consider safety and economical aspects at the same time. The bond behaviour of reinforced concrete has been investigated with different experimental methods at the University of the Bundeswehr Munich (UniBw and the Joint Research Centre (JRC in Ispra. Both static and dynamic tests have been carried out, where innovative experimental apparatuses have been used. The bond stress-slip relationship and maximum pull-out-forces for varying diameter of the bar, concrete compressive strength and loading rates have been obtained. It is expected that these experimental results will contribute to a better understanding of the rate dependent bond behaviour and will serve for calibration of numerical models.

  10. High counting rate resistive-plate chamber

    International Nuclear Information System (INIS)

    Peskov, V.; Anderson, D.F.; Kwan, S.

    1993-05-01

    Parallel-plate avalanche chambers (PPAC) are widely used in physics experiments because they are fast ( 5 counts/mm 2 . A resistive-plate chamber (RPC) is similar to the PPAC in construction except that one or both of the electrodes are made from high resistivity (≥10 10 Ω·cm) materials. In practice RPCs are usually used in the spark mode. Resistive electrodes are charged by sparks, locally reducing the actual electric field in the gap. The size of the charged surface is about 10 mm 2 , leaving the rest of the detector unaffected. Therefore, the rate capability of such detectors in the spark mode is considerably higher than conventional spark counters. Among the different glasses tested the best results were obtained with electron type conductive glasses, which obey Ohm's law. Most of the work with such glasses was done with high pressure parallel-plate chambers (10 atm) for time-of-flight measurements. Resistive glasses have been expensive and produced only in small quantities. Now resistive glasses are commercially available, although they are still expensive in small scale production. From the positive experience of different groups working with the resistive glasses, it was decided to review the old idea to use this glass for the RPC. This work has investigated the possibility of using the RPC at 1 atm and in the avalanche mode. This has several advantages: simplicity of construction, high rate capability, low voltage operation, and the ability to work with non-flammable gases

  11. Development of the model describing highly excited states of odd deformed nuclei

    International Nuclear Information System (INIS)

    Malov, L.A.; Solov'ev, V.G.

    1975-01-01

    An approximate method is given for solving the system of equations obtained earlier for describing the structure of states with intermediate and high energies in the framework of the model taking into account the interaction of quasiparticles with phonons. The new method possesses a number of advantages over the approximate methods of solving the system of equations mentioned. The study is performed for the example of an odd deformed nucleus when several one-quasiparticle components are taken into account at the same time

  12. G-phase precipitation in austenitic stainless steel deformed by high pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Shuro, I., E-mail: innoshuro@martens.me.tut.ac.jp [Functional Materials Engineering, Toyohashi University of Technology, 1-1, Toyohashi, Aichi 441-8580 (Japan); Kuo, H.H. [Functional Materials Engineering, Toyohashi University of Technology, 1-1, Toyohashi, Aichi 441-8580 (Japan); Sasaki, T.; Hono, K. [National Institute for Materials Sciences, Sengen 1-2-1, Tsukuba 305-0047 (Japan); Todaka, Y.; Umemoto, M. [Functional Materials Engineering, Toyohashi University of Technology, 1-1, Toyohashi, Aichi 441-8580 (Japan)

    2012-08-30

    Highlights: Black-Right-Pointing-Pointer Using TEM and APT analyses, G-phase precipitation was observed in HPTed SUS304 with no trace of spinodal decomposition. Black-Right-Pointing-Pointer G-phase precipitation occurred much shorter time than previous studies probably due to the elimination of prior SD and enhanced diffusion by severe plastic deformation. Black-Right-Pointing-Pointer G-phase composition is a function of aging time. Black-Right-Pointing-Pointer Tensile tests showed that in SUS304 embrittlement occurs solely due to G-phase precipitation. - Abstract: G phase an intermetallic silicide has been observed in martensite of precipitation hardened stainless steels and in the ferrite of dual (austenite and ferrite) phase stainless steels. In both cases, before G-phase precipitates, the matrix composition changes due to spinodal decomposition and solute partitioning between ferrite and austenite. Thus in the present study, single bcc phase and high Ni content stainless steel, was selected to study G-phase precipitation expecting elimination of the interference from spinodal decomposition and solute partitioning. Fe-18Cr-8Ni (SUS304) austenitic stainless steel samples were deformed at room temperature by high pressure torsion to obtain 100% volume fraction of deformation induced martensite ({alpha} Prime ). HPT deformation was chosen due to its ability to induce high strength by grain refinement and also attain 100% {alpha} Prime at room temperature. After annealing at 400 Degree-Sign C for 500 h, G-phase precipitation was observed in the fully martensitic matrix without spinodal decomposition. Crystallographic analysis of annealed samples using high resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS) detected a Mn-Ni-Si rich G-phase with fcc crystal structure with lattice parameter of 1.16 nm. The value of lattice parameter corresponds well with previously reported values. Chemical analysis by atom probe tomography

  13. G-phase precipitation in austenitic stainless steel deformed by high pressure torsion

    International Nuclear Information System (INIS)

    Shuro, I.; Kuo, H.H.; Sasaki, T.; Hono, K.; Todaka, Y.; Umemoto, M.

    2012-01-01

    Highlights: ► Using TEM and APT analyses, G-phase precipitation was observed in HPTed SUS304 with no trace of spinodal decomposition. ► G-phase precipitation occurred much shorter time than previous studies probably due to the elimination of prior SD and enhanced diffusion by severe plastic deformation. ► G-phase composition is a function of aging time. ► Tensile tests showed that in SUS304 embrittlement occurs solely due to G-phase precipitation. - Abstract: G phase an intermetallic silicide has been observed in martensite of precipitation hardened stainless steels and in the ferrite of dual (austenite and ferrite) phase stainless steels. In both cases, before G-phase precipitates, the matrix composition changes due to spinodal decomposition and solute partitioning between ferrite and austenite. Thus in the present study, single bcc phase and high Ni content stainless steel, was selected to study G-phase precipitation expecting elimination of the interference from spinodal decomposition and solute partitioning. Fe–18Cr–8Ni (SUS304) austenitic stainless steel samples were deformed at room temperature by high pressure torsion to obtain 100% volume fraction of deformation induced martensite (α′). HPT deformation was chosen due to its ability to induce high strength by grain refinement and also attain 100% α′ at room temperature. After annealing at 400 °C for 500 h, G-phase precipitation was observed in the fully martensitic matrix without spinodal decomposition. Crystallographic analysis of annealed samples using high resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS) detected a Mn–Ni–Si rich G-phase with fcc crystal structure with lattice parameter of 1.16 nm. The value of lattice parameter corresponds well with previously reported values. Chemical analysis by atom probe tomography (APT) showed G-phase of composition Mn 21 Ni 50 Si 24 Fe 4 Cr. Tensile tests showed that G-phase precipitation leads to

  14. Deformation Induced Martensitic Transformation and Its Initial Microstructure Dependence in a High Alloyed Duplex Stainless Steel

    DEFF Research Database (Denmark)

    Xie, Lin; Huang, Tian Lin; Wang, Yu Hui

    2017-01-01

    Deformation induced martensitic transformation (DIMT) usually occurs in metastable austenitic stainless steels. Recent studies have shown that DIMT may occur in the austenite phase of low alloyed duplex stainless steels. The present study demonstrates that DIMT can also take place in a high alloyed...... Fe–23Cr–8.5Ni duplex stainless steel, which exhibits an unexpectedly rapid transformation from γ-austenite into α′-martensite. However, an inhibited martensitic transformation has been observed by varying the initial microstructure from a coarse alternating austenite and ferrite band structure...

  15. Solute grain boundary segregation during high temperature plastic deformation in a Cr-Mo low alloy steel

    International Nuclear Information System (INIS)

    Chen, X.-M.; Song, S.-H.; Weng, L.-Q.; Liu, S.-J.

    2011-01-01

    Highlights: → The segregation of P and Mo is evidently enhanced by plastic deformation. → The boundary concentrations of P and Mo increase with increasing strain. → A model with consideration of site competition in grain boundary segregation in a ternary system is developed. → Model predictions show a reasonable agreement with the observations. - Abstract: Grain boundary segregation of Cr, Mo and P to austenite grain boundaries in a P-doped 1Cr0.5Mo steel is examined using field emission gun scanning transmission electron microscopy for the specimens undeformed and deformed by 10% with a strain rate of 2 x 10 -3 s -1 at 900 deg. C, and subsequently water quenched to room temperature. Before deformation, there is some segregation for Mo and P, but the segregation is considerably increased after deformation. The segregation of Cr is very small and there is no apparent difference between the undeformed and deformed specimens. Since the thermal equilibrium segregation has been attained prior to deformation, the segregation produced during deformation has a non-equilibrium characteristic. A theoretical model with consideration of site competition in grain boundary segregation between two solutes in a ternary alloy is developed to explain the experimental results. Model predictions are made, which show a reasonable agreement with the observations.

  16. On high interest rates in Brazil

    Directory of Open Access Journals (Sweden)

    Francisco Lafaiete Lopes

    2014-03-01

    Full Text Available This article examines the question of why interest rates are so high in Brazil as compared to the international average. It looks at theoretical arguments based on excessive government deficits, structural lack of private savings, inflation bias, excessive investment demand and fear of floating. An informal look at the evidence does not strongly corroborate any of these arguments. Hence a wise central bank should consider "testing" the market to make sure it is not dealing with an extreme equilibrium configuration or a long standing disequilibrium.

  17. Flashing motor at high transition rate

    International Nuclear Information System (INIS)

    Ai Baoquan; Wang Liqiu; Liu Lianggang

    2007-01-01

    The movement of a Brownian particle in a fluctuating two-state periodic potential is investigated. At high transition rate, we use a perturbation method to obtain the analytical solution of the model. It is found that the net current is a peaked function of thermal noise, barrier height and the fluctuation ratio between the two states. The thermal noise may facilitate the directed motion at a finite intensity. The asymmetry parameter of the potential is sensitive to the direction of the net current

  18. Using cold deformation methods in flow-production of steel high precision shaped sections

    International Nuclear Information System (INIS)

    Zajtsev, M.L.; Makhnev, I.F.; Shkurko, I.I.

    1975-01-01

    A final size with a preset tolerance and a required surface finish of steel high-precision sections could be achieved by a cold deformation of hot-rolled ingots-by drawing through dismountable, monolith or roller-type drawing tools or by cold rolling in roller dies. The particularities of the both techniques are compared as regards a number of complicated shaped sections and the advantages of cold rolling are showna more uniform distribution of deformations (strain hardening) across the section, that is a greater margin of plasticity with the same reductions, the less number of the operations required. Rolling is recommended in all the cases when possible as regards the section shape and the bulk volume. The rolling-mill for the calibration of high-precision sections should have no less than two shafts (so that the size could be controlled in both directions) and arrangements to withstand high axial stresses on the rollers (the stresses appearing during rolling in skew dies). When manufacturing precise shaped sections by the cold rolling method the operations are less plentiful than in the cold drawing manufacturing

  19. The long-term strength and deformation properties of crystalline rock in a high level nuclear waste repository

    International Nuclear Information System (INIS)

    Tuokko, T.

    1990-12-01

    The time-dependent phenomena which can affect the strength and deformation properties of hard crystal line rock are clarified. Suitable measuring methods for field conditions are also summarized. The significance of time is evaluated around a shaft in a high level nuclear waste repository. According to the investigation it is generally held that creep and cyclic fatigue are the most important phenomena. They arise from subcritical crack growth which is most affected by stress intensity, chemical environment, temperature, and microstructure. There are many theoretical models, which can be used to analyse creep and cyclic fatigue, but they are defective in describing the triaxial stress condition and strength criteria. Additionally, the required parameters are often too difficult to determine with adequate accuracy. The joint creep rate depends on the affecting stress regime, on the water conditions, and on the properties of filling material. The acoustic emission method is suited to observe long-term microcrack development in field conditions. The computer program developed by Atomic Energy of Canada Limited (AECL) is used to evaluate the time-dependent de-formation around a main shaft. According to the model the enlargement of the shaft radius by 30 cm takes millions of years. The possible reduction of shaft radius by 3 mm will happen during 200 years. The model is very sensitive to changes in stress state, in the uniaxial compressive strength, and in the stress corrosion index

  20. High dose rate brachytherapy for oral cancer

    International Nuclear Information System (INIS)

    Yamazaki, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Koizumi, Masahiko; Ogawa, Kazuhiko; Furukawa, Souhei

    2013-01-01

    Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer. (author)

  1. High dose rate brachytherapy for oral cancer.

    Science.gov (United States)

    Yamazaki, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Furukawa, Souhei; Koizumi, Masahiko; Ogawa, Kazuhiko

    2013-01-01

    Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer.

  2. Flow behavior and microstructures of powder metallurgical CrFeCoNiMo0.2 high entropy alloy during high temperature deformation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiawen [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Liu, Yong, E-mail: yonliu@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Liu, Bin, E-mail: binliu@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Wang, Yan [School of Aeronautics and Astronautics, Central South University, Changsha 410083 (China); Cao, Yuankui; Li, Tianchen; Zhou, Rui [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

    2017-03-24

    Dynamic recrystallization (DRX) refine grains of high entropy alloys (HEAs) and significant improve the mechanical property of HEAs, but the effect of high melting point element molybdenum (Mo) on high temperature deformation behavior has not been fully understood. In the present study, flow behavior and microstructures of powder metallurgical CrFeCoNiMo{sub 0.2} HEA were investigated by hot compression tests performed at temperatures ranging from 700 to 1100 °C with strain rates from 10{sup −3} to 1 s{sup −1}. The Arrhenius constitutive equation with strain-dependent material constants was used for modeling and prediction of flow stress. It was found that at 700 °C, the dynamic recovery is the dominant softening mechanism, whilst with the increase in compression testing temperature, the DRX becomes the dominant mechanism of softening. In the present HEA, the addition of Mo results in the high activation energy (463 kJ mol{sup −1}) and the phase separation during hot deformation. The formation of Mo-rich σ phase particles pins grain boundary migration during DRX, and therefore refines the size of recrystallized grains.

  3. Ultra Fast, High Rep Rate, High Voltage Spark Gap Pulser

    Science.gov (United States)

    1995-07-01

    current rise time. The spark gap was designed to have a coaxial geometry reducing its inductance. Provisions were made to pass flowing gas between the...ULTRA FAST, HIGH REP RATE, HIGH VOLTAGE SPARK GAP PULSER Robert A. Pastore Jr., Lawrence E. Kingsley, Kevin Fonda, Erik Lenzing Electrophysics and...Modeling Branch AMSRL-PS-EA Tel.: (908)-532-0271 FAX: (908)-542-3348 U.S. Army Research Laboratory Physical Sciences Directorate Ft. Monmouth

  4. High Rate Micromechanical Behavior of Grafted Polymer Nanoparticle Films

    Science.gov (United States)

    Thomas, Edwin

    We report the ultra high strain rate behavior of films comprised of polymer grafted nanoparticles (NPs) and compare the results to homopolymer films. The films are formed by flow coating a suspension of polystyrene (PS) chains of 230 kg/mol grafted to 16nm diameter SiO2\\ at a graft density of 0.6 chains/nm2 resulting a film with 1 vol % SiO2. Films of 267 kg/mol PS were also flow coated and both films were impacted at velocities 350-700 ms-1 using 3.7 micron SiO2\\ projectiles to achieve increments in kinetic energy (KE) of 1:2:4. The KE of the projectiles before and after penetration was measured to determine the penetration energy. TEM and SEM suggest the projectile initially induces plastic flow due to the adiabatic temperature rise from impact. As the projectile deforms the film, the lower magnitude, biaxial stress state in the peripherial regions causes material microvoid formation and initiation of craze growth in the radial and tangential directions. The anchoring of the grafted polymer chains to the NPs increases the penetration energy relative to the pure homopolymer by 50% and the films capacity to delocalize the impact by 200%. These results suggest that highly grafted NP films may be useful in lightweight protection systems. In collaboration with Omri Fried, Olawale Lawal, Yang Jiao, Victor Hsaio, Thevamaran Ramathasan, Mujin Zhou, Richard Vaia.

  5. Strengthening mechanisms in nanostructured high-purity aluminium deformed to high strain and annealed

    DEFF Research Database (Denmark)

    Kamikawa, Naoya; Huang, Xiaoxu; Tsuji, Nobuhiro

    2009-01-01

    Samples of pure aluminium (99.99%) have been produced by accumulative roll-bonding to a large strain followed by a heat treatment, where a two-step annealing process has been used to produce samples with large variations in structural parameters such as boundary spacing, misorientation angle...... and dislocation density. These parameters have been quantified by a structural analysis applying transmission electron microscopy and electron backscatter diffraction, and the mechanical properties have been determined by tensile testing at room temperature. Strength–structure relationships have been analysed...... based on the operation of two strengthening mechanisms—grain boundary and dislocation strengthening—and good agreement with experiments has been found for the deformed sample. However, for samples where the density of dislocation sources has been reduced significantly by annealing, an additional...

  6. Constitutive Modelling and Deformation Band Angle Predictions for High Porosity Sandstones

    Science.gov (United States)

    Richards, M. C.; Issen, K. A.; Ingraham, M. D.

    2017-12-01

    The development of a field-scale deformation model requires a constitutive framework that is capable of representing known material behavior and able to be calibrated using available mechanical response data. This work employs the principle of hyperplasticity (e.g., Houlsby and Puzrin, 2006) to develop such a constitutive framework for high porosity sandstone. Adapting the works of Zimmerman et al. (1986) and Collins and Houlsby (1997), the mechanical data set of Ingraham et al. (2013 a, b) was used to develop a specific constitutive framework for Castlegate sandstone, a high porosity fluvial-deposited reservoir analog rock. Using the mechanical data set of Ingraham et al. (2013 a, b), explicit expressions and material parameters of the elastic moduli and strain tensors were obtained. With these expressions, analytical and numerical techniques were then employed to partition the total mechanical strain into elastic, coupled, and plastic strain components. With the partitioned strain data, yield surfaces in true-stress space, coefficients of internal friction, dilatancy factors, along with the theorectical predictions of the deformation band angles were obtained. These results were also evaluated against band angle values obtained from a) measurements on specimen jackets (Ingraham et al., 2013a), b) plane fits through located acoustic emissions (AE) events (Ingraham et al. 2013b), and c) X-ray micro-computed tomography (micro-CT) calculations.

  7. Influence of Cyclic Straining on Fatigue, Deformation, and Fracture Behavior of High-Strength Alloy Steel

    Science.gov (United States)

    Manigandan, K.; Srivatsan, T. S.; Vasudevan, V. K.; Tammana, D.; Poorganji, B.

    2016-01-01

    In this paper, the results of a study on microstructural influences on mechanical behavior of the high-strength alloy steel Tenax™ 310 are presented and discussed. Under the influence of fully reversed strain cycling, the stress response of this alloy steel revealed softening from the onset of deformation. Cyclic strain resistance exhibited a linear trend for the variation of both elastic strain amplitude with reversals-to-failure, and plastic strain amplitude with reversals-to-failure. Fracture morphology was essentially the same at the macroscopic level over the entire range of cyclic strain amplitudes examined. However, at the fine microscopic level, this high-strength alloy steel revealed fracture to be mixed-mode with features reminiscent of "locally" ductile and brittle mechanisms. The macroscopic mechanisms governing stress response at the fine microscopic level, resultant fatigue life, and final fracture behavior are presented and discussed in light of the mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the microstructural constituents during fully reversed strain cycling, cyclic strain amplitude, and resultant response stress.

  8. High-Efficiency Multiscale Modeling of Cell Deformations in Confined Microenvironments in Microcirculation and Microfluidic Devices

    Science.gov (United States)

    Lu, Huijie; Peng, Zhangli

    2017-11-01

    Our goal is to develop a high-efficiency multiscale modeling method to predict the stress and deformation of cells during the interactions with their microenvironments in microcirculation and microfluidic devices, including red blood cells (RBCs) and circulating tumor cells (CTCs). There are more than 1 billion people in the world suffering from RBC diseases, e.g. anemia, sickle cell diseases, and malaria. The mechanical properties of RBCs are changed in these diseases due to molecular structure alternations, which is not only important for understanding the disease pathology but also provides an opportunity for diagnostics. On the other hand, the mechanical properties of cancer cells are also altered compared to healthy cells. This can lead to acquired ability to cross the narrow capillary networks and endothelial gaps, which is crucial for metastasis, the leading cause of cancer mortality. Therefore, it is important to predict the deformation and stress of RBCs and CTCs in microcirculations. We are developing a high-efficiency multiscale model of cell-fluid interaction to study these two topics.

  9. Chloride-induced corrosion mechanism and rate of enamel- and epoxy-coated deformed steel bars embedded in mortar

    International Nuclear Information System (INIS)

    Tang, Fujian; Chen, Genda; Brow, Richard K.

    2016-01-01

    The chloride-induced corrosion mechanisms of uncoated, pure enamel (PE)-coated, mixed enamel (ME)-coated, double enamel (DE)-coated, and fusion bonded epoxy (FBE)-coated deformed steel bars embedded in mortar cylinders are investigated in 3.5 wt.% NaCl solution and compared through electrochemical tests and visual inspection. Corrosion initiated after 29 or 61 days of tests in all uncoated and enamel-coated steel bars, and after 244 days of tests in some FBE-coated steel bars. In active stage, DE- and FBE-coated steel bars are subjected to the highest and lowest corrosion rates, respectively. The uncoated and ME-coated steel bars revealed relatively uniform corrosion while the PE-, DE-, and FBE-coated steel bars experienced pitting corrosion around damaged coating areas. Due to the combined effect of ion diffusion and capillary suction, wet–dry cyclic immersion caused more severe corrosion than continuous immersion. Both exposure conditions affected the corrosion rate more significantly than the water–cement ratio in mortar design.

  10. Operation of high rate microstrip gas chambers

    CERN Document Server

    Barr, A J; Bouclier, Roger; Capéans-Garrido, M; Dominik, Wojciech; Manzin, G; Million, Gilbert; Hoch, M; Ropelewski, Leszek; Sauli, Fabio; Sharma, A

    1996-01-01

    We describe recent measurements carried out in well controlled and reproducible conditions to help understanding the factors affecting the short and long term behaviour of Microstrip Gas Chambers. Special care has been taken concerning the gas purity and choice of materials used in the system and for the detectors construction. Detectors built on glasses with surface resistivity in the range $10^{13}-10^{15} \\Omega/\\Box$ have shown satisfactory performance as they do not show charging-up process at high rate and stand the large doses required for the future high luminosity experiments (~10 mC·cm-1·yr-1). Concerning the lifetime measurements, it has been observed that chambers manufactured on high-resistivity glass are far more susceptible of suffering ageing than detectors made on low resistivity, electron-conducting supports, independently of the metal used for the artwork (chromium or gold) at least in clean gas conditions. The successfully operation in the laboratory of detectors manufactured on diamond-...

  11. Understanding the different rotational behaviors of $^{252}$No and $^{254}$No in terms of high-order deformation

    CERN Document Server

    Liu, H L; Walker, P M

    2012-01-01

    Total Routhian surface calculations have been performed to investigate rapidly rotating transfermium nuclei, the heaviest nuclei accessible by detailed spectroscopy experiments. The observed fast alignment in $^{252}$No and slow alignment in $^{254}$No are well reproduced by the calculations incorporating high-order deformations. The different rotational behaviors of $^{252}$No and $^{254}$No can be understood for the first time in terms of $\\beta_6$ deformation that decreases the energies of the $\

  12. Statistical analysis of the description accuracy of dependence of flow stresses upon the deformation rate in the state of superplasticity by phenomenological equations

    International Nuclear Information System (INIS)

    Bojtsov, V.V.; Tsepin, M.A.; Karpilyanskij, N.N.; Ershov, A.N.

    1982-01-01

    Results of statistical analysis of the description accuracy of superplasticity S-form curve by different analytic expressions, suggested on the basis of phenomenological and metallophysical concepts about the nature of superplastic deformation, are given. Experimental investigations into the dependence of flow stresses on the deformation rate were conducted on VT3-1 two-phase titanium alloy. Test samples were cut out of a rod, 30 mm in diameter, produced by lengthwise rolling in α+#betta#-region. Optimal temperature of superplasticity manifestation was determined by the method of stress relaxation from a relaxation time value to a given stress. It was established that the Smirnov phemonemological equation describes in the best way the rate dependence of flow stress of superplastic material. This equation can be used for solution of problems of studying mechanism, physical nature of superplastic deformation, analysing strain-stress state and the structure of deformation zone during the processes of pressure shaping of superplastic materials, when considerably wide range (in the limits of 7-8 orders) of deformation rate variation takes place

  13. Kinetics and mechanisms of low temperature deformation in high purity niobium single crystals

    International Nuclear Information System (INIS)

    Karam, N.H.

    1985-01-01

    This study included three main aspects: (1) an extensive examination of the temperature and strain rate dependence of the flow stress without any thermodynamic analysis; (2) detailed thermodynamic analysis of the experimental data with no specific models involved, and (3) testing the results against specific models as well as modification of Seeger's model (1981-1983) to account for the results. The temperature and strain rate dependence of the tau/sub f/, tau/sup */, and tau/sub μ/ was experimentally determined over the temperature range 300 to 4.2 K with intervals ΔT ≤ 20K. The value of tau/sub μ/(T/sub k/) was found experimentally by decremental unloading, stress relaxation, and back extrapolation techniques giving tau/sub μ/(T/sub k/) = 19 MPa in agreement with the analytical analysis. The knee temperature was found T/sub k/ = 300K and the Peierls stress was determined as taup = 370 MPa. The strain rate sensitivity λ was evaluated using both strain rate cycle and stress relaxation techniques which were in excellent agreement. λ reached its maximum at 77K. Experimental data are best described by double kink nucleation models where deformation occurs by the formation of double kinks on screw dislocations that are resisted by a lattice friction arising from the periodic lattice potential

  14. Consideration of wear rates at high velocity

    Science.gov (United States)

    Hale, Chad S.

    The development of the research presented here is one in which high velocity relative sliding motion between two bodies in contact has been considered. Overall, the wear environment is truly three-dimensional. The attempt to characterize three-dimensional wear was not economically feasible because it must be analyzed at the micro-mechanical level to get results. Thus, an engineering approximation was carried out. This approximation was based on a metallographic study identifying the need to include viscoplasticity constitutive material models, coefficient of friction, relationships between the normal load and velocity, and the need to understand wave propagation. A sled test run at the Holloman High Speed Test Track (HHSTT) was considered for the determination of high velocity wear rates. In order to adequately characterize high velocity wear, it was necessary to formulate a numerical model that contained all of the physical events present. The experimental results of a VascoMax 300 maraging steel slipper sliding on an AISI 1080 steel rail during a January 2008 sled test mission were analyzed. During this rocket sled test, the slipper traveled 5,816 meters in 8.14 seconds and reached a maximum velocity of 1,530 m/s. This type of environment was never considered previously in terms of wear evaluation. Each of the features of the metallography were obtained through micro-mechanical experimental techniques. The byproduct of this analysis is that it is now possible to formulate a model that contains viscoplasticity, asperity collisions, temperature and frictional features. Based on the observations of the metallographic analysis, these necessary features have been included in the numerical model, which makes use of a time-dynamic program which follows the movement of a slipper during its experimental test run. The resulting velocity and pressure functions of time have been implemented in the explicit finite element code, ABAQUS. Two-dimensional, plane strain models

  15. A New High-Resolution Spectral Approach to Noninvasively Evaluate Wall Deformations in Arteries

    Directory of Open Access Journals (Sweden)

    Ivonne Bazan

    2014-01-01

    Full Text Available By locally measuring changes on arterial wall thickness as a function of pressure, the related Young modulus can be evaluated. This physical magnitude has shown to be an important predictive factor for cardiovascular diseases. For evaluating those changes, imaging segmentation or time correlations of ultrasonic echoes, coming from wall interfaces, are usually employed. In this paper, an alternative low-cost technique is proposed to locally evaluate variations on arterial walls, which are dynamically measured with an improved high-resolution calculation of power spectral densities in echo-traces of the wall interfaces, by using a parametric autoregressive processing. Certain wall deformations are finely detected by evaluating the echoes overtones peaks with power spectral estimations that implement Burg and Yule Walker algorithms. Results of this spectral approach are compared with a classical cross-correlation operator, in a tube phantom and “in vitro” carotid tissue. A circulating loop, mimicking heart periods and blood pressure changes, is employed to dynamically inspect each sample with a broadband ultrasonic probe, acquiring multiple A-Scans which are windowed to isolate echo-traces packets coming from distinct walls. Then the new technique and cross-correlation operator are applied to evaluate changing parietal deformations from the detection of displacements registered on the wall faces under periodic regime.

  16. Particle deposition and deformation from high speed impaction of Ag nanoparticles

    International Nuclear Information System (INIS)

    Chitrakar, T.V.; Keto, J.W.; Becker, M.F.; Kovar, D.

    2017-01-01

    The impaction of a single Ag nanoparticle onto an (001) Ag substrate was studied as a function of particle diameter (2–9 nm) and impaction velocity (10–1500 m/sec) using molecular dynamics simulations. The final crystallographic structures were observed to transition from a polycrystalline to an epitaxial morphology as impaction velocity was increased and the velocity required to achieve epitaxy increased with particle size. To understand how the crystallographic structures evolved to their final state, the deformation mechanisms were then studied over a range of time scales, beginning immediately upon impaction. The observed mechanisms included disordering of the atoms and the initiation and propagation of partial dislocations. Deformation increased with impaction velocity due to increases in the degree of disordering and the partial dislocation density. At longer time scales, relaxation of the disordered particles produced epitaxial morphologies, whereas polycrystalline morphologies were observed following incomplete disordering. These results suggest that the microstructures of thick films produced by high speed impaction of nanoparticle aerosols are strongly influenced by processing parameters.

  17. A New High-Resolution Spectral Approach to Noninvasively Evaluate Wall Deformations in Arteries

    Science.gov (United States)

    Bazan, Ivonne; Negreira, Carlos; Ramos, Antonio; Brum, Javier; Ramirez, Alfredo

    2014-01-01

    By locally measuring changes on arterial wall thickness as a function of pressure, the related Young modulus can be evaluated. This physical magnitude has shown to be an important predictive factor for cardiovascular diseases. For evaluating those changes, imaging segmentation or time correlations of ultrasonic echoes, coming from wall interfaces, are usually employed. In this paper, an alternative low-cost technique is proposed to locally evaluate variations on arterial walls, which are dynamically measured with an improved high-resolution calculation of power spectral densities in echo-traces of the wall interfaces, by using a parametric autoregressive processing. Certain wall deformations are finely detected by evaluating the echoes overtones peaks with power spectral estimations that implement Burg and Yule Walker algorithms. Results of this spectral approach are compared with a classical cross-correlation operator, in a tube phantom and “in vitro” carotid tissue. A circulating loop, mimicking heart periods and blood pressure changes, is employed to dynamically inspect each sample with a broadband ultrasonic probe, acquiring multiple A-Scans which are windowed to isolate echo-traces packets coming from distinct walls. Then the new technique and cross-correlation operator are applied to evaluate changing parietal deformations from the detection of displacements registered on the wall faces under periodic regime. PMID:24688596

  18. Hybrid High-Order methods for finite deformations of hyperelastic materials

    Science.gov (United States)

    Abbas, Mickaël; Ern, Alexandre; Pignet, Nicolas

    2018-01-01

    We devise and evaluate numerically Hybrid High-Order (HHO) methods for hyperelastic materials undergoing finite deformations. The HHO methods use as discrete unknowns piecewise polynomials of order k≥1 on the mesh skeleton, together with cell-based polynomials that can be eliminated locally by static condensation. The discrete problem is written as the minimization of a broken nonlinear elastic energy where a local reconstruction of the displacement gradient is used. Two HHO methods are considered: a stabilized method where the gradient is reconstructed as a tensor-valued polynomial of order k and a stabilization is added to the discrete energy functional, and an unstabilized method which reconstructs a stable higher-order gradient and circumvents the need for stabilization. Both methods satisfy the principle of virtual work locally with equilibrated tractions. We present a numerical study of the two HHO methods on test cases with known solution and on more challenging three-dimensional test cases including finite deformations with strong shear layers and cavitating voids. We assess the computational efficiency of both methods, and we compare our results to those obtained with an industrial software using conforming finite elements and to results from the literature. The two HHO methods exhibit robust behavior in the quasi-incompressible regime.

  19. A GPU based high-resolution multilevel biomechanical head and neck model for validating deformable image registration

    International Nuclear Information System (INIS)

    Neylon, J.; Qi, X.; Sheng, K.; Low, D. A.; Kupelian, P.; Santhanam, A.; Staton, R.; Pukala, J.; Manon, R.

    2015-01-01

    Purpose: Validating the usage of deformable image registration (DIR) for daily patient positioning is critical for adaptive radiotherapy (RT) applications pertaining to head and neck (HN) radiotherapy. The authors present a methodology for generating biomechanically realistic ground-truth data for validating DIR algorithms for HN anatomy by (a) developing a high-resolution deformable biomechanical HN model from a planning CT, (b) simulating deformations for a range of interfraction posture changes and physiological regression, and (c) generating subsequent CT images representing the deformed anatomy. Methods: The biomechanical model was developed using HN kVCT datasets and the corresponding structure contours. The voxels inside a given 3D contour boundary were clustered using a graphics processing unit (GPU) based algorithm that accounted for inconsistencies and gaps in the boundary to form a volumetric structure. While the bony anatomy was modeled as rigid body, the muscle and soft tissue structures were modeled as mass–spring-damper models with elastic material properties that corresponded to the underlying contoured anatomies. Within a given muscle structure, the voxels were classified using a uniform grid and a normalized mass was assigned to each voxel based on its Hounsfield number. The soft tissue deformation for a given skeletal actuation was performed using an implicit Euler integration with each iteration split into two substeps: one for the muscle structures and the other for the remaining soft tissues. Posture changes were simulated by articulating the skeletal structure and enabling the soft structures to deform accordingly. Physiological changes representing tumor regression were simulated by reducing the target volume and enabling the surrounding soft structures to deform accordingly. Finally, the authors also discuss a new approach to generate kVCT images representing the deformed anatomy that accounts for gaps and antialiasing artifacts that may

  20. A GPU based high-resolution multilevel biomechanical head and neck model for validating deformable image registration

    Energy Technology Data Exchange (ETDEWEB)

    Neylon, J., E-mail: jneylon@mednet.ucla.edu; Qi, X.; Sheng, K.; Low, D. A.; Kupelian, P.; Santhanam, A. [Department of Radiation Oncology, University of California Los Angeles, 200 Medical Plaza, #B265, Los Angeles, California 90095 (United States); Staton, R.; Pukala, J.; Manon, R. [Department of Radiation Oncology, M.D. Anderson Cancer Center, Orlando, 1440 South Orange Avenue, Orlando, Florida 32808 (United States)

    2015-01-15

    Purpose: Validating the usage of deformable image registration (DIR) for daily patient positioning is critical for adaptive radiotherapy (RT) applications pertaining to head and neck (HN) radiotherapy. The authors present a methodology for generating biomechanically realistic ground-truth data for validating DIR algorithms for HN anatomy by (a) developing a high-resolution deformable biomechanical HN model from a planning CT, (b) simulating deformations for a range of interfraction posture changes and physiological regression, and (c) generating subsequent CT images representing the deformed anatomy. Methods: The biomechanical model was developed using HN kVCT datasets and the corresponding structure contours. The voxels inside a given 3D contour boundary were clustered using a graphics processing unit (GPU) based algorithm that accounted for inconsistencies and gaps in the boundary to form a volumetric structure. While the bony anatomy was modeled as rigid body, the muscle and soft tissue structures were modeled as mass–spring-damper models with elastic material properties that corresponded to the underlying contoured anatomies. Within a given muscle structure, the voxels were classified using a uniform grid and a normalized mass was assigned to each voxel based on its Hounsfield number. The soft tissue deformation for a given skeletal actuation was performed using an implicit Euler integration with each iteration split into two substeps: one for the muscle structures and the other for the remaining soft tissues. Posture changes were simulated by articulating the skeletal structure and enabling the soft structures to deform accordingly. Physiological changes representing tumor regression were simulated by reducing the target volume and enabling the surrounding soft structures to deform accordingly. Finally, the authors also discuss a new approach to generate kVCT images representing the deformed anatomy that accounts for gaps and antialiasing artifacts that may

  1. High Data Rate Architecture (HiDRA)

    Science.gov (United States)

    Hylton, Alan; Raible, Daniel

    2016-01-01

    high-rate laser terminals. These must interface with the existing, aging data infrastructure. The High Data Rate Architecture (HiDRA) project is designed to provide networked store, carry, and forward capability to optimize data flow through both the existing radio frequency (RF) and new laser communications terminal. The networking capability is realized through the Delay Tolerant Networking (DTN) protocol, and is used for scheduling data movement as well as optimizing the performance of existing RF channels. HiDRA is realized as a distributed FPGA memory and interface controller that is itself controlled by a local computer running DTN software. Thus HiDRA is applicable to other arenas seeking to employ next-generation communications technologies, e.g. deep space. In this paper, we describe HiDRA and its far-reaching research implications.

  2. High spin states and the competition of spherical and strongly deformed shapes in the A = 70 to 80 region

    International Nuclear Information System (INIS)

    Hamilton, J.H.; Ramayya, A.V.; Piercey, R.B.

    1982-01-01

    A wide variety of collective band structures are seen in Ge to Sr nuclei to make this an important new testing ground for nuclear models. These include bands built on coexisting and competing near-spherical and deformed shapes, γ vibrational bands and multiple positive and negative parity bands. Ground state bands in Ge and Kr but not 78 80 Sr are crossed at the 8 + to 12 + levels. Gaps in the Nilsson levels for both N and Z = 38 at large deformation lead to large ground state deformation in Kr and Sr around N = 38. The crossing of rotation aligned bands based on (g/sub 9/2/) 2 configuration are correlated with the ground state deformations. A second high spin crossing is seen in 74 Kr. Measured g factors in 68 Ge yield a two-quasineutron structure for the 8 2 + state. 30 references

  3. High Rate of Recurrence Following Proximal Medial Opening Wedge Osteotomy for Correction of Moderate Hallux Valgus.

    Science.gov (United States)

    Iyer, Sravisht; Demetracopoulos, Constantine A; Sofka, Carolyn M; Ellis, Scott J

    2015-07-01

    The proximal medial opening wedge (PMOW) osteotomy has become more popular to treat moderate to severe hallux valgus with the recent development of specifically designed, low-profile modular plates. Despite the promising results previously reported in the literature, we have noted a high incidence of recurrence in patients treated with a PMOW. The purpose of this study was to report the clinical and radiographic outcomes of an initial cohort of patients treated with a PMOW osteotomy for moderate hallux valgus. We retrospectively analyzed prospectively gathered data on a cohort of 17 consecutive patients who were treated by the senior author using a PMOW osteotomy for moderate hallux valgus deformity. Average time to follow-up was 2.4 years (range, 1.0-3.5 years). The intermetatarsal angle (IMA), the hallux valgus angle (HVA), and the distal metatarsal articular angle (DMAA) were assessed on standard weightbearing radiographs of the foot preoperatively and at all follow-up visits. The Foot and Ankle Outcome Score (FAOS) was collected on all patients preoperatively and at final follow-up. Despite demonstrating good correction of their deformity initially, 11 of the 17 patients (64.7%) had evidence of recurrence of their hallux valgus deformity at final follow-up. Patients who recurred had a greater preoperative HVA (P = .023) and DMAA (P = .049) than patients who maintained their correction. Improvement in the quality-of-life subscale of the FAOS was noted at final follow-up for all patients (P = .05). There was no significant improvement in any of the other FAOS subscales. There was a high rate of recurrence of the hallux valgus deformity in this cohort of patients. Recurrence was associated with greater preoperative deformity and an increased preoperative DMAA. The PMOW without a concomitant distal metatarsal osteotomy may be best reserved for patients with mild hallux valgus deformity without an increased DMAA. Level IV, retrospective case series. © The Author

  4. High resolution deformation measurements at active volcanoes: a new remote sensing technology

    Science.gov (United States)

    Hort, M. K.; Scharff, L.; Gerst, A.; Meier, K.; Falk, S.; Peters, G.; Ripepe, M.

    2013-12-01

    It is known from observations at different volcanoes using ULP seismic observations that the volcanic edifice deforms slightly prior to an eruption. It can be expected that immediately prior to an eruption the largest deformation should occur in the vicinity of the vent. However, placing instruments at the vent is impossible as they will be destroyed during an eruption. Here we present new, high temporal resolution (up to 300Hz) deformation measurement that utilizes the phase information of a frequency modulated Doppler radar system. We decompose the Doppler signal into two parts, one part which allows us to measure speeds significantly above 0.5m/s (i.e. the movement of volcanic ash and clasts). The other part utilizes the slow phase changes of the signal reflected from non-moving objects, i.e. the volcanic edifice. This signal is used to measure very slow and longer term deformations, which are the main subject of this study. The method has been tested measuring the displacement of high rise buildings during strong winds. It can be shown that displacements down to 50 μm can be resolved without a problem. We apply this method to different data sets collected at Stromboli volcano, Italy, as well as Santiaguito volcano, Guatemala. At Stromboli we observed the NE crater once in 2008 and once in 2011. During both campaigns we observe on average a displacement between 1 and 5mm before different eruptions. This displacement can be interpreted as a widening of the conduit prior to an eruption. In a couple of cases even an oscillatory movement is observed with frequencies of about 0.5Hz. Finite element modeling of the rise of a pressurized slug indicates that deformations at the crater rim on the order of a 1mm or less are certainly reasonable. In the case of Santiaguito volcano prior to an eruption we observe a pre eruptive displacement 5-15mm and after the end of an eruption a displacement of up to 1m before the next eruption occurs. This can be interpreted as in

  5. Internal deformation in layered Zechstein-III K-Mg salts. Structures formed by complex deformation and high contrasts in viscosity observed in drill cores.

    Science.gov (United States)

    Raith, Alexander; Urai, Janos L.

    2016-04-01

    During the evaporation of a massive salt body, alternations of interrupted and full evaporation sequences can form a complex layering of different lithologies. Viscosity contrasts of up to five orders of magnitude between these different lithologies are possible in this environment. During the late stage of an evaporation cycle potassium and magnesium (K-Mg) salts are precipitated. These K-Mg salts are of economic interest but also a known drilling hazard due to their very low viscosity. How up to 200m thick layers of these evaporites affect salt deformation at different scales is not well known. A better understanding of salt tectonics with extreme mechanical stratification is needed for better exploration and production of potassium-magnesium salts and to predict the internal structure of potential nuclear waste repositories in salt. To gain a better understanding of the internal deformation of these layers we analyzed K-Mg salt rich drill cores out of the Zechstein III-1b subunit from the Veendam Pillow 10 km southeast of Groningen, near the city Veendam in the NE Netherlands. The study area has a complex geological history with multiple tectonic phases of extension and compression forming internal deformation in the pillow but also conserving most of the original layering. Beside halite the most common minerals in the ZIII-1b are carnallite, kieserite, anhydrite and bischofite alternating in thin layers of simple composition. Seismic interpretation revealed that the internal structure of the Veendam Pillow shows areas, in which the K-Mg salt rich ZIII 1b layer is much thicker than elsewhere, as a result of salt deformation. The internal structure of the ZIII-1b on the other hand, remains unknown. The core analysis shows a strong strain concentration in the weaker Bischofite (MgCl2*6H20) and Carnallite (KMgCl3*6H20) rich layers producing tectonic breccias and highly strained layers completely overprinting the original layering. Layers formed by alternating beds

  6. Modeling of the anode surface deformation in high-current vacuum arcs with AMF contacts

    International Nuclear Information System (INIS)

    Huang, Xiaolong; Wang, Lijun; Deng, Jie; Jia, Shenli; Qin, Kang; Shi, Zongqian

    2016-01-01

    A high-current vacuum arc subjected to an axial magnetic field is maintained in a diffuse status. With an increase in arc current, the energy carried by the arc column to the anode becomes larger and finally leads to the anode temperature exceeding the melting point of the anode material. When the anode melting pool is formed, and the rotational plasma of the arc column delivers its momentum to the melting pool, the anode melting pool starts to rotate and also flow outwards along the radial direction, which has been photographed by some researchers using high-speed cameras. In this paper, the anode temperature and melting status is calculated using the melting and solidification model. The swirl flow of the anode melting pool and deformation of the anode is calculated using the magneto-hydrodynamic (MHD) model with the volume of fraction (VOF) method. All the models are transient 2D axial-rotational symmetric models. The influence of the impaction force of the arc plasma, electromagnetic force, viscosity force, and surface tension of the liquid metal are all considered in the model. The heat flux density injected into the anode and the arc pressure are obtained from the 3D numerical simulation of the high-current vacuum arc using the MHD model, which gives more realistic parameters for the anode simulation. Simulation results show that the depth of the anode melting pool increases with an increase in the arc current. Some droplets sputter out from the anode surface, which is caused by the inertial centrifugal force of the rotational melting pool and strong plasma pressure. Compared with the previous anode melting model without consideration of anode deformation, when the deformation and swirl flow of the anode melting pool are considered, the anode temperature is relatively lower, and just a little more than the melting point of Cu. This is because of liquid droplets sputtering out of the anode surface taking much of the energy away from the anode surface. The

  7. Photocathodes for High Repetition Rate Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi, Ilan [Stony Brook Univ., NY (United States). Dept. of Physics and Astronomy. Center for Accelerator Science and Education

    2014-04-20

    This proposal brought together teams at Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL) and Stony Brook University (SBU) to study photocathodes for high repetition rate light sources such as Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). Below details the Principal Investigators and contact information. Each PI submits separately for a budget through his corresponding institute. The work done under this grant comprises a comprehensive program on critical aspects of the production of the electron beams needed for future user facilities. Our program pioneered in situ and in operando diagnostics for alkali antimonide growth. The focus is on development of photocathodes for high repetition rate Free Electron Lasers (FELs) and Energy Recovery Linacs (ERLs), including testing SRF photoguns, both normal-­conducting and superconducting. Teams from BNL, LBNL and Stony Brook University (SBU) led this research, and coordinated their work over a range of topics. The work leveraged a robust infrastructure of existing facilities and the support was used for carrying out the research at these facilities. The program concentrated in three areas: a) Physics and chemistry of alkali-­antimonide cathodes (BNL – LBNL) b) Development and testing of a diamond amplifier for photocathodes (SBU -­ BNL) c) Tests of both cathodes in superconducting RF photoguns (SBU) and copper RF photoguns (LBNL) Our work made extensive use of synchrotron radiation materials science techniques, such as powder-­ and single-­crystal diffraction, x-­ray fluorescence, EXAFS and variable energy XPS. BNL and LBNL have many complementary facilities at the two light sources associated with these laboratories (NSLS and ALS, respectively); use of these will be a major thrust of our program and bring our understanding of these complex materials to a new level. In addition, CHESS at Cornell will be used to continue seamlessly throughout the NSLS dark period and

  8. Establishment and comparison of four constitutive relationships of PC/ABS from low to high uniaxial strain rates

    Science.gov (United States)

    Wang, Haitao; Zhang, Yun; Huang, Zhigao; Tang, Zhongbin; Wang, Yanpei; Zhou, Huamin

    2017-10-01

    The objective of this paper is to accurately predict the rate/temperature-dependent deformation of a polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) blend at low, moderate, and high strain rates for various temperatures. Four constitutive models have been employed to predict stress-strain responses of PC/ABS under these conditions, including the DSGZ model, the original Mulliken-Boyce (M-B) model, the modified M-B model, and an adiabatic model named the Wang model. To more accurately capture the large deformation of PC/ABS under the high strain rate loading, the original M-B model is modified by allowing for the evolution of the internal shear strength. All of the four constitutive models above have been implemented in the finite element software ABAQUS/Explicit. A comparison of prediction accuracies of the four constitutive models over a wide range of strain rates and temperatures has been presented. The modified M-B model is observed to be more accurate in predicting the deformation of PC/ABS at high strain rates for various temperatures than the original M-B model, and the Wang model is demonstrated to be the most accurate in simulating the deformation of PC/ABS at low, moderate, and high strain rates for various temperatures.

  9. Transient deformation in the Asal-Ghoubbet Rift (Djibouti) since the 1978 diking event: Is deformation controlled by magma supply rates?

    Science.gov (United States)

    Smittarello, D.; Grandin, R.; de Chabalier, J. B.; Doubre, C.; Deprez, A.; Masson, F.; Socquet, A.; Ibrahim Ahmed, S.

    2016-12-01

    Within the Afar Depression, the Asal-Ghoubbet Rift (AG Rift)in Djibouti lies in the subaerial continuation of the Aden ridge system. This segment constitutes a natural laboratory to study rifting processes and mechanisms involved in continental breakup and oceanic spreading. In November 1978, an exceptional rifting event occurred in the AG Rift. Regularly upgraded and improved geodetic technology has been used to monitor this event and the postdiking deformation. In light of recent results obtained for the Manda Hararo-Dabbahu rifting event (2005-2010), we propose that the horizontal and vertical geodetic data can be modeled with a double source, involving a dike-like inflation component aligned along the rift axis and a spherical pressure source located at midsegment below the Fieale caldera. By revisiting the codiking data, we propose that the reservoir below Fieale could have fed, at least partially, the 1978 injection and the contemporaneous Ardoukoba eruption and potentially induced local subsidence due to magma draining out of the central reservoir. As an alternative to previously proposed viscoelastic relaxation models, we reinterpret postdiking observations using a purely elastic rheology. We determine the relative contribution of a midsegment reservoir inflation and a dike-like opening component, together with their respective time evolutions. Our results suggest that interactions between steadily accumulating tectonic strain and temporal variations in melt supply to the shallow magma plumbing system below the AG Rift may entirely explain the geodetic observations and that viscoelastic deformation processes played a minor role in the 30 years following the 1978 rifting event.

  10. Brachytherapy treatment with high dose rate

    International Nuclear Information System (INIS)

    Santana Rodriguez, Sergio Marcelino; Rodriguez Rodriguez, Lissi Lisbet; Ciscal Chiclana, Onelio Alberto

    2009-01-01

    Retrospectively analyze results and prognostic factors of cervical cancer patients treated with radio concomitant cisplatin-based chemotherapy, radiation therapy combined modality. Methods: From January 2003 to December 2007, 198 patients with invasive cervical cancer were treated at the Oncology Department of Hospital Robau Celestino Hernandez (brachytherapy performed at INOR). The most common age group was 31 to 40 years. The histology in squamous cell carcinoma accounted for 84.3% of cases. The treatment consisted of external pelvic irradiation and vaginal brachytherapy, high dose rate. Concomitant chemotherapy consisted of cisplatin 40 mg/m2 weekly with a maximum of 70 mg for 5 weeks. Results: 66.2% of patients completed 5 cycles of chemotherapy. The median overall survival was 39 months, overall survival, disease-free survival and survival free of locoregional recurrence at 5 years of 78%, 76% and 78.6% respectively .. We found that clinical stage, histological type (adenocarcinoma worst outcome) were statistically related to level of response. Conclusions: Treatment with external pelvic radiation, brachytherapy and concurrent weekly cisplatin in patients with stage IIIB cervical cancer is feasible in the Chilean public health system, well tolerated and results comparable to international literature. (Author)

  11. Recovery and deformation substructures of zircaloy-4 in high temperature plasticity under stationary or non-stationary stress

    International Nuclear Information System (INIS)

    Bocek, M.; Armas, I.

    1982-01-01

    It was the aim of the present investigation to examine how the recovery rate in creep is influenced by a non-stationary stress. For purposes of phenomenological analysis it is postulated that, irrespective of whether the applied stress is stationary or not, for large strains the mean internal stress sigmasub(i) approaches a stationary value sigmasub(i,s). The stationary recovery rate Rsub(s) for constant load creep turns out be governed by the applied stress indicating that the recovery mechanism is dynamic in nature. For sigma-ramp loading, Rsub(s) is dependent on the stress rate sigma. In tensional stress cycling, Rsub(s) is governed by the maximum stress sigmasub(M) and is also dependent on the ratio of sigmasub(M) to the minimum stress sigma 0 . TEM examination of Zircaloy-4 specimens crept at 800 0 C at constant and cycling load respectively could not reveal any differences in the deformation substructure for the two loading types. Subgrain formation did not appear, individual dislocations were observed only rarely. However, typical networks were formed as well as pileups which perhaps are responsible for the back stress in high temperature plasticity (HTP). (orig.)

  12. Deformation mechanism in graphene nanoplatelet reinforced tantalum carbide using high load in situ indentation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Cheng; Boesl, Benjamin [Plasma Forming Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States); Silvestroni, Laura; Sciti, Diletta [Institute of Science and Technology for Ceramics (ISTEC), CNR-ISTEC, Via Granarolo 64, 48018 Faenza (Italy); Agarwal, Arvind, E-mail: agarwala@fiu.edu [Plasma Forming Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States)

    2016-09-30

    High load in-situ indentation testing with real time SEM imaging was carried out on spark plasma sintered graphene nanoplatelets (GNP) reinforced TaC composites. The prime goal of this study was to understand the deformation behavior and the reinforcing mechanisms of GNPs. The results suggest that addition of GNPs had significant effect on dissipating indentation energy and confining the overall damage area to a localized region of TaC. The average crack length reduced by 26% whereas total damage area shrunk by 85% in TaC-5 vol% GNP sample as compared to pure TaC. TEM analysis concluded that well dispersed GNPs result in a strong and clean interface between TaC and GNP with trace amount of amorphous layer that leads to improved energy dissipation mechanism.

  13. Neutron scattering experiments of the ionic crystal deformed plastically with uniaxial compression under high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Yoshinori; Minakawa, Nobuaki; Aizawa, Kazuya; Ozawa, Kunio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1996-04-01

    As an aim of huge growth of alkali halide (AH) single crystal, a mosaic structure of small size AH single crystal deformed plastically with uniaxial compression under high temperature was evaluated due to its neutron irradiation experiment. Using TAS-2 installed at JRR-3M guide hole of Japan Atomic Energy Research Institute, locking curve at a representative face factor of the specimen was measured to observe the mosaic structure accompanied with expansion of the crystal due to compression. As a result, though the specimen before compression could be supposed to be divided to some parts already, the locking curve under 10 sec. of compression time showed already some fracture to divisions to suppose finer degradation of the crystal, and division of the locking curve at 600 sec. of compression time could be observed onto its 220 face. And, every compressed specimens showed some changes of crystallization method from standard sample. (G.K.)

  14. Adaptive Optics System with Deformable Composite Mirror and High Speed, Ultra-Compact Electronics

    Science.gov (United States)

    Chen, Peter C.; Knowles, G. J.; Shea, B. G.

    2006-06-01

    We report development of a novel adaptive optics system for optical astronomy. Key components are very thin Deformable Mirrors (DM) made of fiber reinforced polymer resins, subminiature PMN-PT actuators, and low power, high bandwidth electronics drive system with compact packaging and minimal wiring. By using specific formulations of fibers, resins, and laminate construction, we are able to fabricate mirror face sheets that are thin (2 KHz. By utilizing QorTek’s proprietary synthetic impendence power supply technology, all the power, control, and signal extraction for many hundreds to 1000s of actuators and sensors can be implemented on a single matrix controller printed circuit board co-mounted with the DM. The matrix controller, in turn requires only a single serial bus interface, thereby obviating the need for massive wiring harnesses. The technology can be scaled up to multi-meter aperture DMs with >100K actuators.

  15. Application of Deformable Templates for Recognizing Tracks Detected with High Pressure Drift Tubes

    International Nuclear Information System (INIS)

    Baginyan, S.; Baranov, S.; Glazov, A.; Ososkov, G.

    1994-01-01

    The modification of the deformable template method (DTM) application to the problem of track finding and track parameter determination for data detected with high pressure drift tubes (HPDT) in the design of ATLAS for the muon spectrometer experiment is proposed. Our DTM applications consist of two parts, according to two stages of the study. The first part relates to the stage of HPDT study on the CERN muon beam (BEAM-TEST) with the simplest one-prong events without noise signals, where the main obstacle is the left-right ambiguities for each tube. In the second part more complicated HPDT data are to be handled with noise signals. It was shown that the suggested DTM development solves the problem of track recognition and track parameter determination for both noiseless and noise data. Results are obtained on the real beam test data and on data simulating the muon spectrometer on the basis of HPDT. 14 refs., 10 figs

  16. Electromechanical stability of electro-active silicone filled with high permittivity particles undergoing large deformation

    International Nuclear Information System (INIS)

    Liu, Liwu; Liu, Yanju; Zhang, Zhen; Leng, Jinsong; Li, Bo

    2010-01-01

    In this paper, an expression for the permittivity of electro-active silicone undergoing large deformation with high permittivity particles filled uniformly has been proposed. Two expressions are proposed for the permittivity, one based on experimental tests and the other based on the theory of composite material. By applying the thermodynamic model incorporating linear dielectric permittivity and nonlinear hyperelastic performance, the mechanical performance and electromechanical stability of the coupling system constituted by silicone filled with PMN–PT have been studied. The results show that the critical electric field decreases, namely the stability performance of the system declines when the content of PMN–PT c(v) increases and the electrostrictive coefficients increase. The results are beneficial for us to understand deeply the influence of the filled particle on the stability performance of silicone and to guide the design and manufacture of actuators and sensors based on dielectric elastomers

  17. Microstructure and texture evolution of different high manganese cast steels during hot deformation and subsequent treatment

    Energy Technology Data Exchange (ETDEWEB)

    Lima, M.N.S.; Andrade, C.D.; Abreu, H.F.G. de; Klug, J.; Masoumi, M., E-mail: mohammad@alu.ufc.br [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Depto. de Engenharia Metalurgica e de Materiais; Ferreira, W.M. [Universidade Federal do Piaui (UFPI), Teresina, PI (Brazil). Curso de Engenharia Mecanica

    2016-07-01

    Microstructure and texture evolution were studied in two different austenitic high manganese cast steels in each processing condition. Special attention was paid to the effects of hot deformation and subsequent treatment on grain orientation behavior. The roles of Mn and C elements as well as heat treatment processes were investigated by Thermo-Calc. The texture evolutions in the as-cast, solution heat treatment, as-rolled and subsequent treatment were explored via orientation distribution function. The results showed that face-centred cube austenite was developed in steels. Strong {110}<115> texture component was characterized in as-cast in both alloys. Then, the inhomogeneity microstructure and the pronounced microsegregations were removed by annealing and Brass {110}<112>, {110}<111> and {221}<102> components were formed. Finally, cube {001}<100> component was developed during hot rolling in samples. (author)

  18. Microstructure and texture evolution of different high manganese cast steels during hot deformation and subsequent treatment

    International Nuclear Information System (INIS)

    Lima, M.N.S.; Andrade, C.D.; Abreu, H.F.G. de; Klug, J.; Masoumi, M.; Ferreira, W.M.

    2016-01-01

    Microstructure and texture evolution were studied in two different austenitic high manganese cast steels in each processing condition. Special attention was paid to the effects of hot deformation and subsequent treatment on grain orientation behavior. The roles of Mn and C elements as well as heat treatment processes were investigated by Thermo-Calc. The texture evolutions in the as-cast, solution heat treatment, as-rolled and subsequent treatment were explored via orientation distribution function. The results showed that face-centred cube austenite was developed in steels. Strong {110}<115> texture component was characterized in as-cast in both alloys. Then, the inhomogeneity microstructure and the pronounced microsegregations were removed by annealing and Brass {110}<112>, {110}<111> and {221}<102> components were formed. Finally, cube {001}<100> component was developed during hot rolling in samples. (author)

  19. Grain boundary sliding mechanism during high temperature deformation of AZ31 Magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Roodposhti, Peiman Shahbeigi, E-mail: pshahbe@ncsu.edu [North Carolina State University (United States); University of Connecticut (United States); Sarkar, Apu; Murty, Korukonda Linga [North Carolina State University (United States); Brody, Harold [University of Connecticut (United States); Scattergood, Ronald [North Carolina State University (United States)

    2016-07-04

    High temperature tensile creep tests were conducted on AZ31 Magnesium alloy at low stress range of 1–13 MPa to clarify the existence of grain boundary sliding (GBS) mechanism during creep deformation. Experimental data within the GBS regime shows the stress exponent is ~2 and the activation energy value is close to that for grain boundary diffusion. Analyses of the fracture surface of the sample revealed that the GBS provides many stress concentrated sites for diffusional cavities formation and leads to premature failure. Scanning electron microscopy images show the appearances of both ductile and brittle type fracture mechanism. X-ray diffraction line profile analysis (based on Williamson-Hall technique) shows a reduction in dislocation density due to dynamic recovery (DRV). A correlation between experimental data and Langdon's model for GBS was also demonstrated.

  20. Deformations on Hole and Projectile Surfaces Caused By High Velocity Friction During Ballistic Impact

    Science.gov (United States)

    Karamış, M. B.

    2018-01-01

    In this study, the deformations caused by the ballistic impact on the MM composites and on projectile surfaces are examined. The hole section and grain deformation of unreinforced targets are also examined after impact. The relatively high complexity of impact problems is caused by the large number of intervening parameters like relative velocity of projectile and target, shape of colliding objects, relative stiffness and masses, time-dependent surface of contact, geometry and boundary conditions and material characteristics. The material used in this investigation are 2024 and 7075 aluminum alloys as matrix reinforced with SiC and Al2O3 particles. The matrix materials are extensively used in defense applications due to its favorable ballistic properties, moderate strength, high corrosion resistance and super plastic potential. Two different composites were produced; one by casting and the other by lamination. The ballistic tests of the composite targets were carried out according to NIJ Standard-0101.04, Temperature 21 °C, RH=65% with 7.62 mm projectiles. The bullet weight was 9.6 g and their muzzle velocities were in the range of 770-800 m/s. The projectiles consisted of a steel core, copper jacket and lead material. The composite targets were positioned 15 m from the rifle. The interaction between projectiles and the target hole created after impact were examined by light microscopy and photography. Different damage and failure mechanisms such as petalling, cracking, spalling, dishing, etc., were observed on the target body. On the other hand, dramatic wear and damages on the projectile surface were also observed. The targets were supported with Al-5083 backing blocks having 40 mm thickness.

  1. High Temperature Deformation of Twin-Roll Cast Al-Mn-Based Alloys after Equal Channel Angular Pressing.

    Science.gov (United States)

    Málek, Přemysl; Šlapáková Poková, Michaela; Cieslar, Miroslav

    2015-11-12

    Twin roll cast Al-Mn- and Al-Mn-Zr-based alloys were subjected to four passes of equal channel angular pressing. The resulting grain size of 400 nm contributes to a significant strengthening at room temperature. This microstructure is not fully stable at elevated temperatures and recrystallization and vast grain growth occur at temperatures between 350 and 450 °C. The onset of these microstructure changes depends on chemical and phase composition. Better stability is observed in the Al-Mn-Zr-based alloy. High temperature tensile tests reveal that equal channel angular pressing results in a softening of all studied materials at high temperatures. This can be explained by an active role of grain boundaries in the deformation process. The maximum values of ductility and strain rate sensitivity parameter m found in the Al-Mn-Zr-based alloy are below the bottom limit of superplasticity (155%, m = 0.25). However, some features typical for superplastic behavior were observed-the strain rate dependence of the parameter m , the strengthening with increasing grain size, and the fracture by diffuse necking. Grain boundary sliding is believed to contribute partially to the overall strain in specimens where the grain size remained in the microcrystalline range.

  2. Deformation and Phase Transformation Processes in Polycrystalline NiTi and NiTiHf High Temperature Shape Memory Alloys

    Science.gov (United States)

    Benafan, Othmane

    2012-01-01

    The deformation and transformation mechanisms of polycrystalline Ni49.9Ti50.1 and Ni50.3Ti29.7Hf20 (in at.%) shape memory alloys were investigated by combined experimental and modeling efforts aided by an in situ neutron diffraction technique at stress and temperature. The thermomechanical response of the low temperature martensite, the high temperature austenite phases, and changes between these two states during thermomechanical cycling were probed and reported. In the cubic austenite phase, stress-induced martensite, deformation twinning and slip processes were observed which helped in constructing a deformation map that contained the limits over which each of the identified mechanisms was dominant. Deformation of the monoclinic martensitic phase was also investigated where the microstructural changes (texture, lattice strains, and phase fractions) during room-temperature deformation and subsequent thermal cycling were compared to the bulk macroscopic response. When cycling between these two phases, the evolution of inelastic strains, along with the shape setting procedures were examined and used for the optimization of the transformation properties as a function of deformation levels and temperatures. Finally, this work was extended to the development of multiaxial capabilities at elevated temperatures for the in situ neutron diffraction measurements of shape memory alloys on the VULCAN Diffractometer at Oak Ridge National Laboratory.

  3. Size effects in fcc crystals during the high rate compression test

    International Nuclear Information System (INIS)

    Yaghoobi, Mohammadreza; Voyiadjis, George Z.

    2016-01-01

    The present work studies the different mechanisms of size effects in fcc metallic samples of confined volumes during high rate compression tests using large scale atomistic simulation. Different mechanisms of size effects, including the dislocation starvation, source exhaustion, and dislocation source length effect are investigated for pillars with different sizes. The results show that the controlling mechanisms of size effects depend only on the pillar size and not on the value of applied strain. Dislocation starvation is the governing mechanism for very small pillars, i.e. pillars with diameters less than 30 nm. Increasing the pillar size, the dislocation exhaustion mechanism becomes active and there is no more source-limited activations. Next, the average dislocation source length is obtained and compared for pillars with different sizes. The results show that in the case of high rate deformations, the source length does not depend on the sample size, and the related size effects mechanisms are not active anymore. Also, in the case of high rate deformations, there are no size effects for pristine pillars with the diameters larger than 135 nm. In other words, increasing the strain rate decreases the pillar size at which there is no more size effects in the absence of strain gradient. The governing mechanisms of plastic deformation at high strain rate experiments are also different from those of the quasi-static tests. First, the diameter in which the dislocation nucleation at the free surface becomes the dominant mechanism changes from around 200 nm–30 nm. Next, in the case of the pillars with larger diameters, the plastic deformation is governed by the cross-slip instead of the operation of truncated dislocation sources, which is dominant at slower rates of deformation. In order to study the effects of pillar initial structure on the controlling mechanism of size effects, an initial loading and unloading procedure is conducted on some samples prior to the

  4. Deformation microstructures

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Hughes, D.A.

    2004-01-01

    Microstructural characterization and modeling has shown that a variety of metals deformed by different thermomechanical processes follows a general path of grain subdivision, by dislocation boundaries and high angle boundaries. This subdivision has been observed to very small structural scales...... of the order of 10 nm, produced by deformation under large sliding loads. Limits to the evolution of microstructural parameters during monotonic loading have been investigated based on a characterization by transmission electron microscopy. Such limits have been observed at an equivalent strain of about 10...

  5. High mitogenomic evolutionary rates and time dependency.

    NARCIS (Netherlands)

    Subramanian, S.; Denver, D.R.; Millar, C.D.; Heupink, T.; Aschrafi, A.; Emslie, S.D.; Baroni, C.; Lambert, D.M.

    2009-01-01

    Using entire modern and ancient mitochondrial genomes of Adelie penguins (Pygoscelis adeliae) that are up to 44000 years old, we show that the rates of evolution of the mitochondrial genome are two to six times greater than those estimated from phylogenetic comparisons. Although the rate of

  6. Effects of torsional deformation on the microstructures and mechanical properties of a CoCrFeNiMo0.15 high-entropy alloy

    Science.gov (United States)

    Wu, Wenqian; Guo, Lin; Liu, Bin; Ni, Song; Liu, Yong; Song, Min

    2017-12-01

    The effects of torsional deformation on the microstructures and mechanical properties of a CoCrFeNiMo0.15 high-entropy alloy have been investigated. The torsional deformation generates a gradient microstructure distribution due to the gradient torsional strain. Both dislocation activity and deformation twinning dominated the torsional deformation process. With increasing the torsional equivalent strain, the microstructural evolution can be described as follows: (1) formation of pile-up dislocations parallel to the trace of {1 1 1}-type slip planes; (2) formation of Taylor lattices; (3) formation of highly dense dislocation walls; (3) formation of microbands and deformation twins. The extremely high deformation strain (strained to fracture) results in the activation of wavy slip. The tensile strength is very sensitive to the torsional deformation, and increases significantly with increasing the torsional angle.

  7. Direct measurement of erythrocyte deformability in diabetes mellitus with a transparent microchannel capillary model and high-speed video camera system.

    Science.gov (United States)

    Tsukada, K; Sekizuka, E; Oshio, C; Minamitani, H

    2001-05-01

    To measure erythrocyte deformability in vitro, we made transparent microchannels on a crystal substrate as a capillary model. We observed axisymmetrically deformed erythrocytes and defined a deformation index directly from individual flowing erythrocytes. By appropriate choice of channel width and erythrocyte velocity, we could observe erythrocytes deforming to a parachute-like shape similar to that occurring in capillaries. The flowing erythrocytes magnified 200-fold through microscopy were recorded with an image-intensified high-speed video camera system. The sensitivity of deformability measurement was confirmed by comparing the deformation index in healthy controls with erythrocytes whose membranes were hardened by glutaraldehyde. We confirmed that the crystal microchannel system is a valuable tool for erythrocyte deformability measurement. Microangiopathy is a characteristic complication of diabetes mellitus. A decrease in erythrocyte deformability may be part of the cause of this complication. In order to identify the difference in erythrocyte deformability between control and diabetic erythrocytes, we measured erythrocyte deformability using transparent crystal microchannels and a high-speed video camera system. The deformability of diabetic erythrocytes was indeed measurably lower than that of erythrocytes in healthy controls. This result suggests that impaired deformability in diabetic erythrocytes can cause altered viscosity and increase the shear stress on the microvessel wall. Copyright 2001 Academic Press.

  8. Damage Analysis and Evaluation of High Strength Concrete Frame Based on Deformation-Energy Damage Model

    Directory of Open Access Journals (Sweden)

    Huang-bin Lin

    2015-01-01

    Full Text Available A new method of characterizing the damage of high strength concrete structures is presented, which is based on the deformation energy double parameters damage model and incorporates both of the main forms of damage by earthquakes: first time damage beyond destruction and energy consumption. Firstly, test data of high strength reinforced concrete (RC columns were evaluated. Then, the relationship between stiffness degradation, strength degradation, and ductility performance was obtained. And an expression for damage in terms of model parameters was determined, as well as the critical input data for the restoring force model to be used in analytical damage evaluation. Experimentally, the unloading stiffness was found to be related to the cycle number. Then, a correction for this changing was applied to better describe the unloading phenomenon and compensate for the shortcomings of structure elastic-plastic time history analysis. The above algorithm was embedded into an IDARC program. Finally, a case study of high strength RC multistory frames was presented. Under various seismic wave inputs, the structural damages were predicted. The damage model and correction algorithm of stiffness unloading were proved to be suitable and applicable in engineering design and damage evaluation of a high strength concrete structure.

  9. Formation of defects at high temperature plastic deformation of gallium arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Mikhnovich, V.V.

    2006-03-14

    The purpose of the present thesis consists in acquiring more concrete information concerning the mechanism of the movement of dislocations and types of defects that appear during the process of dislocation motion on the basis of systematic experimental studies of the GaAs deformation. Experimental studies concerning the dependence of the stress of the samples from their deformation at different values of the deformation parameters (like temperature and deformation speed) were conducted in this paper. To determine the concentration of defects introduced in samples during the deformation process the positron annihilation spectroscopy (PAS) method was used. The second chapter of this paper deals with models of movement of dislocations and origination of defects during deformation of the samples. In the third chapter channels and models of positron annihilation in the GaAs samples are investigated. In the forth chapter the used experimental methods, preparation procedure of test samples and technical data of conducted experiments are described. The fifth chapter shows the results of deformation experiments. The sixth chapter shows the results of positron lifetime measurements by the PAS method. In the seventh chapter one can find analyses of the values of defects concentration that were introduced in samples during deformation. (orig.)

  10. Cheetah: A high frame rate, high resolution SWIR image camera

    Science.gov (United States)

    Neys, Joel; Bentell, Jonas; O'Grady, Matt; Vermeiren, Jan; Colin, Thierry; Hooylaerts, Peter; Grietens, Bob

    2008-10-01

    A high resolution, high frame rate InGaAs based image sensor and associated camera has been developed. The sensor and the camera are capable of recording and delivering more than 1700 full 640x512pixel frames per second. The FPA utilizes a low lag CTIA current integrator in each pixel, enabling integration times shorter than one microsecond. On-chip logics allows for four different sub windows to be read out simultaneously at even higher rates. The spectral sensitivity of the FPA is situated in the SWIR range [0.9-1.7 μm] and can be further extended into the Visible and NIR range. The Cheetah camera has max 16 GB of on-board memory to store the acquired images and transfer the data over a Gigabit Ethernet connection to the PC. The camera is also equipped with a full CameralinkTM interface to directly stream the data to a frame grabber or dedicated image processing unit. The Cheetah camera is completely under software control.

  11. Deformation-Induced Dissolution and Precipitation of Nitrides in Austenite and Ferrite of a High-Nitrogen Stainless Steel

    Science.gov (United States)

    Shabashov, V. A.; Makarov, A. V.; Kozlov, K. A.; Sagaradze, V. V.; Zamatovskii, A. E.; Volkova, E. G.; Luchko, S. N.

    2018-02-01

    Methods of Mössbauer spectroscopy and electron microscopy have been used to study the effect of the severe plastic deformation by high pressure torsion in Bridgman anvils on the dissolution and precipitation of chromium nitrides in the austenitic and ferritic structure of an Fe71.2Cr22.7Mn1.3N4.8 high-nitrogen steel. It has been found that an alternative process of dynamic aging with the formation of secondary nitrides affects the kinetics of the dissolution of chromium nitrides. The dynamic aging of ferrite is activated with an increase in the deformation temperature from 80 to 573 K.

  12. DNA deformability changes of single base pair mutants within CDE binding sites in S. Cerevisiae centromere DNA correlate with measured chromosomal loss rates and CDE binding site symmetries

    Directory of Open Access Journals (Sweden)

    Marx Kenneth A

    2006-03-01

    Full Text Available Abstract Background The centromeres in yeast (S. cerevisiae are organized by short DNA sequences (125 bp on each chromosome consisting of 2 conserved elements: CDEI and CDEIII spaced by a CDEII region. CDEI and CDEIII are critical sequence specific protein binding sites necessary for correct centromere formation and following assembly with proteins, are positioned near each other on a specialized nucleosome. Hegemann et al. BioEssays 1993, 15: 451–460 reported single base DNA mutants within the critical CDEI and CDEIII binding sites on the centromere of chromosome 6 and quantitated centromere loss of function, which they measured as loss rates for the different chromosome 6 mutants during cell division. Olson et al. Proc Natl Acad Sci USA 1998, 95: 11163–11168 reported the use of protein-DNA crystallography data to produce a DNA dinucleotide protein deformability energetic scale (PD-scale that describes local DNA deformability by sequence specific binding proteins. We have used the PD-scale to investigate the DNA sequence dependence of the yeast chromosome 6 mutants' loss rate data. Each single base mutant changes 2 PD-scale values at that changed base position relative to the wild type. In this study, we have utilized these mutants to demonstrate a correlation between the change in DNA deformability of the CDEI and CDEIII core sites and the overall experimentally measured chromosome loss rates of the chromosome 6 mutants. Results In the CDE I and CDEIII core binding regions an increase in the magnitude of change in deformability of chromosome 6 single base mutants with respect to the wild type correlates to an increase in the measured chromosome loss rate. These correlations were found to be significant relative to 105 Monte Carlo randomizations of the dinucleotide PD-scale applied to the same calculation. A net loss of deformability also tends to increase the loss rate. Binding site position specific, 4 data-point correlations were also

  13. Deformation analyse of the high point field Košická Nová Ves

    Directory of Open Access Journals (Sweden)

    Sedlák Vladimír

    2003-09-01

    Full Text Available From the science point of view the deformation measurements serve to an objective determination of movements and from the technical point of view the deformation measurements serve to a determinantion of the building technologies and the construction procedures. Detrmined movements by means of using the geodetic terrestrial or satellite navigation technologies give informations about displacements in a concrete time information on the base of repeated geodetic measurements in the concrete time intervals (epochs.Level deformation investigation of the point of the monitoring station stabled in the fill slope territory Košická Nová Ves is the main task of the presented paper. Level measurements are realized in autumn 2000 (the epoch 200.9 - it is considered as the first epoch of the deformation measurement, and in spring 2001 (the epoch 2001.3 – it is considered as the second epoch of the deformation measurement.

  14. Low-temperature internal friction in high-purity monocrystalline and impure polycrystalline niobium after plastic deformation

    International Nuclear Information System (INIS)

    Wasserbaech, W.; Thompson, E.

    2001-01-01

    The internal friction Q -1 of plastically deformed, high-purity monocrystalline and impure polycrystalline niobium specimens was measured in the temperature range between 65 mK and about 2 K. Plastic deformation has a pronounced effect on the internal friction Q -1 of the high-purity monocrystalline specimens, and the effect has been found to be almost temperature independent. By contrast, surprisingly, the internal friction Q -1 of the impure polycrystalline specimens was found to be almost independent of the extent of plastic deformation. Comparison of the experimental results with different models of a dynamic scattering of acoustic phonons by dislocations leads to the conclusion that the results cannot be explained with the two-level tunneling model. Instead it is suggested that a strong interaction between acoustic phonons and geometrical kinks in non-screw dislocations is responsible for the observed internal friction Q -1 . (orig.)

  15. Direct observation of radial distribution change during tensile deformation of metallic glass by high energy X-ray diffraction method

    Energy Technology Data Exchange (ETDEWEB)

    Nasu, Toshio, E-mail: nasu@kekexafs.kj.yamagata-u.ac.j [Faculty of Education, Arts and Science, Yamagata University, 1-4-12 Kojirakawa, Yamagata, Yamagata, 990-8560 (Japan); Sasaki, Motokatsu [Faculty of Education, Arts and Science, Yamagata University, 1-4-12 Kojirakawa, Yamagata, Yamagata, 990-8560 (Japan); Usuki, Takeshi; Sekine, Mai [Faculty of Science, Yamagata University, Yamagata 990-8560 (Japan); Takigawa, Yorinobu; Higashi, Kenji [Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8531 (Japan); Kohara, Shinji [Japan Synchrotron Radiation Research Institute, Harima Science Garden City, Sayo town, Hyogo 679-5198 (Japan); Sakurai, Masaki; Wei Zhang; Inoue, Akihisa [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2009-08-26

    The purpose of this research is to investigate the micro-mechanism of deformation behavior of metallic glasses. We report the results of direct observations of short-range and medium-range structural change during tensile deformation of metallic glasses by high energy X-ray diffraction method. Cu{sub 50}Zr{sub 50} and Ni{sub 30}Zr{sub 70} metallic glass samples in the ribbon shape (1.5 mm width and 25 mum) were made by using rapid quenching method. Tensile deformation added to the sample was made by using special equipment adopted for measuring the high energy X-ray diffraction. The peaks in pair distribution function g(r) for Cu{sub 50}Zr{sub 50} and N{sub 30}iZr{sub 70} metallic glasses move zigzag into front and into rear during tensile deformation. These results of direct observation on atomic distribution change for Cu{sub 50}Zr{sub 50} and Ni{sub 30}Zr{sub 70} metallic glass ribbons during tensile deformation suggest that the micro-relaxations occur.

  16. Measurement and correlation of high frequency behaviors of a very flexible beam undergoing large deformation

    International Nuclear Information System (INIS)

    Lee, Jae Wook; Kim, Hyun Woo; Ku, Hi Chun; Yoo, Wan Suk

    2009-01-01

    A correlation method of high frequency behaviors of a very flexible beam undergoing large displacement is presented. The suggested method based on the experimental modal analysis leads to more accurate correlation results because it directly uses the modal parameters of each mode achieved from experiment. First, the modal testing and the parameter identification method are suggested for flexible multibody dynamics. Due to the flexibility of a very thin beam, traditional testing methods such as impact hammer or contact type accelerometer are not working well. The suggested measurement with high speed camera, even though the test beam is very flexible, is working well. Using measurements with a high speed camera, modal properties until the 5th mode are measured. And After measuring each damping ratio until the 5th mode, a generic damping model is constructed using inverse modal transformation technique. It's very interesting that the modal transformation technique can be also applied even in the ANCF simulation which uses the global displacement and finite slope as the nodal coordinates. The results of experiment and simulation are compared until the 5th mode frequency, respectively, by using ANCF forced vibration analysis. Through comparison between numerical simulation and experiment, this study showed that the proposed generic damping matrix, modal testing and parameter identification method is very proper in flexible multibody dynamic problems undergoing large deformation

  17. Calculation of gaint Elambda-resonances of high multipolarity in deformed nuclei

    International Nuclear Information System (INIS)

    Kiselev, M.A.; Malov, L.A.; Nesterenko, V.O.; Solov'ev, V.G.

    1978-01-01

    High-miltipole ( lambda=4-7 ) single-phonon states and strength functions of Elambda(0sup(+) → lambdasup(π))-transitions from the ground states to the excited Isup(π)K states with I=lambda in deformed nuclei are calculated. Possible existance of high-multipole ( lambda >= 4 ) giant Elambda-resonances is considered. Magnitudes of isoscalar and isovector constants of multipole-multipole interaction, required for a description of phonons as quasiparticles of the phonon model, are discussed. All the calculations have been carried out in the random-phase approximation of the general semimicroscopic approach. There is a tendency towards broadening resonances and shifting the maxima into the region of high excitation energies as lambda increases. Broad isoscalar resonances at energies of 10-17 MeV, 10-25 MeV, 15-25 MeV and 10-40 MeV for lambda=4, 5, 6 and 7 respectively. Isovector resonances at lambda=4, 5, 6 and 7 show up themselves as well sufficiently clearly

  18. Planetesimal core formation with partial silicate melting using in-situ high P, high T, deformation x-ray microtomography

    Science.gov (United States)

    Anzures, B. A.; Watson, H. C.; Yu, T.; Wang, Y.

    2017-12-01

    Differentiation is a defining moment in formation of terrestrial planets and asteroids. Smaller planetesimals likely didn't reach high enough temperatures for widescale melting. However, we infer that core formation must have occurred within a few million years from Hf-W dating. In lieu of a global magma ocean, planetesimals likely formed through inefficient percolation. Here, we used in-situ high temperature, high pressure, x-ray microtomography to track the 3-D evolution of the sample at mantle conditions as it underwent shear deformation. Lattice-Boltzmann simulations for permeability were used to characterize the efficiency of melt percolation. Mixtures of KLB1 peridotite plus 6.0 to 12.0 vol% FeS were pre-sintered to achieve an initial equilibrium microstructure, and then imaged through several consecutive cycles of heating and deformation. The maximum calculated melt segregation velocity was found to be 0.37 cm/yr for 6 vol.% FeS and 0.61 cm/year for 12 vol.% FeS, both below the minimum velocity of 3.3 cm/year required for a 100km planetesimal to fully differentiate within 3 million years. However, permeability is also a function of grain size and thus the samples having smaller grains than predicted for small planetesimals could have contributed to low permeability and also low migration velocity. The two-phase (sulfide melt and silicate melt) flow at higher melt fractions (6 vol.% and 12 vol.% FeS) was an extension of a similar study1 containing only sulfide melt at lower melt fraction (4.5 vol.% FeS). Contrary to the previous study, deformation did result in increased permeability until the sample was sheared by twisting the opposing Drickamer anvils by 360 degrees. Also, the presence of silicate melt caused the FeS melt to coalesce into less connected pathways as the experiment with 6 vol.% FeS was found to be less permeable than the one with 4.5 vol.% FeS but without any partial melt. The preliminary data from this study suggests that impacts as well as

  19. Ceramic high-rate timing RPCs

    International Nuclear Information System (INIS)

    Lopes, L.; Ferreira Marques, R.; Fonte, P.; Hennetier, L.; Pereira, A.; Sousa Correia, A.M.

    2006-01-01

    Following some previous work, we report here considerable improvements on the counting rate capability of timing RPCs by the use of ceramic electrodes with a resistivity of 10 9 Ω.cm. The X-ray sensitivity of the detector depends linearly on the counting rate with a slope of 9% per 100 kHz/cm 2 , free from charge depletion effects, while keeping a timing accuracy, measured with 511 keV synchronous photon pairs, around 90 ps σ up to 75 kHz/cm 2

  20. Thermal behavior of Nickel deformed to ultra-high strain by high pressure torsion

    DEFF Research Database (Denmark)

    Zhang, Hongwang; Huang, Xiaoxu; Pippan, Richard

    2012-01-01

    . The isochronal annealing leads to a hardness drop in three stages: a relatively small decrease at low temperatures (recovery) followed by a rapid decrease at intermediate temperatures (discontinuous recrystallization) and a slow decrease at high temperatures (grain growth). Due to the presence of a small amount...

  1. Understanding deformation with high angular resolution electron backscatter diffraction (HR-EBSD)

    Science.gov (United States)

    Britton, T. B.; Hickey, J. L. R.

    2018-01-01

    High angular resolution electron backscatter diffraction (HR-EBSD) affords an increase in angular resolution, as compared to ‘conventional’ Hough transform based EBSD, of two orders of magnitude, enabling measurements of relative misorientations of 1 x 10-4 rads (~ 0.006°) and changes in (deviatoric) lattice strain with a precision of 1 x 10-4. This is achieved through direct comparison of two or more diffraction patterns using sophisticated cross-correlation based image analysis routines. Image shifts between zone axes in the two-correlated diffraction pattern are measured with sub-pixel precision and this realises the ability to measure changes in interplanar angles and lattice orientation with a high degree of sensitivity. These shifts are linked to strains and lattice rotations through simple geometry. In this manuscript, we outline the basis of the technique and two case studies that highlight its potential to tackle real materials science challenges, such as deformation patterning in polycrystalline alloys.

  2. γ-spectroscopy and radioactive beams: search for highly deformed exotic nuclei

    International Nuclear Information System (INIS)

    Rosse, B.

    2006-07-01

    This work is devoted to the search for highly deformed nuclei under extreme conditions of isospin, located near the proton drip-line, around A ∼ 130. The experiment was performed at GANIL (Caen) with the SPIRAL radioactive beam facility. The nuclei of interest were produced by fusion-evaporation reactions induced by the neutron deficient Kr 76 radioactive beam (T1/2 = 14.8 h). γ-rays were detected by the EXOGAM array, composed of 11 segmented germanium clover detectors, for which a new segment calibration method has been developed. To extract fusion-evaporation events of a overwhelming background due to the radioactivity of the beam, the EXOGAM array was coupled with the light charged particle detector DIAMANT and the high acceptance VAMOS spectrometer. The latter was used for the first time to detect fusion-evaporation residues. The detailed data analysis allowed us to demonstrate that the EXOGAM + DIAMANT + VAMOS coupling is operational and essential to investigate the structure of these nuclei. Furthermore, the first γ transition was observed in the very exotic odd-odd Pm 130 nucleus. The results have been interpreted with static and dynamic self-consistent microscopic calculations in collaboration with the Theoretical Physicists of the IPN Lyon. (author)

  3. γ-spectroscopy and radioactive beams: search for highly deformed exotic nuclei

    International Nuclear Information System (INIS)

    Rosse, Bertrand

    2006-01-01

    This work is devoted to the search for highly deformed nuclei under extreme conditions of isospin, located near the proton drip-line, around A∼130. The experiment was performed at GANIL (Caen) with the SPIRAL radioactive beam facility. The nuclei of interest were produced by fusion-evaporation reactions induced by the neutron deficient 76 Kr radioactive beam (T 1/2 = 14.8 h). γ-rays were detected by the EXOGAM array, composed of 11 segmented germanium clover detectors, for which a new segment calibration method has been developed. To extract fusion-evaporation events of a overwhelming background due to the radioactivity of the beam, the EXOGAM array was coupled with the light charged particle detector DIAMANT and the high acceptance VAMOS spectrometer. The latter was used for the first time to detect fusion-evaporation residues. The detailed data analysis allowed us to demonstrate that the EXOGAM + DIAMANT + VAMOS coupling is operational and essential to investigate the structure of these nuclei. Furthermore, the first γ transition was observed in the very exotic odd-odd 130 Pm nucleus. The results have been interpreted with static and dynamic self-consistent microscopic calculations in collaboration with the Theoretical Physicists of the IPN Lyon. (author)

  4. Influence of cold deformation and annealing on hydrogen embrittlement of cold hardening bainitic steel for high strength bolts

    Energy Technology Data Exchange (ETDEWEB)

    Hui, Weijun, E-mail: wjhui@bjtu.edu.cn [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Yongjian; Zhao, Xiaoli; Shao, Chengwei [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Wang, Kaizhong; Sun, Wei; Yu, Tongren [Technical Center, Maanshan Iron & Steel Co., Ltd., Maanshan 243002, Anhui (China)

    2016-04-26

    The influence of cold drawing and annealing on hydrogen embrittlement (HE) of newly developed cold hardening bainitic steel was investigated by using slow strain rate testing (SSRT) and thermal desorption spectrometry (TDS), for ensuring safety performance of 10.9 class high strength bolts made of this kind of steel against HE under service environments. Hydrogen was introduced into the specimen by electrochemical charging. TDS analysis shows that the hydrogen-charged cold drawn specimen exhibits an additional low-temperature hydrogen desorption peak besides the original high-temperature desorption peak of the as-rolled specimen, causing remarkable increase of absorbed hydrogen content. It is found that cold drawing significantly enhances the susceptibility to HE, which is mainly attributed to remarkable increase of diffusible hydrogen absorption, the occurrence of strain-induced martensite as well as the increase of strength level. Annealing after cold deformation is an effective way to improve HE resistance and this improvement strongly depends on annealing temperature, i.e. HE susceptibility decreases slightly with increasing annealing temperature up to 200 °C and then decreases significantly with further increasing annealing temperature. This phenomenon is explained by the release of hydrogen, the recovery of cold worked microstructure and the decrease of strength with increasing annealing temperature.

  5. Transition to high rate aerospace NDI processes

    Science.gov (United States)

    Vanderheiden, Bert; Thomson, Clint; Ivakhnenko, Igor; Garner, Chuck

    2018-04-01

    With the rapidly expanding use of carbon fiber composite materials in military and commercial aircraft, processes to manufacture and inspect the structural components must evolve to ensure economic viability. Inspection techniques which were developed to inspect products produced at a rate of one or two structures a month are not fast or flexible enough to inspect more than 8500 parts per month. This presentation describes the evolution of phased array ultrasonic inspection systems to provide the increased rate capacity, the flexibility to accommodate multiple unique designs, and the ability to rapidly adjust to product design changes. The paper will describe how system developments were made in response to new programs resulting in a much less expensive, higher degree of accuracy, increased flexibility, and lower cycle time inspections.

  6. High exposure rate hardware ALARA plan

    International Nuclear Information System (INIS)

    Nellesen, A.L.

    1996-10-01

    This as low as reasonably achievable review provides a description of the engineering and administrative controls used to manage personnel exposure and to control contamination levels and airborne radioactivity concentrations. HERH waste is hardware found in the N-Fuel Storage Basin, which has a contact dose rate greater than 1 R/hr and used filters. This waste will be collected in the fuel baskets at various locations in the basins

  7. Why Are Real Interest Rates So High?

    OpenAIRE

    Zvi Bodie; Alex Kane; Robert L. McDonald

    1983-01-01

    This paper applies the Capital Asset Pricing Model to help explain the anomalous behavior of real interest rates during the last several years. Specifically,we are able to show that the increased volatility of bond prices since the change in Federal Reserve operating procedure in October 1979 has substantially increased the required real risk premium on long term bonds. We also consider and reject the possibility that increased risk alone accounts for the recent increase in the short-term rea...

  8. Aspects of dislocation substructures associated with the deformation stages of stainless steel AISI 304 at high temperatures

    International Nuclear Information System (INIS)

    Oliveira, J.L.L.; Reis Filho, J.A.B.S.; Almeida, L.H. de; Monteiro, S.N.

    1978-07-01

    The development of dislocation substrutures in type 304 austenitic stainless steel at high temperatures has been associated with the deformation stages through log dσ/d epsilon x log epsilon plots, which show the transition point independently. The mechanisms responsible for the Dynamic Strain Aging particulary the Portevin-LeChatelier effect were related to the appearence of the stages. The results indicate that the deformation stages can be divided into two distinct regions. Each one of these region show particular characteristics with respect to the stress level, transition point, developed substructure and type of crystalline defects interaction with dislocations. (Author) [pt

  9. Quasi-instantaneous and Long-term Deformations of High-Performance Concrete with Some Related Properties

    OpenAIRE

    Persson, Bertil

    1998-01-01

    This report outlines an experimental and numerical study on quasi-instantaneous and long-term deformations of High-Performance Concrete, HPC, with some related properties. For this purpose about two hundred small cylinders and about one thousand cubes of eight types of HPC were cast. The age at loading varied between 18h and 28 days. Other principal properties of HPC were studied up to 4 years' age. Creep deformations of the HPC were studied from 0.01 s of loading time until 5 years' ...

  10. Effect of Deformation Temperature on Microstructure Evolution and Mechanical Properties of Low-Carbon High-Mn Steel

    Directory of Open Access Journals (Sweden)

    Adam Grajcar

    2018-01-01

    Full Text Available This work addresses the influence of deformation temperature in a range from −40°C to 200°C on the microstructure evolution and mechanical properties of a low-carbon high-manganese austenitic steel. The temperature range was chosen to cope at the time during sheet processing or car crash events. Experimental results show that yield stress and ultimate tensile strength gradually deteriorate with an increase in the tensile testing temperature. The dominant mechanism responsible for the strain hardening of steel changes as a function of deformation temperature, which is related to stacking fault energy (SFE changes. When the deformation temperature rises, twinning decreases while a role of dislocation slip increases.

  11. Effects of Friction and Anvil Design on Plastic Deformation during the Compression Stage of High-Pressure Torsion

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yuepeng; Chen, Miaomiao; Xu, Baoyan; Guo, Jing; Xu, Lingfeng; Wang, Zheng [Mechanical and Electronic Engineering College, Tai’an (China); Gao, Dongsheng [Shandong Provincial Key Laboratory of Horticultural Machineries and Equipments, Tai’an (China); Kim, Hyoung Seop [Department of Materials Science and Engineering, Pohang (Korea, Republic of)

    2016-11-15

    Herein, we report the results of our investigation on the effect of friction and anvil design on the heterogeneous plastic-deformation characteristics of copper during the compressive stage of high-pressure torsion (HPT), using the finite element method. The results indicate that the friction and anvil geometry play important roles in the homogeneity of the deformation. These variables affect the heterogeneous level of strain in the HPT compressed disks, as well as the flash in the disk edge region. The heterogeneous plastic deformation of the disks becomes more severe with the increasing depth of the cavity, as anvil angle and friction coefficient increase. However, the homogeneity increases with increases in the wall angle. The length of flash and the area of the dead metal zone increase with the depth of the cavity, while they decrease at a wall angle of 180°.

  12. Mechanical Properties and Fractographic Analysis of High Manganese Steels After Dynamic Deformation Tests

    Directory of Open Access Journals (Sweden)

    Jabłońska M.B.

    2014-10-01

    Full Text Available Since few years many research centres conducting research on the development of high-manganese steels for manufacturing of parts for automotive and railway industry. Some of these steels belong to the group of AHS possessing together with high strength a great plastic elongation, and an ideal uniform work hardening behavior. The article presents the dynamic mechanical properties of two types of high manganese austenitic steel with using a flywheel machine at room temperature with strain rates between 5×102÷3.5×103s?–1. It was found that the both studied steels exhibit a high sensitivity Rm to the strain rate. With increasing the strain rate from 5×102 to 3.5×103s?–1 the hardening dominates the process. The fracture analysis indicate that after dynamic test both steel is characterized by ductile fracture surfaces which indicate good plasticity of investigated steels.

  13. Development of a model for the description of highly excited states in odd-A deformed nuclei

    International Nuclear Information System (INIS)

    Malov, L.A.; Soloviev, V.G.

    1975-01-01

    An approximate method is suggested for solution of the set of equations, obtained earlier for describing the structure of intermediate-and high-excitation states within the framework of the model taking into account quasiparticle-phonon interaction. The analysis is conducted for the case of an odd deformed nucleus, when several one-quasiparticle components are simultaneously taken into account

  14. Prediction of the fatigue curve parameters of high strength steels in terms of the static and microplastic deformations of samples

    International Nuclear Information System (INIS)

    Shetulov, D.I.; Kryukov, L.T.; Myasnikov, A.M.

    2015-01-01

    The cycling and static strengths of a wide range of high-strength steels have been experimentally tested. Correlation between the three parameters-microplastic deformation, strain hardening coefficient, and the slope of the curve to the axis of load cycles-has been established [ru

  15. Microplastic deformation of TiB/sub 2/ particles during vibrocrushing and pressing in high pressure chambers

    Energy Technology Data Exchange (ETDEWEB)

    Ordan' yan, S.S.; Kravchik, A.E.; Ponomarenko, V.A.; Chunov, V.D. (Leningradskij Tekhnologicheskij Inst. (USSR))

    1984-04-01

    The character of plastic strain in titanium diboride particles is described. It is shown that during titanium diboride vibrocrushing unlike that of carbide there is practically no microplastic deformation that is observed only when TiB/sub 2/ particles are squeezed in high-pressure chambers at pressures not less than 3GPa.

  16. Evolution of microstructural parameters and flow stresses toward limits in nickel deformed to ultra-high strains

    DEFF Research Database (Denmark)

    Zhang, Hongwang; Huang, Xiaoxu; Hansen, Niels

    2008-01-01

    A quantitative analysis of microstructure and strength as a function of strain is presented for polycrystalline nickel (99.5%) deformed by high-pressure torsion in the strain range vertical bar-300 (epsilon(VM), von Mises strain). Typical lamellar structures consisting of extended boundaries...

  17. Toward high-speed 3D nonlinear soft tissue deformation simulations using Abaqus software.

    Science.gov (United States)

    Idkaidek, Ashraf; Jasiuk, Iwona

    2015-12-01

    We aim to achieve a fast and accurate three-dimensional (3D) simulation of a porcine liver deformation under a surgical tool pressure using the commercial finite element software Abaqus. The liver geometry is obtained using magnetic resonance imaging, and a nonlinear constitutive law is employed to capture large deformations of the tissue. Effects of implicit versus explicit analysis schemes, element type, and mesh density on computation time are studied. We find that Abaqus explicit and implicit solvers are capable of simulating nonlinear soft tissue deformations accurately using first-order tetrahedral elements in a relatively short time by optimizing the element size. This study provides new insights and guidance on accurate and relatively fast nonlinear soft tissue simulations. Such simulations can provide force feedback during robotic surgery and allow visualization of tissue deformations for surgery planning and training of surgical residents.

  18. Modeling the Mechanical Behavior of Aluminum Laminated Metal Composites During High Temperature Deformation

    National Research Council Canada - National Science Library

    Grishber, R

    1997-01-01

    A constitutive model for deformation of a novel laminated metal composite (LMC) which is comprised of 21 alternating layers of Al 5182 alloy and Al 6090/SiC/25p metal matrix composite (MMC) has been proposed...

  19. Modelling and simulation of dynamic recrystallization (DRX) in OFHC copper at very high strain rates

    Science.gov (United States)

    Testa, G.; Bonora, N.; Ruggiero, A.; Iannitti, G.; Persechino, I.; Hörnqvist, M.; Mortazavi, N.

    2017-01-01

    At high strain rates, deformation processes are essentially adiabatic and if the plastic work is large enough dynamic recrystallization can occur. In this work, an examination on microstructure evolution of OFHC copper in Dynamic Tensile Extrusion (DTE) test, performed at 400 m/s, was carried out. EBSD investigations, along the center line of the fragment remaining in the extrusion die, showed a progressive elongation of the grains, and an accompanying development of a strong + dual fiber texture. Discontinuous dynamic recrystallization (DRX) occurred at larger strains, and it was showed that nucleation occurred during straining. A criterion for DRX to occur, based on the evolution of Zener-Hollomon parameter during the dynamic deformation process, is proposed. Finally, DTE test was simulated using the modified Rusinek-Klepaczko constitutive model incorporating a model for the prediction of DRX initiation.

  20. Influence of Volume Deformation Rate on the Intensity of Oil-Bearing Crop Pressing-out in Relation to Rape Extrudate

    Science.gov (United States)

    Slavnov, E. V.; Petrov, I. A.

    2015-07-01

    The influence of the volume deformation rate on the intensity of piston pressing-out of oil has been investigated. The results of pressing by a piston moving with different speeds are presented. Mathematical simulation is carried out for the stage of pressing-out after the termination of sample loading, when oil release occurs due to the accumulated deformations of the skeleton. It has been assumed that in mechanical pressing there remains the least residual content of oil. A dimensionless complex representing the ratio of the characteristic times of loading to the material response (the process of pressing) has been obtained. The dependence of the rate of oil pressing-out at the stage of pressure relaxation on the dimensionless complex has been determined.

  1. Micro-deformation behavior in micro-compression with high-purity aluminum processed by ECAP

    Directory of Open Access Journals (Sweden)

    Xu Jie

    2015-01-01

    Full Text Available Ultrafine-grained (UFG materials have a potential for applications in micro-forming since grain size appears to be the dominant factor which determines the limiting size of the geometrical features. In this research, high-purity Al was processed by equal-channel angular pressing (ECAP at room temperature through 1–8 passes. Analysis shows that processing by ECAP produces a UFG structure with a grain size of ~1.3 μm and with microhardness and microstructural homogeneity. Micro-compression testing was carried out with different specimen dimensions using the annealed sample and after ECAP processing through 1–8 passes. The results show the flow stress increases significantly after ECAP processing by comparison with the annealed material. The flow stress generally reaches a maximum value after 2 passes which is consistent with the results of microhardness. The flow stress decreases with decreasing specimen diameter from 4 mm to 1 mm which demonstrates that size effects also exist in the ultrafine-grained materials. However, the deformation mechanism in ultrafine-grained pure Al changes from strain strengthening to softening by dynamic recovery by comparison with the annealed material.

  2. Multiscale deformations lead to high toughness and circularly polarized emission in helical nacre-like fibres.

    Science.gov (United States)

    Zhang, Jia; Feng, Wenchun; Zhang, Huangxi; Wang, Zhenlong; Calcaterra, Heather A; Yeom, Bongjun; Hu, Ping An; Kotov, Nicholas A

    2016-02-24

    Nacre-like composites have been investigated typically in the form of coatings or free-standing sheets. They demonstrated remarkable mechanical properties and are used as ultrastrong materials but macroscale fibres with nacre-like organization can improve mechanical properties even further. The fiber form or nacre can, simplify manufacturing and offer new functional properties unknown yet for other forms of biomimetic materials. Here we demonstrate that nacre-like fibres can be produced by shear-induced self-assembly of nanoplatelets. The synergy between two structural motifs--nanoscale brick-and-mortar stacking of platelets and microscale twisting of the fibres--gives rise to high stretchability (>400%) and gravimetric toughness (640 J g(-1)). These unique mechanical properties originate from the multiscale deformation regime involving solid-state self-organization processes that lead to efficient energy dissipation. Incorporating luminescent CdTe nanowires into these fibres imparts the new property of mechanically tunable circularly polarized luminescence. The nacre-like fibres open a novel technological space for optomechanics of biomimetic composites, while their continuous spinning methodology makes scalable production realistic.

  3. High-strain-induced deformation mechanisms in block-graft and multigraft copolymers

    KAUST Repository

    Schlegel, Ralf

    2011-12-13

    The molecular orientation behavior and structural changes of morphology at high strains for multigraft and block-graft copolymers based on polystyrene (PS) and polyisoprene (PI) were investigated during uniaxial monotonic loading via FT-IR and synchrotron SAXS. Results from FT-IR revealed specific orientations of PS and PI segments depending on molecular architecture and on the morphology, while structural investigations revealed a typical decrease in long-range order with increasing strain. This decrease was interpreted as strain-induced dissolution of the glassy blocks in the soft matrix, which is assumed to affect an additional enthalpic contribution (strain-induced mixing of polymer chains) and stronger retracting forces of the network chains during elongation. Our interpretation is supported by FT-IR measurements showing similar orientation of rubbery and glassy segments up to high strains. It also points to highly deformable PS domains. By synchrotron SAXS, we observed in the neo-Hookean region an approach of glassy domains, while at higher elongations the intensity of the primary reflection peak was significantly decreasing. The latter clearly verifies the assumption that the glassy chains are pulled out from the domains and are partly mixed in the PI matrix. Results obtained by applying models of rubber elasticity to stress-strain and hysteresis data revealed similar correlations between the softening behavior and molecular and morphological parameters. Further, an influence of the network modality was observed (random grafted branches). For sphere forming multigraft copolymers the domain functionality was found to be less important to achieve improved mechanical properties but rather size and distribution of the domains. © 2011 American Chemical Society.

  4. A constitutive model for particulate-reinforced titanium matrix composites subjected to high strain rates and high temperatures

    Directory of Open Access Journals (Sweden)

    Song Wei-Dong

    2013-01-01

    Full Text Available Quasi-static and dynamic tension tests were conducted to study the mechanical properties of particulate-reinforced titanium matrix composites at strain rates ranging from 0.0001/s to 1000/s and at temperatures ranging from 20 °C to 650 °C Based on the experimental results, a constitutive model, which considers the effects of strain rate and temperature on hot deformation behavior, was proposed for particulate-reinforced titanium matrix composites subjected to high strain rates and high temperatures by using Zener-Hollomon equations including Arrhenius terms. All the material constants used in the model were identified by fitting Zener-Hollomon equations against the experimental results. By comparison of theoretical predictions presented by the model with experimental results, a good agreement was achieved, which indicates that this constitutive model can give an accurate and precise estimate for high temperature flow stress for the studied titanium matrix composites and can be used for numerical simulations of hot deformation behavior of the composites.

  5. High readmission rate after heart valve surgery

    DEFF Research Database (Denmark)

    Sibilitz, K L; Berg, S K; Thygesen, L C

    2015-01-01

    investigated. RESULTS: After valve surgery, the self-reported health was lower (Short Form-36 (SF-36) Physical Component Scale (PCS): 44.5 vs. 50.6 and Mental Component Scale (MCS): 51.9 vs. 55.0, pClinical signs......BACKGROUND: After heart valve surgery, knowledge on long-term self-reported health status and readmission is lacking. Thus, the optimal strategy for out-patient management after surgery remains unclear. METHODS: Using a nationwide survey with linkage to Danish registers with one year follow-up, we...... included all adults 6-12months after heart valve surgery irrespective of valve procedure, during Jan-June 2011 (n=867). Participants completed a questionnaire regarding health-status (n=742), and answers were compared with age- and sex-matched healthy controls. Readmission rates and mortality were...

  6. Hallux Valgus and Lesser Toe Deformities are Highly Heritable in Adult Men and Women: the Framingham Foot Study

    Science.gov (United States)

    Hannan, Marian T.; Menz, Hylton B.; Jordan, Joanne M.; Cupples, L. Adrienne; Cheng, Chia-Ho; Hsu, Yi-Hsiang

    2013-01-01

    Objective To estimate heritability of three common disorders affecting the forefoot: hallux valgus, lesser toe deformities and plantar forefoot soft tissue atrophy in adult Caucasian men and women. Methods Between 2002-2008, a trained examiner used a validated foot exam to document presence of hallux valgus, lesser toe deformities and plantar soft tissue atrophy in 2,446 adults from the Framingham Foot Study. Among these, 1,370 participants with available pedigree structure were included. Heritability (h2) was estimated using pedigree structures by Sequential Oligogenic Linkage Analysis Routines (SOLAR) package. Results were adjusted for age, sex and BMI. Results Mean age of participants was 66 years (range 39 to 99 years) and 57% were female. Prevalence of hallux valgus, lesser toe deformities and plantar soft tissue atrophy was 31%, 29.6% and 28.4%, respectively. Significant h2 was found for hallux valgus (0.29 ~ 0.89, depending on age and sex) and lesser toe deformity (0.49 ~ 0.90 depending on age and sex). The h2 for lesser toe deformity in men and women aged 70+ years was 0.65 (p= 9×10−7). Significant h2 was found for plantar soft tissue atrophy in men and women aged 70+ years (h2 = 0.37; p=3.8×10−3). Conclusion To our knowledge, these are the first findings of heritability of foot disorders in humans, and they confirm the widely-held view that hallux valgus and lesser toe deformities are highly heritable in European-descent Caucasian men and women, underscoring the importance of future work to identify genetic determinants of the underlying genetic susceptibility to these common foot disorders. PMID:23696165

  7. High Strain Rate Testing of Welded DOP-26 Iridium

    Energy Technology Data Exchange (ETDEWEB)

    Schneibel, J. H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Miller, R. G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Carmichael, C. A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fox, E. E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); George, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    The iridium alloy DOP-26 is used to produce Clad Vent Set cups that protect the radioactive fuel in radioisotope thermoelectric generators (RTGs) which provide electric power for spacecraft and rovers. In a previous study, the tensile properties of DOP-26 were measured over a wide range of strain rates and temperatures and reported in ORNL/TM-2007/81. While that study established the properties of the base material, the fabrication of the heat sources requires welding, and the mechanical properties of welded DOP-26 have not been extensively characterized in the past. Therefore, this study was undertaken to determine the mechanical properties of DOP-26 specimens containing a transverse weld in the center of their gage sections. Tensile tests were performed at room temperature, 750, 900, and 1090°C and engineering strain rates of 1×10-3 and 10 s-1. Room temperature testing was performed in air, while testing at elevated temperatures was performed in a vacuum better than 1×10-4 Torr. The welded specimens had a significantly higher yield stress, by up to a factor of ~2, than the non-welded base material. The yield stress did not depend on the strain rate except at 1090°C, where it was slightly higher for the faster strain rate. The ultimate tensile stress, on the other hand, was significantly higher for the faster strain rate at temperatures of 750°C and above. At 750°C and above, the specimens deformed at 1×10-3 s-1 showed pronounced necking resulting sometimes in perfect chisel-edge fracture. The specimens deformed at 10 s-1 exhibited this fracture behavior only at the highest test temperature, 1090°C. Fracture occurred usually in the fusion zone of the weld and was, in most cases, primarily intergranular.

  8. High dose rate brachytherapy source measurement intercomparison.

    Science.gov (United States)

    Poder, Joel; Smith, Ryan L; Shelton, Nikki; Whitaker, May; Butler, Duncan; Haworth, Annette

    2017-06-01

    This work presents a comparison of air kerma rate (AKR) measurements performed by multiple radiotherapy centres for a single HDR 192 Ir source. Two separate groups (consisting of 15 centres) performed AKR measurements at one of two host centres in Australia. Each group travelled to one of the host centres and measured the AKR of a single 192 Ir source using their own equipment and local protocols. Results were compared to the 192 Ir source calibration certificate provided by the manufacturer by means of a ratio of measured to certified AKR. The comparisons showed remarkably consistent results with the maximum deviation in measurement from the decay-corrected source certificate value being 1.1%. The maximum percentage difference between any two measurements was less than 2%. The comparisons demonstrated the consistency of well-chambers used for 192 Ir AKR measurements in Australia, despite the lack of a local calibration service, and served as a valuable focal point for the exchange of ideas and dosimetry methods.

  9. High-lying Gamow-Teller excited states in the deformed nuclei,76Ge,82Se and N = 20 nuclei in the island of inversion by the Deformed QRPA (DQRPA)

    Science.gov (United States)

    Cheoun, Myung-Ki; Ha, Eunja

    2013-07-01

    With the advent of high analysis technology in detecting the Gamow-Teller (GT) excited states beyond one nucleon emission threshold, the quenching of the GT strength to the Ikeda sum rule (ISR) seems to be recovered by the high-lying (HL) GT states. We address that these HL GT excited states result from the smearing of the Fermi surface by the increase of the chemical potential owing to the deformation within a framework of the deformed quasi-particle random phase approximation (DQRPA). Detailed mechanism leading to the smearing is discussed, and comparisons to the available experimental data on 76Ge,82Se and N = 20 nuclei are shown to explain the strong peaks on the HL GT excited states.

  10. High-lying Gamow-Teller excited states in the deformed nuclei,76Ge,82Se and N = 20 nuclei in the island of inversion by the Deformed QRPA (DQRPA)

    International Nuclear Information System (INIS)

    Cheoun, Myung-Ki; Ha, Eunja

    2013-01-01

    With the advent of high analysis technology in detecting the Gamow-Teller (GT) excited states beyond one nucleon emission threshold, the quenching of the GT strength to the Ikeda sum rule (ISR) seems to be recovered by the high-lying (HL) GT states. We address that these HL GT excited states result from the smearing of the Fermi surface by the increase of the chemical potential owing to the deformation within a framework of the deformed quasi-particle random phase approximation (DQRPA). Detailed mechanism leading to the smearing is discussed, and comparisons to the available experimental data on 76 Ge, 82 Se and N = 20 nuclei are shown to explain the strong peaks on the HL GT excited states

  11. High-pressure behavior of intermediate scapolite: compressibility, structure deformation and phase transition

    Science.gov (United States)

    Lotti, Paolo; Comboni, Davide; Merlini, Marco; Hanfland, Michael

    2018-05-01

    Scapolites are common volatile-bearing minerals in metamorphic rocks. In this study, the high-pressure behavior of an intermediate member of the scapolite solid solution series (Me47), chemical formula (Na1.86Ca1.86K0.23Fe0.01)(Al4.36Si7.64)O24[Cl0.48(CO3)0.48(SO4)0.01], has been investigated up to 17.79 GPa, by means of in situ single-crystal synchrotron X-ray diffraction. The isothermal elastic behavior of the studied scapolite has been described by a III-order Birch-Murnaghan equation of state, which provided the following refined parameters: V 0 = 1110.6(7) Å3, {K_{{V_0}}} = 70(2) GPa ({β _{{V_0}}} = 0.0143(4) GPa-1) and {K_{{V}}^' = 4.8(7). The refined bulk modulus is intermediate between those previously reported for Me17 and Me68 scapolite samples, confirming that the bulk compressibility among the solid solution increases with the Na content. A discussion on the P-induced structure deformation mechanisms of tetragonal scapolite at the atomic scale is provided, along with the implications of the reported results for the modeling of scapolite stability. In addition, a single-crystal to single-crystal phase transition, which is displacive in character, has been observed toward a triclinic polymorph at 9.87 GPa. The high-pressure triclinic polymorph was found to be stable up to the highest pressure investigated.

  12. High-deposition-rate ceramics synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, M.D.; Osterheld, T.H.; Outka, D.A. [Sandia National Laboratories, Livermore, CA (United States)] [and others

    1995-05-01

    Parallel experimental and computational investigations are conducted in this project to develop validated numerical models of ceramic synthesis processes. Experiments are conducted in the High-Temperature Materials Synthesis Laboratory in Sandia`s Combustion Research Facility. A high-temperature flow reactor that can accommodate small preforms (1-3 cm diameter) generates conditions under which deposition can be observed, with flexibility to vary both deposition temperature (up to 1500 K) and pressure (as low as 10 torr). Both mass spectrometric and laser diagnostic probes are available to provide measurements of gas-phase compositions. Experiments using surface analytical techniques are also applied to characterize important processes occuring on the deposit surface. Computational tools developed through extensive research in the combustion field are employed to simulate the chemically reacting flows present in typical industrial reactors. These include the CHEMKIN and Surface-CHEMKIN suites of codes, which permit facile development of complex reaction mechanisms and vastly simplify the implementation of multi-component transport and thermodynamics. Quantum chemistry codes are also used to estimate thermodynamic and kinetic data for species and reactions for which this information is unavailable.

  13. Liquid Argon Calorimeter performance at High Rates

    CERN Document Server

    Seifert, F; The ATLAS collaboration

    2013-01-01

    The expected increase of luminosity at HL-LHC by a factor of ten with respect to LHC luminosities has serious consequences for the signal reconstruction, radiation hardness requirements and operations of the ATLAS liquid argon calorimeters in the endcap, respectively forward region. Small modules of each type of calorimeter have been built and exposed to a high intensity proton beam of 50 GeV at IHEP/Protvino. The beam is extracted via the bent crystal technique, offering the unique opportunity to cover intensities ranging from $10^6$ p/s up to $3\\cdot10^{11}$ p/s. This exceeds the deposited energy per time expected at HL-LHC by more than a factor of 100. The correlation between beam intensity and the read-out signal has been studied. The data show clear indications of pulse shape distortion due to the high ionization build-up, in agreement with MC expectations. This is also confirmed from the dependence of the HV currents on beam intensity.

  14. Dynamic Behavior of AA2519-T8 Aluminum Alloy Under High Strain Rate Loading in Compression

    Science.gov (United States)

    Olasumboye, A. T.; Owolabi, G. M.; Odeshi, A. G.; Yilmaz, N.; Zeytinci, A.

    2018-02-01

    In this study, the effects of strain rate on the dynamic behavior, microstructure evolution and hence, failure of the AA2519-T8 aluminum alloy were investigated under compression at strain rates ranging from 1000 to 3500 s-1. Cylindrical specimens of dimensions 3.3 mm × 3.3 mm (L/D = 1) were tested using the split-Hopkinson pressure bar integrated with a digital image correlation system. The microstructure of the alloy was assessed using optical and scanning electron microscopes. Results showed that the dynamic yield strength of the alloy is strain rate dependent, with the maximum yield strength attained by the material being 500 MPa. The peak flow stress of 562 MPa was attained by the material at 3500 s-1. The alloy also showed a significant rate of strain hardening that is typical of other Al-Cu alloys; the rate of strain hardening, however, decreased with increase in strain rate. It was determined that the strain rate sensitivity coefficient of the alloy within the range of high strain rates used in this study is approximately 0.05 at 0.12 plastic strain; a more significant value than what was reported in literature under quasi-static loading. Micrographs obtained showed potential sites for the evolution of adiabatic shear band at 3500 s-1, with a characteristic circular-shaped surface profile comprising partially dissolved second phase particles in the continuous phase across the incident plane of the deformed specimen. The regions surrounding the site showed little or no change in the size of particles. However, the constituent coarse particles were observed as agglomerations of fractured pieces, thus having a shape factor different from those contained in the as-received alloy. Since the investigated alloy is a choice material for military application where it can be exposed to massive deformation at high strain rates, this study provides information on its microstructural and mechanical responses to such extreme loading condition.

  15. A High-Performance Deformable Mirror with Integrated Driver ASIC for Space Based Active Optics

    Science.gov (United States)

    Shelton, Chris

    Direct imaging of exoplanets is key to fully understanding these systems through spectroscopy and astrometry. The primary impediment to direct imaging of exoplanets is the extremely high brightness ratio between the planet and its parent star. Direct imaging requires a technique for contrast suppression, which include coronagraphs, and nulling interferometers. Deformable mirrors (DMs) are essential to both of these techniques. With space missions in mind, Microscale is developing a novel DM with direct integration of DM and its electronic control functions in a single small envelope. The Application Specific Integrated Circuit (ASIC) is key to the shrinking of the electronic control functions to a size compatible with direct integration with the DM. Through a NASA SBIR project, Microscale, with JPL oversight, has successfully demonstrated a unique deformable mirror (DM) driver ASIC prototype based on an ultra-low power switch architecture. Microscale calls this the Switch-Mode ASIC, or SM-ASIC, and has characterized it for a key set of performance parameters, and has tested its operation with a variety of actuator loads, such as piezo stack and unimorph, and over a wide temperature range. These tests show the SM-ASIC's capability of supporting active optics in correcting aberrations of a telescope in space. Microscale has also developed DMs to go with the SM-ASIC driver. The latest DM version produced uses small piezo stack elements in an 8x8 array, bonded to a novel silicon facesheet structure fabricated monolithically into a polished mirror on one side and mechanical linkage posts that connect to the piezoelectric stack actuators on the other. In this Supporting Technology proposal we propose to further develop the ASIC-DM and have assembled a very capable team to do so. It will be led by JPL, which has considerable expertise with DMs used in Adaptive Optics systems, with high-contrast imaging systems for exoplanet missions, and with designing DM driver

  16. Friction properties and deformation mechanisms of halite(-mica) gouges from low to high sliding velocities

    NARCIS (Netherlands)

    Buijze, L.; Niemeijer, A.R.; Han, R.; Shimamoto, T.; Spiers, C.J.

    2017-01-01

    The evolution of friction as a function of slip rate is important in understanding earthquake nucleation and propagation. Many laboratory experiments investigating friction of fault rocks are either conducted in the low velocity regime (10−8–10−4 ms−1) or in the high velocity regime (0.01–1 m s−1).

  17. Friction properties and deformation mechanisms of halite(-mica) gouges from low to high sliding velocities

    NARCIS (Netherlands)

    Buijze, Loes|info:eu-repo/dai/nl/411880306; Niemeijer, André R.|info:eu-repo/dai/nl/370832132; Han, Raehee; Shimamoto, Toshihiko; Spiers, Christopher J.|info:eu-repo/dai/nl/304829323

    2017-01-01

    The evolution of friction as a function of slip rate is important in understanding earthquake nucleation and propagation. Many laboratory experiments investigating friction of fault rocks are either conducted in the low velocity regime (10−810−8–View the MathML source10−4 ms−1) or in the high

  18. High School Graduation Rates:Alternative Methods and Implications

    OpenAIRE

    Jing Miao; Walt Haney

    2004-01-01

    The No Child Left Behind Act has brought great attention to the high school graduation rate as one of the mandatory accountability measures for public school systems. However, there is no consensus on how to calculate the high school graduation rate given the lack of longitudinal databases that track individual students. This study reviews literature on and practices in reporting high school graduation rates, compares graduation rate estimates yielded from alternative methods, and estimates d...

  19. Static response of deformable microchannels

    Science.gov (United States)

    Christov, Ivan C.; Sidhore, Tanmay C.

    2017-11-01

    Microfluidic channels manufactured from PDMS are a key component of lab-on-a-chip devices. Experimentally, rectangular microchannels are found to deform into a non-rectangular cross-section due to fluid-structure interactions. Deformation affects the flow profile, which results in a nonlinear relationship between the volumetric flow rate and the pressure drop. We develop a framework, within the lubrication approximation (l >> w >> h), to self-consistently derive flow rate-pressure drop relations. Emphasis is placed on handling different types of elastic response: from pure plate-bending, to half-space deformation, to membrane stretching. The ``simplest'' model (Stokes flow in a 3D rectangular channel capped with a linearly elastic Kirchhoff-Love plate) agrees well with recent experiments. We also simulate the static response of such microfluidic channels under laminar flow conditions using ANSYSWorkbench. Simulations are calibrated using experimental flow rate-pressure drop data from the literature. The simulations provide highly resolved deformation profiles, which are difficult to measure experimentally. By comparing simulations, experiments and our theoretical models, we show good agreement in many flow/deformation regimes, without any fitting parameters.

  20. A METHOD FOR THE EXTRACTION OF LONG-TERM DEFORMATION CHARACTERISTICS OF LONG-SPAN HIGH-SPEED RAILWAY BRIDGES USING HIGH-RESOLUTION SAR IMAGES

    OpenAIRE

    Jia, H. G.; Liu, L. Y.

    2016-01-01

    Natural causes and high-speed train load will result in the structural deformation of long-span bridges, which greatly influence the safety operation of high-speed railway. Hence it is necessary to conduct the deformation monitoring and regular status assessment for long-span bridges. However for some traditional surveying technique, e.g. control-point-based surveying techniques, a lot of human and material resources are needed to perform the long-term monitoring for the whole bridge. In this...

  1. Emplacement and Deformation of Mesozoic Gabbros of the High Atlas (Morocco): Paleomagnetism and Magnetic Fabrics

    Science.gov (United States)

    Calvín, P.; Ruiz-Martínez, V. C.; Villalaín, J. J.; Casas-Sainz, A. M.; Moussaid, B.

    2017-12-01

    A paleomagnetic and magnetic fabric study is performed in Upper Jurassic gabbros of the central High Atlas (Morocco). These gabbros were emplaced in the core of preexisting structures developed during the extensional stage and linked to basement faults. These structures were reactivated as anticlines during the Cenozoic compressional inversion. Gabbros from 19 out of the 33 sampled sites show a stable characteristic magnetization, carried by magnetite, which has been interpreted as a primary component. This component shows an important dispersion due to postemplacement tectonic movements. The absence of paleoposition markers in these igneous rocks precludes direct restorations. A novel approach analyzing the orientation of the primary magnetization is used here to restore the magmatic bodies and to understand the deformational history recorded by these rocks. Paleomagnetic vectors are distributed along small circles with horizontal axes, indicating horizontal axis rotations of the gabbro bodies. These rotations are higher when the ratio between shales and gabbros in the core of the anticlines increases. Due to the uncertainties inherent to this work (the igneous bodies recording strong rotations), interpretations must be qualitative. The magnetic fabric is carried by ferromagnetic (s.s.) minerals mimicking the magmatic fabric. Anisotropy of magnetic susceptibility (AMS) axes, using the rotation routine inferred from paleomagnetic results, result in more tightly clustered magnetic lineations, which also become horizontal and are considered in terms of magma flow trend during its emplacement: NW-SE (parallel to the general extensional direction) in the western sector and NE-SW (parallel to the main faults) in the easternmost structures.

  2. High-resolution adaptive optics scanning laser ophthalmoscope with multiple deformable mirrors

    Science.gov (United States)

    Chen, Diana C.; Olivier, Scot S.; Jones; Steven M.

    2010-02-23

    An adaptive optics scanning laser ophthalmoscopes is introduced to produce non-invasive views of the human retina. The use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the MEMS mirror alone, and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. The large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina.

  3. Hartree-Fock calculations for strongly deformed and highly excited nuclei using the Skyrme force

    International Nuclear Information System (INIS)

    Zint, P.G.

    1975-01-01

    It has been shown that in CHF-calculations the Skyrme-force is usefull to describe strongly deformed nuclei with even proton and neutron number till separation. Thereby the eigenfunctions of the two-centre Hamiltonian form an adequate basis. With this procedure, we obtain the correct deformation of the 32 S-system. Induding the spurious energy of relative motion between the 16 O-fragments, the energy curve is a good approximation for the real potential, extracted form scattering experiments. (orig./WL) [de

  4. A comparison of Lagrangian/Eulerian approaches for tracking the kinematics of high deformation solid motion.

    Energy Technology Data Exchange (ETDEWEB)

    Ames, Thomas L.; Farnsworth, Grant V.; Ketcheson, David Isaac; Robinson, Allen Conrad

    2009-09-01

    The modeling of solids is most naturally placed within a Lagrangian framework because it requires constitutive models which depend on knowledge of the original material orientations and subsequent deformations. Detailed kinematic information is needed to ensure material frame indifference which is captured through the deformation gradient F. Such information can be tracked easily in a Lagrangian code. Unfortunately, not all problems can be easily modeled using Lagrangian concepts due to severe distortions in the underlying motion. Either a Lagrangian/Eulerian or a pure Eulerian modeling framework must be introduced. We discuss and contrast several Lagrangian/Eulerian approaches for keeping track of the details of material kinematics.

  5. High School Graduation Rates:Alternative Methods and Implications

    Directory of Open Access Journals (Sweden)

    Jing Miao

    2004-10-01

    Full Text Available The No Child Left Behind Act has brought great attention to the high school graduation rate as one of the mandatory accountability measures for public school systems. However, there is no consensus on how to calculate the high school graduation rate given the lack of longitudinal databases that track individual students. This study reviews literature on and practices in reporting high school graduation rates, compares graduation rate estimates yielded from alternative methods, and estimates discrepancies between alternative results at national, state, and state ethnic group levels. Despite the graduation rate method used, results indicate that high school graduation rates in the U.S. have been declining in recent years and that graduation rates for black and Hispanic students lag substantially behind those of white students. As to graduation rate method preferred, this study found no evidence that the conceptually more complex methods yield more accurate or valid graduation rate estimates than the simpler methods.

  6. Structural evolution of a deformed Σ=9 (122) grain boundary in silicon. A high resolution electron microscopy study

    International Nuclear Information System (INIS)

    Putaux, Jean-Luc

    1991-01-01

    This research thesis addresses the study by high resolution electron microscopy of the evolution of a silicon bi-crystal under deformation at different temperatures. The author notably studied the structural evolution of the boundary as well as that of grains at the vicinity of the boundary. Two observation scales have been used: the evolution of sub-structures of dislocations induced by deformation in grains and in boundary, and the structure of all defects at an atomic scale. After a presentation of experimental tools (the necessary perfect quality of the electronic optics is outlined), the author recalls some descriptive aspects of grain boundaries (geometric network concepts to describe coinciding networks, concepts of delimiting boundaries and of structural unit to describe grain boundary atomic structure), recalls the characteristics of the studied bi-crystal, and the conditions under which it is deformed. He presents the structures of all perfectly coinciding boundaries, describes defects obtained by deformation at the vicinity of the boundary, describes the entry of dissociated dislocations into the boundaries, and discusses the characterization of boundary dislocations (the notion of Burgers vector is put into question again), and the atomic mechanism of displacement of dislocations in boundaries [fr

  7. High Temperature Deformation Mechanism in Hierarchical and Single Precipitate Strengthened Ferritic Alloys by In Situ Neutron Diffraction Studies.

    Science.gov (United States)

    Song, Gian; Sun, Zhiqian; Li, Lin; Clausen, Bjørn; Zhang, Shu Yan; Gao, Yanfei; Liaw, Peter K

    2017-04-07

    The ferritic Fe-Cr-Ni-Al-Ti alloys strengthened by hierarchical-Ni 2 TiAl/NiAl or single-Ni 2 TiAl precipitates have been developed and received great attentions due to their superior creep resistance, as compared to conventional ferritic steels. Although the significant improvement of the creep resistance is achieved in the hierarchical-precipitate-strengthened ferritic alloy, the in-depth understanding of its high-temperature deformation mechanisms is essential to further optimize the microstructure and mechanical properties, and advance the development of the creep resistant materials. In the present study, in-situ neutron diffraction has been used to investigate the evolution of elastic strain of constitutive phases and their interactions, such as load-transfer/load-relaxation behavior between the precipitate and matrix, during tensile deformation and stress relaxation at 973 K, which provide the key features in understanding the governing deformation mechanisms. Crystal-plasticity finite-element simulations were employed to qualitatively compare the experimental evolution of the elastic strain during tensile deformation at 973 K. It was found that the coherent elastic strain field in the matrix, created by the lattice misfit between the matrix and precipitate phases for the hierarchical-precipitate-strengthened ferritic alloy, is effective in reducing the diffusional relaxation along the interface between the precipitate and matrix phases, which leads to the strong load-transfer capability from the matrix to precipitate.

  8. {gamma}-spectroscopy and radioactive beams: search for highly deformed exotic nuclei; Detection {gamma} et faisceaux radioactifs: recherche de noyaux exotiques tres deformes

    Energy Technology Data Exchange (ETDEWEB)

    Rosse, B

    2006-07-15

    This work is devoted to the search for highly deformed nuclei under extreme conditions of isospin, located near the proton drip-line, around A {approx} 130. The experiment was performed at GANIL (Caen) with the SPIRAL radioactive beam facility. The nuclei of interest were produced by fusion-evaporation reactions induced by the neutron deficient Kr{sup 76} radioactive beam (T1/2 = 14.8 h). {gamma}-rays were detected by the EXOGAM array, composed of 11 segmented germanium clover detectors, for which a new segment calibration method has been developed. To extract fusion-evaporation events of a overwhelming background due to the radioactivity of the beam, the EXOGAM array was coupled with the light charged particle detector DIAMANT and the high acceptance VAMOS spectrometer. The latter was used for the first time to detect fusion-evaporation residues. The detailed data analysis allowed us to demonstrate that the EXOGAM + DIAMANT + VAMOS coupling is operational and essential to investigate the structure of these nuclei. Furthermore, the first {gamma} transition was observed in the very exotic odd-odd Pm{sup 130} nucleus. The results have been interpreted with static and dynamic self-consistent microscopic calculations in collaboration with the Theoretical Physicists of the IPN Lyon. (author)

  9. The Effect of Minimum Wage Rates on High School Completion

    Science.gov (United States)

    Warren, John Robert; Hamrock, Caitlin

    2010-01-01

    Does increasing the minimum wage reduce the high school completion rate? Previous research has suffered from (1. narrow time horizons, (2. potentially inadequate measures of states' high school completion rates, and (3. potentially inadequate measures of minimum wage rates. Overcoming each of these limitations, we analyze the impact of changes in…

  10. Men with Sickle Cell Anemia and Priapism Exhibit Increased Hemolytic Rate, Decreased Red Blood Cell Deformability and Increased Red Blood Cell Aggregate Strength.

    Directory of Open Access Journals (Sweden)

    Kizzy-Clara Cita

    Full Text Available To investigate the association between priapism in men with sickle cell anemia (SCA and hemorheological and hemolytical parameters.Fifty-eight men with SCA (median age: 38 years were included; 28 who had experienced priapism at least once during their life (priapism group and 30 who never experienced this complication (control group. Twenty-two patients were treated with hydroxycarbamide, 11 in each group. All patients were at steady state at the time of inclusion. Hematological and biochemical parameters were obtained through routine procedures. The Laser-assisted Optical Rotational Cell Analyzer was used to measure red blood cell (RBC deformability at 30 Pa (ektacytometry and RBC aggregation properties (laser backscatter versus time. Blood viscosity was measured at a shear rate of 225 s-1 using a cone/plate viscometer. A principal component analysis was performed on 4 hemolytic markers (i.e., lactate dehydrogenase (LDH, aspartate aminotransferase (ASAT, total bilirubin (BIL levels and reticulocyte (RET percentage to calculate a hemolytic index.Compared to the control group, patients with priapism exhibited higher ASAT (p = 0.01, LDH (p = 0.03, RET (p = 0.03 levels and hemolytic indices (p = 0.02. Higher RBC aggregates strength (p = 0.01 and lower RBC deformability (p = 0.005 were observed in patients with priapism compared to controls. After removing the hydroxycarbamide-treated patients, RBC deformability (p = 0.01 and RBC aggregate strength (p = 0.03 were still different between the two groups, and patients with priapism exhibited significantly higher hemolytic indices (p = 0.01 than controls.Our results confirm that priapism in SCA is associated with higher hemolytic rates and show for the first time that this complication is also associated with higher RBC aggregate strength and lower RBC deformability.

  11. High regression rate, high density hybrid fuels, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR program will investigate high energy density novel nanofuels combined with high density binders for use with an N2O oxidizer. Terves has developed...

  12. Effect of different stages of tensile deformation on micromagnetic parameters in high-strength, low-alloy steel

    Energy Technology Data Exchange (ETDEWEB)

    Vaidyanathan, S.; Moorthy, V.; Kalyanasundaram, P.; Jayakumar, T.; Raj, B. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Metallurgy and Materials Group

    1999-08-01

    The influence of tensile deformation on the magnetic Barkhausen emissions (MBE) and hysteresis loop has been studied in a high-strength, low-alloy steel (HSLA) and its weldment. The magnetic measurements were made both in loaded and unloaded conditions for different stress levels. The root-mean-square (RMS) voltage of the MBE has been used for analysis. This study shows that the preyield and postyield deformation can be identified from the change in the MBE profile. The initial elastic deformation showed a linear increase in the MBE level in the loaded condition, and the MBE level remained constant in the unloaded condition. The microplastic yielding, well below the macroyield stress, significantly reduces the MBE, indicating the operation of grain-boundary dislocation sources below the macroyield stress. This is indicated by the slow increase in the MBE level in the loaded condition and the decrease in the MBE level in the unloaded condition. The macroyielding resulted in a significant increase in the MBE level in the loaded condition and, more clearly, in the unloaded condition. The increase in the MBE level during macroyielding has been attributed to the grain rotation phenomenon, in order to maintain the boundary integrity between adjacent grains, which would preferentially align the magnetic domains along the stress direction. This study shows that MBE during tensile deformation can be classified into four stages: (1) perfectly elastic, (2) microplastic yielding, (3) macroyielding, and (4) progressive plastic deformation. A multimagnetic parameter approach, combining the hysteresis loop and MBE, has been suggested to evaluate the residual stresses.

  13. The american high school graduation rate : trends and levels

    OpenAIRE

    Heckman, James J.; LaFontaine, Paul A.

    2008-01-01

    This paper uses multiple data sources and a unified methodology to estimate the trends and levels of the U.S. high school graduation rate. Correcting for important biases that plague previous calculations, we establish that (a) the true high school graduation rate is substantially lower than the official rate issued by the National Center for Educational Statistics; (b) it has been declining over the past 40 years; (c) majority/minority graduation rate differentials are substantial and have n...

  14. a Method for the Extraction of Long-Term Deformation Characteristics of Long-Span High-Speed Railway Bridges Using High-Resolution SAR Images

    Science.gov (United States)

    Jia, H. G.; Liu, L. Y.

    2016-06-01

    Natural causes and high-speed train load will result in the structural deformation of long-span bridges, which greatly influence the safety operation of high-speed railway. Hence it is necessary to conduct the deformation monitoring and regular status assessment for long-span bridges. However for some traditional surveying technique, e.g. control-point-based surveying techniques, a lot of human and material resources are needed to perform the long-term monitoring for the whole bridge. In this study we detected the long-term bridge deformation time-series by persistent scatterer interferometric synthetic aperture radar (PSInSAR) technique using the high-resolution SAR images and external digital elevation model. A test area in Nanjing city in China is chosen and TerraSAR-X images and Tandem-X for this area have been used. There is the Dashengguan bridge in high speed railway in this area as study object to evaluate this method. Experiment results indicate that the proposed method can effectively extract the long-term deformation of long-span high-speed railway bridge with higher accuracy.

  15. A METHOD FOR THE EXTRACTION OF LONG-TERM DEFORMATION CHARACTERISTICS OF LONG-SPAN HIGH-SPEED RAILWAY BRIDGES USING HIGH-RESOLUTION SAR IMAGES

    Directory of Open Access Journals (Sweden)

    H. G. Jia

    2016-06-01

    Full Text Available Natural causes and high-speed train load will result in the structural deformation of long-span bridges, which greatly influence the safety operation of high-speed railway. Hence it is necessary to conduct the deformation monitoring and regular status assessment for long-span bridges. However for some traditional surveying technique, e.g. control-point-based surveying techniques, a lot of human and material resources are needed to perform the long-term monitoring for the whole bridge. In this study we detected the long-term bridge deformation time-series by persistent scatterer interferometric synthetic aperture radar (PSInSAR technique using the high-resolution SAR images and external digital elevation model. A test area in Nanjing city in China is chosen and TerraSAR-X images and Tandem-X for this area have been used. There is the Dashengguan bridge in high speed railway in this area as study object to evaluate this method. Experiment results indicate that the proposed method can effectively extract the long-term deformation of long-span high-speed railway bridge with higher accuracy.

  16. Temporal dynamics of high repetition rate pulsed single longitudinal ...

    Indian Academy of Sciences (India)

    ing (GIG) cavity, single-mode dye laser pumped by high repetition rate ... in a high loss cavity, a detailed theoretical study and optimization of cavity ..... rate for high conversion efficiency and longer pulse width of the single-mode dye laser.

  17. Quantum data locking for high-rate private communication

    OpenAIRE

    Lupo, Cosmo; Lloyd, Seth

    2015-01-01

    We show that, if the accessible information is used as a security quantifier, quantum channels with a certain symmetry can convey private messages at a tremendously high rate, as high as less than one bit below the rate of non-private classical communication. This result is obtained by exploiting the quantum data locking effect. The price to pay to achieve such a high private communication rate is that accessible information security is in general not composable. However, composable security ...

  18. High-Rate Strong-Signal Quantum Cryptography

    Science.gov (United States)

    Yuen, Horace P.

    1996-01-01

    Several quantum cryptosystems utilizing different kinds of nonclassical lights, which can accommodate high intensity fields and high data rate, are described. However, they are all sensitive to loss and both the high rate and the strong-signal character rapidly disappear. A squeezed light homodyne detection scheme is proposed which, with present-day technology, leads to more than two orders of magnitude data rate improvement over other current experimental systems for moderate loss.

  19. Development of a deformation and failure model for Zircaloy at high temperatures for light water reactor loss-of-coolant-accident investigations

    International Nuclear Information System (INIS)

    Raff, S.

    1982-11-01

    To describe Zircaloy-4 deformation and failure behaviour at high temperatures (600 to 1400 0 C), the phenomenological model NORA was developed and verified against numerous experimental results. The model can be applied to the calculation of fuel rod cladding deformation during small and large break loss-of-coolant-accidents. (orig./RW) [de

  20. Mechanisms of plastic deformation in highly cross-linked UHMWPE for total hip components--the molecular physics viewpoint.

    Science.gov (United States)

    Takahashi, Yasuhito; Shishido, Takaaki; Yamamoto, Kengo; Masaoka, Toshinori; Kubo, Kosuke; Tateiwa, Toshiyuki; Pezzotti, Giuseppe

    2015-02-01

    Plastic deformation is an unavoidable event in biomedical polymeric implants for load-bearing application during long-term in-vivo service life, which involves a mass transfer process, irreversible chain motion, and molecular reorganization. Deformation-induced microstructural alterations greatly affect mechanical properties and durability of implant devices. The present research focused on evaluating, from a molecular physics viewpoint, the impact of externally applied strain (or stress) in ultra-high molecular weight polyethylene (UHMWPE) prostheses, subjected to radiation cross-linking and subsequent remelting for application in total hip arthroplasty (THA). Two different types of commercial acetabular liners, which belong to the first-generation highly cross-linked UHMWPE (HXLPE), were investigated by means of confocal/polarized Raman microprobe spectroscopy. The amount of crystalline region and the spatial distribution of molecular chain orientation were quantitatively analyzed according to a combined theory including Raman selection rules for the polyethylene orthorhombic structure and the orientation distribution function (ODF) statistical approach. The structurally important finding was that pronounced recrystallization and molecular reorientation increasingly appeared in the near-surface regions of HXLPE liners with increasing the amount of plastic (compressive) deformation stored in the microstructure. Such molecular rearrangements, occurred in response to external strains, locally increase surface cross-shear (CS) stresses, which in turn trigger microscopic wear processes in HXLPE acetabular liners. Thus, on the basis of the results obtained at the molecular scale, we emphasize here the importance of minimizing the development of irrecoverable deformation strain in order to retain the pristine and intrinsically high wear performance of HXLPE components. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Crustal deformation rates in Assam Valley, Shillong Plateau, Eastern Himalaya, and Indo-Burmese region from 11 years (2002-2013) of GPS measurements

    Science.gov (United States)

    Barman, Prakash; Jade, Sridevi; Shrungeshwara, T. S.; Kumar, Ashok; Bhattacharyya, Sanjeev; Ray, Jagat Dwipendra; Jagannathan, Saigeetha; Jamir, Wangshi Menla

    2017-09-01

    The present study reports the contemporary deformation of the tectonically complex northeast India using 11 years (2002-2013) of GPS observations. The central Shillong Plateau and few sites north of Plateau located in Assam Valley behave like a rigid block with 7 mm/year India-fixed southward velocity. The Euler pole of rotation of this central Shillong Plateau-Assam Valley (SH-AS) block is estimated to be at -25.1° ± 0.2°N, -97.8° ± 1.8°E with an angular velocity of 0.533° ± 0.10° Myr-1 relative to India-fixed reference frame. Kopili fault located between Shillong Plateau and Mikir massif records a dextral slip of 4.7 ± 1.3 mm/year with a locking depth of 10.2 ± 1.4 km indicating the fragmentation of Assam Valley across the fault. Presently, western edge of Mikir massif appears to be locked to Assam block indicating strain accumulation in this region. First-order elastic dislocation modelling of the GPS velocities estimates a slip rate of 16 mm/year along the Main Himalayan Thrust in Eastern Himalaya which is locked over a width of 130 km from the surface to a depth of 17 km with underthrusting Indian plate. Around 9 mm/year arc-normal convergence is accommodated in Lesser Himalaya just south of Main Central Thrust indicating high strain accumulation. Out of 36 mm/year (SSE) India-Sunda plate motion, about 16 mm/year motion is accommodated in Indo-Burmese Fold and Thrust Belt, both as normal convergence ( 6 mm/year) and active slip ( 7-11 mm/year) in this region.

  2. Thermal behavior of Ni (99.967% and 99.5% purity) deformed to an ultra-high strain by high pressure torsion

    DEFF Research Database (Denmark)

    Zhang, H.W.; Huang, Xiaoxu; Pippan, R.

    2010-01-01

    Polycrystalline Ni of two purities (99.967% (4N) and 99.5% (2N)) was deformed to an ultra-high strain of εvM = 100 (εvM, von Mises strain) by high pressure torsion at room temperature. The 4N and 2N samples at this strain are nanostructured with an average boundary spacing of 100 nm, a high density...

  3. Retention and Deformation of Cobalt-Chromium and High-Impact Polyamide Clasps

    Directory of Open Access Journals (Sweden)

    Övül Kümbüloğlu

    2018-04-01

    Full Text Available Objective: The use of metal clasps especially in anterior region may cause aesthetic problems. Polyamide resin has been suggested as an alternative aesthetic denture clasp material. This study compared the retentive force and deformation of cobalt-chromium and polyamide clasps after 36 months of simulated clinical use. Materials and Methods: The retentive force for clasp removal was measured in distilled water using a custom-made apparatus with intervals corresponding to 0, 6, 12, 18, 24, 30 and 36 months of simulated clinical use. The distance (mm between the retentive and reciprocal clasp tips was measured using a microscope before and after the insertion-removal procedures. Results: Significant difference was observed in distance between clasp tips for metal clasps between baseline and 36 months for molars and premolars (p0.05. Conclusion: Polyamide clasps could be alternative to metal clasps particularly on premolars with reliable retention and deformation.

  4. Role of transitional levels in 237Np (γ,f): Perspectives for studying highly deformed systems

    International Nuclear Information System (INIS)

    Arruda-Neto, J. D. T.; Mesa, J.; Garcia, F.; Rodriguez, O.; Geraldo, L. P.; Garcia, C.; Guzman, F.; Rodrigues, T. E.; Shtejer, K.; Semmler, R.

    2006-01-01

    The transition levels at the top of the two 237 Np fission barriers were obtained for the first time by means of the so-called semimicroscopic combined method, which we have developed and implemented. To overcome the difficulties in dealing with large nuclear deformations, we used our developed BARRIER code, which calculates single-particle spectra in a deformed Woods-Saxon potential using a coordinate system based on Cassini ovaloids as nuclear shape parametrization. The results enabled us to describe the experimentally observed near-barrier photofission cross-section structures for 237 Np, as well as a subbarrier shelf, the latter being consistently interpreted in terms of the accumulation of levels at the top of the inner and outer double fission barrier of 237 Np

  5. High-rate tensile behavior of steel fiber-reinforced concrete for nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Jin; Park, Gi-Joon [Department of Civil and Environmental Engineering, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of); Kim, Dong Joo, E-mail: djkim75@sejong.ac.kr [Department of Civil and Environmental Engineering, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of); Moon, Jae Heum; Lee, Jang Hwa [Korea Institute of Construction Technology, 2311 Daewha-Dong, Ilsan-Gu, Goyang-Si, Gyeonggi-Do 411-712 (Korea, Republic of)

    2014-01-15

    Highlights: • The final goal is to develop a fiber reinforced concrete for containment buildings. • High rate tensile behavior of FRC was investigated. • Strain energy frame impact machine was used for tensile impact tests. • Different rate sensitivity of FRC was found according to the type fiber. • Adding more fibers by increasing S/a is positive for higher impact resistance of FRC. -- Abstract: The direct tensile behavior of fiber-reinforced concrete (FRC) at high strain rates were investigated for their potential to enhance the resistance of the containment building of nuclear power plants (NPPs) against aircraft impact. Two types of deformed steel, hooked (H) and twisted (T) fibers were employed. To improve the tensile resistance of FRCs even at higher rates by adding more fibers, the mixture of concrete was modified by either increasing the sand-to-coarse aggregate ratio or decreasing the maximum size of coarse aggregate. All FRC specimens produced two to six times greater tensile strength and one to five times higher toughness at high strain rates (4–53 s{sup −1}) than those at a static rate (0.000167 s{sup −1}). T-fiber generally produced higher tensile strength and toughness than H-fiber at both static and high rates. Although both fibers showed favorable rate sensitivity, T-fiber produced much greater enhancement, at higher strain rates, in tensile strength and slightly lower enhancement in toughness than H-fiber. As the maximum size of coarse aggregate decreased from 19 to 5 mm, the tensile strength and toughness of FRCs with T-fibers noticeably increased at both static and high strain rates.

  6. Microstructure evolution and its influence on deformation mechanisms during high temperature creep of a nickel base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Safari, Javad [Materials Science and Engineering Department, Shahid Chamran University, Ahwaz (Iran, Islamic Republic of)], E-mail: javadsafari@yahoo.com; Nategh, Saeed [Materials Science and Engineering Department, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of)], E-mail: nategh@sharif.edu

    2009-01-15

    The interaction of dislocation with strengthening particles, including primary and secondary {gamma}', during different stages of creep of Rene-80 was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). During creep of the alloy at 871 deg. C under stress of 290 MPa, the dislocation network was formed during the early stages of creep, and the dislocation glide and climb process were the predominant mechanism of deformation. The density of dislocation network became more populated during the later stages of the creep, and at the latest stage of the creep, primary particles shearing were observed alongside with the dislocation glide and climb. Shearing of {gamma}' particles in creep at 871 deg. C under stress of 475 MPa was commenced at the earlier creep times and governed the creep deformation mechanism. In two levels of examined stresses, as far as the creep deformation was controlled by glide and climb, creep curves were found to be at the second stage of creep and commence of the tertiary creep, with increasing creep rate, were found to be in coincidence with the particles shearing. Microstructure evolution, with regard to {gamma}' strengthening particles, led to particles growth and promoted activation of other deformation mechanisms such as dislocation bypassing by orowan loop formation. Dislocation-secondary {gamma}' particles interaction was detected to be the glide and climb at the early stages of creep, while at the later stages, the dislocation bypassed the secondary precipitation by means of orowan loops formation, as the secondary particle were grown and the mean inter-particle distance increased.

  7. High prevalence of morphometric vertebral deformities in patients with inflammatory bowel disease

    OpenAIRE

    Heijckmann, AC; Huijberts, MSP; Schoon, EJ; GEUSENS, Piet; de Vries, J.; Menheere, Paul P. C. A.; van der Veer, E.; Wolffenbuttel, BHR; Stockbrugger, RW; Dumitrescu, B; Kruseman, ACN

    2008-01-01

    Background Earlier studies have documented that the prevalence of decreased bone mineral density (BMD) is elevated in patients with inflammatory bowel disease. The objective of this study was to investigate the prevalence of vertebral deformities in inflammatory bowel disease patients and their relation with BMD and bone turnover. Methods One hundred and nine patients with Crohn's disease (CD) and 72 with ulcerative colitis (UC) (age 44.5 +/- 14.2 years) were studied. BMD of the hip (by dual ...

  8. How Deformation Behavior Controls Product Performance After Twin Screw Granulation With High Drug Loads and Crospovidone as Disintegrant.

    Science.gov (United States)

    Meier, Robin; Moll, Klaus-Peter; Krumme, Markus; Kleinebudde, Peter

    2017-01-01

    This study addresses the quantitative influence of 12 different materials (active pharmaceutical ingredients and excipients as surrogate active pharmaceutical ingredients) on the critical quality attributes of twin screw granulated products and subsequently produced tablets. Prestudies demonstrated the significant influence of the chosen model materials (in combination with crospovidone) on the disintegration behavior of the resulting tablets, despite comparable tablet porosities. This study elucidates possible reasons for the varying disintegration behavior by investigating raw material, granule, and tablet properties. An answer could be found in the mechanical properties of the raw materials and the produced granules. Through compressibility studies, the materials could be classified into materials with high compressibility, which deform rather plastically under compression stress, and low compressibility, which display breakages under compression stress. In general, and apart from (pseudo)-polymorphic transformations, brittle materials featured excellent disintegration performance, even at low resulting tablet porosities plastically deformable materials mostly did not reveal any disintegration. These findings must be considered in the development of simplified formulations with high drug loads, in which the active pharmaceutical ingredient predominantly defines the deformation behavior of the granule. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  9. Simultaneous correction of large low-order and high-order aberrations with a new deformable mirror technology

    Science.gov (United States)

    Rooms, F.; Camet, S.; Curis, J. F.

    2010-02-01

    A new technology of deformable mirror will be presented. Based on magnetic actuators, these deformable mirrors feature record strokes (more than +/- 45μm of astigmatism and focus correction) with an optimized temporal behavior. Furthermore, the development has been made in order to have a large density of actuators within a small clear aperture (typically 52 actuators within a diameter of 9.0mm). We will present the key benefits of this technology for vision science: simultaneous correction of low and high order aberrations, AO-SLO image without artifacts due to the membrane vibration, optimized control, etc. Using recent papers published by Doble, Thibos and Miller, we show the performances that can be achieved by various configurations using statistical approach. The typical distribution of wavefront aberrations (both the low order aberration (LOA) and high order aberration (HOA)) have been computed and the correction applied by the mirror. We compare two configurations of deformable mirrors (52 and 97 actuators) and highlight the influence of the number of actuators on the fitting error, the photon noise error and the effective bandwidth of correction.

  10. High rate flame synthesis of highly crystalline iron oxide nanorods

    International Nuclear Information System (INIS)

    Merchan-Merchan, W; Taylor, A M; Saveliev, A V

    2008-01-01

    Single-step flame synthesis of iron oxide nanorods is performed using iron probes inserted into an opposed-flow methane oxy-flame. The high temperature reacting environment of the flame tends to convert elemental iron into a high density layer of iron oxide nanorods. The diameters of the iron oxide nanorods vary from 10 to 100 nm with a typical length of a few microns. The structural characterization performed shows that nanorods possess a highly ordered crystalline structure with parameters corresponding to cubic magnetite (Fe 3 O 4 ) with the [100] direction oriented along the nanorod axis. Structural variations of straight nanorods such as bends, and T-branched and Y-branched shapes are frequently observed within the nanomaterials formed, opening pathways for synthesis of multidimensional, interconnected networks

  11. Deformation mechanisms induced under high cycle fatigue tests in a metastable austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Roa, J.J., E-mail: joan.josep.roa@upc.edu [CIEFMA-Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, 08028 Barcelona (Spain); CRnE, Campus Diagonal Sud, Edificio C’, Universitat Politècnica de Catalunya, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Fargas, G. [CIEFMA-Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, 08028 Barcelona (Spain); Jiménez-Piqué, E. [CIEFMA-Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, 08028 Barcelona (Spain); CRnE, Campus Diagonal Sud, Edificio C’, Universitat Politècnica de Catalunya, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Mateo, A. [CIEFMA-Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, 08028 Barcelona (Spain)

    2014-03-01

    Advanced techniques were used to study the deformation mechanisms induced by fatigue tests in a metastable austenitic stainless steel AISI 301LN. Observations by Atomic Force Microscopy were carried out to study the evolution of a pre-existing martensite platelet at increasing number of cycles. The sub-superficial deformation mechanisms of the austenitic grains were studied considering the cross-section microstructure obtained by Focused Ion Beam and analysed by Scanning Electron Microscopy and Transmission Electron Microscopy. The results revealed no deformation surrounding the pre-existing martensitic platelet during fatigue tests, only the growth on height was observed. Martensite formation was associated with shear bands on austenite, mainly in the {111} plane, and with the activation of the other intersecting austenite {111}〈110〉 slip system. Furthermore, transmission electron microscopy results showed that the nucleation of ε-martensite follows a two stages phase transformation (γ{sub fcc}→ε{sub hcp}→α'{sub bcc})

  12. Liquid Segregation Phenomenological Behaviors of Ti14 Alloy during Semisolid Deformation

    Directory of Open Access Journals (Sweden)

    Y. N. Chen

    2014-05-01

    Full Text Available The liquid segregation phenomenon and its effect on deformation mechanism of Ti14 alloy in semisolid metal processing were investigated by thermal simulation test. Microstructure of depth profile was determined by cross-section quantitative metallography, and liquid segregation phenomenon was described by Darcy's law. The results show that segregation phenomenon was affected by solid fraction, strain rate, and deformation rate. More liquid segregated from center to edge portion with high strain rate and/or deformation ratio as well as low solid fraction, which caused different distribution of dominating deformation mechanism. The relationship between liquid segregation and main deformation mechanism was also discussed by phenomenological model.

  13. Constant Fault Slip-Rates Over Hundreds of Millenia Constrained By Deformed Quaternary Palaeoshorelines: the Vibo and Capo D'Orlando Faults, Southern Italy.

    Science.gov (United States)

    Meschis, M.; Roberts, G.; Robertson, J.; Houghton, S.; Briant, R. M.

    2017-12-01

    Whether slip-rates on active faults accumulated over multiple seismic events is constant or varying over tens to hundreds of millenia timescales is an open question that can be addressed through study of deformed Quaternary palaeoshorelines. It is important to know the answer so that one can judge whether shorter timescale measurements (e.g. Holocene palaeoseismology or decadal geodesy) are suitable for determining earthquake recurrence intervals for Probabilistic Seismic Hazard Assessment or more suitable for studying temporal earthquake clustering. We present results from the Vibo Fault and the Capo D'Orlando Fault, that lie within the deforming Calabrian Arc, which has experienced damaging seismic events such as the 1908 Messina Strait earthquake ( Mw 7) and the 1905 Capo Vaticano earthquake ( Mw 7). These normal faults deform uplifted Late Quaternary palaeoshorelines, which outcrop mainly within their hangingwalls, but also partially in their footwalls, showing that a regional subduction and mantle-related uplift outpaces local fault-related subsidence. Through (1) field and DEM-based mapping of palaeoshorelines, both up flights of successively higher, older inner edges, and along the strike of the faults, and (2) utilisation of synchronous correlation of non-uniformly-spaced inner edge elevations with non-uniformly spaced sea-level highstand ages, we show that slip-rates decrease towards fault tips and that slip-rates have remained constant since 340 ka (given the time resolution we obtain). The slip-rates for the Capo D'Orlando Fault and Vibo Fault are 0.61mm/yr and 1mm/yr respectively. We show that the along-strike gradients in slip-rate towards fault tips differ for the two faults hinting at fault interaction and also discuss this in terms of other regions of extension like the Gulf of Corinth, Greece, where slip-rate has been shown to change through time through the Quaternary. We make the point that slip-rates may change through time as fault systems grow

  14. HIGH-RATE DISINFECTION TECHNIQUES FOR COMBIND SEWER OVERFLOW

    Science.gov (United States)

    This paper presents high-rate disinfection technologies for combined sewer overflow (CSO). The high-rate disinfection technologies of interest are: chlorination/dechlorination, ultraviolet light irradiation (UV), chlorine dioxide (ClO2 ), ozone (O3), peracetic acid (CH3COOOH )...

  15. High Graduate Unemployment Rate and Taiwanese Undergraduate Education

    Science.gov (United States)

    Wu, Chih-Chun

    2011-01-01

    An expansion in higher education in combination with the recent global economic recession has resulted in a high college graduate unemployment rate in Taiwan. This study investigates how the high unemployment rate and financial constraints caused by economic cutbacks have shaped undergraduates' class choices, job needs, and future income…

  16. Circuit and interconnect design for high bit-rate applications

    NARCIS (Netherlands)

    Veenstra, H.

    2006-01-01

    This thesis presents circuit and interconnect design techniques and design flows that address the most difficult and ill-defined aspects of the design of ICs for high bit-rate applications. Bottlenecks in interconnect design, circuit design and on-chip signal distribution for high bit-rate

  17. Strain rate dependent tensile behavior of advanced high strength steels: Experiment and constitutive modeling

    International Nuclear Information System (INIS)

    Kim, Ji-Hoon; Kim, Daeyong; Han, Heung Nam; Barlat, F.; Lee, Myoung-Gyu

    2013-01-01

    High strain rate tensile tests were conducted for three advanced high strength steels: DP780, DP980 and TRIP780. A high strain rate tensile test machine was used for applying the strain rate ranging from 0.1/s to 500/s. Details of the measured stress–strain responses were comparatively analyzed for the DP780 and TRIP780 steels which show similar microstructural feature and ultimate tensile strength, but different strengthening mechanisms. The experimental observations included: usual strain rate dependent plastic flow stress behavior in terms of the yield stress (YS), the ultimate tensile strength (UTS), the uniform elongation (UE) and the total elongation (TE) which were observed for the three materials. But, higher strain hardening rate at early plastic strain under quasi-static condition than that of some increased strain rates was featured for TRIP780 steel, which might result from more active transformation during deformation with lower velocity. The uniform elongation that explains the onset of instability and the total elongation were larger in case of TRIP steel than the DP steel for the whole strain rate range, but interestingly the fracture strain measured by the reduction of area (RA) method showed that the TRIP steel has lower values than DP steel. The fractographs using scanning electron microscopy (SEM) at the fractured surfaces were analyzed to relate measured fracture strain and the microstructural difference of the two materials during the process of fracture under various strain rates. Finally, constitutive modeling for the plastic flow stresses under various strain rates was provided in this study. The proposed constitutive law could represent both Hollomon-like and Voce-like hardening laws and the ratio between the two hardening types was efficiently controlled as a function of strain rate. The new strength model was validated successfully under various strain rates for several grades of steels such as mild steels, DP780, TRIP780, DP980 steels.

  18. Introduction to State Estimation of High-Rate System Dynamics.

    Science.gov (United States)

    Hong, Jonathan; Laflamme, Simon; Dodson, Jacob; Joyce, Bryan

    2018-01-13

    Engineering systems experiencing high-rate dynamic events, including airbags, debris detection, and active blast protection systems, could benefit from real-time observability for enhanced performance. However, the task of high-rate state estimation is challenging, in particular for real-time applications where the rate of the observer's convergence needs to be in the microsecond range. This paper identifies the challenges of state estimation of high-rate systems and discusses the fundamental characteristics of high-rate systems. A survey of applications and methods for estimators that have the potential to produce accurate estimations for a complex system experiencing highly dynamic events is presented. It is argued that adaptive observers are important to this research. In particular, adaptive data-driven observers are advantageous due to their adaptability and lack of dependence on the system model.

  19. High dose rate brachytherapy in treatment of high grade astrocytomas

    International Nuclear Information System (INIS)

    Garcia-Alejo, R.; Delgado, J.M.; Cerro, E. del; Torres, J.J.; Martinez, R.

    1996-01-01

    From May 1994 to June 1995, 18 patients with high grade astrocytomas were entered prospectively on a selective protocol combining surgery, external beam radiotherapy, stereotactic interstitial implantation with HDR Iridium 192 and chemotherapy. Only those patients with tumor size 100cc or less average dimension, high grade astrocytoma, Karnofsky 70 or greater, unilateral, circumscribed, unifocal, tumor stable or responding to external radiation and supratentorial were included in the study. Ages ranged from 16 to 69 years. There were 13 males and 5 females. Surgery consisted of biopsy only in 3 patients, subtotal resection in 11, and gross total resection in 4 patients. Focal external beam radiation portals included the contrast enhancing mass on CT scan plus a 3 cm margin. The protocol called for minimum tumor dose of 60 Gy to be given in 2 Gy daily fractions. An interstitial brachytherapy boost was to be performed two weeks after the conclusion of external beam radiation. The dose was 30 Gy in 4 fractions. The authors analyze on basis on their personal experience, the possibilities and the limits offered by this therapeutic procedure in neuro-oncology. Using stereotactic techniques, interstitial brachytherapy of brain tumors was technically possible with negligible acute morbidity and mortality, and appeared to be effective and may provide for an increase in tumor control in selected cases

  20. Microstructure and deformation behavior of Ti-6Al-4V alloy by high-power laser solid forming

    International Nuclear Information System (INIS)

    Ren, Y.M.; Lin, X.; Fu, X.; Tan, H.; Chen, J.; Huang, W.D.

    2017-01-01

    This work investigated the microstructure and tensile deformation behavior of Ti-6Al-4V alloy fabricated using a high-power laser solid forming (LSF) additive manufacturing. The results show that the post-fabricated heat-treated microstructure consists of coarse columnar prior-β grains (630–1000 μm wide) and α-laths (5–9 μm) under different scanning velocities (900 and 1500 mm/min), which caused large elongation (∼18%) superior to the conventional laser additive manufacturing Ti-6Al-4V alloy. The deformation behavior of the LSF Ti-6Al-4V alloy was investigated using in situ tensile test scanning electron microscopy. The results show that shear-bands appeared along the α/β interface and slip-bands occurred within the α-laths, which lead to cracks decaying in a zigzag-pattern in the LSF Ti-6Al-4V alloy with basket-weave microstructure. These results demonstrate that the small columnar prior-β grains and fine basket-weave microstructure exhibiting more α/β interfaces and α-laths can disperse the load and resist the deformation in the LSF Ti-6Al-4V components. In addition, a modified microstructure selection map of the LSF Ti-6Al-4V alloy was established, which can reasonably predict the microstructure evolution and relative grain size in the LSF process.

  1. Report on Microgravity Experiments of Dynamic Surface Deformation Effects on Marangoni Instability in High-Prandtl-Number Liquid Bridges

    Science.gov (United States)

    Yano, Taishi; Nishino, Koichi; Matsumoto, Satoshi; Ueno, Ichiro; Komiya, Atsuki; Kamotani, Yasuhiro; Imaishi, Nobuyuki

    2018-04-01

    This paper reports an overview and some important results of microgravity experiments called Dynamic Surf, which have been conducted on board the International Space Station from 2013 to 2016. The present project mainly focuses on the relations between the Marangoni instability in a high-Prandtl-number (Pr= 67 and 112) liquid bridge and the dynamic free surface deformation (DSD) as well as the interfacial heat transfer. The dynamic free surface deformations of large-scale liquid bridges (say, for diameters greater than 10 mm) are measured with good accuracy by an optical imaging technique. It is found that there are two causes of the dynamic free surface deformation in the present study: the first is the time-dependent flow behavior inside the liquid bridge due to the Marangoni instability, and the second is the external disturbance due to the residual acceleration of gravity, i.e., g-jitter. The axial distributions of DSD along the free surface are measured for several conditions. The critical parameters for the onset of oscillatory Marangoni convection are also measured for various aspect ratios (i.e., relative height to the diameter) of the liquid bridge and various thermal boundary conditions. The characteristics of DSD and the onset conditions of instability are discussed in this paper.

  2. Dynamic Response of AA2519 Aluminum Alloy under High Strain Rates

    Science.gov (United States)

    Olasumboye, Adewale Taiwo

    Like others in the AA2000 series, AA2519 is a heat-treatable Al-Cu alloy. Its excellent ballistic properties and stress corrosion cracking resistance, combined with other properties, qualify it as a prime candidate for armored vehicle and aircraft applications. However, available data on its high strain-rate response remains limited. In this study, AA2519 aluminum alloy was investigated in three different temper conditions: T4, T6, and T8, to determine the effects of heat treatment on the microstructure and dynamic deformation behavior of the material at high strain rates ranging within 1000 ≤ epsilon ≤ 4000 s-1. Split Hopkinson pressure bar integrated with digital image correlation system was used for mechanical response characterization. Optical microscopy and scanning electron microscopy were used to assess the microstructure of the material after following standard metallographic specimen preparation techniques. Results showed heterogeneous deformation in the three temper conditions. It was observed that dynamic behavior in each condition was dependent on strength properties due to the aging type controlling the strengthening precipitates produced and initial microstructure. At 1500 s -1, AA2519-T6 exhibited peak dynamic yield strength and flow stress of 509 and 667 MPa respectively, which are comparable with what were observed in T8 condition at higher rate of 3500 s-1 but AA2519-T4 showed the least strength and flow stress properties. Early stress collapse, dynamic strain aging, and higher susceptibility to shear band formation and fracture were observed in the T6 condition within the selected range of high strain rates. The alloy's general mode of damage evolution was by dispersoid particle nucleation, shearing and cracking.

  3. Plastic deformation of FeSi at high pressures: implications for planetary cores

    Science.gov (United States)

    Kupenko, Ilya; Merkel, Sébastien; Achorner, Melissa; Plückthun, Christian; Liermann, Hanns-Peter; Sanchez-Valle, Carmen

    2017-04-01

    The cores of terrestrial planets is mostly comprised of a Fe-Ni alloy, but it should additionally contain some light element(s) in order to explain the observed core density. Silicon has long been considered as a likely candidate because of geochemical and cosmochemical arguments: the Mg/Si and Fe/Si ratios of the Earth does not match those of the chondrites. Since silicon preferentially partition into iron-nickel metal, having 'missing' silicon in the core would solve this problem. Moreover, the evidence of present (e.g. Mercury) or ancient (e.g. Mars) magnetic fields on the terrestrial planets is a good indicator of (at least partially) liquid cores. The estimated temperature profiles of these planets, however, lay below iron melting curve. The addition of light elements in their metal cores could allow reducing their core-alloy melting temperature and, hence, the generation of a magnetic field. Although the effect of light elements on the stability and elasticity of Fe-Ni alloys has been widely investigated, their effect on the plasticity of core materials remains largely unknown. Yet, this information is crucial for understanding how planetary cores deform. Here we investigate the plastic deformation of ɛ-FeSi up to 50 GPa at room temperature employing a technique of radial x-ray diffraction in diamond anvil cells. Stoichiometric FeSi endmember is a good first-order approximation of the Fe-FeSi system and a good starting material to develop new experimental perspectives. In this work, we focused on the low-pressure polymorph of FeSi that would be the stable phase in the cores of small terrestrial planets. We will present the analysis of measured data and discuss their potential application to constrain plastic deformation in planetary cores.

  4. The effect of prior deformation on stress corrosion cracking growth rates of Alloy 600 materials in a simulated pressurized water reactor primary water

    International Nuclear Information System (INIS)

    Yamazaki, Seiya; Lu Zhanpeng; Ito, Yuzuru; Takeda, Yoichi; Shoji, Tetsuo

    2008-01-01

    The effect of prior deformation on stress corrosion cracking (SCC) growth rates of Alloy 600 materials in a simulated pressurized water reactor primary water environment is studied. The prior deformation was introduced by welding procedure or by cold working. Values of Vickers hardness in the Alloy 600 weld heat-affected zone (HAZ) and in the cold worked (CW) Alloy 600 materials are higher than that in the base metal. The significantly hardened area in the HAZ is within a distance of about 2-3 mm away from the fusion line. Electron backscatter diffraction (EPSD) results show significant amounts of plastic strain in the Alloy 600 HAZ and in the cold worked Alloy 600 materials. Stress corrosion cracking growth rate tests were performed in a simulated pressurized water reactor primary water environment. Extensive intergranular stress corrosion cracking (IGSCC) was found in the Alloy 600 HAZ, 8% and 20% CW Alloy 600 specimens. The crack growth rate in the Alloy 600 HAZ is close to that in the 8% CW base metal, which is significantly lower than that in the 20% CW base metal, but much higher than that in the as-received base metal. Mixed intergranular and transgranular SCC was found in the 40% CW Alloy 600 specimen. The crack growth rate in the 40% CW Alloy 600 was lower than that in the 20% CW Alloy 600. The effect of hardening on crack growth rate can be related to the crack tip mechanics, the sub-microstructure (or subdivision of grain) after cross-rolling, and their interactions with the oxidation kinetics

  5. Biaxial creep deformation of Zircaloy-4 in the high alpha phase temperature range

    International Nuclear Information System (INIS)

    Donaldson, A.T.; Horwood, R.A.; Healey, T.

    1983-01-01

    The ballooning response of Zircaloy-4 fuel tubes during a postulated loss-of-coolant accident may be calculated from a knowledge of the thermal environment of the rods and the creep deformation characteristics of the cladding. In support of such calculations biaxial creep studies have been performed on fuel tubes supplied by Westinghouse, Wolverine and Sandvik of temperatures in the alpha phase range. This paper presents the results of an investigation of their respective creep behaviour which has resulted in the formulation of equations for use in LOCA fuel ballooning codes. (author)

  6. Effects of Temperature and Strain Rate on Tensile Deformation Behavior of 9Cr-0.5Mo-1.8W-VNb Ferritic Heat-Resistant Steel

    Science.gov (United States)

    Guo, Xiaofeng; Weng, Xiaoxiang; Jiang, Yong; Gong, Jianming

    2017-09-01

    A series of uniaxial tensile tests were carried out at different strain rate and different temperatures to investigate the effects of temperature and strain rate on tensile deformation behavior of P92 steel. In the temperature range of 30-700 °C, the variations of flow stress, average work-hardening rate, tensile strength and ductility with temperature all show three temperature regimes. At intermediate temperature, the material exhibited the serrated flow behavior, the peak in flow stress, the maximum in average work-hardening rate, and the abnormal variations in tensile strength and ductility indicates the occurrence of DSA, whereas the sharp decrease in flow stress, average work-hardening rate as well as strength values, and the remarkable increase in ductility values with increasing temperature from 450 to 700 °C imply that dynamic recovery plays a dominant role in this regime. Additionally, for the temperature ranging from 550 to 650 °C, a significant decrease in flow stress values is observed with decreasing in strain rate. This phenomenon suggests the strain rate has a strong influence on flow stress. Based on the experimental results above, an Arrhenius-type constitutive equation is proposed to predict the flow stress.

  7. Remote Sensing of Deformation of a High Concrete-Faced Rockfill Dam Using InSAR: A Study of the Shuibuya Dam, China

    Directory of Open Access Journals (Sweden)

    Wei Zhou

    2016-03-01

    Full Text Available Settlement is one of the most important deformation characteristics of high concrete faced rockfill dams (CFRDs, >100 m. High CFRDs safety would pose a great threat to the security of people’s lives and property downstream if this kind of deformation were not to be measured correctly, as traditional monitoring approaches have limitations in terms of durability, coverage, and efficiency. It has become urgent to develop new monitoring techniques to complement or replace traditional monitoring approaches for monitoring the safety and operation status of high CFRDs. This study examines the Shuibuya Dam (up to 233.5 m in height in China, which is currently the highest CFRD in the world. We used space-borne Interferometric Synthetic Aperture Radar (InSAR time series to monitor the surface deformation of the Shuibuya Dam. Twenty-one ALOS PALSAR images that span the period from 28 February 2007 to 11 March 2011 were used to map the spatial and temporal deformation of the dam. A high correlation of 0.93 between the InSAR and the in-situ monitoring results confirmed the reliability of the InSAR method; the deformation history derived from InSAR is also consistent with the in-situ settlement monitoring system. In addition, the InSAR results allow continuous investigation of dam deformation over a wide area that includes the entire dam surface as well as the surrounding area, offering a clear picture continuously of the dam deformation.

  8. Characterization of microstructure and local deformation in 316NG weld heat-affected zone and stress corrosion cracking in high temperature water

    International Nuclear Information System (INIS)

    Lu Zhanpeng; Shoji, Tetsuo; Meng Fanjiang; Xue He; Qiu Yubing; Takeda, Yoichi; Negishi, Koji

    2011-01-01

    Research highlights: → Away from the fusion line, kernel average misorientation and hardness decrease. → Away from the fusion line, the fraction of Σ3 boundaries increases. → Crack growth in high temperature water correlates to kernel average misorientation and hardness. → SCC along random boundaries as well as extensive intergranular branching near the fusion line. - Abstract: Microstructure and local deformation in 316NG weld heat-affected zones were measured by electron-back scattering diffraction and hardness measurements. With increasing the distance from the fusion line, kernel average misorientation decreases and the fraction of Σ3 boundaries increases. Stress corrosion cracking growth rates in high temperature water were measured at different locations in the heat-affected zones that correspond to different levels of strain-hardening represented by kernel average misorientation and hardness distribution. Intergranular cracking along random boundaries as well as extensive intergranular crack branching is observed in the heat-affected zone near the weld fusion line.

  9. Flexible solid-state symmetric supercapacitors based on MnO2 nanofilms with high rate capability and long cyclability

    Science.gov (United States)

    Wu, Lingxia; Li, Ruizhi; Guo, Junling; Zhou, Cheng; Zhang, Wenpei; Wang, Chong; Huang, Yu; Li, Yuanyuan; Liu, Jinping

    2013-08-01

    Flexible solid-state symmetric supercapacitor was fabricated using MnO2 nanofilms growing directly on carbon cloth as the electrodes and PVA/H3PO4 gel as the electrolyte/separator. The device can be operated at a stable cell-voltage up to 1.4 V, obviously larger than that of conventional solid-state symmetric supercapacitors (≤1 V). It exhibited excellent rate capability with a scan rate as high as 20 V s-1 and a long cyclability (˜60000 cycles) even under severe mechanical deformation. The charge storage mechanism at different scan rates was also quantitatively analyzed.

  10. Flexible solid-state symmetric supercapacitors based on MnO2 nanofilms with high rate capability and long cyclability

    Directory of Open Access Journals (Sweden)

    Lingxia Wu

    2013-08-01

    Full Text Available Flexible solid-state symmetric supercapacitor was fabricated using MnO2 nanofilms growing directly on carbon cloth as the electrodes and PVA/H3PO4 gel as the electrolyte/separator. The device can be operated at a stable cell-voltage up to 1.4 V, obviously larger than that of conventional solid-state symmetric supercapacitors (≤1 V. It exhibited excellent rate capability with a scan rate as high as 20 V s−1 and a long cyclability (∼60000 cycles even under severe mechanical deformation. The charge storage mechanism at different scan rates was also quantitatively analyzed.

  11. Texture, deformation twinning and hardening in a newly developed Mg-Dy-Al-Zn-Zr alloy processed with high pressure torsion

    Czech Academy of Sciences Publication Activity Database

    Kocich, R.; Kunčická, L.; Král, Petr; Lowe, T. C.

    2016-01-01

    Roč. 90, JAN (2016), s. 1092-1099 ISSN 0264-1275 Institutional support: RVO:68081723 Keywords : Magnesium * High pressure torsion * Texture * Deformation twinning * Hardening Subject RIV: JG - Metallurgy Impact factor: 4.364, year: 2016

  12. In-line high-rate evaporation of aluminum for the metallization of silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Mader, Christoph Paul

    2012-07-11

    This work focuses on the in-line high-rate evaporation of aluminum for contacting rear sides of silicon solar cells. The substrate temperature during the deposition process, the wafer bow after deposition, and the electrical properties of evaporated contacts are investigated. Furthermore, this work demonstrates for the first time the formation of aluminum-doped silicon regions by the in-line high-rate evaporation of aluminum without any further temperature treatment. The temperature of silicon wafers during in-line high-rate evaporation of aluminum is investigated in this work. The temperatures are found to depend on the wafer thickness W, the aluminum layer thickness d, and on the wafer emissivity {epsilon}. Two-dimensional finite-element simulations reproduce the measured peak temperatures with an accuracy of 97%. This work also investigates the wafer bow after in-line high-rate evaporation and shows that the elastic theory overestimates the wafer bow of planar Si wafers. The lower bow is explained with plastic deformation in the Al layer. Due to the plastic deformation only the first 79 K in temperature decrease result in a bow formation. Furthermore the electrical properties of evaporated point contacts are examined in this work. Parameterizations for the measured saturation currents of contacted p-type Si wafers and of contacted boron-diffused p{sup +}-type layers are presented. The contact resistivity of the deposited Al layers to silicon for various deposition processes and silicon surface concentrations are presented and the activation energy of the contact formation is determined. The measured saturation current densities and contact resistivities of the evaporated contacts are used in one-dimensional numerical Simulations and the impact on energy conversion efficiency of replacing a screen-printed rear side by an evaporated rear side is presented. For the first time the formation of aluminum-doped p{sup +}-type (Al-p{sup +}) silicon regions by the in

  13. Deformability measurement of red blood cells using a microfluidic channel array and an air cavity in a driving syringe with high throughput and precise detection of subpopulations.

    Science.gov (United States)

    Kang, Yang Jun; Ha, Young-Ran; Lee, Sang-Joon

    2016-01-07

    Red blood cell (RBC) deformability has been considered a potential biomarker for monitoring pathological disorders. High throughput and detection of subpopulations in RBCs are essential in the measurement of RBC deformability. In this paper, we propose a new method to measure RBC deformability by evaluating temporal variations in the average velocity of blood flow and image intensity of successively clogged RBCs in the microfluidic channel array for specific time durations. In addition, to effectively detect differences in subpopulations of RBCs, an air compliance effect is employed by adding an air cavity into a disposable syringe. The syringe was equally filled with a blood sample (V(blood) = 0.3 mL, hematocrit = 50%) and air (V(air) = 0.3 mL). Owing to the air compliance effect, blood flow in the microfluidic device behaved transiently depending on the fluidic resistance in the microfluidic device. Based on the transient behaviors of blood flows, the deformability of RBCs is quantified by evaluating three representative parameters, namely, minimum value of the average velocity of blood flow, clogging index, and delivered blood volume. The proposed method was applied to measure the deformability of blood samples consisting of homogeneous RBCs fixed with four different concentrations of glutaraldehyde solution (0%-0.23%). The proposed method was also employed to evaluate the deformability of blood samples partially mixed with normal RBCs and hardened RBCs. Thereafter, the deformability of RBCs infected by human malaria parasite Plasmodium falciparum was measured. As a result, the three parameters significantly varied, depending on the degree of deformability. In addition, the deformability measurement of blood samples was successfully completed in a short time (∼10 min). Therefore, the proposed method has significant potential in deformability measurement of blood samples containing hematological diseases with high throughput and precise detection of

  14. Quantum data locking for high-rate private communication

    International Nuclear Information System (INIS)

    Lupo, Cosmo; Lloyd, Seth

    2015-01-01

    We show that, if the accessible information is used as a security quantifier, quantum channels with a certain symmetry can convey private messages at a tremendously high rate, as high as less than one bit below the rate of non-private classical communication. This result is obtained by exploiting the quantum data locking effect. The price to pay to achieve such a high private communication rate is that accessible information security is in general not composable. However, composable security holds against an eavesdropper who is forced to measure her share of the quantum system within a finite time after she gets it. (paper)

  15. Phase composition and microhardness of rapidly quenched Al-Fe alloys after high pressure torsion deformation

    Energy Technology Data Exchange (ETDEWEB)

    Tcherdyntsev, V.V.; Kaloshkin, S.D.; Gunderov, D.V.; Afonina, E.A.; Brodova, I.G.; Stolyarov, V.V.; Baldokhin, Yu.V.; Shelekhov, E.V.; Tomilin, I.A

    2004-07-15

    Aluminium-based Al-Fe alloys with Fe content of 2, 8, and 10 wt.% were prepared by rapid quenching (RQ) from the melt at a rate of 10{sup 6} K/s. Structure of the alloys was examined by X-ray diffraction (XRD) and Moessbauer spectroscopy. Phase transformations of RQ alloys by high pressure torsion (HPT) were studied. Dependences of phase composition on the intensity of HPT were investigated. Microhardness measurements of HPT alloys show a considerable structural heterogeneity of specimens, the dependence of microhardness on the radius of the pills was found out. Phase composition and microhardness during the heating were investigated. At the initial step of heating (120-150 deg. C), an increase in microhardness was observed, whereas further heating leads to a decrease in the microhardness.

  16. TEM sample preparation by femtosecond laser machining and ion milling for high-rate TEM straining experiments

    Energy Technology Data Exchange (ETDEWEB)

    Voisin, Thomas; Grapes, Michael D. [Dept. of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States); Zhang, Yong [Dept. of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States); Lorenzo, Nicholas; Ligda, Jonathan; Schuster, Brian [US Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, MD 21005 (United States); Weihs, Timothy P. [Dept. of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2017-04-15

    To model mechanical properties of metals at high strain rates, it is important to visualize and understand their deformation at the nanoscale. Unlike post mortem Transmission Electron Microscopy (TEM), which allows one to analyze defects within samples before or after deformation, in situ TEM is a powerful tool that enables imaging and recording of deformation and the associated defect motion during mechanical loading. Unfortunately, all current in situ TEM mechanical testing techniques are limited to quasi-static strain rates. In this context, we are developing a new test technique that utilizes a rapid straining stage and the Dynamic TEM (DTEM) at the Lawrence Livermore National Laboratory (LLNL). The new straining stage can load samples in tension at strain rates as high as 4×10{sup 3}/s using two piezoelectric actuators operating in bending while the DTEM at LLNL can image in movie mode with a time resolution as short as 70 ns. Given the piezoelectric actuators are limited in force, speed, and displacement, we have developed a method for fabricating TEM samples with small cross-sectional areas to increase the applied stresses and short gage lengths to raise the applied strain rates and to limit the areas of deformation. In this paper, we present our effort to fabricate such samples from bulk materials. The new sample preparation procedure combines femtosecond laser machining and ion milling to obtain 300 µm wide samples with control of both the size and location of the electron transparent area, as well as the gage cross-section and length. - Highlights: • Tensile straining TEM specimens made by femtosecond laser machining and ion milling. • Accurate positioning of the electron transparent area within a controlled gauge region. • Optimization of femtosecond laser and ion milling parameters. • Fast production of numerous samples with a highly repeatable geometry.

  17. Effectiveness of high interest rate policy on exchange rates: A reexamination of the Asian financial crisis

    Directory of Open Access Journals (Sweden)

    Chin Diew Lai

    2006-09-01

    Full Text Available One of the most controversial issues in the aftermath of the Asian financial crisis has been the appropriate response of monetary policy to a sharp decline in the value of some currencies. In this paper, we empirically examine the effects on Asian exchange rates of sharply higher interest rates during the Asian financial crisis. Taking account of the currency contagion effect, our results indicate that sharply higher interest rates helped to support the exchange rates of South Korea, the Philippines, and Thailand. For Malaysia, no significant causal relation is found from the rate of interest to exchange rates, as the authorities in Malaysia did not actively adopt a high interest rate policy to defend the currency.

  18. Hyaluronic acid filler injections for tear-trough deformity: injection technique and high-frequency ultrasound follow-up evaluation.

    Science.gov (United States)

    De Pasquale, Antonino; Russa, Giuseppina; Pulvirenti, Manuela; Di Rosa, Luigi

    2013-06-01

    This study aimed to describe the technique used by the authors in treating tear-trough deformity and to illustrate the effectiveness of high-frequency diagnostic ultrasound in the assessment of dermal filler longevity. In this consecutive interventional nonrandomized case series, 22 patients (18 women and 4 men) were evaluated. They ranged in age from 29 to 65 years (mean, 46.59 years ± 10.0 years). The patients were given multiple hyaluronic acid injections in the tear-trough area between 2009 and 2011. The injected areas then were evaluated with sonographic scans during the follow-up period. All the patients were examined preoperatively, 7 days after injection, then after 1, 6, and 12 months, and finally once a year. Pre- and postoperative photographs using standard positioning and lighting were taken as well as high-frequency ultrasound scans using a 15-MHz scanner with an axial resolution of 15 mm. The injection technique consisted of three to five injections perpendicular to the skin. These were administered just under the orbital rim, creating three column-shaped hyaluronic acid deposits deep in the orbicularis oculi muscle, from 0.2 mm to 0.5 mm below the orbital rim. Approximately 0.1 ml-0.3 ml was injected at a time. This technique creates a deep scaffolding that can fill the orbital hollow. The amount of filler used in each area ranged from 0.1 ml to 0.3 ml (mean, 0.267 ml ± 0.128 ml), whereas the mean filler quantity in each eyelid was 0.45 ml ± 0.14 ml. During the follow-up visit 1 week after the treatment, 21 patients (90 %) required a second series of injections either in the exact same areas or right next to the injected area to obtain a smoother appearance of the skin surface. During the sonographer examination, it was always possible to identify and measure the filler at the site of the injection. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please

  19. Deformation mechanisms of nanotwinned Al

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xinghang [Texas A & M Univ., College Station, TX (United States)

    2016-11-10

    The objective of this project is to investigate the role of different types of layer interfaces on the formation of high density stacking fault (SF) in Al in Al/fcc multilayers, and understand the corresponding deformation mechanisms of the films. Stacking faults or twins can be intentionally introduced (via growth) into certain fcc metals with low stacking fault energy (such as Cu, Ag and 330 stainless steels) to achieve high strength, high ductility, superior thermal stability and good electrical conductivity. However it is still a major challenge to synthesize these types of defects into metals with high stacking fault energy, such as Al. Although deformation twins have been observed in some nanocrystalline Al powders by low temperature, high strain rate cryomilling or in Al at the edge of crack tip or indentation (with the assistance of high stress intensity factor), these deformation techniques typically introduce twins sporadically and the control of deformation twin density in Al is still not feasible. This project is designed to test the following hypotheses: (1) Certain type of layer interfaces may assist the formation of SF in Al, (2) Al with high density SF may have deformation mechanisms drastically different from those of coarse-grained Al and nanotwinned Cu. To test these hypotheses, we have performed the following tasks: (i) Investigate the influence of layer interfaces, stresses and deposition parameters on the formation and density of SF in Al. (ii) Understand the role of SF on the deformation behavior of Al. In situ nanoindentation experiments will be performed to probe deformation mechanisms in Al. The major findings related to the formation mechanism of twins and mechanical behavior of nanotwinned metals include the followings: 1) Our studies show that nanotwins can be introduced into metals with high stacking fault energy, in drastic contrast to the general anticipation. 2) We show two strategies that can effectively introduce growth twins in

  20. Deformation mechanisms of nanotwinned Al

    International Nuclear Information System (INIS)

    Zhang, Xinghang

    2016-01-01

    The objective of this project is to investigate the role of different types of layer interfaces on the formation of high density stacking fault (SF) in Al in Al/fcc multilayers, and understand the corresponding deformation mechanisms of the films. Stacking faults or twins can be intentionally introduced (via growth) into certain fcc metals with low stacking fault energy (such as Cu, Ag and 330 stainless steels) to achieve high strength, high ductility, superior thermal stability and good electrical conductivity. However it is still a major challenge to synthesize these types of defects into metals with high stacking fault energy, such as Al. Although deformation twins have been observed in some nanocrystalline Al powders by low temperature, high strain rate cryomilling or in Al at the edge of crack tip or indentation (with the assistance of high stress intensity factor), these deformation techniques typically introduce twins sporadically and the control of deformation twin density in Al is still not feasible. This project is designed to test the following hypotheses: (1) Certain type of layer interfaces may assist the formation of SF in Al, (2) Al with high density SF may have deformation mechanisms drastically different from those of coarse-grained Al and nanotwinned Cu. To test these hypotheses, we have performed the following tasks: (i) Investigate the influence of layer interfaces, stresses and deposition parameters on the formation and density of SF in Al. (ii) Understand the role of SF on the deformation behavior of Al. In situ nanoindentation experiments will be performed to probe deformation mechanisms in Al. The major findings related to the formation mechanism of twins and mechanical behavior of nanotwinned metals include the followings: 1) Our studies show that nanotwins can be introduced into metals with high stacking fault energy, in drastic contrast to the general anticipation. 2) We show two strategies that can effectively introduce growth twins in

  1. Mechanical energy losses in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zelada, Griselda I. [Laboratorio de Materiales, Escuela de Ingenieria Electrica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avda. Pellegrini 250, 2000 Rosario (Argentina); Lambri, Osvaldo Agustin [Laboratorio de Materiales, Escuela de Ingenieria Electrica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avda. Pellegrini 250, 2000 Rosario (Argentina); Instituto de Fisica Rosario - CONICET, Member of the CONICET& #x27; s Research Staff, Avda. Pellegrini 250, 2000 Rosario (Argentina); Bozzano, Patricia B. [Laboratorio de Microscopia Electronica, Unidad de Actividad Materiales, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Avda. Gral. Paz 1499, 1650 San Martin (Argentina); Garcia, Jose Angel [Departamento de Fisica Aplicada II, Facultad de Ciencias y Tecnologia, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao, Pais Vasco (Spain)

    2012-10-15

    Mechanical spectroscopy (MS) and transmission electron microscopy (TEM) studies have been performed in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum, oriented for single slip, in order to study the dislocation dynamics in the temperature range within one third of the melting temperature. A damping peak related to the interaction of dislocation lines with both prismatic loops and tangles of dislocations was found. The peak temperature ranges between 900 and 1050 K, for an oscillating frequency of about 1 Hz. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. How Did Successful High Schools Improve Their Graduation Rates?

    Science.gov (United States)

    Robertson, Janna Siegel; Smith, Robert W.; Rinka, Jason

    2016-01-01

    The researchers surveyed 23 North Carolina high schools that had markedly improved their graduation rates over the past five years. The administrators reported on the dropout prevention practices and programs to which they attributed their improved graduation rates. The majority of schools reported policy changes, especially with suspension. The…

  3. Effect of high heating rate on thermal decomposition behaviour of ...

    Indian Academy of Sciences (India)

    the thermal decomposition behaviour of the aforementioned powder at high heating rates was taken into considera- ... does not change the process of releasing hydrogen from titanium hydride ... from titanium hydride in a sequence of steps.

  4. Treatment of the prostate cancer with high dose rate brachytherapy

    International Nuclear Information System (INIS)

    Martinez, Alvaro; Torres Silva, Felipe

    2002-01-01

    The prostate cancer treatment in early stages is controversial. The high dose rate brachytherapy has been used like monotherapy or boost with external beam radiotherapy in advanced disease. This paper describes the technique and the advantages over other modalities

  5. Effect of high heating rate on thermal decomposition behaviour of ...

    Indian Academy of Sciences (India)

    Effect of high heating rate on thermal decomposition behaviour of titanium hydride ... hydride powder, while switching it from internal diffusion to chemical reaction. ... TiH phase and oxides form on the powder surface, controlling the process.

  6. Increased strength of concrete subject to high loading rates

    International Nuclear Information System (INIS)

    Curbach, M.

    1987-01-01

    Within the scope of this work various problems are discussed which occur in connection with concrete under high tensile loading rates (e.g. when a plane crashes on a nuclear power plant very high loads occur which act only for a very short time). Particularly the causes for the already frequently noticed increases in strength with increasing loading rates are investigated and also the question whether this increased strength can be taken into account when dimensioning a construction. (MM) [de

  7. Quantum Communication with a High-Rate Entangled Photon Source

    Science.gov (United States)

    Wilson, Nathaniel C.; Chaffee, Dalton W.; Lekki, John D.; Wilson, Jeffrey D.

    2016-01-01

    A high generation rate photon-pair source using a dual element periodically-poled potassium titanyl phosphate (PP KTP) waveguide is described. The photon-pair source features a high pair generation rate, a compact power-efficient package, and continuous wave (CW) or pulsed operation. Characterization and test results are presented. Details and preliminary results of a laboratory free-space QKD experiment with the B92 protocol are also presented.

  8. Highly Deformable Liquid Embedded Soft-Matter Capacitors and Inductors for Stretchable Electronics

    Science.gov (United States)

    Fassler, Andrew; Majidi, Carmel

    2013-03-01

    We have developed a family of soft-matter capacitors and inductors that can be stretched to several times their natural length. These circuit elements are composed of microchannels of a liquid-phase Gallium-Indium-Tin alloy (Galinstan) embedded in a soft silicone elastomer (Ecoflex® 00-30). As the elastomer stretches, the embedded liquid channels deform, causing the capacitance and inductance to change monotonically. The relative changes in capacitance and inductance are experimentally measured as a function of stretch in three directions. The relationships found show potential for these devices to be used as strain sensors and tunable electronic filters. Additionally, theoretical predictions derived using finite elasticity kinematics are consistent with these experimentally found relationships.

  9. Transient regimes during high-temperature deformation of a bulk metallic glass: A free volume approach

    International Nuclear Information System (INIS)

    Bletry, M.; Guyot, P.; Brechet, Y.; Blandin, J.J.; Soubeyroux, J.L.

    2007-01-01

    The homogeneous deformation of a zirconium-based bulk metallic glass is investigated in the glass transition range. Compression and stress-relaxation tests have been conducted. The stress-strain curves are modeled in the framework of the free volume theory, including transient phenomena (overshoot and undershoot). This approach allows several physical parameters (activation volume, flow defect creation and relaxation coefficient) to be determined from a mechanical experiment. This model is able to rationalize the dependency of stress overshoot on relaxation time. It is shown that, due to the relationship between flow defect concentration and free volume model, it is impossible to determine the equilibrium flow defect concentration. However, the relative variation of flow defect is always the same, and all the model parameters depend on the equilibrium flow defect concentration. The methodology presented in this paper should, in the future, allow the consistency of the free volume model to be assessed

  10. Deformation behaviors of Cu29Zr32Ti15Al5Ni19 high entropy bulk metallic glass during nanoindentation

    Science.gov (United States)

    Fang, Qihong; Yi, Ming; Li, Jia; Liu, Bin; Huang, Zaiwang

    2018-06-01

    The deformation behaviors of Cu29Zr32Ti15Al5Ni19 high entropy bulk metallic glass (HE-BMG) during the nanoindentation are presented via the large-scale molecular dynamics (MD) simulations. The indentation tests are carried out using spherical rigid indenter to investigate the microstructural evolution on the mechanical properties of HE-BMGs in terms of shear strain, indentation force, and surface morphology as well as radial distribution function (RDF). Based on the Hertzian fitting the load-displacement curve, HE-BMG Cu29Zr32Ti15Al5Ni19 has the Young's modulus of 93.1 GPa and hardness of 8.8 GPa. The indentation force requiring for the continual increasing contacted area between the indenter and the substrate goes up with the increasing of indentation depth. In addition, the symmetrical distribution of atomic displacement reveals the isotropic of HE-BMG after the indentation treatment. In the deformation region, the Al element would lead to the serious fluctuation in the first peak of RDF, which is much stronger than the other elements. The severe distortion from the atomic size difference maybe reduce the activation energy to the occurrence of shear deformation in HE-BMG, leading to the transition from brittle to ductile observed by the whole sliding of the local atom group. Through the indentation load-displacement curves at various temperatures, the softening of HE-BMG at high temperatures is in qualitative agreement with the experimental findings. Moreover, this effective strategy is used to accelerate the discovery of excellent mechanical properties of HE-BMGs by means of MD simulation, as well as understand the fundamental nanoindentation response of HE-BMGs.

  11. Effect of test temperature and strain rate on the tensile properties of high-strength, high-conductivity copper alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Eatherly, W.S. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    The unirradiated tensile properties of wrought GlidCop AL25 (ITER grade zero, IGO) solutionized and aged CuCrZr, and cold-worked and aged and solutionized and aged Hycon 3HP{trademark} CuNiBe have been measured over the temperature range of 20-500{degrees}C at strain rates between 4 x 10{sup {minus}4} s{sup {minus}1} and 0.06 s{sup {minus}1}. The measured room temperature electrical conductivity ranged from 64 to 90% IACS for the different alloys. All of the alloys were relatively insensitive to strain rate at room temperature, but the strain rate sensitivity of GlidCop Al25 increased significantly with increasing temperature. The CuNiBe alloys exhibited the best combination of high strength and high conductivity at room temperature. The strength of CuNiBe decreased slowly with increasing temperature. However, the ductility of CuNiBe decreased rapidly with increasing temperature due to localized deformation near grain boundaries, making these alloy heats unsuitable for typical structural applications above 300{degrees}C. The strength and uniform elongation of GlidCop Al25 decreased significantly with increasing temperature at a strain rate of 1 x 10{sup {minus}3} s{sup {minus}1}, whereas the total elongation was independent of test temperature. The strength and ductility of CuCrZr decreased slowly with increasing temperature.

  12. Strain Rate Dependent Deformation of a Polymer Matrix Composite with Different Microstructures Subjected to Off-Axis Loading

    Directory of Open Access Journals (Sweden)

    Xiaojun Zhu

    2014-01-01

    Full Text Available This paper aims to investigate the comprehensive influence of three microstructure parameters (fiber cross-section shape, fiber volume fraction, and fiber off-axis orientation and strain rate on the macroscopic property of a polymer matrix composite. During the analysis, AS4 fibers are considered as elastic solids, while the surrounding PEEK resin matrix exhibiting rate sensitivities are described using the modified Ramaswamy-Stouffer viscoplastic state variable model. The micromechanical method based on generalized model of cells has been used to analyze the representative volume element of composites. An acceptable agreement is observed between the model predictions and experimental results found in the literature. The research results show that the stress-strain curves are sensitive to the strain rate and the microstructure parameters play an important role in the behavior of polymer matrix.

  13. Calculation of deformation rate of interstitial solid solutions under irradiation with usage of the object-oriented approach

    International Nuclear Information System (INIS)

    Lopuga, A.D.; Pyatiletov, Yu.S.

    2000-01-01

    The creep rate is determined by streams of self point defects and mobile complexes impurity - free point defect on the dislocation. These streams are by the numerical method, if the stationary distributions of point defects in a neighbourhood of sinks are known. For solution of this composite system of the nonlinear differential equations the object-oriented approach utilized, which one represents series iterative process consisting of four stages: the analysis, designing, evolution and modification. On the basis of the object-oriented approach, the program application DefRate.exe for research of radiation creep rate is created. The application works in an operating system Windows. As all parameters are set interactive, the designed program can be easily utilized for research of the broad set of materials. The introduced object-oriented method is applicable for research of the broad set of processes controlled by the diffusion, such as the swelling and radiation creep of construction materials, the hydrogen permeability etc

  14. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli

    Science.gov (United States)

    Huertas, Juan-Pablo; Aznar, Arantxa; Esnoz, Arturo; Fernández, Pablo S.; Iguaz, Asunción; Periago, Paula M.; Palop, Alfredo

    2016-01-01

    Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing. PMID:27563300

  15. A multiple dating approach (luminescence and electron spin resonance) to assess rates of crustal deformation using Quaternary fluvial terraces of the lower Moulouya River (NE Morocco)

    Science.gov (United States)

    Bartz, Melanie; Rixhon, Gilles; Duval, Mathieu; King, Georgina; Brückner, Helmut

    2017-04-01

    40 and MIS 32, whilst the last terrace formation in the hanging wall is dated between 1.19±0.11 and 1.61±0.15 Ma, indicating even older fluvial deposition. This study shows the high potential of the multiple centre approach in ESR dating, especially when dealing with samples beyond the dating range of luminescence techniques. Nevertheless, independent age control is still required to evaluate the reliability of the ESR dating results; this will be achieved in the near future using palaeomagnetism (CENIEH, Burgos) and isochron burial dating (26Al/10Be) on the same deposits. The acquisition of a reliable chronological framework based on different techniques will eventually give new insights into the rate of Quaternary crustal deformation in this region of Morocco. References: Barcos, L., Jabaloy, A., Azdimousa, A., Asebriy, L., Gómez-Ortiz, D., Rodríguez-Peces, M.J., Tejero, R., Pérez-Peña, J.V., 2014. Study of relief changes related to active doming in the eastern Moroccan Rif (Morocco) using geomorphological indices. J. African Earth Sci. 100, 493-509. Duval, M., Sancho, C., Calle, M., Guilarte, V., Penna-Monné, J.L., 2015. On the interest of using the multiple centre approach in ESR dating of optically bleached quartz grains: Some examples from the Early Pleistocene terraces of the Alcanadre River (Ebro basin, Spain). Quat. Geochr. 29, 58-69. Huntley, 2006. An explanation of the power-law decay of luminescence. Journal of Physics: Condensed Matter 18, 1359-1365. Kars, R.H., Wallinga, J., Cohen, K.M., 2008. A new approach towards anomalous fading correction for feldspar IRSL dating - tests on samples in field saturation. Radiation Measurements 43, 786-790. Rixhon, G., Bartz, M., El Ouahabi, M., Szemkus, N., Brückner, H., 2017, Contrasting terrace systems of the lower Moulouya river as indicator of crustal deformation in NE Morocco. J. African Earth Sci. 126, 45-47.

  16. Solidification at the High and Low Rate Extreme

    Energy Technology Data Exchange (ETDEWEB)

    Meco, Halim [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    The microstructures formed upon solidification are strongly influenced by the imposed growth rates on an alloy system. Depending on the characteristics of the solidification process, a wide range of growth rates is accessible. The prevailing solidification mechanisms, and thus the final microstructure of the alloy, are governed by these imposed growth rates. At the high rate extreme, for instance, one can have access to novel microstructures that are unattainable at low growth rates. While the low growth rates can be utilized for the study of the intrinsic growth behavior of a certain phase growing from the melt. Although the length scales associated with certain processes, such as capillarity, and the diffusion of heat and solute, are different at low and high rate extremes, the phenomena that govern the selection of a certain microstructural length scale or a growth mode are the same. Consequently, one can analyze the solidification phenomena at both high and low rates by using the same governing principles. In this study, we examined the microstructural control at both low and high extremes. For the high rate extreme, the formation of crystalline products and factors that control the microstructure during rapid solidification by free-jet melt spinning are examined in Fe-Si-B system. Particular attention was given to the behavior of the melt pool at different quench-wheel speeds. Since the solidification process takes place within the melt-pool that forms on the rotating quench-wheel, we examined the influence of melt-pool dynamics on nucleation and growth of crystalline solidification products and glass formation. High-speed imaging of the melt-pool, analysis of ribbon microstructure, and measurement of ribbon geometry and surface character all indicate upper and lower limits for melt-spinning rates for which nucleation can be avoided, and fully amorphous ribbons can be achieved. Comparison of the relevant time scales reveals that surface-controlled melt

  17. Pedalling rate affects endurance performance during high-intensity cycling

    DEFF Research Database (Denmark)

    Nielsen, Jens Steen; Hansen, Ernst Albin; Sjøgaard, Gisela

    2004-01-01

    The purpose of this study into high-intensity cycling was to: (1) test the hypothesis that endurance time is longest at a freely chosen pedalling rate (FCPR), compared to pedalling rates 25% lower (FCPR-25) and higher (FCPR+25) than FCPR, and (2) investigate how physiological variables......, and endurance time at W90 with FCPR-25, FCPR, and FCPR+25. Power reserve was calculated as the difference between applied power output at a given pedalling rate and peak crank power at this same pedalling rate. W90 was 325 (47) W. FCPR at W90 was 78 (11) rpm, resulting in FCPR-25 being 59 (8) rpm and FCPR+25...... time was negatively related to VO(2max), W90 and % MHC I, while positively related to power reserve. In conclusion, at group level, endurance time was longer at FCPR and at a pedalling rate 25% lower compared to a pedalling rate 25% higher than FCPR. Further, inter-individual physiological variables...

  18. Structure and performance of anisotropic nanocrystalline Nd-Fe-B magnets fabricated by high-velocity compaction followed by deformation

    Science.gov (United States)

    Zhao, L. Z.; Deng, X. X.; Yu, H. Y.; Guan, H. J.; Li, X. Q.; Xiao, Z. Y.; Liu, Z. W.; Greneche, J. M.

    2017-12-01

    High-velocity compaction (HVC) has been proposed as an effective approach for the fabrication of nanocrystalline Nd-Fe-B magnets. In this work, the effect of powder size on the density of HVCed magnets has been studied and the anisotropic nanocrystalline Nd-Fe-B magnets were prepared by HVC followed by hot deformation (HD). It is found that a proper particle size range is beneficial to high density. The investigations on the microstructure, magnetic domain structure, and hyperfine structure, indicate that the deformed grain structure and the magnetic domain structure with uniform paramagnetic grain boundary phase give good magnetic properties of HVC + HDed magnets. These magnets also have good mechanical and anti-corrosion properties. The results indicate that HVC is not only a near-net-shape, room temperature and binder-free process but is also able to maintain uniform nanostructure and to achieve good magnetic properties in both isotropic and anisotropic magnets. As a result, HVC can be employed as an ideal alternative process for bonding or hot pressing for the conventional MQI, MQII and MQIII magnets.

  19. Influence of pre-deformation, sensitization and oxidation in high temperature water on corrosion resistance of AISI 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Jinlong, E-mail: ljltsinghua@126.com [Beijing Key Laboratory of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Zhongguancun Street, Haidian District, Beijing 100084 (China); State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China); Liang, Tongxiang [Beijing Key Laboratory of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Zhongguancun Street, Haidian District, Beijing 100084 (China); State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China); Luo, Hongyun [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Xueyuan Road 37, Beijing 100191 (China)

    2016-12-01

    Highlights: • The pre-strain accelerated desensitization and sensitization for austenitic stainless steels. • Low temperature sensitization (carbide precipitation) induced α′-martensite. • The sensitization level could affect directly corrosion resistance of the oxide film. - Abstract: The effects of pre-deformation on sensitization of AISI 304 stainless steel were investigated by the double loop electrochemical potentiokinetic reactivation test. The effects of pre-deformation and sensitization on high temperature oxidized film formed in high temperature water were analyzed by a XRD and SEM. The electrochemical impedance spectroscopy at room temperature was used to study corrosion resistance of oxidized film. The point defect density of oxidized film was calculated by Mott–Schottky plots. The results showed that the value of the degree of sensitization first decreased and then slight increased with the increasing of engineering strain. Moreover, low temperature promoted to form sensitization induced “secondary” α′-martensite. The sample with 20% engineering strain had higher impedance value than other samples. The result was supported by further Mott–Schottky experiments. Considering increased α′-martensite with the increasing of strain, the results of the impedance were more consistent with values of the degree of sensitization.

  20. Structural and mechanical behaviour of severe plastically deformed high purity aluminium sheets processed by constrained groove pressing technique

    International Nuclear Information System (INIS)

    Satheesh Kumar, S.S.; Raghu, T.

    2014-01-01

    Highlights: • High purity aluminium sheets constrained groove pressed up to plastic strain of 5.8. • Microstructural evolution studied by TEM and X-ray diffraction profile analysis. • Ultrafine grained structure with grain size ∼900 nm achieved in sheets. • Yield strength increased by 5.3 times and tensile strength doubled after first pass. • Enhanced deformation homogeneity seen with increased accumulated plastic strain. - Abstract: High purity aluminium sheets (∼99.9%) are subjected to intense plastic straining by constrained groove pressing method successfully up to 5 passes thereby imparting an effective plastic strain of 5.8. Transmission electron microscopy studies of constrained groove pressed sheets divulged significant grain refinement and the average grain sizes obtained after five pass is estimated to be ∼0.9 μm. In addition to that, microstructural evolution of constrained groove pressed sheets is characterized by X-ray diffraction peak profile analysis employing Williamson–Hall method and the results obtained fairly concur with electron microscopy findings. The tensile behaviour evolution with increased straining indicates substantial improvement of yield strength by ∼5.3 times from 17 MPa to 90 MPa during first pass corroborated to grain refinement observed. Marginal increase in strengths is noticed during second pass followed by minor drop in strengths attributed to predominance of dislocation recovery is noticed in subsequent passes. Quantitative assessment of degree of deformation homogeneity using microhardness profiles reveal relatively better strain homogeneity at higher number of passes

  1. Analysis of high temperature deformation mechanism in ODS EUROFER97 alloy

    Science.gov (United States)

    Ramar, A.; Spätig, P.; Schäublin, R.

    2008-12-01

    Oxide dispersion in tempered martensitic EUROFER97 steel is an efficient approach to improve its strength. The oxide dispersion strengthened (ODS) EUROFER97 steel shows a good strength up to 600 °C, but degrades rapidly beyond that temperature. To understand the origin in the microstructure of this drop in strength in situ heating experiment in TEM was performed from room temperature to 1000 °C. Upon heating neither microstructure changes nor dislocation movement are observed up to 600 °C. Movement of dislocations are observed above 680 °C. Phase transformation to austenite starts at 840 °C. Yttria particles remain stable up to 1000 °C. Changes in mechanical properties thus do not relate to changes in yttria dispersion. It is attempted to relate these observations to the thermal activation parameters measured by the technique of conventional strain rate experiment, which allow to identify at a mesoscopic scale the microstructural mechanisms responsible for the degradation of ODS steel at high temperatures.

  2. Bunionette deformity.

    Science.gov (United States)

    Cohen, Bruce E; Nicholson, Christopher W

    2007-05-01

    The bunionette, or tailor's bunion, is a lateral prominence of the fifth metatarsal head. Most commonly, bunionettes are the result of a widened 4-5 intermetatarsal angle with associated varus of the metatarsophalangeal joint. When symptomatic, these deformities often respond to nonsurgical treatment methods, such as wider shoes and padding techniques. When these methods are unsuccessful, surgical treatment is based on preoperative radiographs and associated lesions, such as hyperkeratoses. In rare situations, a simple lateral eminence resection is appropriate; however, the risk of recurrence or overresection is high with this technique. Patients with a lateral bow to the fifth metatarsal are treated with a distal chevron-type osteotomy. A widened 4-5 intermetatarsal angle often requires a diaphyseal osteotomy for correction.

  3. Decay rate of the false vacuum at high temperatures

    International Nuclear Information System (INIS)

    Eboli, O.J.P.; Marques, G.C.

    1986-01-01

    We investigate, within the semiclassical approach, the high temperature behaviour of the decay rate (Γ) of the metastable vacuum in Field Theory. We exhibit some exactly soluble (1+1) and (3+1) dimensional examples and develop a formal expression for γ in the high temperature limit. (Author) [pt

  4. Authoritative School Climate and High School Dropout Rates

    Science.gov (United States)

    Jia, Yuane; Konold, Timothy R.; Cornell, Dewey

    2016-01-01

    This study tested the association between school-wide measures of an authoritative school climate and high school dropout rates in a statewide sample of 315 high schools. Regression models at the school level of analysis used teacher and student measures of disciplinary structure, student support, and academic expectations to predict overall high…

  5. Investigating thermomechanical parameters of the EhP693VD heat resisting alloys deformation

    International Nuclear Information System (INIS)

    Garibov, G.S.; Galkin, A.M.; Ermanok, M.Z.; Trepilets, A.E.

    1975-01-01

    The purpose of the present publication consists in complex research of the deformation resistance and plastic characteristics of heat-resistant hard-to-form alloy EhP693VD at the temperatures and deformation rates peculiar for the pressing process. The test conditions are: temperature 1000 to 1200 deg C; rate of deformation 0.5, 5.0 and 25 s -1 . The curves of deformation hardening of alloy EhP693VD show that the alloy is characterized by very high values of forming resistance index Ssub(f). With the increase of the rates of deformation, the maximum of curves Ssub(f) /antiepsilon/ is shifted towards greater degrees of deformation. The increase of the temperature results in the lower deformation hardening of the alloy. The intensity of the growth of the deformation resistance with the decrease of temperature becomes higher at lower degrees of deformation. Variation of plasticity at temperatures of up to 1150 deg C correlates with the curves showing variation of the deformation resistance. At a temperature of 1200 deg C, the drop of the deformation resistance is accompanied by the intensive drop of the plastic characteristics. The planning matrices, test results and complete disperse analysis tables are given. The analysis of the obtained equations makes it possible to draw a conclusion that the rise of the test temperature and drop of the rates of deformation entail the increase of the plastic characteristics

  6. High-repetition-rate short-pulse gas discharge.

    Science.gov (United States)

    Tulip, J; Seguin, H; Mace, P N

    1979-09-01

    A high-average-power short-pulse gas discharge is described. This consists of a volume-preionized transverse discharge of the type used in gas lasers driven by a Blumlein energy storage circuit. The Blumlein circuit is fabricated from coaxial cable, is pulse-charged from a high-repetition-rate Marx-bank generator, and is switched by a high-repetition-rate segmented rail gap. The operation of this discharge under conditions typical of rare-gas halide lasers is described. A maximum of 900 pps was obtained, giving a power flow into the discharge of 30 kW.

  7. Authoritative school climate and high school dropout rates.

    Science.gov (United States)

    Jia, Yuane; Konold, Timothy R; Cornell, Dewey

    2016-06-01

    This study tested the association between school-wide measures of an authoritative school climate and high school dropout rates in a statewide sample of 315 high schools. Regression models at the school level of analysis used teacher and student measures of disciplinary structure, student support, and academic expectations to predict overall high school dropout rates. Analyses controlled for school demographics of school enrollment size, percentage of low-income students, percentage of minority students, and urbanicity. Consistent with authoritative school climate theory, moderation analyses found that when students perceive their teachers as supportive, high academic expectations are associated with lower dropout rates. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  8. Evolution of high tooth replacement rates in sauropod dinosaurs.

    Science.gov (United States)

    D'Emic, Michael D; Whitlock, John A; Smith, Kathlyn M; Fisher, Daniel C; Wilson, Jeffrey A

    2013-01-01

    Tooth replacement rate can be calculated in extinct animals by counting incremental lines of deposition in tooth dentin. Calculating this rate in several taxa allows for the study of the evolution of tooth replacement rate. Sauropod dinosaurs, the largest terrestrial animals that ever evolved, exhibited a diversity of tooth sizes and shapes, but little is known about their tooth replacement rates. We present tooth replacement rate, formation time, crown volume, total dentition volume, and enamel thickness for two coexisting but distantly related and morphologically disparate sauropod dinosaurs Camarasaurus and Diplodocus. Individual tooth formation time was determined by counting daily incremental lines in dentin. Tooth replacement rate is calculated as the difference between the number of days recorded in successive replacement teeth. Each tooth family in Camarasaurus has a maximum of three replacement teeth, whereas each Diplodocus tooth family has up to five. Tooth formation times are about 1.7 times longer in Camarasaurus than in Diplodocus (315 vs. 185 days). Average tooth replacement rate in Camarasaurus is about one tooth every 62 days versus about one tooth every 35 days in Diplodocus. Despite slower tooth replacement rates in Camarasaurus, the volumetric rate of Camarasaurus tooth replacement is 10 times faster than in Diplodocus because of its substantially greater tooth volumes. A novel method to estimate replacement rate was developed and applied to several other sauropodomorphs that we were not able to thin section. Differences in tooth replacement rate among sauropodomorphs likely reflect disparate feeding strategies and/or food choices, which would have facilitated the coexistence of these gigantic herbivores in one ecosystem. Early neosauropods are characterized by high tooth replacement rates (despite their large tooth size), and derived titanosaurs and diplodocoids independently evolved the highest known tooth replacement rates among archosaurs.

  9. Evolution of high tooth replacement rates in sauropod dinosaurs.

    Directory of Open Access Journals (Sweden)

    Michael D D'Emic

    Full Text Available BACKGROUND: Tooth replacement rate can be calculated in extinct animals by counting incremental lines of deposition in tooth dentin. Calculating this rate in several taxa allows for the study of the evolution of tooth replacement rate. Sauropod dinosaurs, the largest terrestrial animals that ever evolved, exhibited a diversity of tooth sizes and shapes, but little is known about their tooth replacement rates. METHODOLOGY/PRINCIPAL FINDINGS: We present tooth replacement rate, formation time, crown volume, total dentition volume, and enamel thickness for two coexisting but distantly related and morphologically disparate sauropod dinosaurs Camarasaurus and Diplodocus. Individual tooth formation time was determined by counting daily incremental lines in dentin. Tooth replacement rate is calculated as the difference between the number of days recorded in successive replacement teeth. Each tooth family in Camarasaurus has a maximum of three replacement teeth, whereas each Diplodocus tooth family has up to five. Tooth formation times are about 1.7 times longer in Camarasaurus than in Diplodocus (315 vs. 185 days. Average tooth replacement rate in Camarasaurus is about one tooth every 62 days versus about one tooth every 35 days in Diplodocus. Despite slower tooth replacement rates in Camarasaurus, the volumetric rate of Camarasaurus tooth replacement is 10 times faster than in Diplodocus because of its substantially greater tooth volumes. A novel method to estimate replacement rate was developed and applied to several other sauropodomorphs that we were not able to thin section. CONCLUSIONS/SIGNIFICANCE: Differences in tooth replacement rate among sauropodomorphs likely reflect disparate feeding strategies and/or food choices, which would have facilitated the coexistence of these gigantic herbivores in one ecosystem. Early neosauropods are characterized by high tooth replacement rates (despite their large tooth size, and derived titanosaurs and

  10. Low dose rate and high dose rate intracavitary treatment for cervical cancer

    International Nuclear Information System (INIS)

    Hareyama, Masato; Oouchi, Atsushi; Shidou, Mitsuo

    1997-01-01

    From 1984 through 1993, 144 previous untreated patients with carcinoma of uterine cervix were treated with either low dose rate 137 Cs therapy (LDR) or high dose rate 60 Co therapy (HDR). The local failure rates for more than 2-years for the primary lesions were 11.8% (8 of 63 patients) for LDR and 18.0% (11 of 61 patients). Rectal complication rates were significantly lower for HDR versus LDR (14.3% VS. 32.8%. p<0.01). Also, bladder complication rates were significantly lower for HDR versus LDR (0% VS. 10.4%, p<0.005). Treatment results in term of local control were equivalent for HDR and LDR treatment. However, the incidence of complications was higher for the LDR group than for the HDR group. (author)

  11. High-precision mass measurements in the realm of the deformed shell closure N=152

    Energy Technology Data Exchange (ETDEWEB)

    Eibach, Martin Andreas

    2013-12-04

    The nuclear masses reflect the sum of all interactions inside a nucleus. Their precise knowledge can be used to benchmark nuclear mass models and to gain nuclear structure information. Penning-trap mass spectrometers have proven their potential to obtain lowest uncertainties. Uniquely located at a nuclear reactor, the double Penning-trap mass spectrometer TRIGA-TRAP is dedicated to measurements in the neutron-rich region. For a gain in sensitivity a non-destructive detection system for single ion mass measurements was adopted. This includes the implementation of a narrow band-pass filter tuned to the heavy ion cyclotron frequency as well as a cryogenic low-noise amplifier. For on-line mass measurements, the laser ablation ion source was equipped with a newly developed miniature radiofrequency quadrupole trap in order to improve the extraction efficiency. A more economic use of the radioactive material enabled mass measurements using only 10{sup 15} atoms of target material. New mass measurements were performed within this work in the realm of the deformed shell closure N=152. Their implementation into the atomic-mass evaluation improved the uncertainty of more than 80 nuclides in the heavy mass region and simultaneously shifted the absolute mass of two α decay chains.

  12. Effect of directional solidification rate on the microstructure and properties of deformation-processed Cu–7Cr–0.1Ag in situ composites

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Keming [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China); School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Jiang, Zhengyi; Zhao, Jingwei [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Zou, Jin; Chen, Zhibao [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China); Lu, Deping, E-mail: llludp@163.com [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China)

    2014-11-05

    Highlights: • Effect of directional solidification (DS) rate on a Cu–Cr–Ag in situ composite. • The microstructure and properties of the DS in situ composite were investigated. • The second-phase Cr grains were parallel to drawing direction, and were finer. • The tensile strength was higher and the combination of properties was better. - Abstract: The influence of directional solidification rate on the microstructure, mechanical properties and conductivity of deformation-processed Cu–7Cr–0.1Ag in situ composites produced by thermo-mechanical processing was systematically investigated. The microstructure was analyzed by optical microscopy and scanning electronic microscopy. The mechanical properties and conductivity were evaluated by tensile-testing machine and micro-ohmmeter, respectively. The results indicate that the size, shape and distribution of second-phase Cr grains are significantly different in the Cu–7Cr–0.1Ag alloys with different growth rates. At a growth rate of 200 μm s{sup −1}, the Cr grains transform into fine Cr fiber-like grains parallel to the pulling direction from the Cr dendrites. The tensile strength of the Cu–7Cr–0.1Ag in situ composites from the directional solidification (DS) alloys is significantly higher than that from the as-cast alloy, while the conductivity of the in situ composites from the DS alloys is slightly lower than that from the as-cast alloy. The following combinations of tensile strength, elongation to fracture and conductivity of the Cu–7Cr–0.1Ag in situ composites from the DS alloy with a growth rate of 200 μm s{sup −1} and a cumulative cold deformation strain of 8 after isochronic aging treatment for 1 h can be obtained respectively as: (i) 1067 MPa, 2.9% and 74.9% IACS; or (ii) 1018 MPa, 3.0%, and 76.0% IACS or (iii) 906 MPa, 3.3% and 77.6% IACS.

  13. Characterizing high-temperature deformation of internally heated nuclear fuel element simulators

    Energy Technology Data Exchange (ETDEWEB)

    Belov, A.I.; Fong, R.W.L.; Leitch, B.W.; Nitheanandan, T.; Williams, A., E-mail: alexander.belov@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2016-06-15

    The sag behaviour of a simulated nuclear fuel element during high-temperature transients has been investigated in an experiment utilizing an internal indirect heating method. The major motivation of the experiment was to improve understanding of the dominant mechanisms underlying the element thermo-mechanical response under loss-of-coolant accident conditions and to obtain accurate experimental data to support development of 3-D computational fuel element models. The experiment was conducted using an electrically heated CANDU fuel element simulator. Three consecutive thermal cycles with peak temperatures up to ≈1000 {sup o}C were applied to the element. The element sag deflections and sheath temperatures were measured. On heating up to 600 {sup o}C, only minor lateral deflections of the element were observed. Further heating to above 700 {sup o}C resulted in an element multi-rate creep and significant permanent bow. Post-test visual and X-ray examinations revealed a pronounced necking of the sheath at the pellet-to-pellet interface locations. A wall thickness reduction was detected in the necked region that is interpreted as a sheath longitudinal strain localization effect. The sheath cross-sectioning showed signs of a 'hard' pellet-cladding interaction due to the applied cycles. A 3-D model of the experiment was generated using the ANSYS finite element code. As a fully coupled thermal mechanical simulation is computationally expensive, it was deemed sufficient to use the measured sheath temperatures as a boundary condition, and thus an uncoupled mechanical simulation only was conducted. The ANSYS simulation results match the experiment sag observations well up to the point at which the fuel element started cooling down. (author)

  14. Nanocrystallization in Al85Ce8Ni5Co2 amorphous alloy obtained by different strain rate during high pressure torsion

    International Nuclear Information System (INIS)

    Henits, P.; Kovacs, Zs.; Schafler, E.; Varga, L.K.; Labar, J.L.; Revesz, A.

    2010-01-01

    In order to elucidate the role of total strain and strain rate during high pressure torsion of Al 85 Ce 8 Ni 5 Co 2 metallic glass, different deformation conditions were applied to devitrify the as-quenched alloy. The disk-shaped specimens were characterized by X-ray diffraction, transmission electron microscopy and thermal analysis.

  15. Mechanical strength model for plastic bonded granular materials at high strain rates and large strains

    International Nuclear Information System (INIS)

    Browning, R.V.; Scammon, R.J.

    1998-01-01

    Modeling impact events on systems containing plastic bonded explosive materials requires accurate models for stress evolution at high strain rates out to large strains. For example, in the Steven test geometry reactions occur after strains of 0.5 or more are reached for PBX-9501. The morphology of this class of materials and properties of the constituents are briefly described. We then review the viscoelastic behavior observed at small strains for this class of material, and evaluate large strain models used for granular materials such as cap models. Dilatation under shearing deformations of the PBX is experimentally observed and is one of the key features modeled in cap style plasticity theories, together with bulk plastic flow at high pressures. We propose a model that combines viscoelastic behavior at small strains but adds intergranular stresses at larger strains. A procedure using numerical simulations and comparisons with results from flyer plate tests and low rate uniaxial stress tests is used to develop a rough set of constants for PBX-9501. Comparisons with the high rate flyer plate tests demonstrate that the observed characteristic behavior is captured by this viscoelastic based model. copyright 1998 American Institute of Physics

  16. Measurement of viscosity of slush at high shear rates

    OpenAIRE

    小林, 俊一; 川村, 公之; 津川, 圭一; 和泉, 薫; Kobayashi, Shun'ichi; Kawamura, Kimiyuki; Tugawa, Keiichi; Izumi, Kaoru

    1988-01-01

    Measurements of viscosity of slush were carried out using a method of flow along an inclined smooth surface in a 0℃cold room. The method was used to get the values of viscosity under high shear rates (25 and 75s^). From our experiments two important results were obtained: 1) the viscosity of slush decreases with increasing shear rates; 2) The fluid behavior is pseudoplastic that the values of non-Newtonian index of viscosity were less than unity.

  17. Radiobiological aspects of continuous low dose-rate irradiation and fractionated high dose-rate irradiation

    International Nuclear Information System (INIS)

    Turesson, I.

    1990-01-01

    The biological effects of continuous low dose-rate irradiation and fractionated high dose-rate irradiation in interstitial and intracavitary radiotherapy and total body irradiation are discussed in terms of dose-rate fractionation sensitivity for various tissues. A scaling between dose-rate and fraction size was established for acute and late normal-tissue effects which can serve as a guideline for local treatment in the range of dose rates between 0.02 and 0.005 Gy/min and fraction sizes between 8.5 and 2.5 Gy. This is valid provided cell-cycle progression and proliferation can be ignored. Assuming that the acute and late tissue responses are characterized by α/β values of about 10 and 3 Gy and a mono-exponential repair half-time of about 3 h, the same total doses given with either of the two methods are approximately equivalent. The equivalence for acute and late non-hemopoietic normal tissue damage is 0.02 Gy/min and 8.5 Gy per fraction; 0.01 Gy/min and 5.5 Gy per fraction; and 0.005 Gy/min and 2.5Gy per fraction. A very low dose rate, below 0.005 Gy/min, is thus necessary to simulate high dose-rate radiotherapy with fraction sizes of about 2Gy. The scaling factor is, however, dependent on the repair half-time of the tissue. A review of published data on dose-rate effects for normal tissue response showed a significantly stronger dose-rate dependence for late than for acute effects below 0.02 Gy/min. There was no significant difference in dose-rate dependence between various acute non-hemopoietic effects or between various late effects. The consistent dose-rate dependence, which justifies the use of a general scaling factor between fraction size and dose rate, contrasts with the wide range of values for repair half-time calculated for various normal-tissue effects. This indicates that the model currently used for repair kinetics is not satisfactory. There are also few experimental data in the clinical dose-rate range, below 0.02 Gy/min. It is therefore

  18. Full-frame, high-speed 3D shape and deformation measurements using stereo-digital image correlation and a single color high-speed camera

    Science.gov (United States)

    Yu, Liping; Pan, Bing

    2017-08-01

    Full-frame, high-speed 3D shape and deformation measurement using stereo-digital image correlation (stereo-DIC) technique and a single high-speed color camera is proposed. With the aid of a skillfully designed pseudo stereo-imaging apparatus, color images of a test object surface, composed of blue and red channel images from two different optical paths, are recorded by a high-speed color CMOS camera. The recorded color images can be separated into red and blue channel sub-images using a simple but effective color crosstalk correction method. These separated blue and red channel sub-images are processed by regular stereo-DIC method to retrieve full-field 3D shape and deformation on the test object surface. Compared with existing two-camera high-speed stereo-DIC or four-mirror-adapter-assisted singe-camera high-speed stereo-DIC, the proposed single-camera high-speed stereo-DIC technique offers prominent advantages of full-frame measurements using a single high-speed camera but without sacrificing its spatial resolution. Two real experiments, including shape measurement of a curved surface and vibration measurement of a Chinese double-side drum, demonstrated the effectiveness and accuracy of the proposed technique.

  19. U.S. High School Graduation Rates: Patterns and Explanations

    OpenAIRE

    Richard J. Murnane

    2013-01-01

    I survey the evidence on patterns in U.S. high school graduation rates over the period 1970–2010 and report the results of new research conducted to fill in holes in the evidence. I begin by pointing out the strengths and limitations of existing data sources. I then describe six striking patterns in graduation rates. They include stagnation over the last three decades of the twentieth century, significant race-, income-, and gender-based gaps, and significant increases in graduation rates o...

  20. THE AMERICAN HIGH SCHOOL GRADUATION RATE: TRENDS AND LEVELS*

    Science.gov (United States)

    Heckman, James J.; LaFontaine, Paul A.

    2009-01-01

    This paper applies a unified methodology to multiple data sets to estimate both the levels and trends in U.S. high school graduation rates. We establish that (a) the true rate is substantially lower than widely used measures; (b) it peaked in the early 1970s; (c) majority/minority differentials are substantial and have not converged for 35 years; (d) lower post-1970 rates are not solely due to increasing immigrant and minority populations; (e) our findings explain part of the slowdown in college attendance and rising college wage premiums; and (f) widening graduation differentials by gender help explain increasing male-female college attendance gaps. PMID:20625528

  1. THE AMERICAN HIGH SCHOOL GRADUATION RATE: TRENDS AND LEVELS.

    Science.gov (United States)

    Heckman, James J; Lafontaine, Paul A

    2010-05-01

    This paper applies a unified methodology to multiple data sets to estimate both the levels and trends in U.S. high school graduation rates. We establish that (a) the true rate is substantially lower than widely used measures; (b) it peaked in the early 1970s; (c) majority/minority differentials are substantial and have not converged for 35 years; (d) lower post-1970 rates are not solely due to increasing immigrant and minority populations; (e) our findings explain part of the slowdown in college attendance and rising college wage premiums; and (f) widening graduation differentials by gender help explain increasing male-female college attendance gaps.

  2. A review of reaction rates in high temperature air

    Science.gov (United States)

    Park, Chul

    1989-01-01

    The existing experimental data on the rate coefficients for the chemical reactions in nonequilibrium high temperature air are reviewed and collated, and a selected set of such values is recommended for use in hypersonic flow calculations. For the reactions of neutral species, the recommended values are chosen from the experimental data that existed mostly prior to 1970, and are slightly different from those used previously. For the reactions involving ions, the recommended rate coefficients are newly chosen from the experimental data obtained more recently. The reacting environment is assumed to lack thermal equilibrium, and the rate coefficients are expressed as a function of the controlling temperature, incorporating the recent multitemperature reaction concept.

  3. Study on the Leak Rate Estimation of SG Tubes and Residual Stress Estimation based on Plastic Deformation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Jin; Chang, Yoon Suk; Lee, Dock Jin; Lee, Tae Rin; Choi, Shin Beom; Jeong, Jae Uk; Yeum, Seung Won [Sungkyunkwan University, Seoul (Korea, Republic of)

    2009-02-15

    In this research project, a leak rate estimation model was developed for steam generator tubes with through wall cracks. The modelling was based on the leak data from 23 tube specimens. Also, the procedure of finite element analysis was developed for residual stress calculation of dissimilar metal weld in a bottom mounted instrumentation. The effect of geometric variables related with the residual stress in penetration weld part was investigated by using the developed analysis procedure. The key subjects dealt in this research are: 1. Development of leak rate estimation model for steam generator tubes with through wall cracks 2. Development of the program which can perform the structure and leakage integrity evaluation for steam generator tubes 3. Development of analysis procedure for bottom mounted instrumentation weld residual stress 4. Analysis on the effects of geometric variables on weld residual stress It is anticipated that the technologies developed in this study are applicable for integrity estimation of steam generator tubes and weld part in NPP.

  4. High rate tests of the LHCb RICH Upgrade system

    CERN Multimedia

    Blago, Michele Piero

    2016-01-01

    One of the biggest challenges for the upgrade of the LHCb RICH detectors from 2020 is to readout the photon detectors at the full 40 MHz rate of the LHC proton-proton collisions. A test facility has been setup at CERN with the purpose to investigate the behaviour of the Multi Anode PMTs, which have been proposed for the upgrade, and their readout electronics at high trigger rates. The MaPMTs are illuminated with a monochromatic laser that can be triggered independently of the readout electronics. A first series of tests, including threshold scans, is performed at low trigger rates (20 kHz) for both the readout and the laser with the purpose to characterise the behaviour of the system under test. Then the trigger rate is increased in two separate steps. First the MaPMTs are exposed to high illumination by triggering the pulsed laser at a high (20 MHz) repetition rate while the DAQ is readout at the same low rate as before. In this way the performance of the MaPMTs and the attached electronics can be evaluated ...

  5. Fabrics and deformational mechanisms in the high-pressure granulite of the Bacariza Formation (Cabo Ortegal Complex, NW Spain); Fabricas y mecanismos deformacionales en las granulitas de alta presion de la Formacion Bacariza (Complejo de Cabo Ortegal, NO de Espana)

    Energy Technology Data Exchange (ETDEWEB)

    Puelles, P.

    2009-07-01

    In the Cabo Ortegal Complex, mylonitic high-pressure granulites occur at the contacts between the HP granulitic Bacariza Formation and the adjacent units. This mylonitic stage is associated with the initial exhumation of the complex. The petrographic, microstructural and crystallographic analysis of the main constituent minerals in these rocks might provide valuable information on the deformation mechanisms operative at depth. Garnet accommodated part of the deformation by dislocation creep and rigid rotation, augite underwent dislocation creep accompanied by mass transfer and anisotropic growth while plagioclase, in turn, suffered dynamic subgrain rotation-recrystallization and climb-accommodated dislocation creep. Quartz fabrics developed under at least amphibolite-facies conditions. The shear sense criteria are consistent with a top-to-the-NE displacement of the hanging wall blocks. During their ascent to the surface, a static amphibolite-facies retrogressive stage was followed by plastic deformation accommodation under green schist- to lower amphibolite facies conditions. Deformation during the latest stages of exhumation was characterized by micro fracturing and seismic activity in conditions of high differential stresses and strain rates. (Author) 52 refs.

  6. Semi-solid electrodes having high rate capability

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Yet-Ming; Duduta, Mihai; Holman, Richard; Limthongkul, Pimpa; Tan, Taison

    2017-11-28

    Embodiments described herein relate generally to electrochemical cells having high rate capability, and more particularly to devices, systems and methods of producing high capacity and high rate capability batteries having relatively thick semi-solid electrodes. In some embodiments, an electrochemical cell includes an anode, a semi-solid cathode that includes a suspension of an active material and a conductive material in a liquid electrolyte, and an ion permeable membrane disposed between the anode and the cathode. The semi-solid cathode has a thickness in the range of about 250 .mu.m-2,500 .mu.m, and the electrochemical cell has an area specific capacity of at least 5 mAh/cm.sup.2 at a C-rate of C/2.

  7. Structural developments in un-stabilized ultra low carbon steel during warm deformation and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Unnikrishnan, Rahul, E-mail: rahulunnikrishnannair@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Kumar, Amit, E-mail: chaudhary65amit@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Khatirkar, Rajesh K., E-mail: rajesh.khatirkar@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Shekhawat, Satish K., E-mail: satishshekhawat@gmail.com [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay (IITB), Powai, Mumbai 400076, Maharashtra (India); Sapate, Sanjay G., E-mail: sgsapate@yahoo.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India)

    2016-11-01

    In the present investigation, ultra low carbon steel samples were deformed in plane strain compression mode in a deformation simulator. The deformation was carried out at four different temperatures in the warm rolling region (293, 473, 673 and 873 K) upto 70% strain at two different strain rates (0.1/s and 1/s). Subsequently, all the deformed samples were fully recrystallized at 1073 K. Afterwards, all the deformed and fully recrystallized samples were subjected to detailed microstructural characterization using optical microscope, scanning electron microscope and electron backscattered diffraction. Bulk texture was measured for all the samples by X-ray diffraction. In-grain misorientation developments (kernel average misorientations) were estimated for the deformed γ-fibre (ND//<111>) and α-fibre (RD//<110>). Deformed γ-fibre showed an increase in in-grain misorientation at intermediate deformation temperatures. This increase was explained by using the plastic instability criterion. After complete recrystallization, the γ-fibre strengthened for deformation at lower temperatures (293 K and 473 K), while Goss texture developed for samples deformed at higher temperatures (673 K and 873 K). - Highlights: • ULC steel samples were deformed in near plane strain condition. • Microstructural developments were characterized using EBSD. • Increase in in-grain misorientation at intermediate deformation temperatures. • γ-fibre strengthened for low temperature deformation. • Goss texture developed for high temperature deformation.

  8. Glacio-tectonic thrust and deformation structures in the Vejle Fjord, Denmark revealed by high-resolution subbottom-profile data

    DEFF Research Database (Denmark)

    Andresen, Katrine Juul; Boldreel, Lars Ole; Wahlgreen, Katrine Bak

    Surface geomorphological features and partial cliff exposures up till now represent the predominant source of information of glaciation related deformation in Denmark. In this study we apply high-resolution marine reflection seismic data from the Vejle Fjord area, supported by gravity and Rumohr...... coring, to document intense glacio-tectonic deformation in the shallow subsurface of Denmark. The subbottom profiler seismic data have a peak frequency around 13 kHz and a vertical resolution in the order of 10-20 cm. The data reveal several variations of glacio-tectonic deformation structures, primarily...... movements from outcrops and shallow cores. The subbottom profiler data provides larger (longer and deeper) sectional views on for instance deformation and deposition complexes related to ice progressions and retreats and thus represents a very good supplement and valuable input to field mapping and outcrops...