WorldWideScience

Sample records for plastic strain energy

  1. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...... element solution method is presented, which delivers the slip-rate field and the velocity-field based on two minimum principles. Some plane deformation problems relevant for certain specific orientations of a face centered cubic crystal under plane loading conditions are studied, and effective in......-plane parameters are developed based on the crystallographic properties of the material. The problem of cyclic shear of a single crystal between rigid platens is studied as well as void growth of a cylindrical void....

  2. Computational strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...... oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale....

  3. A strain gradient plasticity theory with application to wire torsion

    KAUST Repository

    Liu, J. X.; El Sayed, Tamer S.

    2014-01-01

    Based on the framework of the existing strain gradient plasticity theories, we have examined three kinds of relations for the plastic strain dependence of the material intrinsic length scale, and thus developed updated strain gradient plasticity

  4. What is behind the plastic strain rate?

    NARCIS (Netherlands)

    Hütter, M.; Grmela, M.; Öttinger, H.C.

    2009-01-01

    The plastic strain rate plays a central role in macroscopic models on elasto-viscoplasticity. In order to discuss the concept behind this quantity, we propose, first, a kinetic toy model to describe the dynamics of sliding layers representative of plastic deformation of single crystalline metals.

  5. On fracture in finite strain gradient plasticity

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof

    2016-01-01

    In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields are invest......In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields...... are investigated. Differences and similarities between the two approaches within continuum SGP modeling are highlighted and discussed. Local strain hardening promoted by geometrically necessary dislocations (GNDs) in the vicinity of the crack leads to much higher stresses, relative to classical plasticity...... in the multiple parameter version of the phenomenological SGP theory. Since this also dominates the mechanics of indentation testing, results suggest that length parameters characteristic of mode I fracture should be inferred from nanoindentation....

  6. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2002-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter...

  7. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter...... the tangent moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that is at odds with what is expected from a strain gradient theory....... The findings raise questions about the physical acceptability of this class of strain gradient theories....

  8. Influence of plastic strain on deformation-induced martensitic transformations

    NARCIS (Netherlands)

    Perdahcioglu, Emin Semih; Geijselaers, Hubertus J.M.; Groen, M.

    2008-01-01

    The effects of plastic strain on deformation-induced martensitic transformations have been investigated experimentally. Austenitic metastable stainless steel samples were heated to a temperature at which the transformation is suppressed and were plastically strained to different amounts. The

  9. An incremental flow theory for crystal plasticity incorporating strain gradient effects

    DEFF Research Database (Denmark)

    Nellemann, Christopher; Niordson, Christian Frithiof; Nielsen, Kim Lau

    2017-01-01

    The present work investigates a new approach to formulating a rate-independent strain gradient theory for crystal plasticity. The approach takes as offset recent discussions published in the literature for isotropic plasticity, and a key ingredient of the present work is the manner in which...... a gradient enhanced effective slip measure governs hardening evolution. The effect of both plastic strains and plastic strain gradients are combined into this scalar effective slip quantity, the energy associated with plastic strain is dissipative (unrecoverable), while the energy from plastic strain...... gradients is recoverable (free). The framework developed forms the basis of a finite element implementation and is demonstrated on benchmark problems designed to bring out effects such as strengthening and hardening. Monotonic loading and plane strain deformation is assumed throughout, but despite this, non...

  10. Influence of the Martensitic Transformation on the Microscale Plastic Strain Heterogeneities in a Duplex Stainless Steel

    Science.gov (United States)

    Lechartier, Audrey; Martin, Guilhem; Comby, Solène; Roussel-Dherbey, Francine; Deschamps, Alexis; Mantel, Marc; Meyer, Nicolas; Verdier, Marc; Veron, Muriel

    2017-01-01

    The influence of the martensitic transformation on microscale plastic strain heterogeneity of a duplex stainless steel has been investigated. Microscale strain heterogeneities were measured by digital image correlation during an in situ tensile test within the SEM. The martensitic transformation was monitored in situ during tensile testing by high-energy synchrotron X-ray diffraction. A clear correlation is shown between the plasticity-induced transformation of austenite to martensite and the development of plastic strain heterogeneities at the phase level.

  11. Strain gradient effects on cyclic plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Legarth, Brian Nyvang

    2010-01-01

    Size effects on the cyclic shear response are studied numerically using a recent higher order strain gradient visco-plasticity theory accounting for both dissipative and energetic gradient hardening. Numerical investigations of the response under cyclic pure shear and shear of a finite slab between...... rigid platens have been carried out, using the finite element method. It is shown for elastic–perfectly plastic solids how dissipative gradient effects lead to increased yield strength, whereas energetic gradient contributions lead to increased hardening as well as a Bauschinger effect. For linearly...... hardening materials it is quantified how dissipative and energetic gradient effects promote hardening above that of conventional predictions. Usually, increased hardening is attributed to energetic gradient effects, but here it is found that also dissipative gradient effects lead to additional hardening...

  12. Energy recovery from plastic wastes

    Energy Technology Data Exchange (ETDEWEB)

    Baur, A; Atzger, J

    1983-07-01

    The conversion of plastic wastes to energy is suggested as a practicable and advantageous alternative to recycling. A two-stage pilot gasification plant for the pyrolysis of wastes is described and the utilization of the resulting fuel gas discussed.

  13. Plastic strain and flux jumps in hard and composite superconductors

    International Nuclear Information System (INIS)

    Maksimov, I.L.; Mints, R.G.

    1981-01-01

    A study is made into the effect of the critical current density dependence upon the value of plastic strain on the critical state stability in hard and composite superconductors under conditions of plastic yield of the material. Criteria of the critical state stability relative to the jointly developing magnetic flux jumps and plastic strain jerks, are found. (author)

  14. Finite element analysis of a finite-strain plasticity problem

    International Nuclear Information System (INIS)

    Crose, J.G.; Fong, H.H.

    1984-01-01

    A finite-strain plasticity analysis was performed of an engraving process in a plastic rotating band during the firing of a gun projectile. The aim was to verify a nonlinear feature of the NIFDI/RB code: plastic large deformation analysis of nearly incompressible materials using a deformation theory of plasticity approach and a total Lagrangian scheme. (orig.)

  15. Plastic strain caused by contraction of pores in polycrystalline graphites

    International Nuclear Information System (INIS)

    Ioka, Ikuo; Yoda, Shinichi; Konishi, Takashi.

    1989-01-01

    The effects of porosity on mechanical properties and deformation behavior of four isotropic polycrystalline graphites were studied. The pore size distributions of the graphites were measured using a conventional mercury penetration technique. The average pore radius of ISO-88 graphite was about one-tenth of that of ISEM-1, IG-11 or IG-15 graphites. Young's modulus of the graphites decreased with increasing porosity. The stress-strain curve of each graphite was measured in its lateral and axial directions. Young's modulus of graphite decreased with increasing load. The plastic strain at a given compressive load was calculated from the stress-strain curve and the initial gradient of the unloading curve at the load. The ratio of lateral plastic strain to axial plastic strain for the graphites was less than 0.5, indicating that the volume of the graphites decreased during compressive loading. By assuming that the volume change was caused by contraction of pores, plastic strain associated with contraction of pores was calculated from the axial plastic strain and lateral plastic strain by slips along the basal planes. The plastic strain increased with increasing axial plastic strain and porosity of graphite. (author)

  16. Effect of plastic strain on fracture strength of cracked components

    International Nuclear Information System (INIS)

    Kamaya, Masayuki

    2009-01-01

    Nuclear power plant components are occasionally subjected to large load by earthquake and may suffer plastic strain. Although the plastic strain induced in materials increases the strength, it may reduce the fracture toughness due to a crack in the components. In this study, the effect of the plastic strain on strength of cracked components was investigated. Firstly, the change in the tensile properties and fracture toughness due to plastic strain were examined for Type 316 stainless steel and carbon steel (SM490). The degree of nominal plastic strain was 5%, 10%, 20% and 40% (only for stainless steel). Secondly, the J-integral values of surface crack on a pipe were evaluated by finite element analyses. Finally, the critical load for fracture of the cracked pipe was evaluated for various pipe and crack geometries using the J-integral values and the fracture toughness obtained. It was concluded that the plastic strain enhances the fracture strength of the cracked components when the induced plastic strain is less than 10%, although the extremely large plastic strain could reduce the strength. (author)

  17. Effect of plastic strain on fracture strength of cracked components

    International Nuclear Information System (INIS)

    Kamaya, Masayuki

    2010-01-01

    Nuclear power plant components are occasionally subjected to excessive load by earthquake and may suffer plastic strain. Although the plastic strain introduced in materials increases the strength, it may reduce the fracture toughness. In this study, the effect of the plastic strain on strength of cracked components was investigated. Firstly, the change in the tensile properties and fracture toughness due to plastic strain were examined for Type 316 stainless steel and carbon steel (SM 490). The degree of nominal plastic strain was 5%, 10%, 20% and 40% (only for stainless steel). Secondly, the J-integral values of surface crack on a pipe were evaluated by finite element analyses. Finally, the critical load for fracture of the cracked pipe was evaluated for various pipe and crack geometries using the J-integral values and the fracture toughness obtained. It was concluded that the plastic strain enhances the fracture strength of the cracked components when the induced plastic strain is less than 10%, although the extremely large plastic strain could reduce the strength. (author)

  18. Strain gradient plasticity effects in whisker-reinforced metals

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2002-01-01

    A metal reinforced by fibers in the micron range is studied using the strain gradient plasticity theory of Fleck and Hutchinson (2001). Cell-model analyzes are used to study the influence of the material length parameters numerically. Different higher order boundary conditions are considered...... at the fiber-matrix interface. The results are presented as overall stress-strain curves for the whisker-reinforced metal, and also contour plots of effective plastic strain are shown. The strain gradient plasticity theory predicts a significant stiffening effect when compared to conventional models...

  19. Strain gradient crystal plasticity effects on flow localization

    DEFF Research Database (Denmark)

    Borg, Ulrik

    2007-01-01

    for metals described by the reformulated Fleck-Hutchinson strain gradient plasticity theory. The theory is implemented numerically within a finite element framework using slip rate increments and displacement increments as state variables. The formulation reduces to the classical crystal plasticity theory...... in the absence of strain gradients. The model is used to study the effect of an internal material length scale on the localization of plastic flow in shear bands in a single crystal under plane strain tension. It is shown that the mesh sensitivity is removed when using the nonlocal material model considered...

  20. Fracture of anisotropic materials with plastic strain-gradient effects

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang

    2013-01-01

    A unit cell is adopted to numerically analyze the effect of plastic anisotropy on frac-ture evolution in a micro-reinforced fiber-composite. The matrix material exhibit size-effects and an anisotropic strain-gradient plasticity model accounting for such size-effects through a mate-rial length scale...

  1. Strain path dependency in metal plasticity

    NARCIS (Netherlands)

    Viatkina, E.M.; Brekelmans, W.A.M.; Geers, M.G.D.

    2003-01-01

    A change in strain path has a significant effect on the mechanical response of metals. Strain path change effects physically originate from a complex microstructure evolution. This paper deals with the contribution of cell structure evolution to the strain path change effect. The material with cells

  2. A strain gradient plasticity theory with application to wire torsion

    KAUST Repository

    Liu, J. X.

    2014-06-05

    Based on the framework of the existing strain gradient plasticity theories, we have examined three kinds of relations for the plastic strain dependence of the material intrinsic length scale, and thus developed updated strain gradient plasticity versions with deformation-dependent characteristic length scales. Wire torsion test is taken as an example to assess existing and newly built constitutive equations. For torsion tests, with increasing plastic strain, a constant intrinsic length predicts too high a torque, while a decreasing intrinsic length scale can produce better predictions instead of the increasing one, different from some published observations. If the Taylor dislocation rule is written in the Nix-Gao form, the derived constitutive equations become singular when the hardening exponent gets close to zero, which seems questionable and calls for further experimental clarifications on the exact coupling of hardening due to statistically stored dislocations and geometrically necessary dislocations. Particularly, when comparing the present model with the mechanism-based strain gradient plasticity, the present model satisfies the reciprocity relation naturally and gives different predictions even under the same parameter setting. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  3. Fatique of Copper Polycrystals at Low Plastic Strain Amplitudes

    DEFF Research Database (Denmark)

    Rasmussen, K. V.; Pedersen, Ole Bøcker

    1980-01-01

    Single crystals and polycrystals of pure copper were fatigued in tension-compression at constant low amplitudes of plastic strain and low cycling frequencies at room temperature in air. Surface patterns of persistent slip bands were quantitatively examined by optical microscopy. Bulk dislocation...

  4. Strain gradient plasticity effects in whisker-reinforced metals

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2003-01-01

    A metal reinforced by fibers in the micron range is studied using the strain gradient plasticity theory of Fleck and Hutchinson (J. Mech. Phys. Solids 49 (2001) 2245). Cell-model analyses are used to study the influence of the material length parameters numerically, for both a single parameter...

  5. Stress-strain response of plastic waste mixed soil.

    Science.gov (United States)

    Babu, G L Sivakumar; Chouksey, Sandeep Kumar

    2011-03-01

    Recycling plastic waste from water bottles has become one of the major challenges worldwide. The present study provides an approach for the use plastic waste as reinforcement material in soil. The experimental results in the form of stress-strain-pore water pressure response are presented. Based on experimental test results, it is observed that the strength of soil is improved and compressibility reduced significantly with addition of a small percentage of plastic waste to the soil. The use of the improvement in strength and compressibility response due to inclusion of plastic waste can be advantageously used in bearing capacity improvement and settlement reduction in the design of shallow foundations. Copyright © 2010 Elsevier Ltd. All rights reserved.

  6. A new macroscopically anisotropic pressure dependent yield function for metal matrix composite based on strain gradient plasticity for the microstructure

    DEFF Research Database (Denmark)

    Azizi, Reza; Legarth, Brian Nyvang; Niordson, Christian Frithiof

    2013-01-01

    Metal matrix composites with long aligned elastic fibers are studied using an energetic rate independent strain gradient plasticity theory with an isotropic pressure independent yield function at the microscale. The material response is homogenized to obtain a conventional macroscopic model...... is investigated numerically using a unit cell model with periodic boundary conditions containing a single fiber deformed under generalized plane strain conditions. The homogenized response can be modeled by conventional plasticity with an anisotropic yield surface and a free energy depending on plastic strain...

  7. Shear banding in large strain plasticity - Influence of specimen dimensions

    Science.gov (United States)

    Mucha, Marzena; Wcisło, Balbina; Pamin, Jerzy

    2018-01-01

    The paper deals with numerical analysis of shear banding which occurs in an elongated rectangular plate for a large strain elastic-plastic material model. It is focused on the influence of plate size proportions and finite element mesh density on numerical results. The discussion is limited to isothermal conditions and ideal plasticity. First a plain strain case is computed for different lengths of the plate, then simulations are repeated for plane stress for which different thicknesses of the plate are considered. Most of the computations are performed for three finite element meshes to verify discretization sensitivity of the results. The simulations are performed using AceGen and AceFEM packages for Wolfram Mathematica.

  8. The behavior of intermetallic compounds at large plastic strains

    International Nuclear Information System (INIS)

    Gray, G.T.; Embury, J.D.

    1993-01-01

    This paper contains a summary of a broad study of intermetallics which includes the following materials, Ni 3 Al, Ti-48Al-1V, Ti-24Al-11Nb, Ti-48Al-2Cr-2Nb, and Ti-24.5 Al-10.5Nb-1.5Mo. Much effort has been devoted to the study of ordered materials at modes plastic strains and the problem of premature failure. However by utilizing stress states other than simple tension it is possible to study the deformation of intermetallic compounds up to large plastic strains and to consider the behavior of these materials in the regime where stresses approach the theoretical stress. The current work outlines studies of the work hardening rate of a number of titanium and nickel-based intermetallic compounds deformed in compression. Attention is given to the structural basis of the sustained work hardening. The large strain plasticity of these materials is summarized in a series of diagrams. Fracture in these materials in compression occurs via catastrophic shear at stresses of the order of E/80 (where E is the elastic modulus)

  9. 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

  10. Mechanisms of large strain, high strain rate plastic flow in the explosively driven collapse of Ni-Al laminate cylinders

    International Nuclear Information System (INIS)

    Olney, K L; Chiu, P H; Nesterenko, V F; Higgins, A; Serge, M; Weihs, T P; Fritz, G; Stover, A; Benson, D J

    2014-01-01

    Ni-Al laminates have shown promise as reactive materials due to their high energy release through intermetallic reaction. In addition to the traditional ignition methods, the reaction may be initiated in hot spots that can be created during mechanical loading. The explosively driven thick walled cylinder (TWC) technique was performed on two Ni-Al laminates composed of thin foil layers with different mesostructues: concentric and corrugated. These experiments were conducted to examine how these materials accommodate large plastic strain under high strain rates. Finite element simulations of these specimens with mesostuctures digitized from the experimental samples were conducted to provide insight into the mesoscale mechanisms of plastic flow. The dependence of dynamic behaviour on mesostructure may be used to tailor the hot spot formation and therefore the reactivity of the material system.

  11. Linking strain anisotropy and plasticity in copper metallization

    International Nuclear Information System (INIS)

    Murray, Conal E.; Jordan-Sweet, Jean; Priyadarshini, Deepika; Nguyen, Son

    2015-01-01

    The elastic anisotropy of copper leads to significant variation in the x-ray elastic constants (XEC), which link diffraction-based strain measurements to stress. An accurate depiction of the mechanical response in copper thin films requires a determination of an appropriate grain interaction model that lies between Voigt and Reuss limits. It is shown that the associated XEC weighting fraction, x*, between these limits provides a metric by which strain anisotropy can be quantified. Experimental values of x*, as determined by a linear regression scheme of diffraction data collected from multiple reflections, reveal the degree of strain anisotropy and its dependence on plastic deformation induced during in-situ and ex-situ thermal treatments

  12. Analytic examination of mechanism for compressive residual stress introduction with low plastic strain using peening

    International Nuclear Information System (INIS)

    Ishibashi, Ryo; Hato, Hisamitsu; Miyazaki, Katsumasa; Yoshikubo, Fujio

    2016-01-01

    Our goal for this study was to understand the cause of the differences in surface properties between surfaces processed using water jet peening (WJP) and shot peening (SP) and to examine the compressive residual stress introduction process with low plastic strain using SP. The dynamic behaviors of stress and strain in surfaces during these processes were analyzed through elasto-plastic calculations using a finite-element method program, and the calculated results were compared with measured results obtained through experiments. Media impacting a surface results in a difference in the hardness and microstructure of the processed surface. During SP, a shot deforms the surface locally with stress concentration in the early stages of the impact, while shock waves deform the surface evenly throughout the wave passage across the surface during WJP. A shot with a larger diameter creates a larger impact area on the surface during shot impact. Thus, SP with a large-diameter shot suppresses the stress concentration under the same kinetic energy condition. As the shot diameter increases, the equivalent plastic strain decreases. On the other hand, the shot is subject to size restriction since the calculated results indicate the compressive residual stress at the surface decreased and occasionally became almost zero as the shot diameter increased. Thus, compressive residual stress introduction with low plastic strain by using SP is considered achievable by using shots with a large diameter and choosing the appropriate peening conditions. (author)

  13. Application of the strain energy for fatigue life prediction (LCF) of metals by the energy-based criterion

    International Nuclear Information System (INIS)

    Shahram Shahrooi; Ibrahim Henk Metselaar; Zainul Huda; Ghezavati, H.R.

    2009-01-01

    Full text: In this study, the plastic strain energy under multiaxial fatigue condition has been calculated in the cyclic plasticity models by the stress-strain hysteresis loops. Then, using the results of these models, the fatigue lives in energy-based fatigue model is predicted and compared to experimental data. Moreover, a weighting factor on shear plastic work is presented to decrease the life factors in the model fatigue. (author)

  14. Metallic nanomaterials formed by exerting large plastic strains

    International Nuclear Information System (INIS)

    Richert, M; Richert, J.; Zasadzinski, J.; Hawrylkiewicz, S.

    2002-01-01

    The investigations included pure Al and Cu single crystals, AlMg5 alloy and AlCuZr alloy have been presented. The materials were deformed by the cyclic extrusion compression method (CEC) within the range of true strains φ = 0.4-59.8 (1 to 67 deformation cycles by the CEC method). In all examined materials a strong tendency to form banded was observed. Within the range of very large plastic strains there was observed intensive rebuilding of the banded microstructure into subgrains, at first of rhombic shape, and next into equiaxial subgrains. A characteristic feature of the newly formed subgrains, not encountered in the range of conventional deformations, was the occurrence of large misorientation angles between the newly formed subgrains. The proportion of large misorientation angles in the microstructure varied, and it increased with increasing deformation. Reduction of the recovery process in AlMg5 and AlCuZr alloys preserved the growth of the newly formed nanograins, favoring the retaining of the nanomeric dimensions. This results show that there is the effective possibility of production of metallic nanomaterials by exerting of very large nonconventional plastic strains. (author)

  15. Clay behaviour under thermal gradients elastic and plastic strains

    International Nuclear Information System (INIS)

    Pintado, Xavier; Autio, Jorma; Punkkinen, Olli

    2010-01-01

    Document available in extended abstract form only. The nuclear waste repositories will generate strong temperature gradients at the clay barrier. The heat and water transport generate volume change in the clay. An experimental work is proposed here. The clay reference is the MX-80. The test device imposes a fixed heat flow in one side of the sample and maintains constant the temperature on the other side. Two samples are tested for symmetry. The samples are unconfined and the total mass of water remains constant. This situation creates a strong thermal gradient in the samples. The final radial strains in some places of the sample, the total vertical strain and the water content distribution will be measured just at the end of the test and some weeks later in order to distinguish the elastic strains from the plastic strains. The test period mustn't be longer than two weeks because a large quantity of water loses through the rubber membrane and the heads of the sample. The maximum temperature reached in the cooper is 90 degrees because with higher temperature, the rubber membrane is damaged. This test is already simulated by a numerical code. Thermal, thermo-hydraulic and thermo-hydro-mechanical analyses are being done. These analyses allow studying the different fluxes inside the sample and its quantification. Water content distribution is compared with the water content calculated from the reference parameters in the clay. The water distribution and the change of diameter after the test will also be studied. This experimental work will allow to know what is the percentage of the strains elastic or plastic and check the mechanical model. The experimental diameter change is compared with the diameter change calculated from the reference parameters of the clay. (authors)

  16. On the homogenization of metal matrix composites using strain gradient plasticity

    DEFF Research Database (Denmark)

    Azizi, Reza; Niordson, Christian Frithiof; Legarth, Brian Nyvang

    2014-01-01

    The homogenized response of metal matrix composites (MMC) is studied using strain gradient plasticity. The material model employed is a rate independent formulation of energetic strain gradient plasticity at the micro scale and conventional rate independent plasticity at the macro scale. Free...

  17. Finite strain logarithmic hyperelasto-plasticity with softening: a strongly non-local implicit gradient framework

    NARCIS (Netherlands)

    Geers, M.G.D.

    2004-01-01

    This paper addresses the extension of a Eulerian logarithmic finite strain hyperelasto-plasticity model in order to incorporate an isotropic plastic damage variable that leads to softening and failure of the plastic material. It is shown that a logarithmic elasto-plastic model with a strongly

  18. A new approach for elasto-plastic finite strain analysis of cantilever ...

    Indian Academy of Sciences (India)

    A new approach for elasto-plastic finite strain analysis of cantilever beams subjected to uniform bending moment ... Curvature; deflection curve; cantilever beam; elasto-plastic analysis; tapered beam subjected to tipmoment; ... Sadhana | News.

  19. Effect of transient change in strain rate on plastic flow behaviour of ...

    Indian Academy of Sciences (India)

    Steels; stress–strain measurement; plastic flow; mechanical properties; metallurgy. Abstract. Plastic flow behaviour of low carbon steel has been studied at room temperature during tensile deformation by ... Bulletin of Materials Science | News.

  20. Investigation of grain subdivision at very low plastic strains in a magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hong, X. [Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Godfrey, A., E-mail: awgodfrey@mail.tsinghua.edu.cn [Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zhang, C.L.; Liu, W. [Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Chapuis, A. [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China)

    2017-05-02

    In-situ tensile loading combined with electron backscatter diffraction (EBSD) measurements has been used to investigate the plastic deformation of a magnesium alloy. A novel EBSD mapping is presented, based on construction of maps showing the rotation axis component in the sample coordinate frame of the misorientation from each pixel to the average grain orientation in the deformed sample. Using this mapping it is shown that the pattern of grain subdivision, even at very low plastic strains, can be revealed simultaneously in a large number of grains. In addition, it is demonstrated how maps of the rotation axis corresponding to the misorientation between each pixel and the initial grain orientation provide complimentary information directly useful for crystal plasticity analysis. A detailed slip system analysis shows that the grain subdivision can be accounted for according to the low energy dislocation structures (LEDS) model of work-hardening by differences in the slip amplitudes within different parts of each grain.

  1. On higher-order boundary conditions at elastic-plastic boundaries in strain-gradient plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2008-01-01

    are suppressed by using a very high artificial hardening modulus. Through numerical studies of pure bending under plane strain conditions, it is shown that this method predicts the build-up of higher order stresses in the pseudo-elastic regime. This has the effect of delaying the onset of incipient yield......, as well as extending the plastic zone further toward the neutral axis of the beam, when compared to conventional models. Arguments supporting the present method are presented that rest on both mathematical and physical grounds. The results obtained are compared with other methods for dealing with higher...

  2. Effect of cyclic plastic pre-strain on low cycle fatigue life

    International Nuclear Information System (INIS)

    Kanno, Satoshi; Nakane, Motoki; Yorikawa, Morio; Takagi, Yoshio

    2010-01-01

    In order to evaluate structural integrity of nuclear components subjected large seismic load which produce locally plastic strain, low cycle fatigue life was examined using cyclic plastic pre-strained materials of austenitic steel (SUS316, SUS316L, SUS304TP: JIS (Japanese Industrial Standards)) and ferritic steel (SFVQ1A, STS480, STPT410, SFVC2B, SS400: JIS). It was not found that cyclic plastic pre-strain up to range of 16%, 2.5 times affected on low cycle fatigue life. The validity of existing procedure of fatigue life estimation based on usage factor was confirmed when large seismic load brought nuclear materials cyclic plastic strain. (author)

  3. An alternative treatment of phenomenological higher-order strain-gradient plasticity theory

    DEFF Research Database (Denmark)

    Kuroda, Mitsutoshi; Tvergaard, Viggo

    2010-01-01

    strain is discussed, applying a dislocation theory-based consideration. Then, a differential equation for the equivalent plastic strain-gradient is introduced as an additional governing equation. Its weak form makes it possible to deduce and impose extra boundary conditions for the equivalent plastic...... strain. A connection between the present treatment and strain-gradient theories based on an extended virtual work principle is discussed. Furthermore, a numerical implementation and analysis of constrained simple shear of a thin strip are presented....

  4. Plastic Strain Induced Damage Evolution and Martensitic Transformation in Ductile Materials at Cryogenic Temperatures

    CERN Document Server

    Garion, C

    2002-01-01

    The Fe-Cr-Ni stainless steels are well known for their ductile behaviour at cryogenic temperatures. This implies development and evolution of plastic strain fields in the stainless steel components subjected to thermo-mechanical loads at low temperatures. The evolution of plastic strain fields is usually associated with two phenomena: ductile damage and strain induced martensitic transformation. Ductile damage is described by the kinetic law of damage evolution. Here, the assumption of isotropic distribution of damage (microcracks and microvoids) in the Representative Volume Element (RVE) is made. Formation of the plastic strain induced martensite (irreversible process) leads to the presence of quasi-rigid inclusions of martensite in the austenitic matrix. The amount of martensite platelets in the RVE depends on the intensity of the plastic strain fields and on the temperature. The evolution of the volume fraction of martensite is governed by a kinetic law based on the accumulated plastic strain. Both of thes...

  5. The effect of plastic strain on the evolution of crystallographic texture in Zircaloy-2

    International Nuclear Information System (INIS)

    Ballinger, R.G.; Lucas, G.E.; Pelloux, R.M.

    1984-01-01

    The evolution of crystallographic texture during plastic deformation was investigated in Zircaloy-2 using X-ray and metallographic techniques. Inverse pole figures, the resolved fraction of basal poles, and the volume fraction of twinned material, were determined as a function of plastic strain for several strain paths and initial textures at 298 K and 623 K. Incremental transverse platic strain ratios (R) were measured as a function of plastic strain. Texture rotation occurs early in the deformation process, after as little as 1.5% plastic strain. For compressive plastic strains, the resolved fraction of basal poles increases in the direction parallel to the strain axis. For tensile plastic strains, the resolved fraction of basal poles decreases in the direction parallel to the strain axis. The rate of change of the resolved fraction of basal poles with plastic strain is a function of the initial resolved fraction of basal poles. The texture rotation can be explained by considering the operating of the principal tensile twinning systems, [10anti 12], . (orig.)

  6. Effect of plastic strain on the evolution of crystallographic texture in Zircaloy-2

    Energy Technology Data Exchange (ETDEWEB)

    Ballinger, R.G. (Massachusetts Inst. of Tech., Cambridge (USA)); Lucas, G.E. (California Univ., Santa Barbara (USA)); Pelloux, R.M. (Massachusetts Inst. of Tech., Cambridge (USA). Dept. of Materials Science and Engineering)

    1984-09-01

    The evolution of crystallographic texture during plastic deformation was investigated in Zircaloy-2 using X-ray and metallographic techniques. Inverse pole figures, the resolved fraction of basal poles, and the volume fraction of twinned material, were determined as a function of plastic strain for several strain paths and initial textures at 298 K and 623 K. Incremental transverse platic strain ratios (R) were measured as a function of plastic strain. Texture rotation occurs early in the deformation process, after as little as 1.5% plastic strain. For compressive plastic strains, the resolved fraction of basal poles increases in the direction parallel to the strain axis. For tensile plastic strains, the resolved fraction of basal poles decreases in the direction parallel to the strain axis. The rate of change of the resolved fraction of basal poles with plastic strain is a function of the initial resolved fraction of basal poles. The texture rotation can be explained by considering the operating of the principal tensile twinning systems, (10anti 12), .

  7. The effect of plastic strain on the evolution of crystallographic texture in Zircaloy-2

    Science.gov (United States)

    Ballinger, R. G.; Lucas, G. E.; Pelloux, R. M.

    1984-09-01

    The evolution of crystallographic texture during plastic deformation was investigated in Zircaloy-2 using X-ray and metallographic techniques. Inverse pole figures, the resolved fraction of basal poles, and the volume fraction of twinned material, were determined as a function of plastic strain for several strain paths and initial textures at 298 K and 623 K. Incremental transverse platic strain ratios ( R) were mesured as a function of plastic strain. Texture rotation occurs early in the deformation process, after as little as 1.5% plastic strain. For compressive plastic strains, the resolved fraction of basal poles increases in the direction parallel to the strain axis. For tensile plastic strains, the resolved fraction of basal poles decreases in the direction parallel to the strain axis. The rate of change of the resolved fraction of basal poles with plastic strain is a function of the initial resolved fraction of basal poles. The texture rotation can be explained by considering the operation of the principal tensile twinning systems, {101¯2}.

  8. 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

  9. Energetic dislocation interactions and thermodynamical aspects of strain gradient crystal plasticity theories

    NARCIS (Netherlands)

    Ertürk, I.; Dommelen, van J.A.W.; Geers, M.G.D.

    2009-01-01

    This paper focuses on the unification of two frequently used and apparently different strain gradient crystal plasticity frameworks: (i) the physicallymotivated strain gradient crystal plasticity models proposed by Evers et al. (2004a,b) and Bayley et al. (2006, 2007) (here referred to as

  10. Plastic strain accumulation during asymmetric cyclic loading of Zircaloy-2 at room temperature

    International Nuclear Information System (INIS)

    Rajpurohit, R.S.; Santhi Srinivas, N.C.; Singh, Vakil

    2016-01-01

    Asymmetric cyclic loading leads to accumulation of cyclic plastic strain and reduces the fatigue life of components. This phenomenon is known as ratcheting fatigue. Zircaloy-2 is a important structural material in nuclear reactors and used as pressure tubes and fuel cladding in pressurized light and heavy water nuclear reactors. Due to power fluctuations, these components experience plastic strain cycles in the reactor and their life is reduced due to strain cycles. Power fluctuations also cause asymmetric straining of the material and leads to accumulation of plastic strain. The present investigation deals with the effect of the magnitude of mean stress, stress amplitude and stress rate on hardening/softening behavior of Zircaloy-2 under asymmetric cyclic loading, at room temperature. It was observed that plastic strain accumulation increased with mean stress and stress amplitude; however, it decreased with stress rate. (author)

  11. Stress and strain fluctuations in plastic deformation of crystals with disordered microstructure

    International Nuclear Information System (INIS)

    Kapetanou, O; Zaiser, M; Weygand, D

    2015-01-01

    We investigate the spatial structure of stress and strain patterns in crystal plasticity. To this end, we combine theoretical arguments with plasticity simulations using three different models: (i) a generic model of bulk crystal plasticity with stochastic evolution of the local microstructure, (ii) a 2D discrete dislocation simulation assuming single-slip deformation in a bulk crystal, and (iii) a 3D discrete dislocation model for deformation of micropillars in multiple slip. For all three models we investigate the scale-dependent magnitude of local fluctuations of internal stress and plastic strain, and we determine the spatial structure of the respective auto- and cross-correlation functions. The investigations show that, in the course of deformation, nontrivial long range correlations emerge in the stress and strain patterns. We investigate the influence of boundary conditions on the observed spatial patterns of stress and strain, and discuss implications of our findings for larger-scale plasticity models. (paper)

  12. A study of microindentation hardness tests by mechanism-based strain gradient plasticity

    International Nuclear Information System (INIS)

    Huang, Y.; Xue, Z.; Gao, H.; Nix, W. D.; Xia, Z. C.

    2000-01-01

    We recently proposed a theory of mechanism-based strain gradient (MSG) plasticity to account for the size dependence of plastic deformation at micron- and submicron-length scales. The MSG plasticity theory connects micron-scale plasticity to dislocation theories via a multiscale, hierarchical framework linking Taylor's dislocation hardening model to strain gradient plasticity. Here we show that the theory of MSG plasticity, when used to study micro-indentation, indeed reproduces the linear dependence observed in experiments, thus providing an important self-consistent check of the theory. The effects of pileup, sink-in, and the radius of indenter tip have been taken into account in the indentation model. In accomplishing this objective, we have generalized the MSG plasticity theory to include the elastic deformation in the hierarchical framework. (c) 2000 Materials Research Society

  13. Calculation of elastic-plastic strain ranges for fatigue analysis based on linear elastic stresses

    International Nuclear Information System (INIS)

    Sauer, G.

    1998-01-01

    Fatigue analysis requires that the maximum strain ranges be known. These strain ranges are generally computed from linear elastic analysis. The elastic strain ranges are enhanced by a factor K e to obtain the total elastic-plastic strain range. The reliability of the fatigue analysis depends on the quality of this factor. Formulae for calculating the K e factor are proposed. A beam is introduced as a computational model for determining the elastic-plastic strains. The beam is loaded by the elastic stresses of the real structure. The elastic-plastic strains of the beam are compared with the beam's elastic strains. This comparison furnishes explicit expressions for the K e factor. The K e factor is tested by means of seven examples. (orig.)

  14. Strain-energy effects on dynamic fragmentation

    International Nuclear Information System (INIS)

    Glenn, L.A.; Chudnovsky, A.

    1986-01-01

    Grady's model of the dynamic fragmentation process, in which the average fragment size is determined by balancing the local kinetic energy and the surface energy, is modified to include the stored elastic (strain) energy. The revised model predicts that the strain energy should dominate for brittle materials, with low fracture toughness and high fracture-initiation stress. This conclusion is not borne out, however, by limited experimental data on brittle steels, even when the kinetic-energy density is small compared with the strain-energy density

  15. The role of plastic slip anisotropy in the modelling of strain path change effects

    NARCIS (Netherlands)

    Viatkina, E.M.; Brekelmans, W.A.M.; Geers, M.G.D.

    2009-01-01

    Most industrial metal forming processes are characterised by a complex strain path history. A change in strain path may have a significant effect on the mechanical response of metals. This paper concentrates on the role of the plastic slip anisotropy in the strain path dependency of materials

  16. Detection of thermal aging degradation and plastic strain damage for duplex stainless steel using SQUID sensor

    International Nuclear Information System (INIS)

    Otaka, M.; Evanson, S.; Hesegawa, K.; Takaku, K.

    1991-01-01

    An apparatus using a SQUID sensor is developed for nondestructive inspection. The measurements are obtained with the SQUID sensor located approximately 150 mm from the specimen. The degradation of thermal aging and plastic strain for duplex stainless steel is successfully detected independently from the magnetic characterization measurements. The magnetic flux density under high polarizing field is found to be independent of thermal aging. Coercive force increases with thermal aging time. On the other hand, the magnetic flux density under high field increases with the plastic strain. Coercive force is found to be independent of the plastic strain. (author)

  17. Modeling Shock Induced Plasticity in Copper Single Crystal: Numerical and Strain Localization Issues

    International Nuclear Information System (INIS)

    Shehadeh, M

    2011-01-01

    Multiscale dislocation dynamics plasticity (MDDP) simulations are carried out to address the following issues in modeling shock-induced plasticity: 1- the effect of finite element (FE) boundary conditions on shock wave characteristics and wave-dislocation interaction, 2- the effect of the evolution of the dislocation microstructure on lattice rotation and strain localization. While uniaxial strain is achieved with high accuracy using confined boundary condition, periodic boundary condition yields a disturbed wave profile due the edge effect. Including lattice rotation in the analysis leads to higher dislocation density and more localized plastic strain. (author)

  18. Plastic incompatibility stresses and stored elastic energy in plastically deformed copper

    Energy Technology Data Exchange (ETDEWEB)

    Baczmanski, A. [Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland)], E-mail: baczman@ftj.agh.edu.pl; Hfaiedh, N.; Francois, M. [LASMIS, Universite de Technologie de Troyes, 11 rue Marie Curie, B.P. 2060, 10010 Troyes (France); Wierzbanowski, K. [Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland)

    2009-02-15

    The X-ray diffraction method and theoretical model of elastoplastic deformation were used to examine the residual stresses in polycrystalline copper. To this end, the {l_brace}2 2 0{r_brace} strain pole figures were determined for samples subjected to different magnitudes of tensile deformation. Using diffraction data and the self-consistent model, the tensor of plastic incompatibility stress was found for each orientation of a polycrystalline grain. Crystallographic textures, macroscopic and second-order residual stresses were considered in the analysis. As a result, the distributions of elastic stored energy and von Mises equivalent stress were presented in Euler space and correlated with the preferred orientations of grains. Moreover, using the model prediction, the variation of the critical resolved shear stress with grain orientation was determined.

  19. Neutron-diffraction measurement of the evolution of strain for non-uniform plastic deformation

    CERN Document Server

    Rogge, R B; Boyce, D

    2002-01-01

    Neutrons are particularly adept for the validation of modeling predictions of stress and strain. In recent years, there has been a significant effort to model the evolution of both the macroscopic stresses and the intergranular stress during plastic deformation. These have had broad implications with regard to understanding the evolution of residual stress and to diffraction-based measurements of strain. Generally the modeling and associated measurements have been performed for simple uniaxial tension, leaving questions with regard to plastic deformation under multi-axial stress and non-uniform stress. Extensive measurements of the strain profile across a plastic hinge for each of a series of loading and unloading cycles to progressively higher degrees of plastic deformation are presented. These measurements are used to assess multiple-length-scale finite-element modeling (FEM) of the plastic hinge, in which the elements will range in size from single crystallites (as used in successful simulations of uniaxia...

  20. Plastic limit analysis with non linear kinematic strain hardening for metalworking processes applications

    International Nuclear Information System (INIS)

    Chaaba, Ali; Aboussaleh, Mohamed; Bousshine, Lahbib; Boudaia, El Hassan

    2011-01-01

    Limit analysis approaches are widely used to deal with metalworking processes analysis; however, they are applied only for perfectly plastic materials and recently for isotropic hardening ones excluding any kind of kinematic hardening. In the present work, using Implicit Standard Materials concept, sequential limit analysis approach and the finite element method, our objective consists in extending the limit analysis application for including linear and non linear kinematic strain hardenings. Because this plastic flow rule is non associative, the Implicit Standard Materials concept is adopted as a framework of non standard plasticity modeling. The sequential limit analysis procedure which considers the plastic behavior with non linear kinematic strain hardening as a succession of perfectly plastic behavior with yielding surfaces updated after each sequence of limit analysis and geometry updating is applied. Standard kinematic finite element method together with a regularization approach is used for performing two large compression cases (cold forging) in plane strain and axisymmetric conditions

  1. Elasto-plastic strain analysis by a semi-analytical method

    Indian Academy of Sciences (India)

    Non-uniform taper bar; rotating disk; elasto-plastic strain analysis; loaded natural frequency. ... The location of initiation of elasto-plastic front and its growth are found to be functions of geometry of the bar and loading ... Sadhana | News.

  2. CYCLIC PLASTIC BEHAVIOUR OF UFG COPPER UNDER CONTROLLED STRESS AND STRAIN LOADING

    Directory of Open Access Journals (Sweden)

    Lucie Navrátilová

    2012-01-01

    Full Text Available The influence of stress- and strain-controlled loading on microstructure and cyclic plastic behaviour of ultrafine-grained copper prepared by equal channel angular pressing was examined. The stability of microstructure is a characteristic feature for stress-controlled test whereas grain coarsening and development of bimodal structure was observed after plastic strain-controlled tests. An attempt to explain the observed behaviour was made.

  3. Plastic strain induced damage evolution and martensitic transformation in ductile materials at cryogenic temperatures

    International Nuclear Information System (INIS)

    Garion, C.; Skoczen, B.T.

    2002-01-01

    The Fe-Cr-Ni stainless steels are well known for their ductile behavior at cryogenic temperatures. This implies development and evolution of plastic strain fields in the stainless steel components subjected to thermo-mechanical loads at low temperatures. The evolution of plastic strain fields is usually associated with two phenomena: ductile damage and strain induced martensitic transformation. Ductile damage is described by the kinetic law of damage evolution. Here, the assumption of isotropic distribution of damage (microcracks and microvoids) in the Representative Volume Element (RVE) is made. Formation of the plastic strain induced martensite (irreversible process) leads to the presence of quasi-rigid inclusions of martensite in the austenitic matrix. The amount of martensite platelets in the RVE depends on the intensity of the plastic strain fields and on the temperature. The evolution of the volume fraction of martensite is governed by a kinetic law based on the accumulated plastic strain. Both of these irreversible phenomena, associated with the dissipation of plastic power, are included into the constitutive model of stainless steels at cryogenic temperatures. The model is tested on the thin-walled corrugated shells (known as bellows expansion joints) used in the interconnections of the Large Hadron Collider, the new proton storage ring being constructed at present at CERN

  4. Strain localization and elastic-plastic coupling during deformation of porous sandstone

    Energy Technology Data Exchange (ETDEWEB)

    Dewers, Thomas A. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Geomechanics Dept.; Issen, Kathleen A. [Clarkson Univ., Potsdam, NY (United States). Mechanical and Aeronautical Engineering; Holcomb, David J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Geomechanics Dept.; Olsson, William A. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Geomechanics Dept.; Ingraham, Mathew D. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Geomechanics Dept.

    2017-09-12

    Results of axisymmetric compression tests on weak, porous Castlegate Sandstone (Cretaceous, Utah, USA), covering a range of dilational and compactional behaviors, are examined for localization behavior. Assuming isotropy, bulk and shear moduli evolve as increasing functions of mean stress and Mises equivalent shear stress respectively, and as decreasing functions of work-conjugate plastic strains. Acoustic emissions events located during testing show onset of localization and permit calculation of observed shear and low-angle compaction localization zones, or bands, as localization commences. Total strain measured experimentally partitions into: A) elastic strain with constant moduli, B) elastic strain due to stress dependence of moduli, C) elastic strain due to moduli degradation with increasing plastic strain, and D) plastic strain. The third term is the elastic-plastic coupling strain, and though often ignored, contributes significantly to pre-failure total strain for brittle and transitional tests. Constitutive parameters and localization predictions derived from experiments are compared to theoretical predictions. In the brittle regime, predictions of band angles (angle between band normal and maximum compression) demonstrate good agreement with observed shear band angles. Compaction localization was observed in the transitional regime in between shear localization and spatially pervasive compaction, over a small range of mean stresses. In contrast with predictions however, detailed acoustic emissions analyses in this regime show low angle, compaction-dominated but shear-enhanced, localization.

  5. adaptation of plastic waste to energy development in lagos

    African Journals Online (AJOL)

    user

    Keywords: Plastic wastes, Energy, Sustainable development, Environment, ... countries to be rationalising energy supply to their people. .... Managing waste in Lagos is may be a herculean task in ..... uncertainties in a life cycle perspective.

  6. Plasticity dependent damage evolution in composites with strain-gradient effects

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang

    2015-01-01

    . (2013). In this study the reinforcement is assumed perfectly stiff and consequently only one new cohesive material parameter is introduced. Results are shown for both conventional isotropy as well as plastic anisotropy with higher-order material behavior. Due to fiber-matrix decohesion a sudden stress......A unit cell approach is adopted to numerically analyze the effect of reinforcement size on fracture evolution in metal matrix composites. The matrix material shows plastic size-effects and is modeled by an anisotropic version of the single parameter strain-gradient (higher-order) plasticity model...... by Fleck and Hutchinson (2001). The fracture process along the fiber-matrix interface is modeled using a recently proposed cohesive law extension, where plasticity affects the fracture process as both the average as well as the jump in plastic strain across the interface are accounted for Tvergaard et al...

  7. Hardening and strengthening behavior in rate-independent strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Nellemann, C.; Niordson, C. F.; Nielsen, K.L.

    2018-01-01

    Two rate-independent strain gradient crystal plasticity models, one new and one previously published, are compared and a numerical framework that encompasses both is developed. The model previously published is briefly outlined, while an in-depth description is given for the new, yet somewhat...... related,model. The difference between the two models is found in the definitions of the plastic work expended in the material and their relation to spatial gradients of plastic strains. The model predictions are highly relevant to the ongoing discussion in the literature, concerning 1) what governs...... the increase in the apparent yield stress due to strain gradients (also referred to as strengthening)? And 2), what is the implication of such strengthening in relation to crystalline material behavior at the micron scale? The present work characterizes material behavior, and the corresponding plastic slip...

  8. Finite element evaluation of elasto-plastic accommodation energies during solid state transformations: Coherent, spherical precipitate in finite matrix

    International Nuclear Information System (INIS)

    Sen, S.; Balasubramaniam, R.; Sethuraman, R.

    1996-01-01

    The molar volume difference between the matrix and the precipitate phases in the case of solid state phase transformations results in the creation of stain energy in the system due to the misfit strains. A finite element model based on the initial strain approach is proposed to evaluate elasto-plastic accommodation energies during solid state transformation. The three-dimensional axisymmetric model has been used to evaluate energies as a function of transformation for α-β hydrogen transformations in the Nb-H system. The transformation has been analyzed for the cases of transformation progressing both from the center to surface and from the surface to center of the system. The effect of plastic deformation has been introduced to make the model realistic, specifically to the Nb-NbH phase transformation which involves a 4% linear misfit strain. It has been observed that plastic deformation reduces the strain energies compared to the linear elastic analysis

  9. Energy recycling of plastic and rubber wastes

    International Nuclear Information System (INIS)

    Hussain, R.

    2003-01-01

    Major areas for applications of plastics and rubbers are building and construction, packaging, transportation, automobiles, furniture, house wares, appliances, electrical and electronics. Approximately 20% of all the plastics produced are utilized by the building and construction industry/sup (1-3)/. Categories of polymers mostly used in the above industries include poly (vinyl chloride), polypropylene, polyethylene, polystyrene phenolics, acrylics and urethanes. Tyres and tubes are almost exclusively made up of rubbers. One third of total consumption of plastics finds applications, like films, bottles and packaging, in food-products that have a maximum life-span of two years, after which these find way to waste dumps. As the polymer industry in Pakistan is set to grow very rapidly in the near future the increase in utilization of plastic products in synchronous with the advent of computers and information technology. About 0.60 Kg per capita of waste generated daily in Lahore /(7.14)/ contains considerable quantity of plastics. (AB)

  10. Resistance to small plastic strains during martensite tempering under tension

    Energy Technology Data Exchange (ETDEWEB)

    Zabil' skij, V.V.; Sarrak, V.I. (AN SSSR, Sverdlovsk. Inst. Fiziki Metallov)

    1982-11-01

    The mechanism of plastic deformation of martensite of a series of hardened steels (N18, 20KhG, 50KhFA and others) during tempering under tension and the role of residual internal microstresses and phase transformations are studied. It is shown that martensite low resistance to small plastic deformations during tempering under tension which is usually associated with phase transformations depends as well on the level of residual internal microstresses in the martensite structure. The decrease of resistance to deformation in the course of the decomposition of a solid solution is due to weakening of martensitic matrix because of carbon departure from the solid solution and carbide coarsening. An assumption is made that martensite plastic deformation during tempering under tension is realized at the expense of the directed microplastic deformation in the regions of higher concentration of internal stresses.

  11. Finite element implementation and numerical issues of strain gradient plasticity with application to metal matrix composites

    DEFF Research Database (Denmark)

    Frederiksson, Per; Gudmundson, Peter; Mikkelsen, Lars Pilgaard

    2009-01-01

    A framework of finite element equations for strain gradient plasticity is presented. The theoretical framework requires plastic strain degrees of freedom in addition to displacements and a plane strain version is implemented into a commercial finite element code. A couple of different elements...... of quadrilateral type are examined and a few numerical issues are addressed related to these elements as well as to strain gradient plasticity theories in general. Numerical results are presented for an idealized cell model of a metal matrix composite under shear loading. It is shown that strengthening due...... to fiber size is captured but strengthening due to fiber shape is not. A few modelling aspects of this problem are discussed as well. An analytic solution is also presented which illustrates similarities to other theories....

  12. Mode I and mixed mode crack-tip fields in strain gradient plasticity

    DEFF Research Database (Denmark)

    Goutianos, Stergios

    2011-01-01

    Strain gradients develop near the crack-tip of Mode I or mixed mode cracks. A finite strain version of the phenomenological strain gradient plasticity theory of Fleck–Hutchinson (2001) is used here to quantify the effect of the material length scales on the crack-tip stress field for a sharp...... stationary crack under Mode I and mixed mode loading. It is found that for material length scales much smaller than the scale of the deformation gradients, the predictions converge to conventional elastic–plastic solutions. For length scales sufficiently large, the predictions converge to elastic solutions....... Thus, the range of length scales over which a strain gradient plasticity model is necessary is identified. The role of each of the three material length scales, incorporated in the multiple length scale theory, in altering the near-tip stress field is systematically studied in order to quantify...

  13. Plane strain analytical solutions for a functionally graded elastic-plastic pressurized tube

    International Nuclear Information System (INIS)

    Eraslan, Ahmet N.; Akis, Tolga

    2006-01-01

    Plane strain analytical solutions to functionally graded elastic and elastic-plastic pressurized tube problems are obtained in the framework of small deformation theory. The modulus of elasticity and the uniaxial yield limit of the tube material are assumed to vary radially according to two parametric parabolic forms. The analytical plastic model is based on Tresca's yield criterion, its associated flow rule and ideally plastic material behaviour. Elastic, partially plastic and fully plastic stress states are investigated. It is shown that the elastoplastic response of the functionally graded pressurized tube is affected significantly by the material nonhomogeneity. Different modes of plasticization may take place unlike the homogeneous case. It is also shown mathematically that the nonhomogeneous elastoplastic solution presented here reduces to that of a homogeneous one by appropriate choice of the material parameters

  14. Study on elastic-plastic deformation analysis using a cyclic stress-strain curve

    International Nuclear Information System (INIS)

    Igari, Toshihide; Setoguchi, Katsuya; Yamauchi, Masafumi

    1983-01-01

    This paper presents the results of the elastic-plastic deformation analysis using a cyclic stress-strain curve with an intention to apply this method for predicting the low-cycle fatigue life. Uniaxial plastic cycling tests were performed on 2 1/4Cr-1Mo steel to investigate the correspondence between the cyclic stress-strain curve and the hysteresis loop, and also to determine what mathematical model should be used for analysis of deformation at stress reversal. Furthermore, a cyclic in-plane bending test was performed on a flat plate to clarify the validity of the cyclic stress-strain curve-based theoretical analysis. The results obtained are as follows: (1) The cyclic stress-strain curve corresponds nearly to the ascending curve of hysteresis loop scaled by a factor of 1/2 for both stress and strain. Therefore, the cyclic stress-strain curve can be determined from the shape of hysteresis loop, for simplicity. (2) To perform the elastic-plastic deformation analysis using the cyclic stress-strain curve is both practical and effective for predicting the cyclic elastic-plastic deformation of structures at the stage of advanced cycles. And Masing model can serve as a suitable mathematical model for such a deformation analysis. (author)

  15. The Finite Strain Johnson Cook Plasticity and Damage Constitutive Model in ALEGRA.

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Jason James [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2018-02-01

    A finite strain formulation of the Johnson Cook plasticity and damage model and it's numerical implementation into the ALEGRA code is presented. The goal of this work is to improve the predictive material failure capability of the Johnson Cook model. The new implementation consists of a coupling of damage and the stored elastic energy as well as the minimum failure strain criteria for spall included in the original model development. This effort establishes the necessary foundation for a thermodynamically consistent and complete continuum solid material model, for which all intensive properties derive from a common energy. The motivation for developing such a model is to improve upon ALEGRA's present combined model framework. Several applications of the new Johnson Cook implementation are presented. Deformation driven loading paths demonstrate the basic features of the new model formulation. Use of the model produces good comparisons with experimental Taylor impact data. Localized deformation leading to fragmentation is produced for expanding ring and exploding cylinder applications.

  16. The use of energy information in plastic scintillator materia

    International Nuclear Information System (INIS)

    Ely, J.; Anderson, K.; Bates, D.; Kouzes, R.; Lo Presti, C.; Runkle, R.; Siciliano, E.; Weier, D.

    2008-01-01

    Plastic scintillator material is often used for gamma-ray detection in many applications due to its relatively good sensitivity and cost-effectiveness compared to other detection materials. However, due to the dominant Compton scattering interaction mechanism, full energy peaks are not observed in plastic scintillator spectra and isotopic identification is impossible. Typically plastic scintillator detectors are solely gross count detectors. In some safeguards and security applications, such as radiation portal monitors for vehicle screening, naturally-occurring radioactive material (NORM) often triggers radiation alarms and results in innocent or nuisance alarms. The limited energy information from plastic scintillator material can be used to discriminate the NORM from targeted materials and reduce the nuisance alarm rate. An overview of the utilization of the energy information from plastic scintillator material will be presented, with emphasis on the detection capabilities and potential limitations for safeguards and security applications. (author)

  17. Effect of plastic strain on elastic-plastic fracture toughness of SM490 carbon steel. Assessment by stress-based criterion for ductile crack initiation

    International Nuclear Information System (INIS)

    Kamaya, Masayuki

    2012-01-01

    Although the plastic strain induced in materials increases the mechanical strength, it may reduce the fracture toughness. In this study, the change in fracture toughness of SM490 carbon steel due to pre-straining was investigated using a stress-based criterion for ductile crack initiation. The specimens with blunt notch of various radiuses were used in addition to those with conventional fatigue pre-cracking. The degree of applied plastic strain was 5%, 10% or 20%. The fracture toughness was largest when the induced plastic strain was 5%, although it decreased for the plastic strains of 10% and 20%. The stress and strain distributions near the crack tip of fracture toughness test specimens was investigated by elastic-plastic finite element analyses using a well-correlated stress-strain curve for large strain. It was shown that the critical condition at the onset of the ductile crack was better correlated with the equivalent stress than the plastic strain at the crack tip. By using the stress-based criterion, which was represented by the equivalent stress and stress triaxiality, the change in the fracture toughness due to pre-straining could be reasonably explained. Based on these results, it was concluded that the stress-based criterion should be used for predicting the ductile crack initiation. (author)

  18. Plastic strain characterization in austenitic stainless steels and nickel alloys by electron backscatter diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Saez-Maderuelo, A., E-mail: alberto.saez@ciemat.es [CIEMAT, Av. Complutense, 22-28040 Madrid (Spain); Castro, L.; Diego, G. de [CIEMAT, Av. Complutense, 22-28040 Madrid (Spain)

    2011-09-01

    Stress corrosion cracking (SCC) is enhanced by cold work and causes many problems in components of the nuclear power plants. Besides, during manufacturing, installation, welding and service of the material, residual strains can be produced increasing the susceptibility to SCC. For this reason, it is important to characterize the degree of plastic strain due to dislocation accumulation in each crystal. Electron backscatter diffraction (EBSD), in conjunction with scanning electron microscope (SEM), has been a great advance in this field because it enables to estimate the plastic strain in a quick and easy way. Nevertheless, over the last few years, a lot of different mathematical expressions to estimate the plastic strain have appeared in the literature. This situation hinders the election of one of them by a novel scientist in this field. Therefore, in this paper some of the more common expressions used in the calculation of the angular misorientation have been presented and discussed in order to clarify their more important aspects. Then, using one of these expressions (average local misorientation), curves relating misorientation density with known levels of strain will be obtained for an austenitic stainless steel 304L and nickel base alloy 690, which have shown a linear behaviour that is in good agreement with results found in the literature. Finally, using curves obtained in previous steps, levels of plastic strain in a plate of nickel base alloy 600 welded with weld metal 182 were estimated between 8 and 10% for a high temperature mill annealing sample.

  19. Plastic strain characterization in austenitic stainless steels and nickel alloys by electron backscatter diffraction

    International Nuclear Information System (INIS)

    Saez-Maderuelo, A.; Castro, L.; Diego, G. de

    2011-01-01

    Stress corrosion cracking (SCC) is enhanced by cold work and causes many problems in components of the nuclear power plants. Besides, during manufacturing, installation, welding and service of the material, residual strains can be produced increasing the susceptibility to SCC. For this reason, it is important to characterize the degree of plastic strain due to dislocation accumulation in each crystal. Electron backscatter diffraction (EBSD), in conjunction with scanning electron microscope (SEM), has been a great advance in this field because it enables to estimate the plastic strain in a quick and easy way. Nevertheless, over the last few years, a lot of different mathematical expressions to estimate the plastic strain have appeared in the literature. This situation hinders the election of one of them by a novel scientist in this field. Therefore, in this paper some of the more common expressions used in the calculation of the angular misorientation have been presented and discussed in order to clarify their more important aspects. Then, using one of these expressions (average local misorientation), curves relating misorientation density with known levels of strain will be obtained for an austenitic stainless steel 304L and nickel base alloy 690, which have shown a linear behaviour that is in good agreement with results found in the literature. Finally, using curves obtained in previous steps, levels of plastic strain in a plate of nickel base alloy 600 welded with weld metal 182 were estimated between 8 and 10% for a high temperature mill annealing sample.

  20. Strain hardening and plastic instability properties of austenitic stainless steels after proton and neutron irradiation

    International Nuclear Information System (INIS)

    Byun, T.S.; Farrell, K.; Lee, E.H.; Hunn, J.D.; Mansur, L.K.

    2001-01-01

    Strain hardening and plastic instability properties were analyzed for EC316LN, HTUPS316, and AL6XN austenitic stainless steels after combined 800 MeV proton and spallation neutron irradiation to doses up to 10.7 dpa. The steels retained good strain-hardening rates after irradiation, which resulted in significant uniform strains. It was found that the instability stress, the stress at the onset of necking, had little dependence on the irradiation dose. Tensile fracture stress and strain were calculated from the stress-strain curve data and were used to estimate fracture toughness using an existing model. The doses to plastic instability and fracture, the accumulated doses at which the yield stress reaches instability stress or fracture stress, were predicted by extrapolation of the yield stress, instability stress, and fracture stress to higher dose. The EC316LN alloy required the highest doses for plastic instability and fracture. Plastic deformation mechanisms are discussed in relation to the strain-hardening properties of the austenitic stainless steels

  1. Basic Strain Gradient Plasticity Theories with Application to Constrained Film Deformation

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, John W.

    2011-01-01

    films: the compression or extension of a finite layer joining rigid platens. Full elastic-plastic solutions are obtained for the same problem based on a finite element method devised for the new class of flow theories. Potential difficulties and open issues associated with the new class of flow theories......A family of basic rate-independent strain gradient plasticity theories is considered that generalize conventional J(2) deformation and flow theories of plasticity to include a dependence on strain gradients in a simple way. The theory builds on three recent developments: the work of Gudmundson (J....... Mech. Phys. Solids 52 (2004), 1379-1406) and Gurtin and Anand (J. Mech. Phys. Solids 57 (2009), 405-421), proposing constitutive relations for flow theories consistent with requirements of positive plastic dissipation; the work of Fleck and Willis (J. Mech. Phys. Solids 57 (2009), 161-177 and 1045...

  2. Measurement of Plastic Stress and Strain for Analytical Method Verification (MSFC Center Director's Discretionary Fund Project No. 93-08)

    Science.gov (United States)

    Price, J. M.; Steeve, B. E.; Swanson, G. R.

    1999-01-01

    The analytical prediction of stress, strain, and fatigue life at locations experiencing local plasticity is full of uncertainties. Much of this uncertainty arises from the material models and their use in the numerical techniques used to solve plasticity problems. Experimental measurements of actual plastic strains would allow the validity of these models and solutions to be tested. This memorandum describes how experimental plastic residual strain measurements were used to verify the results of a thermally induced plastic fatigue failure analysis of a space shuttle main engine fuel pump component.

  3. 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.

  4. Growth of extrusions in localized cyclic plastic straining

    Czech Academy of Sciences Publication Activity Database

    Polák, Jaroslav; Sauzay, M.

    2009-01-01

    Roč. 500, č. 1-2 (2009), s. 122-129 ISSN 0921-5093 R&D Projects: GA ČR GA101/07/1500 Institutional research plan: CEZ:AV0Z20410507 Keywords : extrusion * strain localization * persistent slip band * vacancy Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.901, year: 2009

  5. A new constitutive equation for strain hardening and softening of fcc metals during severe plastic deformation

    International Nuclear Information System (INIS)

    Wei, W.; Wei, K.X.; Fan, G.J.

    2008-01-01

    The stress-strain relationship for strain hardening and softening of high-purity aluminum and copper, which were deformed by equal channel angular pressing (ECAP) at ambient temperature, was analyzed by combining the Estrin and Mecking (EM) model and an Avrami-type equation with experimental data during severe plastic deformation. The initial strain hardening can be described by the EM model, while the flow stress arrives at the peak stress after it was saturated. However, strain softening similar to plastic deformation at high temperatures is observed after the peak stress. Moreover, the peak strain at the maximum flow stress is ∼4 for copper and ∼2 for aluminum. A new constitutive equation was developed to describe strain softening at high strain levels, which was supported well by tensile, compression and microhardness tests at room temperature and low strain rate. It was observed that dynamic recovery and recrystallization occurs in copper, and recrystallized grains and their growth in aluminum. The results indicate that dynamic recovery and recrystallization was the dominant softening mechanism, which was confirmed by scanning electron microscopy-electron channeling contrast observations and the abnormal relationship between the imposed strain during ECAP and subsequent recrystallization temperature after ECAP

  6. Strain fields and line energies of dislocations in uranium dioxide

    International Nuclear Information System (INIS)

    Parfitt, David C; Bishop, Clare L; Wenman, Mark R; Grimes, Robin W

    2010-01-01

    Computer simulations are used to investigate the stability of typical dislocations in uranium dioxide. We explain in detail the methods used to produce the dislocation configurations and calculate the line energy and Peierls barrier for pure edge and screw dislocations with the shortest Burgers vector 1/2 . The easiest slip system is found to be the {100}(110) system for stoichiometric UO 2 , in agreement with experimental observations. We also examine the different strain fields associated with these line defects and the close agreement between the strain field predicted by atomic scale models and the application of elastic theory. Molecular dynamics simulations are used to investigate the processes of slip that may occur for the three different edge dislocation geometries and nudged elastic band calculations are used to establish a value for the Peierls barrier, showing the possible utility of the method in investigating both thermodynamic average behaviour and dynamic processes such as creep and plastic deformation.

  7. Elastic-plastic analysis of local and integral straining behaviour in a cracked plate

    International Nuclear Information System (INIS)

    Grueter, L.; Ruettenauer, B.

    1982-01-01

    For components of the primary coolant system of the German LMFBR prototype reactor SNR-300, integrity against anticipated accidents (Bethe-Tait) has to be shown for a cracked structure. Within this programme a number of tests with cracked wide plate specimens yielding overall limit strains of approximately 15% have been run; finite element calculations have been infinated for the wide plate geometry. The paper discusses the straining behaviour of a cracked plate by considering the numerical simulation of structures strained up to such high levels. The stress-strain diagram of the weldment of the austenitic stainless steel X6 CrNi 18 at 450 0 C has been used. Plane strain and stress conditions have been prescribed. The original plate dimensions (t = thickness = 40 mm; h = height = 400 mm) have been used as well as a similar, but smaller plate of t = 8.8 mm width. The crack length is defined as 0.1 t. The results show that for a cracked plate under high plastic strain the near-crack-tip-field values still govern the structural mechanical behaviour. Concerning the absolute dimensions the effects known for elasticity retain their influence in the plastic regime; however, the crack location becomes more unimportant with increasing strain, i.e. the appropriate pure geometry factor tends to unity in the plastic regime. The center-crack, defined as 2a = 0.1 t, corresponds to an equivalent edge crack of depth a = 0.05 t in the elastic case. It can be shown that for high plastic strains this correspondence remains fully valid. (orig.)

  8. The strain path dependence of plastic deformation response of AA5754: Experiment and modeling

    International Nuclear Information System (INIS)

    Pham, Minh-Son; Hu, Lin; Iadicola, Mark; Creuziger, Adam; Rollett, Anthony D.

    2013-01-01

    This work presents modeling of experiments on a balanced biaxial (BB) pre-strained AA5754 alloy, subsequently reloaded uniaxially along the rolling direction and transverse direction. The material exhibits a complex plastic deformation response during the change in strain path due to 1) crystallographic texture, 2) aging (interactions between dislocations and Mg atoms) and 3) recovery (annihilation and re-arrangement of dislocations). With a BB prestrain of about 5 %, the aging process is dominant, and the yield strength for uniaxially deformed samples is observed to be higher than the flow stress during BB straining. The strain hardening rate after changing path is, however, lower than that for pre-straining. Higher degrees of pre-straining make the dynamic recovery more active. The dynamic recovery at higher strain levels compensates for the aging effect, and results in: 1) a reduction of the yield strength, and 2) an increase in the hardening rate of re-strained specimens along other directions. The yield strength of deformed samples is further reduced if these samples are left at room temperature to let static recovery occur. The synergistic influences of texture condition, aging and recovery processes on the material response make the modeling of strain path dependence of mechanical behavior of AA5754 challenging. In this study, the influence of crystallographic texture is taken into account by incorporating the latent hardening into a visco-plastic self-consistent model. Different strengths of dislocation glide interaction models in 24 slip systems are used to represent the latent hardening. Moreover, the aging and recovery effects are also included into the latent hardening model by considering strong interactions between dislocations and dissolved atom Mg and the microstructural evolution. These microstructural considerations provide a powerful capability to successfully describe the strain path dependence of plastic deformation behavior of AA5754

  9. Neutron-diffraction measurement of the evolution of strain for non-uniform plastic deformation

    International Nuclear Information System (INIS)

    Rogge, R.B.; Dawson, P.R.; Boyce, D.

    2002-01-01

    Neutrons are particularly adept for the validation of modeling predictions of stress and strain. In recent years, there has been a significant effort to model the evolution of both the macroscopic stresses and the intergranular stress during plastic deformation. These have had broad implications with regard to understanding the evolution of residual stress and to diffraction-based measurements of strain. Generally the modeling and associated measurements have been performed for simple uniaxial tension, leaving questions with regard to plastic deformation under multi-axial stress and non-uniform stress. Extensive measurements of the strain profile across a plastic hinge for each of a series of loading and unloading cycles to progressively higher degrees of plastic deformation are presented. These measurements are used to assess multiple-length-scale finite-element modeling (FEM) of the plastic hinge, in which the elements will range in size from single crystallites (as used in successful simulations of uniaxial tension) to macroscopic elements (as typically used in FEM simulations). (orig.)

  10. Continuum and crystal strain gradient plasticity with energetic and dissipative length scales

    Science.gov (United States)

    Faghihi, Danial

    This work, standing as an attempt to understand and mathematically model the small scale materials thermal and mechanical responses by the aid of Materials Science fundamentals, Continuum Solid Mechanics, Misro-scale experimental observations, and Numerical methods. Since conventional continuum plasticity and heat transfer theories, based on the local thermodynamic equilibrium, do not account for the microstructural characteristics of materials, they cannot be used to adequately address the observed mechanical and thermal response of the micro-scale metallic structures. Some of these cases, which are considered in this dissertation, include the dependency of thin films strength on the width of the sample and diffusive-ballistic response of temperature in the course of heat transfer. A thermodynamic-based higher order gradient framework is developed in order to characterize the mechanical and thermal behavior of metals in small volume and on the fast transient time. The concept of the thermal activation energy, the dislocations interaction mechanisms, nonlocal energy exchange between energy carriers and phonon-electrons interactions are taken into consideration in proposing the thermodynamic potentials such as Helmholtz free energy and rate of dissipation. The same approach is also adopted to incorporate the effect of the material microstructural interface between two materials (e.g. grain boundary in crystals) into the formulation. The developed grain boundary flow rule accounts for the energy storage at the grain boundary due to the dislocation pile up as well as energy dissipation caused by the dislocation transfer through the grain boundary. Some of the abovementioned responses of small scale metallic compounds are addressed by means of the numerical implementation of the developed framework within the finite element context. In this regard, both displacement and plastic strain fields are independently discretized and the numerical implementation is performed in

  11. Analytical solution for stress, strain and plastic instability of pressurized pipes with volumetric flaws

    International Nuclear Information System (INIS)

    Cunha, Sérgio B.; Netto, Theodoro A.

    2012-01-01

    The mechanical behavior of internally pressurized pipes with volumetric flaws is analyzed. The two possible modes of circumferentially straining the pipe wall are identified and associated to hypothesized geometries. The radial deformation that takes place by bending the pipe wall is studied by means of axisymmetric flaws and the membrane strain developed by unequal hoop deformation is analyzed with the help of narrow axial flaws. Linear elastic shell solutions for stress and strain are developed, the plastic behavior is studied and the maximum hoop stress at the flaw is related to the undamaged pipe hoop stress by means of stress concentration factors. The stress concentration factors are employed to obtain equations predicting the pressure at which the pipe fails by plastic instability for both types of flaw. These analytical solutions are validated by comparison with burst tests on 3″ diameter pipes and finite element simulations. Forty-one burst tests were carried out and two materials with very dissimilar plastic behavior, carbon steel and austenitic stainless steel, were used in the experiments. Both the analytical and the numerical predictions showed good correlation with the experimentally observed burst pressures. - Highlights: ► An analytical model for the burst of a pipe with a volumetric flaw is developed. ► Deformation, strain and stress are modeled in the elastic and plastic domains. ► The model is comprehensively validated by experiments and numerical simulations. ► The burst pressure model’s accuracy is equivalent to finite element simulations.

  12. Effect of plastic deformation and strain history on X-ray elastic constants

    International Nuclear Information System (INIS)

    Iadicola, Mark A.; Foecke, Tim

    2005-01-01

    The use of X-ray diffraction to measure residual stress in a crystalline material is well known. This method is currently being reapplied to the surface measurement of in situ stresses during biaxial straining of sheet metal specimens. This leads to questions of precision and calibration of the method through plastic deformation. Little is known of the change, with plastic work, in the X-ray elastic constants (XECs) that are required by the technique for stress measurement. Experiments to determine the formability of various materials using this stress measurement technique in conjunction with a typical Marciniak test (with the Raghavan variation of specimen shapes) have been performed assuming a constant value for XECs. New results of calibration experiments are presented which admit the possibility of variation of the XECs with plastic strain history and initial texture of the material. Adjustment of the data from the previously performed formability experiments is shown. Additionally, various phenomena are captured including initial yielding, change of XECs with plastic strain level (both with uniaxial and biaxial strain histories), and some of the effects of texture on the technique. This technique has potential application in verification of the assumptions made during other standard testing methods (in-plane biaxial specimen geometries and bulge testing), verifying stress predictions from finite element analyses (i.e. benchmarking experiments such as BM3), analysis of stress states in localized deformation (yield point effects), and tracking of the effect of prestraining on material formability through the process of multistage forming

  13. Strain gradient crystal plasticity analysis of a single crystal containing a cylindrical void

    DEFF Research Database (Denmark)

    Borg, Ulrik; Kysar, J.W.

    2007-01-01

    to one another. Finite element simulations are performed using a strain gradient crystal plasticity formulation with an intrinsic length scale parameter in a non-local strain gradient constitutive framework. For a vanishing length scale parameter the non-local formulation reduces to a local crystal...... plasticity formulation. The stress and deformation fields obtained with a local non-hardening constitutive formulation are compared to those obtained from a local hardening formulation and to those from a non-local formulation. Compared to the case of the non-hardening local constitutive formulation......, it is shown that a local theory with hardening has only minor effects on the deformation field around the void, whereas a significant difference is obtained with the non-local constitutive relation. Finally, it is shown that the applied stress state required to activate plastic deformation at the void is up...

  14. Strain-rate dependent plasticity in thermo-mechanical transient analysis

    International Nuclear Information System (INIS)

    Rashid, Y.R.; Sharabi, M.N.

    1980-01-01

    The thermo-mechanical transient behavior of fuel element cladding and other reactor components is generally governed by the strain-rate properties of the material. Relevant constitutive modeling requires extensive material data in the form of strain-rate response as function of true-stress, temperature, time and environmental conditions, which can then be fitted within a theoretical framework of an inelastic constitutive model. In this paper, we present a constitutive formulation that deals continuously with the entire strain-rate range and has the desirable advantage of utilizing existing material data. The derivation makes use of strain-rate sensitive stress-strain curve and strain-rate dependent yield surface. By postulating a strain-rate dependent on Mises yield function and a strain-rate dependent kinematic hardening rule, we are able to derive incremental stress-strain relations that describe the strain-rate behavior in the entire deformation range spanning high strain-rate plasticity and creep. The model is sufficiently general as to apply to any materials and loading histories for which data is available. (orig.)

  15. Charge, mass and energy measured in the Plastic Ball

    International Nuclear Information System (INIS)

    Gustafsson, H.A.; Gutbrod, H.H.; Kolb, B.

    1984-01-01

    In relativistic nuclear collisions the multiplicity of charged particles reflects the violence of the reaction and, presumably, the impact parameter. Furthermore, the total transverse energy in a collision might be a signature of compression. Both quantities are global features that can be measured in the Plastic Ball. The total mass in an event in light charge fragments can be detected (with assumptions made in certain kinematic regions) through particle identification. In addition, the neutron detection efficiency is quite high because of the large thickness of the plastic scintillator in the Plastic Ball. Here the authors present several global quantities for the reaction of 400 MeV/nucleon Nb + Nb

  16. Validation of a Crystal Plasticity Model Using High Energy Diffraction Microscopy

    Science.gov (United States)

    Beaudoin, A. J.; Obstalecki, M.; Storer, R.; Tayon, W.; Mach, J.; Kenesei, P.; Lienert, U.

    2012-01-01

    High energy diffraction microscopy is used to measure the crystallographic orientation and evolution of lattice strain in an Al Li alloy. The relative spatial arrangement of the several pancake-shaped grains in a tensile sample is determined through in situ and ex situ techniques. A model for crystal plasticity with continuity of lattice spin is posed, where grains are represented by layers in a finite element mesh following the arrangement indicated by experiment. Comparison is drawn between experiment and simulation.

  17. Plastic strain and grain size effects in the surface roughening of a model aluminum alloy

    Science.gov (United States)

    Moore, Eric Joseph

    To address issues surrounding improved automotive fuel economy, an experiment was designed to study the effect of uniaxial plastic tensile deformation on surface roughness and on slip and grain rotation. Electron backscatter diffraction (EBSD) and scanning laser confocal microscopy (SLCM) were used to track grain size, crystallographic texture, and surface topography as a function of incremental true strain for a coarse-grained binary alloy that is a model for AA5xxx series aluminum alloys. One-millimeter thick sheets were heat treated at 425°C to remove previous rolling texture and to grow grains to sizes in the range ˜10-8000 mum. At five different strain levels, 13 sample regions, containing 43 grains, were identified in both EBSD and SLCM micrographs, and crystallographic texture and surface roughness were measured. After heat treatment, a strong cube texture matrix emerged, with bands of generally non-cube grains embedded parallel to the rolling direction (RD). To characterize roughness, height profiles from SLCM micrographs were extracted and a filtered Fourier transform approach was used to separate the profiles into intergranular (long wavelength) and intragranular (short wavelength) signatures. The commonly-used rms roughness parameter (Rq) characterized intragranular results. Two important parameters assess intergranular results in two grain size regimes: surface tilt angle (Deltatheta) and surface height discontinuity (DeltazH) between neighboring grains at a boundary. In general, the magnitude of Rq and Deltatheta increase monotonically with strain and indicate that intergranular roughness is the major contributor to overall surface roughness for true strains up to epsilon = 0.12. Surface height discontinuity DeltazH is defined due to exceptions in surface tilt angle analyses. The range of observed Deltatheta= 1-10° are consistent with the observed 3-12° rotation of individual grains as measured with EBSD. For some grain boundaries with Deltatheta

  18. 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.

  19. Effect of plastic strain on shape memory characteristics in sputter-deposited Ti-Ni thin films

    International Nuclear Information System (INIS)

    Nomura, K.

    1995-01-01

    The plastic strain which is introduced during cooling and heating under a constant stress has an influence upon the transformation and deformation characteristics of sputter-deposited Ti-Ni shape memory alloy thin films. With increasing the accumulated plastic strain, Ms rises and recovery strain increases. The changes in such characteristics are due to the internal stress field that is formed by plastic deformation. However, the change in Ms in Ti-50.5at%Ni is larger than that in Ti-48.9at%Ni, although the plastic strain in the former is lower than that in the latter. In order to understand this point, the effective internal stresses were estimated in both alloys; the internal stress in the former is more effectively created by the introduction of plastic strain than in the latter. (orig.)

  20. Singular solutions for the rigid plastic double slip and rotation model under plane strain

    Science.gov (United States)

    Alexandrov, S.; Lyamina, E.

    2018-02-01

    In the mechanics of granular and other materials the system of equations comprising the rigid plastic double slip and rotation model together with the stress equilibrium equations under plane strain conditions forms a hyperbolic system. Boundary value problems for this system of equations can involve a frictional interface. An envelope of characteristics may coincide with this interface. In this case, the solution is singular. In particular, some components of the strain rate tensor approach infinity in the vicinity of the frictional interface. Such behavior of solutions is in qualitative agreement with experimental data that show that a narrow layer of localized plastic deformation is often generated near frictional interfaces. The present paper deals with asymptotic analysis of the aforementioned system of equations in the vicinity of an envelope of characteristics. It is shown that the shear strain rate and the spin component in a local coordinate system connected to the envelope follow an inverse square root rule in its vicinity.

  1. A numerical basis for strain-gradient plasticity theory: Rate-independent and rate-dependent formulations

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau; Niordson, Christian Frithiof

    2014-01-01

    of a single plastic zone is analyzed to illustrate the agreement with earlier published results, whereafter examples of (ii) multiple plastic zone interaction, and (iii) elastic–plastic loading/unloading are presented. Here, the simple shear problem of an infinite slab constrained between rigid plates......A numerical model formulation of the higher order flow theory (rate-independent) by Fleck and Willis [2009. A mathematical basis for strain-gradient plasticity theory – part II: tensorial plastic multiplier. Journal of the Mechanics and Physics of Solids 57, 1045-1057.], that allows for elastic–plastic...... loading/unloading and the interaction of multiple plastic zones, is proposed. The predicted model response is compared to the corresponding rate-dependent version of visco-plastic origin, and coinciding results are obtained in the limit of small strain-rate sensitivity. First, (i) the evolution...

  2. Spacecraft Dynamic Characterization by Strain Energies Method

    Science.gov (United States)

    Bretagne, J.-M.; Fragnito, M.; Massier, S.

    2002-01-01

    In the last years the significant increase in satellite broadcasting demand, with the wide band communication dawn, has given a great impulse to the telecommunication satellite market. The big demand is translated from operators (such as SES/Astra, Eutelsat, Intelsat, Inmarsat, EuroSkyWay etc.) in an increase of orders of telecom satellite to the world industrials. The largest part of these telecom satellite orders consists of Geostationary platforms which grow more and more in mass (over 5 tons) due to an ever longer demanded lifetime (up to 20 years), and become more complex due to the need of implementing an ever larger number of repeaters, antenna reflectors and feeds, etc... In this frame, the mechanical design and verification of these large spacecraft become difficult and ambitious at the same time, driven by the dry mass limitation objective. By the Finite Element Method (FEM), and on the basis of the telecom satellite heritage of a world leader constructor such as Alcatel Space Industries it is nowadays possible to model these spacecraft in a realistic and confident way in order to identify the main global dynamic aspects such as mode shapes, mass participation and/or dynamic responses. But on the other hand, one of the main aims consists in identifying soon in a program the most critical aspects of the system behavior in the launch dynamic environment, such as possible dynamic coupling between the different subsystems and secondary structures of the spacecraft (large deployable reflectors, thrusters, etc.). To this aim a numerical method has been developed in the frame of the Alcatel SPACEBUS family program, using MSC/Nastran capabilities and it is presented in this paper. The method is based on Spacecraft sub-structuring and strain energy calculation. The method mainly consists of two steps : 1) subsystem modal strain energy ratio (with respect to the global strain energy); 2) subsystem strain energy calculation for each mode according to the base driven

  3. Plastic

    International Nuclear Information System (INIS)

    Jeong Gi Hyeon

    1987-04-01

    This book deals with plastic, which includes introduction for plastic, chemistry of high polymers, polymerization, speciality and structure of a high molecule property of plastic, molding, thermosetting plastic, such as polyethylene, polyether, polyamide and polyvinyl acetyl, thermal plastic like phenolic resins, xylene resins, melamine resin, epoxy resin, alkyd resin and poly urethan resin, new plastic like ionomer and PPS resin, synthetic laminated tape and synthetic wood, mixed materials in plastic, reprocessing of waste plastic, polymer blend, test method for plastic materials and auxiliary materials of plastic.

  4. Strain rate sensitivity and evolution of dislocations and twins in a twinning-induced plasticity steel

    International Nuclear Information System (INIS)

    Liang, Z.Y.; Wang, X.; Huang, W.; Huang, M.X.

    2015-01-01

    The present work investigated the effect of strain rates (10 −3 to 10 3 s −1 ) on the deformation behaviour of a twinning-induced plasticity (TWIP) steel. The strain rate sensitivity was studied in terms of instantaneous strain rate sensitivity (ISRS) and strain rate sensitivity of work-hardening (SRSW). While ISRS concerns the instantaneous flow stress change upon strain rate jump, SRSW deals with the subsequent modification in microstructure evolution, i.e. change of work-hardening rate. The present TWIP steel demonstrates a positive ISRS which remains stable during deformation and a negative SRSW, i.e. lower work-hardening rate at higher strain rate. Synchrotron X-ray diffraction experiments indicate that the negative SRSW should be attributed to the suppression of dislocations and deformation twins at high strain rate. This unexpected finding is different to conventional face-centred cubic (fcc) metals which generally show enhanced work-hardening rate at higher strain rate. A constitutive model which is strain rate- and temperature-dependent is developed to explain the stable ISRS and the negative SRSW. The modelling results reveal that the stable ISRS should be attributed to the thermally-activated dislocation motion dominated by interstitial carbon atoms and the negative SRSW should be due to the suppression of the dislocations and deformation twins caused by the adiabatic heating associated with high strain rate deformation

  5. A study on plastic strain accumulation caused by traveling of temperature distribution synchronizing with temperature rise

    International Nuclear Information System (INIS)

    Okajima, Satoshi

    2016-01-01

    The prevention of excessive deformation by thermal ratcheting is important in the design of high-temperature components of fast breeder reactors (FBR). This includes evaluation methods for a new type of thermal ratcheting caused by an axial traveling of temperature distribution, which corresponds to moving-up of liquid sodium surface in startup phase. Long range traveling of the axial temperature distribution brings flat plastic deformation profile in wide range. Therefore, at the center of this range, residual stress that brings shakedown behavior does not accumulate. As a result, repeating of this temperature traveling brings continuous accumulation of the plastic strain, even if there is no primary stress. In contrast, in the case with short range traveling, residual stress is caused by constraint against elastic part, and finally it results in shakedown. Because of this mechanism, we supposed that limit for the shakedown behavior depends on distance from the elastic part (i.e. half length of region with plastic deformation). In this paper, we examined characteristics of the accumulation of the plastic strain caused by realistic heat transients, namely, traveling of temperature distribution synchronizing with temperature rise. This examination was based on finite element analyses using elastic-perfectly plastic material. As a result, we confirmed that the shakedown limit depends not on the traveling range of the temperature distribution but the plastic deformation range, which was predicted by the elastic analysis. In the actual application, we can control the plastic deformation range by changing rate of the moving-up of liquid sodium surface. (author)

  6. An Elastic Plastic Contact Model with Strain Hardening for the LAMMPS Granular Package

    Energy Technology Data Exchange (ETDEWEB)

    Kuhr, Bryan [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Brake, Matthew Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Component Science and Mechanics; Lechman, Jeremy B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanoscale and Reactive Processes

    2015-03-01

    The following details the implementation of an analytical elastic plastic contact model with strain hardening for normal im pacts into the LAMMPS granular package. The model assumes that, upon impact, the co llision has a period of elastic loading followed by a period of mixed elastic plas tic loading, with contributions to each mechanism estimated by a hyperbolic seca nt weight function. This function is implemented in the LAMMPS source code as the pair style gran/ep/history. Preliminary tests, simulating the pouring of pure nickel spheres, showed the elastic/plastic model took 1.66x as long as similar runs using gran/hertz/history.

  7. Strain gradient plasticity modeling of hydrogen diffusion to the crack tip

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; del Busto, S.; Niordson, Christian Frithiof

    2016-01-01

    to characterize the gradient-enhanced stress elevation and subsequent diffusion of hydrogen towards the crack tip. Results reveal that GNDs, absent in conventional plasticity predictions, play a fundamental role on hydrogen transport ahead of a crack. SGP estimations provide a good agreement with experimental......In this work hydrogen diffusion towards the fracture process zone is examined accounting for local hardening due to geometrically necessary dislocations (GNDs) by means of strain gradient plasticity (SGP). Finite element computations are performed within the finite deformation theory...

  8. Substructure based modeling of nickel single crystals cycled at low plastic strain amplitudes

    Science.gov (United States)

    Zhou, Dong

    In this dissertation a meso-scale, substructure-based, composite single crystal model is fully developed from the simple uniaxial model to the 3-D finite element method (FEM) model with explicit substructures and further with substructure evolution parameters, to simulate the completely reversed, strain controlled, low plastic strain amplitude cyclic deformation of nickel single crystals. Rate-dependent viscoplasticity and Armstrong-Frederick type kinematic hardening rules are applied to substructures on slip systems in the model to describe the kinematic hardening behavior of crystals. Three explicit substructure components are assumed in the composite single crystal model, namely "loop patches" and "channels" which are aligned in parallel in a "vein matrix," and persistent slip bands (PSBs) connected in series with the vein matrix. A magnetic domain rotation model is presented to describe the reverse magnetostriction of single crystal nickel. Kinematic hardening parameters are obtained by fitting responses to experimental data in the uniaxial model, and the validity of uniaxial assumption is verified in the 3-D FEM model with explicit substructures. With information gathered from experiments, all control parameters in the model including hardening parameters, volume fraction of loop patches and PSBs, and variation of Young's modulus etc. are correlated to cumulative plastic strain and/or plastic strain amplitude; and the whole cyclic deformation history of single crystal nickel at low plastic strain amplitudes is simulated in the uniaxial model. Then these parameters are implanted in the 3-D FEM model to simulate the formation of PSB bands. A resolved shear stress criterion is set to trigger the formation of PSBs, and stress perturbation in the specimen is obtained by several elements assigned with PSB material properties a priori. Displacement increment, plastic strain amplitude control and overall stress-strain monitor and output are carried out in the user

  9. On the ability of some cyclic plasticity models to predict the evolution of stored energy in a type 304L stainless steel submitted to high cycle fatigue

    International Nuclear Information System (INIS)

    Vincent, L.

    2008-01-01

    Fatigue analyses of materials are generally based on a so-called stabilized cycle, on which plastic strain amplitude, plastic energy, maximum shear stress and so on are determined. The part of plastic energy which is dissipated in heat cannot be used to accumulate damage and it should be worthwhile extracting only the part of plastic energy which is stored in material microstructure in order to build a consistent damage model. In this paper, some cyclic plasticity models including a polycrystalline model are reformulated in the thermodynamic framework in order to test their capacity to predict both the stress-strain behaviour and the partition of plastic energy for a high cycle fatigue test on a type 304L stainless steel. For an equivalent description of stress-strain loops, the number of kinematic hardening variables chosen in a model may qualitatively alter the prediction of plastic energy partition due to the modification of the isotropic hardening variable. Measurements of the specimen temperature increase due to plastic dissipation is therefore proposed as a convenient complementary experimental data to identify the constitutive equation of the isotropic hardening variable of a cyclic plasticity model. (author)

  10. Elasto-plastic bond mechanics of embedded fiber optic sensors in concrete under uniaxial tension with strain localization

    Science.gov (United States)

    Li, Qingbin; Li, Guang; Wang, Guanglun

    2003-12-01

    Brittleness of the glass core inside fiber optic sensors limits their practical usage, and therefore they are coated with low-modulus softer protective materials. Protective coatings absorb a portion of the strain, and hence part of the structural strain is sensed. The study reported here corrects for this error through development of a theoretical model to account for the loss of strain in the protective coating of optical fibers. The model considers the coating as an elasto-plastic material and formulates strain transfer coefficients for elastic, elasto-plastic and strain localization phases of coating deformations in strain localization in concrete. The theoretical findings were verified through laboratory experimentation. The experimental program involved fabrication of interferometric optical fiber sensors, embedding within mortar samples and tensile tests in a closed-loop servo-hydraulic testing machine. The elasto-plastic strain transfer coefficients were employed for correction of optical fiber sensor data and results were compared with those of conventional extensometers.

  11. Strong strain rate effect on the plasticity of amorphous silica nanowires

    International Nuclear Information System (INIS)

    Yue, Yonghai; Zheng, Kun

    2014-01-01

    With electron-beam (e-beam) off, in-situ tensile experiments on amorphous silica nanowires (NWs) were performed inside a transmission electron microscope (TEM). By controlling the loading rates, the strain rate can be adjusted accurately in a wide range. The result shows a strong strain rate effect on the plasticity of amorphous silica NWs. At lower strain rate, the intrinsic brittle materials exhibit a pronounced elongation higher than 100% to failure with obvious necking near ambient temperature. At the strain rate higher than 5.23 × 10 −3 /s, the elongation of the NW decreased dramatically, and a brittle fracture feature behavior was revealed. This ductile feature of the amorphous silica NWs has been further confirmed with the in-situ experiments under optical microscopy while the effect of e-beam irradiation could be eliminated.

  12. Dynamic strain aging of twinning-induced plasticity (TWIP) steel in tensile testing and deep drawing

    International Nuclear Information System (INIS)

    Kim, J.G.; Hong, S.; Anjabin, N.; Park, B.H.; Kim, S.K.; Chin, K.-G.; Lee, S.; Kim, H.S.

    2015-01-01

    The dynamic strain aging (DSA) of metallic materials due to solute atom diffusion to mobile dislocations induce deformation instability with load fluctuations and deformation localizations, hence reducing their sheet formability. In this paper, DSA behaviors of twinning induced plasticity (TWIP) steel with and without Al during tensile testing and deep drawing are investigated in terms of strain localization and the Portevin-Le Chatelier (PLC) band. A theoretical DSA model with internal variables of dislocation density and twin volume fraction is presented for an estimation of strain localization and strain hardening behavior of TWIP steels. The simulation results of the load history and PLC bands during tensile testing and deep drawing are in good agreement with the experimental values. A serration behavior is observed in high-Mn TWIP steels and its tensile residual stress is higher than that in the Al-added TWIP steels, which results in a deformation crack or delayed fracture of deep drawn specimens

  13. Micro-Structural Evolution and Size-Effects in Plastically Deformed Single Crystals: Strain Gradient Continuum Modeling

    DEFF Research Database (Denmark)

    El-Naaman, Salim Abdallah

    the macroscopic effects related to strain gradients, most predict smooth micro-structures. The evolution of dislocation micro-structures, during plastic straining of ductile crystalline materials, is highly complex and nonuniform. Published experimental measurements on deformed metal crystals show distinct......An extensive amount of research has been devoted to the development of micro-mechanics based gradient plasticity continuum theories, which are necessary for modeling micron-scale plasticity when large spatial gradients of plastic strain appear. While many models have proven successful in capturing...... strain. It is clear that many challenges are associated with modeling dislocation structures, within a framework based on continuum fields, however, since the strain gradient effects are attributed to the dislocation micro-structure, it is a natural step, in the further development of gradient theories...

  14. Elasto-plastic stress/strain at notches, comparison of test and approximative computations

    International Nuclear Information System (INIS)

    Beste, A.; Seeger, T.

    1979-01-01

    The lifetime of cyclically loaded components is decisively determined by the value of the local load in the notch root. The determination of the elasto-plastic notch-stress and-strain is therefore an important element of recent methods of lifetime determination. These local loads are normally calculated with the help of approximation formulas. Yet there are no details about their accuracy. The basic construction of the approximation formulas is presented, along with some particulars. The use of approximations within the fully plastic range and for material laws which show a non-linear stress-strain (sigma-epsilon-)-behaviour from the beginning is explained. The use of approximation for cyclic loads is particularly discussed. Finally, the approximations are evaluated in terms of their exactness. The test results are compared with the results of the approximation calculations. (orig.) 891 RW/orig. 892 RKD [de

  15. Multiphase-field model of small strain elasto-plasticity according to the mechanical jump conditions

    Science.gov (United States)

    Herrmann, Christoph; Schoof, Ephraim; Schneider, Daniel; Schwab, Felix; Reiter, Andreas; Selzer, Michael; Nestler, Britta

    2018-04-01

    We introduce a small strain elasto-plastic multiphase-field model according to the mechanical jump conditions. A rate-independent J_2 -plasticity model with linear isotropic hardening and without kinematic hardening is applied exemplary. Generally, any physically nonlinear mechanical model is compatible with the subsequently presented procedure. In contrast to models with interpolated material parameters, the proposed model is able to apply different nonlinear mechanical constitutive equations for each phase separately. The Hadamard compatibility condition and the static force balance are employed as homogenization approaches to calculate the phase-inherent stresses and strains. Several verification cases are discussed. The applicability of the proposed model is demonstrated by simulations of the martensitic transformation and quantitative parameters.

  16. Variation of the Young's modulus with plastic strain applying to elastoplastic software

    International Nuclear Information System (INIS)

    Morestin, F.; Boivin, M.

    1993-01-01

    Work hardening of steel involves modifications of the elastic properties of the material, for instance, an increase of its yield stress. It may be also the cause of an appreciable decrease of the Young's modulus. This property decreases as plastic strain increases. Experiments with a microcomputer controlled tensile test machine indicated that diminution could reach more than 10% of the initial value, after only 5% of plastic strain. In spite of this fact, lots of elastoplastic softwares don't combine the decrease of the Young's modulus with plastification though it may involve obvious differences among results. As an application we have developed a software which computes the deformation of steel sheet in press forming, after springback. This software takes into account the decrease of the Young's modulus and its results are very close to experimental values. Quite arbitrarily, we noticed a recovery of the Young's modulus of plastified specimens after few days but not for all steels tested. (author)

  17. Elastic and plastic strains and the stress corrosion cracking of austenitic stainless steels. Final report

    International Nuclear Information System (INIS)

    Vaccaro, F.P.; Hehemann, R.F.; Troiano, A.R.

    1979-08-01

    The influence of elastic (stress) and plastic (cold work) strains on the stress corrosion cracking of a transformable austenitic stainless steel was studied in several aqueous chloride environments. Initial polarization behavior was active for all deformation conditions as well as for the annealed state. Visual observation, potential-time, and current-time curves indicated the development of a pseudo-passive (flawed) film leading to localized corrosion, occluded cells and SCC. SCC did not initiate during active corrosion regardless of the state of strain unless severe low temperature deformation produced a high percentage of martensite. Both elastic and plastic deformation increased the sensitivity to SCC when examined on the basis of percent yield strength. The corrosion potential, the critical cracking potential, and the potential at which the current changes from anodic to cathodic were essentially unaffected by deformation. It is apparent that the basic electrochemical parameters are independent of the bulk properties of the alloy and totally controlled by surface phenomena

  18. Comparison of experiment and theory for elastic-plastic plane strain crack growth

    International Nuclear Information System (INIS)

    Hermann, L.; Rice, J.R.

    1980-02-01

    Recent theoretical results on elastic-plastic plane strain crack growth, and experimental results for crack growth in a 4140 steel in terms of the theoretical concepts are reviewed. The theory is based on a recent asymptotic analysis of crack surface opening and strain distributions at a quasi-statically advancing crack tip in an ideally-plastic solid. The analysis is incomplete in that some of the parameters which appear in it are known only approximately, especially at large scale yielding. Nevertheless, it suffices to derive a relation between the imposed loading and amount of crack growth, prior to general yielding, based on the assumption that a geometrically similar near-tip crack profile is maintained during growth. The resulting predictions for the variation of J with crack growth are found to fit well to the experimental results obtained on deeply cracked compact specimens

  19. Dislocation-mediated strain hardening in tungsten: Thermo-mechanical plasticity theory and experimental validation

    Science.gov (United States)

    Terentyev, Dmitry; Xiao, Xiazi; Dubinko, A.; Bakaeva, A.; Duan, Huiling

    2015-12-01

    A self-consistent thermo-mechanical model to study the strain-hardening behavior of polycrystalline tungsten was developed and validated by a dedicated experimental route. Dislocation-dislocation multiplication and storage, as well dislocation-grain boundary (GB) pinning were the major mechanisms underlying the evolution of plastic deformation, thus providing a link between the strain hardening behavior and material's microstructure. The microstructure of the polycrystalline tungsten samples has been thoroughly investigated by scanning and electron microscopy. The model was applied to compute stress-strain loading curves of commercial tungsten grades, in the as-received and as-annealed states, in the temperature range of 500-1000 °C. Fitting the model to the independent experimental results obtained using a single crystal and as-received polycrystalline tungsten, the model demonstrated its capability to predict the deformation behavior of as-annealed samples in a wide temperature range and applied strain. The relevance of the dislocation-mediated plasticity mechanisms used in the model have been validated using transmission electron microscopy examination of the samples deformed up to different amounts of strain. On the basis of the experimental validation, the limitations of the model are determined and discussed.

  20. Analytical solution for stress, strain and plastic instability of pressurized pipes with volumetric flaws

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Sergio B., E-mail: sbcunha@petrobras.com.br [PETROBRAS/TRANSPETRO, Av. Pres. Vargas 328 - 7th floor, Rio de Janeiro, RJ 20091-060 (Brazil); Netto, Theodoro A., E-mail: tanetto@lts.coppe.ufrj.br [COPPE, Federal University ot Rio de Janeiro, Ocean Engineering Department, PO BOX 68508, Rio de Janeiro - RJ (Brazil)

    2012-01-15

    The mechanical behavior of internally pressurized pipes with volumetric flaws is analyzed. The two possible modes of circumferentially straining the pipe wall are identified and associated to hypothesized geometries. The radial deformation that takes place by bending the pipe wall is studied by means of axisymmetric flaws and the membrane strain developed by unequal hoop deformation is analyzed with the help of narrow axial flaws. Linear elastic shell solutions for stress and strain are developed, the plastic behavior is studied and the maximum hoop stress at the flaw is related to the undamaged pipe hoop stress by means of stress concentration factors. The stress concentration factors are employed to obtain equations predicting the pressure at which the pipe fails by plastic instability for both types of flaw. These analytical solutions are validated by comparison with burst tests on 3 Double-Prime diameter pipes and finite element simulations. Forty-one burst tests were carried out and two materials with very dissimilar plastic behavior, carbon steel and austenitic stainless steel, were used in the experiments. Both the analytical and the numerical predictions showed good correlation with the experimentally observed burst pressures. - Highlights: Black-Right-Pointing-Pointer An analytical model for the burst of a pipe with a volumetric flaw is developed. Black-Right-Pointing-Pointer Deformation, strain and stress are modeled in the elastic and plastic domains. Black-Right-Pointing-Pointer The model is comprehensively validated by experiments and numerical simulations. Black-Right-Pointing-Pointer The burst pressure model's accuracy is equivalent to finite element simulations.

  1. Waste-to-energy: Dehalogenation of plastic-containing wastes.

    Science.gov (United States)

    Shen, Yafei; Zhao, Rong; Wang, Junfeng; Chen, Xingming; Ge, Xinlei; Chen, Mindong

    2016-03-01

    The dehalogenation measurements could be carried out with the decomposition of plastic wastes simultaneously or successively. This paper reviewed the progresses in dehalogenation followed by thermochemical conversion of plastic-containing wastes for clean energy production. The pre-treatment method of MCT or HTT can eliminate the halogen in plastic wastes. The additives such as alkali-based metal oxides (e.g., CaO, NaOH), iron powders and minerals (e.g., quartz) can work as reaction mediums and accelerators with the objective of enhancing the mechanochemical reaction. The dehalogenation of waste plastics could be achieved by co-grinding with sustainable additives such as bio-wastes (e.g., rice husk), recyclable minerals (e.g., red mud) via MCT for solid fuels production. Interestingly, the solid fuel properties (e.g., particle size) could be significantly improved by HTT in addition with lignocellulosic biomass. Furthermore, the halogenated compounds in downstream thermal process could be eliminated by using catalysts and adsorbents. Most dehalogenation of plastic wastes primarily focuses on the transformation of organic halogen into inorganic halogen in terms of halogen hydrides or salts. The integrated process of MCT or HTT with the catalytic thermal decomposition is a promising way for clean energy production. The low-cost additives (e.g., red mud) used in the pre-treatment by MCT or HTT lead to a considerable synergistic effects including catalytic effect contributing to the follow-up thermal decomposition. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Metabolic regulation of neuronal plasticity by the energy sensor AMPK.

    Directory of Open Access Journals (Sweden)

    Wyatt B Potter

    Full Text Available Long Term Potentiation (LTP is a leading candidate mechanism for learning and memory and is also thought to play a role in the progression of seizures to intractable epilepsy. Maintenance of LTP requires RNA transcription, protein translation and signaling through the mammalian Target of Rapamycin (mTOR pathway. In peripheral tissue, the energy sensor AMP-activated Protein Kinase (AMPK negatively regulates the mTOR cascade upon glycolytic inhibition and cellular energy stress. We recently demonstrated that the glycolytic inhibitor 2-deoxy-D-glucose (2DG alters plasticity to retard epileptogenesis in the kindling model of epilepsy. Reduced kindling progression was associated with increased recruitment of the nuclear metabolic sensor CtBP to NRSF at the BDNF promoter. Given that energy metabolism controls mTOR through AMPK in peripheral tissue and the role of mTOR in LTP in neurons, we asked whether energy metabolism and AMPK control LTP. Using a combination of biochemical approaches and field-recordings in mouse hippocampal slices, we show that the master regulator of energy homeostasis, AMPK couples energy metabolism to LTP expression. Administration of the glycolytic inhibitor 2-deoxy-D-glucose (2DG or the mitochondrial toxin and anti-Type II Diabetes drug, metformin, or AMP mimetic AICAR results in activation of AMPK, repression of the mTOR pathway and prevents maintenance of Late-Phase LTP (L-LTP. Inhibition of AMPK by either compound-C or the ATP mimetic ara-A rescues the suppression of L-LTP by energy stress. We also show that enhanced LTP via AMPK inhibition requires mTOR signaling. These results directly link energy metabolism to plasticity in the mammalian brain and demonstrate that AMPK is a modulator of LTP. Our work opens up the possibility of using modulators of energy metabolism to control neuronal plasticity in diseases and conditions of aberrant plasticity such as epilepsy.

  3. Diffraction measurements for evaluating plastic strain in A533B ferritic steel-a feasibility study

    International Nuclear Information System (INIS)

    Lewis, S J; Truman, C E

    2010-01-01

    It is known that the physical properties of many engineering materials may be strongly affected by previous loading, in particular prior plastic deformation. Most obviously, work hardening will alter subsequent yielding behaviour. Plastic deformation may also preferentially align the material microstructure, resulting in anisotropy of subsequent behaviour and a change in material fracture resistance. When physical characterization is undertaken by experimental testing it is, therefore, important to have some knowledge of the current state of the material. As a result, it is desirable to have methods of quantitatively evaluating the level of plastic deformation which specimen material may have experienced prior to testing. This paper presents the results of a feasibility study, using a ferritic reactor pressure vessel steel, into the use of diffractive methods for plastic strain evaluation. Using neutron diffraction, changes in diffraction peak width and anisotropy of peak response were correlated with plastic deformation in a tensile test. The relationships produced were then used to evaluate permanent deformation levels in large samples, representative of standard fracture toughness test specimens.

  4. Interpreting the stress–strain response of Al micropillars through gradient plasticity

    International Nuclear Information System (INIS)

    Zhang, Xu; Aifantis, Katerina E.; Ngan, Alfonso H.W.

    2014-01-01

    Micropillar compression has fascinated the materials and mechanics communities for over a decade, due to the unique stochastic effects and slip zones that dictate their stress–strain curves and microstructure. Although plethora studies exist that capture experimentally the mechanical response of various types of micropillars, limited theoretical models can interpret the observed behavior. Particularly, single crystal micropillars exhibit multiple serrations in their stress–strain response, indicating the activation of slip zones, while bi-crystal pillars, in which the grain boundary lies parallel to the pillar axis, do not display such serrations, but rather a distinct “knee”, which indicates dislocation pileups at the grain boundary. In-situ synchrotron microdiffraction experiments have illustrated that not only dislocations, but also significant plastic strain gradients develop during micropillar compression. In the present study, therefore, appropriate gradient plasticity models that can account for the pillar microstructure, are successfully used to capture the stress–strain response of single- and bi-crystal Al pillars

  5. Study of primary energy transfer process in ultrafast plastic scintillators

    International Nuclear Information System (INIS)

    Bengtson, B.; Moszynski, M.

    1978-01-01

    The study of the light-pulse shape, the initial delay of light pulses and the light yield of plastics prepared by a modification of the NE111 scintillator were performed. The NE111 scintillator doped with several quench agents, the plastics prepared as a solution of butyl PBD in PVT of different concentration and PVT alone were studied. The study confirmed that the light pulse shape from fast binary plastics is well described analytically by the convolution of the clipped Gaussian and exponential functions. The investigation of the PVT-butyl PBD plastics shows that even more than three times larger concentration of butyl PBD compared to that of PBD in the NE111 solution does not improve the rise of the light pulse. Thus the rise time seems to be not controlled by the intermolecular energy transfer process. Finally, the observed rise time of the light pulse from the PVT sample was also approximated well by the Gaussian function. Altogether it brought a strong support for the earlier hypothesis that the initial slow rise of light pulses from plastic scintillators may come from the deexcitation of several higher levels of the solvent molecules excited by nuclear particles. (Auth.)

  6. Attaining the rate-independent limit of a rate-dependent strain gradient plasticity theory

    DEFF Research Database (Denmark)

    El-Naaman, Salim Abdallah; Nielsen, Kim Lau; Niordson, Christian Frithiof

    2016-01-01

    The existence of characteristic strain rates in rate-dependent material models, corresponding to rate-independent model behavior, is studied within a back stress based rate-dependent higher order strain gradient crystal plasticity model. Such characteristic rates have recently been observed...... for steady-state processes, and the present study aims to demonstrate that the observations in fact unearth a more widespread phenomenon. In this work, two newly proposed back stress formulations are adopted to account for the strain gradient effects in the single slip simple shear case, and characteristic...... rates for a selected quantity are identified through numerical analysis. Evidently, the concept of a characteristic rate, within the rate-dependent material models, may help unlock an otherwise inaccessible parameter space....

  7. Modeling and Analysis of Size-Dependent Structural Problems by Using Low- Order Finite Elements with Strain Gradient Plasticity

    International Nuclear Information System (INIS)

    Park, Moon Shik; Suh, Yeong Sung; Song, Seung

    2011-01-01

    An elasto-plastic finite element method using the theory of strain gradient plasticity is proposed to evaluate the size dependency of structural plasticity that occurs when the configuration size decreases to micron scale. For this method, we suggest a low-order plane and three-dimensional displacement-based elements, eliminating the need for a high order, many degrees of freedom, a mixed element, or super elements, which have been considered necessary in previous researches. The proposed method can be performed in the framework of nonlinear incremental analysis in which plastic strains are calculated and averaged at nodes. These strains are then interpolated and differentiated for gradient calculation. We adopted a strain-gradient-hardening constitutive equation from the Taylor dislocation model, which requires the plastic strain gradient. The developed finite elements are tested numerically on the basis of typical size-effect problems such as micro-bending, micro-torsion, and micro-voids. With respect to the strain gradient plasticity, i.e., the size effects, the results obtained by using the proposed method, which are simple in their calculation, are in good agreement with the experimental results cited in previously published papers

  8. New renewable source of energy from municipal solid waste plastics

    Energy Technology Data Exchange (ETDEWEB)

    Sarker, Moinuddin; Zaman, Ashiquz; Mamunor Rashid, Mohammad

    2010-09-15

    Renewable energy plays an important role in the supply of energy. When energy sources are used, the demand for fossil fuels is reduced. Emissions from the evaporation and combustion of these traditional fossil fuels contributing to a range of environmental and health problems, causing poor air quality, and emitting greenhouse gases that contribute to global warming. Alternative fuel created from domestic sources has been proposed as a solution to these problems and many alternative fuels are being developed based on solar, wind and biomass. Natural State Research has developed different alternative hydrocarbon fuel produced from abundant waste plastic materials.

  9. Immune response to Bifidobacterium bifidum strains support Treg/Th17 plasticity.

    Directory of Open Access Journals (Sweden)

    Patricia López

    Full Text Available In this work we analyzed the immune activation properties of different Bifidobacterium strains in order to establish their ability as inductors of specific effector (Th or regulatory (Treg responses. First, we determined the cytokine pattern induced by 21 Bifidobacterium strains in peripheral blood mononuclear cells (PBMCs. Results showed that four Bifidobacterium bifidum strains showed the highest production of IL-17 as well as a poor secretion of IFNγ and TNFα, suggesting a Th17 profile whereas other Bifidobacterium strains exhibited a Th1-suggestive profile. Given the key role of Th17 subsets in mucosal defence, strains suggestive of Th17 responses and the putative Th1 Bifidobacterium breve BM12/11 were selected to stimulate dendritic cells (DC to further determine their capability to induce the differentiation of naïve CD4(+ lymphocytes toward different Th or Treg cells. All selected strains were able to induce phenotypic DC maturation, but showed differences in cytokine stimulation, DC treated with the putative Th17 strains displaying high IL-1β/IL-12 and low IL-12/IL-10 index, whereas BM12/11-DC exhibited the highest IL-12/IL-10 ratio. Differentiation of naïve lymphocytes confirmed Th1 polarization by BM12/11. Unexpectedly, any B. bifidum strain showed significant capability for Th17 generation, and they were able to generate functional Treg, thus suggesting differences between in vivo and vitro responses. In fact, activation of memory lymphocytes present in PBMCS with these bacteria, point out the presence in vivo of specific Th17 cells, supporting the plasticity of Treg/Th17 populations and the key role of commensal bacteria in mucosal tolerance and T cell reprogramming when needed.

  10. Stability of surface plastic flow in large strain deformation of metals

    Science.gov (United States)

    Viswanathan, Koushik; Udapa, Anirduh; Sagapuram, Dinakar; Mann, James; Chandrasekar, Srinivasan

    We examine large-strain unconstrained simple shear deformation in metals using a model two-dimensional cutting system and high-speed in situ imaging. The nature of the deformation mode is shown to be a function of the initial microstructure state of the metal and the deformation geometry. For annealed metals, which exhibit large ductility and strain hardening capacity, the commonly assumed laminar flow mode is inherently unstable. Instead, the imposed shear is accommodated by a highly rotational flow-sinuous flow-with vortex-like components and large-amplitude folding on the mesoscale. Sinuous flow is triggered by a plastic instability on the material surface ahead of the primary region of shear. On the other hand, when the material is extensively strain-hardened prior to shear, laminar flow again becomes unstable giving way to shear banding. The existence of these flow modes is established by stability analysis of laminar flow. The role of the initial microstructure state in determining the change in stability from laminar to sinuous / shear-banded flows in metals is elucidated. The implications for cutting, forming and wear processes for metals, and to surface plasticity phenomena such as mechanochemical Rehbinder effects are discussed.

  11. Use of endochronic plasticity for multi-dimensional small and large strain problems

    International Nuclear Information System (INIS)

    Hsieh, B.J.

    1980-04-01

    The endochronic plasticity theory was proposed in its general form by K.C. Valanis. An intrinsic time measure, which is a property of the material, is used in the theory. the explicit forms of the constitutive equation resemble closely those of the classical theory of linear viscoelasticity. Excellent agreement between the predicted and experimental results is obtained for some metallic and non-metallic materials for one dimensional cases. No reference on the use of endochronic plasticity consistent with the general theory proposed by Valanis is available in the open literature. In this report, the explicit constitutive equations are derived that are consistent with the general theory for one-dimensional (simple tension or compression), two-dimensional plane strain or stress and three-dimensional axisymmetric problems

  12. Robust Return Algorithm for Anisotropic Plasticity Models

    DEFF Research Database (Denmark)

    Tidemann, L.; Krenk, Steen

    2017-01-01

    Plasticity models can be defined by an energy potential, a plastic flow potential and a yield surface. The energy potential defines the relation between the observable elastic strains ϒe and the energy conjugate stresses Τe and between the non-observable internal strains i and the energy conjugat...

  13. Three-dimensional elastic--plastic stress and strain analyses for fracture mechanics: complex geometries

    International Nuclear Information System (INIS)

    Bellucci, H.J.

    1975-11-01

    The report describes the continuation of research into capability for three-dimensional elastic-plastic stress and strain analysis for fracture mechanics. A computer program, MARC-3D, has been completed and was used to analyze a cylindrical pressure vessel with a nozzle insert. A method for generating crack tip elements was developed and a model was created for a cylindrical pressure vessel with a nozzle and an imbedded flaw at the inside nozzle corner. The MARC-3D program was again used to analyze this flawed model. Documentation for the use of the MARC-3D computer program has been included as an appendix

  14. Strain gradient plasticity-based modeling of hydrogen environment assisted cracking

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof; P. Gangloff, Richard

    2016-01-01

    Finite element analysis of stress about a blunt crack tip, emphasizing finite strain and phenomenologicaland mechanism-based strain gradient plasticity (SGP) formulations, is integrated with electrochemical assessment of occluded-crack tip hydrogen (H) solubility and two H-decohesion models...... to predict hydrogen environment assisted crack growth properties. SGP elevates crack tip geometrically necessary dislocation density and flow stress, with enhancement declining with increasing alloy strength. Elevated hydrostatic stress promotes high-trapped H concentration for crack tip damage......; it is imperative to account for SGP in H cracking models. Predictions of the threshold stress intensity factor and H-diffusion limited Stage II crack growth rate agree with experimental data for a high strength austenitic Ni-Cusuperalloy (Monel®K-500) and two modern ultra-high strength martensitic steels (Aer...

  15. In-plane anisotropic strain of elastically and plastically deformed III-nitrides on lithium gallate

    International Nuclear Information System (INIS)

    Namkoong, Gon; Huang, Sa; Moseley, Michael; Doolittle, W. Alan

    2009-01-01

    We have investigated both elastically and plastically deformed GaN films on lithium gallate, LiGaO 2 , by molecular beam epitaxy. The in-plane lattice parameters were determined from high resolution X-ray diffraction and indicated two different groups of in-plane lattice parameters, influenced by the a- and b-axis of LiGaO 2 . The measured in-plane lattice parameters indicate that there exist both compressive and tensile strains of in-plane GaN along the a- and b-axis of LiGaO 2 , respectively. This anisotropic strain in GaN films forms a slight distortion of the basal-plane hexagonal structure of GaN films, leading to a different critical thickness of 4.0 ± 0.17 and 7.8 ± 0.7 nm along the a- and b-axis of LiGaO 2 , respectively.

  16. An improved Armstrong-Frederick-Type Plasticity Model for Stable Cyclic Stress-Strain Responses Considering Nonproportional Hardening

    Science.gov (United States)

    Li, Jing; Zhang, Zhong-ping; Li, Chun-wang

    2018-03-01

    This paper modified an Armstrong-Frederick-type plasticity model for investigating the stable cyclic deformation behavior of metallic materials with different sensitivity to nonproportional loadings. In the modified model, the nonproportionality factor and nonproportional cyclic hardening coefficient coupled with the Jiang-Sehitoglu incremental plasticity model were used to estimate the stable stress-strain responses of the two materials (1045HR steel and 304 stainless steel) under various tension-torsion strain paths. A new equation was proposed to calculate the nonproportionality factor on the basis of the minimum normal strain range. Procedures to determine the minimum normal strain range were presented for general multiaxial loadings. Then, the modified model requires only the cyclic strain hardening exponent and cyclic strength coefficient to determine the material constants. It is convenient for predicting the stable stress-strain responses of materials in engineering application. Comparisons showed that the modified model can reflect the effect of nonproportional cyclic hardening well.

  17. 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.

  18. Energy based methods for determining elastic plastic fracture

    International Nuclear Information System (INIS)

    Witt, F.J.

    1979-01-01

    Several methods are currently in use or under study for calculating various conditions of fracturing for varying degrees of plasticity. Among these are innovations on the J-integral concept, crack opening displacement or angle, the two parameter concept and the equivalent energy method. Methods involving crack arrest and ductile tearing also fall in this category. Each of these methods have many salient points and some efforts are underway to establish the underlying relationship between them. In this paper, the current research directions of J-integral and equivalent energy methodologies are reviewed with a broader discussion presented for the equivalent energy methodology. The fundamental basis of equivalent energy methodology rests with the volumetric energy ratio. For fractures governed by linear elastic fracture mechanics, the volumetric energy ratio is independent of flaw size and geometry and depends only on the scale factor between model and prototype and temperature. The behavioral aspects of the volumetric energy ratios have been investigated throughout the temperature range from brittle fracture to fully ductile fracture. For five different specimen and structural configurations it has been shown experimentally that the volumetric energy ratio retains its basic properties. That is, the volumetric energy ratio while changing in actual value, maintains its independence of geometry and flaw size while retaining a unique dependence on scale factor and temperature. This property interpreted in terms of fracture mechanics leads to the equivalent energy method. (orig.)

  19. Self-consistent modelling of lattice strains during the in-situ tensile loading of twinning induced plasticity steel

    International Nuclear Information System (INIS)

    Saleh, Ahmed A.; Pereloma, Elena V.; Clausen, Bjørn; Brown, Donald W.; Tomé, Carlos N.; Gazder, Azdiar A.

    2014-01-01

    The evolution of lattice strains in a fully recrystallised Fe–24Mn–3Al–2Si–1Ni–0.06C TWinning Induced Plasticity (TWIP) steel subjected to uniaxial tensile loading up to a true strain of ∼35% was investigated via in-situ neutron diffraction. Typical of fcc elastic and plastic anisotropy, the {111} and {200} grain families record the lowest and highest lattice strains, respectively. Using modelling cases with and without latent hardening, the recently extended Elasto-Plastic Self-Consistent model successfully predicted the macroscopic stress–strain response, the evolution of lattice strains and the development of crystallographic texture. Compared to the isotropic hardening case, latent hardening did not have a significant effect on lattice strains and returned a relatively faster development of a stronger 〈111〉 and a weaker 〈100〉 double fibre parallel to the tensile axis. Close correspondence between the experimental lattice strains and those predicted using particular orientations embedded within a random aggregate was obtained. The result suggests that the exact orientations of the surrounding aggregate have a weak influence on the lattice strain evolution

  20. Strain-dependent variations in spatial learning and in hippocampal synaptic plasticity in the dentate gyrus of freely behaving rats

    Directory of Open Access Journals (Sweden)

    Denise eManahan-Vaughan

    2011-03-01

    Full Text Available Hippocampal synaptic plasticity is believed to comprise the cellular basis for spatial learning. Strain-dependent differences in synaptic plasticity in the CA1 region have been reported. However, it is not known whether these differences extend to other synapses within the trisynaptic circuit, although there is evidence for morphological variations within that path. We investigated whether Wistar and Hooded Lister (HL rat strains express differences in synaptic plasticity in the dentate gyrus in vivo. We also explored whether they exhibit differences in the ability to engage in spatial learning in an 8-arm radial maze. Basal synaptic transmission was stable over a 24h period in both rat strains, and the input-output relationship of both strains was not significantly different. Paired-pulse analysis revealed significantly less paired-pulse facilitation in the Hooded Lister strain when pulses were given 40-100 msec apart. Low frequency stimulation at 1Hz evoked long-term depression (>24h in Wistar and short-term depression (<2h in HL rats; 200Hz stimulation induced long-term potentiation (>24h in Wistar, and a transient, significantly smaller potentiation (<1h in HL rats, suggesting that HL rats have higher thresholds for expression of persistent synaptic plasticity. Training for 10d in an 8-arm radial maze revealed that HL rats master the working memory task faster than Wistar rats, although both strains show an equivalent performance by the end of the trial period. HL rats also perform more efficiently in a double working and reference memory task. On the other hand, Wistar rats show better reference memory performance on the final (8-10 days of training. Wistar rats were less active and more anxious than HL rats.These data suggest that strain-dependent variations in hippocampal synaptic plasticity occur in different hippocampal synapses. A clear correlation with differences in spatial learning is not evident however.

  1. Strain Engineering to Modify the Electrochemistry of Energy Storage Electrodes

    Science.gov (United States)

    Muralidharan, Nitin; Carter, Rachel; Oakes, Landon; Cohn, Adam P.; Pint, Cary L.

    2016-01-01

    Strain engineering has been a critical aspect of device design in semiconductor manufacturing for the past decade, but remains relatively unexplored for other applications, such as energy storage. Using mechanical strain as an input parameter to modulate electrochemical potentials of metal oxides opens new opportunities intersecting fields of electrochemistry and mechanics. Here we demonstrate that less than 0.1% strain on a Ni-Ti-O based metal-oxide formed on superelastic shape memory NiTi alloys leads to anodic and cathodic peak potential shifts by up to ~30 mV in an electrochemical cell. Moreover, using the superelastic properties of NiTi to enable strain recovery also recovers the electrochemical potential of the metal oxide, providing mechanistic evidence of strain-modified electrochemistry. These results indicate that mechanical energy can be coupled with electrochemical systems to efficiently design and optimize a new class of strain-modulated energy storage materials. PMID:27283872

  2. In-plane anisotropic strain of elastically and plastically deformed III-nitrides on lithium gallate

    Energy Technology Data Exchange (ETDEWEB)

    Namkoong, Gon, E-mail: gnamkoon@odu.ed [Old Dominion University, Electrical and Computer Engineering, Applied Research Center, 12050 Jefferson Avenue, Newport News, VA 23606 (United States); Huang, Sa; Moseley, Michael; Doolittle, W. Alan [Georgia Institute of Technology, School of Electrical and Computer Engineering, 777 Atlantic Dr., Atlanta, GA 30332 (United States)

    2009-10-30

    We have investigated both elastically and plastically deformed GaN films on lithium gallate, LiGaO{sub 2}, by molecular beam epitaxy. The in-plane lattice parameters were determined from high resolution X-ray diffraction and indicated two different groups of in-plane lattice parameters, influenced by the a- and b-axis of LiGaO{sub 2}. The measured in-plane lattice parameters indicate that there exist both compressive and tensile strains of in-plane GaN along the a- and b-axis of LiGaO{sub 2}, respectively. This anisotropic strain in GaN films forms a slight distortion of the basal-plane hexagonal structure of GaN films, leading to a different critical thickness of 4.0 {+-} 0.17 and 7.8 {+-} 0.7 nm along the a- and b-axis of LiGaO{sub 2}, respectively.

  3. Determining the amount of waste plastics in the feed of Austrian waste-to-energy facilities

    OpenAIRE

    Schwarzb?ck, Therese; Van Eygen, Emile; Rechberger, Helmut; Fellner, Johann

    2016-01-01

    Although thermal recovery of waste plastics is widely practiced in many European countries, reliable information on the amount of waste plastics in the feed of waste-to-energy plants is rare. In most cases the amount of plastics present in commingled waste, such as municipal solid waste, commercial, or industrial waste, is estimated based on a few waste sorting campaigns, which are of limited significance with regard to the characterisation of plastic flows. In the present study, an alternati...

  4. Experimental research of plastic scintillation detector loaded 6Li neutron energy response

    International Nuclear Information System (INIS)

    Wang Lizong; Zhang Chuanfei; Peng Taiping; Guo Cun; Yang Hongqiong; Zhang Jianhua

    2005-01-01

    A new plastic scintillator, plastic scintillator loaded 6 Li, is brought forward and developed in this paper in order to increase low energy neutron sensitivity. Neutron sensitivity of several plastic scintillation detectors loaded 6 Li new developed in neutron energy range 0.2 MeV-5.0 MeV are calibrated by direct current at serial accelerator. Energy response curves of the detectors are obtained in this experiment. It is shown that this new plastic scintillation detector can increase low energy neutron sensitivity in experimental results. (authors)

  5. X-ray measurement of plastic strain by means of Eshelby/Mori-Tanaka model and its application

    International Nuclear Information System (INIS)

    Sasaki, Toshihiko; Lin, Zheng; Hirose, Yukio

    1997-01-01

    A new method is proposed in this paper for determining plastic strains in composite materials using the X-ray diffraction method. The present method was derived by using both Eshelby's approach and the Mori-Tanaka theory to express the stress state in composite materials instead of the elasticity in single-phase materials which is used in the conventional method of X-ray stress measurement. It was found that the plastic strain can be determined from the slope of the linear relation between lattice strains measured by the X-ray diffraction technique and sin 2 ψ using almost the same procedure as that for determining stresses by the conventional X-ray method. The results on ferritic and austenitic dual-phase stainless steel are shown. We discuss the effects of a uniaxial tensile load in a range of plastic deformation on the field of plastic strain as well as on residual macro-, micro- and phase stresses built up in the sample. (author)

  6. Plastic cells for energy from the sun (PLACES)

    Energy Technology Data Exchange (ETDEWEB)

    Halls, J.; Wilson, R.

    2004-07-01

    This research report (130 pages) carried out as the PLACES (Plastic Cells for Energy from the Sun) project describes the substantial progress made in understanding polymer PV devices. In particular, several promising new materials have been developed and techniques to optimise absorption in the active layer are described. The deposition studies on substrates other than glass have shown the feasibility of producing flexible, large-area PV devices. Several developments with materials, devices and processes have, or are, to be patented. It is pointed out that the stability and lifetime of these polymer PV devices need to be assessed in advance of any commercial application. The study was carried out by CDT Ltd and supported by the DTI.

  7. Response function measurement of plastic scintillator for high energy neutrons

    International Nuclear Information System (INIS)

    Sanami, Toshiya; Ban, Syuichi; Takahashi, Kazutoshi; Takada, Masashi

    2003-01-01

    The response function and detection efficiency of 2''φ x 2''L plastic (PilotU) and NE213 liquid (2''NE213) scintillators, which were used for the measurement of secondary neutrons from high energy electron induced reactions, were measured at Heavy Ion Medical Accelerator in Chiba (HIMAC). High energy neutrons were produced via 400 MeV/n C beam bombardment on a thick graphite target. The detectors were placed at 15 deg with respect to C beam axis, 5 m away from the target. As standard, a 5''φ x 5''L NE213 liquid scintillator (5''NE213) was also placed at same position. Neutron energy was determined by the time-of-flight method with the beam pickup scintillator in front of the target. In front of the detectors, veto scintillators were placed to remove charged particle events. All detector signals were corrected with list mode event by event. We deduce neutron spectrum for each detectors. The efficiency curves for pilotU and 2''NE213 were determined on the bases of 5 N E213 neutron spectrum and its efficiency calculated by CECIL code. (author)

  8. Diffraction-amalgamated grain boundary tracking for mapping 3D crystallographic orientation and strain fields during plastic deformation

    International Nuclear Information System (INIS)

    Toda, Hiroyuki; Kamiko, Takanobu; Tanabe, Yasuto; Kobayashi, Masakazu; Leclere, D.J.; Uesugi, Kentaro; Takeuchi, Akihisa; Hirayama, Kyosuke

    2016-01-01

    By amalgamating the X-ray diffraction technique with the grain boundary tracking technique, a novel method, diffraction-amalgamated grain boundary tracking (DAGT), has been developed. DAGT is a non-destructive in-situ analysis technique for characterising bulk materials, which can be applied up to near the point of fracture. It provides information about local crystal orientations and detailed grain morphologies in three dimensions, together with high-density strain mapping inside grains. As it obtains the grain morphologies by utilising X-ray imaging instead of X-ray diffraction, which latter is typically vulnerable to plastic deformation, DAGT is a fairly robust technique for analysing plastically deforming materials. Texture evolution and localised deformation behaviours have here been successfully characterised in Al–Cu alloys, during tensile deformation of 27% in applied strain. The characteristic rotation behaviours of grains were identified, and attributed to the effects of interaction with adjacent grains on the basis of the 3D local orientation and plastic strain distributions. It has also been revealed that 3D strain distribution in grains is highly heterogeneous, which is not explained by known mechanisms such as simple incompatibility with adjacent grains or strain percolation through soft grains. It has been clarified that groups consisting of a few adjacent grains may deform coordinately, especially in shear and lateral deformation, and the characteristic deformation pattern is thereby formed on a mesoscopic scale.

  9. Influence of cold rolling and strain rate on plastic response of powder metallurgy and chemical vapor deposition rhenium

    International Nuclear Information System (INIS)

    Koeppel, B.J.; Subhash, G.

    1999-01-01

    The plastic response of two kinds of rhenium processed via powder metallurgy (PM) and chemical vapor deposition (CVD) were investigated under uniaxial compression over a range of strain rates. The PM rhenium, further cold rolled to 50 and 80 pct of the original thickness, was also investigated to assess the influence of cold work on the plastic behavior. A strong basal texture was detected in all the preceding materials as a result of processing and cold work. Both CVD and PM rhenium exhibited an increase in yield strength and flow stress with increasing strain rate. In PM rhenium, cold work resulted in an increase in hardness and yield strength and a decrease in the work hardening rate. The deformed microstructures revealed extensive twinning in CVD rhenium. At large strains, inhomogeneous deformation mode in the form of classical cup and cone fracture was noticed

  10. Comparison of plastic strains on AA5052 by single point incremental forming process using digital image processing

    Energy Technology Data Exchange (ETDEWEB)

    Mugendiran, V.; Gnanavelbabu, A. [Anna University, Chennai, Tamilnadu (India)

    2017-06-15

    In this study, a surface based strain measurement was used to determine the formability of the sheet metal. A strain measurement may employ manual calculation of plastic strains based on the reference circle and the deformed circle. The manual calculation method has a greater margin of error in the practical applications. In this paper, an attempt has been made to compare the formability by implementing three different theoretical approaches: Namely conventional method, least square method and digital based strain measurements. As the sheet metal was formed by a single point incremental process the etched circles get deformed into elliptical shapes approximately, image acquisition has been done before and after forming. The plastic strains of the deformed circle grids are calculated based on the non- deformed reference. The coordinates of the deformed circles are measured by various image processing steps. Finally the strains obtained from the deformed circle are used to plot the forming limit diagram. To evaluate the accuracy of the system, the conventional, least square and digital based method of prediction of the forming limit diagram was compared. Conventional method and least square method have marginal error when compared with digital based processing method. Measurement of strain based on image processing agrees well and can be used to improve the accuracy and to reduce the measurement error in prediction of forming limit diagram.

  11. Comparison of plastic strains on AA5052 by single point incremental forming process using digital image processing

    International Nuclear Information System (INIS)

    Mugendiran, V.; Gnanavelbabu, A.

    2017-01-01

    In this study, a surface based strain measurement was used to determine the formability of the sheet metal. A strain measurement may employ manual calculation of plastic strains based on the reference circle and the deformed circle. The manual calculation method has a greater margin of error in the practical applications. In this paper, an attempt has been made to compare the formability by implementing three different theoretical approaches: Namely conventional method, least square method and digital based strain measurements. As the sheet metal was formed by a single point incremental process the etched circles get deformed into elliptical shapes approximately, image acquisition has been done before and after forming. The plastic strains of the deformed circle grids are calculated based on the non- deformed reference. The coordinates of the deformed circles are measured by various image processing steps. Finally the strains obtained from the deformed circle are used to plot the forming limit diagram. To evaluate the accuracy of the system, the conventional, least square and digital based method of prediction of the forming limit diagram was compared. Conventional method and least square method have marginal error when compared with digital based processing method. Measurement of strain based on image processing agrees well and can be used to improve the accuracy and to reduce the measurement error in prediction of forming limit diagram.

  12. Hydrogen-induced delayed cracking: 1. Strain energy effects on hydrogen solubility

    International Nuclear Information System (INIS)

    Puls, M.P.

    1978-08-01

    Based on Li, Oriani and Darken's derivation of the chemical potential of a solute in a stressed solid and Eshelby's method for obtaining the strain energy of solids containing coherent inhomogeneous inclusions, we have carried out a detailed theoretical analysis of the factors governing hydrogen solubility in stressed and unstressed zirconium and its alloys. Specifically, the analysis demonstrates the strong influence hydride self-stresses may have on the terminal solid solubility of hydrogen in zirconium. The self-energy arises due to the misfit strains between matrix and precipitate. We have calculated the total molal self-strain energy of some commonly observed δ and γ-hydride shapes and orientations. The magnitude of this energy is substantial. Thus for γ-hydride plates lying on basal planes, it is 4912 J/mol, while for γ-hydride needles with the needle axis parallel to the directions of the α-zirconium matrix, it is 2662 J/mol. This self-strain energy causes a shift in the terminal solid solubility. For example, at 77 o C, assuming fully constrained basal plane δ-hydride plates, the terminal solid solubility is increased 5.4 times over the stress-free case. We have also calculated the effect of external stress on the terminal solid solubility. This is governed by the interaction energy arising from the interaction of the applied stresses with the precipitate's misfit strain components. The interaction energy has been calculated for δ and γ-hydride plates and needles, taking full account of the anisotropy of the misfit. The interaction energy is negative for tensile applied stresses and, as a result of the anisotropic misfit, is texture-dependent. Its magnitude is small for most applied stresses but can achieve values of the order of the self-strain energy in the plastic zone of a plane-strain crack. We have also carried out a careful analysis of the solubility data of Kearns and Erickson and Hardie. This analysis is based partly on the theoretical

  13. Parameters identification in strain-rate and thermal sensitive visco-plastic material model for an alumina dispersion strengthened copper

    CERN Document Server

    Scapin, M; Peroni, M

    2011-01-01

    The main objective of this paper is getting strain-hardening, thermal and strain-rate parameters for a material model in order to correctly reproduce the deformation process that occurs in high strain-rate scenario, in which the material reaches also high levels of plastic deformation and temperature. In particular, in this work the numerical inverse method is applied to extract material strength parameters from experimental data obtained via mechanical tests at different strain-rates (from quasi-static loading to high strain-rate) and temperatures (between 20 C and 1000 C) for an alumina dispersion strengthened copper material, which commercial name is GLIDCOP. Thanks to its properties GLIDCOP finds several applications in particle accelerator technologies, where problems of thermal management, combined with structural requirements, play a key role. Currently, it is used for the construction of structural and functional parts of the particle beam collimation system. Since the extreme condition in which the m...

  14. 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.

  15. Two phase modeling of the influence of plastic strain on the magnetic and magnetostrictive behaviors of ferromagnetic materials

    International Nuclear Information System (INIS)

    Hubert, Olivier; Lazreg, Said

    2017-01-01

    A growing interest of automotive industry in the use of high performance steels is observed. These materials are obtained thanks to complex manufacturing processes whose parameters fluctuations lead to strong variations of microstructure and mechanical properties. The on-line magnetic non-destructive monitoring is a relevant response to this problem but it requires fast models sensitive to different parameters of the forming process. The plastic deformation is one of these important parameters. Indeed, ferromagnetic materials are known to be sensitive to stress application and especially to plastic strains. In this paper, a macroscopic approach using the kinematic hardening is proposed to model this behavior, considering a plastic strained material as a two phase system. Relationship between kinematic hardening and residual stress is defined in this framework. Since stress fields are multiaxial, an uniaxial equivalent stress is calculated and introduced inside the so-called magneto-mechanical multidomain modeling to represent the effect of plastic strain. The modeling approach is complemented by many experiments involving magnetic and magnetostrictive measurements. They are carried out with or without applied stress, using a dual-phase steel deformed at different levels. The main interest of this material is that the mechanically hard phase, soft phase and the kinematic hardening can be clearly identified thanks to simple experiments. It is shown how this model can be extended to single phase materials.

  16. Two phase modeling of the influence of plastic strain on the magnetic and magnetostrictive behaviors of ferromagnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Hubert, Olivier, E-mail: olivier.hubert@lmt.ens-cachan.fr; Lazreg, Said

    2017-02-15

    A growing interest of automotive industry in the use of high performance steels is observed. These materials are obtained thanks to complex manufacturing processes whose parameters fluctuations lead to strong variations of microstructure and mechanical properties. The on-line magnetic non-destructive monitoring is a relevant response to this problem but it requires fast models sensitive to different parameters of the forming process. The plastic deformation is one of these important parameters. Indeed, ferromagnetic materials are known to be sensitive to stress application and especially to plastic strains. In this paper, a macroscopic approach using the kinematic hardening is proposed to model this behavior, considering a plastic strained material as a two phase system. Relationship between kinematic hardening and residual stress is defined in this framework. Since stress fields are multiaxial, an uniaxial equivalent stress is calculated and introduced inside the so-called magneto-mechanical multidomain modeling to represent the effect of plastic strain. The modeling approach is complemented by many experiments involving magnetic and magnetostrictive measurements. They are carried out with or without applied stress, using a dual-phase steel deformed at different levels. The main interest of this material is that the mechanically hard phase, soft phase and the kinematic hardening can be clearly identified thanks to simple experiments. It is shown how this model can be extended to single phase materials.

  17. Parametric analysis of plastic strain and force distribution in single pass metal spinning

    International Nuclear Information System (INIS)

    Choudhary, Shashank; Tejesh, Chiruvolu Mohan; Regalla, Srinivasa Prakash; Suresh, Kurra

    2013-01-01

    Metal spinning also known as spin forming is one of the sheet metal working processes by which an axis-symmetric part can be formed from a flat sheet metal blank. Parts are produced by pressing a blunt edged tool or roller on to the blank which in turn is mounted on a rotating mandrel. This paper discusses about the setting up a 3-D finite element simulation of single pass metal spinning in LS-Dyna. Four parameters were considered namely blank thickness, roller nose radius, feed ratio and mandrel speed and the variation in forces and plastic strain were analysed using the full-factorial design of experiments (DOE) method of simulation experiments. For some of these DOE runs, physical experiments on extra deep drawing (EDD) sheet metal were carried out using En31 tool on a lathe machine. Simulation results are able to predict the zone of unsafe thinning in the sheet and high forming forces that are hint to the necessity for less-expensive and semi-automated machine tools to help the household and small scale spinning workers widely prevalent in India

  18. Parametric analysis of plastic strain and force distribution in single pass metal spinning

    Science.gov (United States)

    Choudhary, Shashank; Tejesh, Chiruvolu Mohan; Regalla, Srinivasa Prakash; Suresh, Kurra

    2013-12-01

    Metal spinning also known as spin forming is one of the sheet metal working processes by which an axis-symmetric part can be formed from a flat sheet metal blank. Parts are produced by pressing a blunt edged tool or roller on to the blank which in turn is mounted on a rotating mandrel. This paper discusses about the setting up a 3-D finite element simulation of single pass metal spinning in LS-Dyna. Four parameters were considered namely blank thickness, roller nose radius, feed ratio and mandrel speed and the variation in forces and plastic strain were analysed using the full-factorial design of experiments (DOE) method of simulation experiments. For some of these DOE runs, physical experiments on extra deep drawing (EDD) sheet metal were carried out using En31 tool on a lathe machine. Simulation results are able to predict the zone of unsafe thinning in the sheet and high forming forces that are hint to the necessity for less-expensive and semi-automated machine tools to help the household and small scale spinning workers widely prevalent in India.

  19. Parametric analysis of plastic strain and force distribution in single pass metal spinning

    Energy Technology Data Exchange (ETDEWEB)

    Choudhary, Shashank, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Tejesh, Chiruvolu Mohan, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Regalla, Srinivasa Prakash, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Suresh, Kurra, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in [Department of Mechanical Engineering, BITS-Pilani, Hyderabad Campus, Shamirpet, Hyderabad, 500078, Andhra Pradesh (India)

    2013-12-16

    Metal spinning also known as spin forming is one of the sheet metal working processes by which an axis-symmetric part can be formed from a flat sheet metal blank. Parts are produced by pressing a blunt edged tool or roller on to the blank which in turn is mounted on a rotating mandrel. This paper discusses about the setting up a 3-D finite element simulation of single pass metal spinning in LS-Dyna. Four parameters were considered namely blank thickness, roller nose radius, feed ratio and mandrel speed and the variation in forces and plastic strain were analysed using the full-factorial design of experiments (DOE) method of simulation experiments. For some of these DOE runs, physical experiments on extra deep drawing (EDD) sheet metal were carried out using En31 tool on a lathe machine. Simulation results are able to predict the zone of unsafe thinning in the sheet and high forming forces that are hint to the necessity for less-expensive and semi-automated machine tools to help the household and small scale spinning workers widely prevalent in India.

  20. Simulation of vacancy migration energy in Cu under high strain

    International Nuclear Information System (INIS)

    Sato, K.; Yoshiie, T.; Satoh, Y.; Xu, Q.; Kiritani, M.

    2003-01-01

    The activation energy for the migration of vacancies in Cu under high strain was calculated by computer simulation using static methods. The migration energy of vacancies was 0.98 eV in the absence of deformation. It varied with the migration direction and stress direction because the distance between a vacancy and its neighboring atoms changes by deformation. For example, the migration energy for the shortest migration distance was reduced to 9.6 and 39.4% of its initial value by 10% compression and 20% elongation, respectively, while that for the longest migration distance was raised to 171.7 by 20% elongation. If many vacancies are created during high-speed deformation, the lowering of migration energy enables vacancies to escape to sinks such as surfaces, even during the shorter deformation period. The critical strain rate above which the strain rate dependence of vacancy accumulation ceases to exist increases with the lowering of vacancy migration energy

  1. Finite element implementation of strain-hardening Drucker–Prager plasticity model with application to tunnel excavation

    Directory of Open Access Journals (Sweden)

    K. Liu

    2017-09-01

    Full Text Available This paper presents a finite element implementation of a strain-hardening Drucker–Prager model and its application to tunnel excavation. The computational model was constructed based on the return mapping scheme, in which an elastic trial step was first executed, followed by plastic correction involving the Newton–Raphson method to return the predicted state of stresses to the supposed yield surface. By combining the plastic shear hardening rule and stress correction equations, the loading index for the strain-hardening Drucker–Prager model was solved. It is therefore possible to update the stresses, elastic and plastic strains, and slope of the yield locus at the end of each incremental step. As an illustrative example, an integration algorithm was incorporated into ABAQUS through the user subroutine UMAT to solve the tunnel excavation problem in strain-hardening Drucker–Prager rock formations. The obtained numerical results were found to be in excellent agreement with the available analytical solutions, thus indicating the validity and accuracy of the proposed UMAT code, as well as the finite element model.

  2. The industrial metabolism of plastics : analysis of material flows, energy consumption and CO2 emissions in the lifecycle of plastics

    NARCIS (Netherlands)

    Joosten, Ludovicus Antonius Josephus

    2001-01-01

    This thesis deals with the question: Which are promising options for decreasing material consumption, energy consumption and CO2 emissions in the lifecycle of plastics? The research described in this thesis mainly focuses on measures that change the material system, i.e. measures that change the

  3. Energy scavenging strain absorber: application to kinetic dielectric elastomer generator

    Science.gov (United States)

    Jean-Mistral, C.; Beaune, M.; Vu-Cong, T.; Sylvestre, A.

    2014-03-01

    Dielectric elastomer generators (DEGs) are light, compliant, silent energy scavengers. They can easily be incorporated into clothing where they could scavenge energy from the human kinetic movements for biomedical applications. Nevertheless, scavengers based on dielectric elastomers are soft electrostatic generators requiring a high voltage source to polarize them and high external strain, which constitutes the two major disadvantages of these transducers. We propose here a complete structure made up of a strain absorber, a DEG and a simple electronic power circuit. This new structure looks like a patch, can be attached on human's wear and located on the chest, knee, elbow… Our original strain absorber, inspired from a sailing boat winch, is able to heighten the external available strain with a minimal factor of 2. The DEG is made of silicone Danfoss Polypower and it has a total area of 6cm per 2.5cm sustaining a maximal strain of 50% at 1Hz. A complete electromechanical analytical model was developed for the DEG associated to this strain absorber. With a poling voltage of 800V, a scavenged energy of 0.57mJ per cycle is achieved with our complete structure. The performance of the DEG can further be improved by enhancing the imposed strain, by designing a stack structure, by using a dielectric elastomer with high dielectric permittivity.

  4. Effect of plastic straining on the F and M centres kinetics in γ-irradiated NaCl

    International Nuclear Information System (INIS)

    Agullo Lopez, F.

    1966-01-01

    The effect of plastic straining on the room-temperature F and H growth curves in a γ-radiation field has been analyzed. Cristal are strained after F-saturation is reached and then irradiation is continued. The new F growth curve consists of an initial fast growing stage due to additional vacancies created by deformation being turned into F centre, followed by a linear stage. Its slope is higher than that prior to straining. Also the role of straining on M centre thermal decay as well as on the F→M reaction under F light, has been investigated. This reaction has been shown to preferentially occur where intense gliding has developed. (Author) 44 refs

  5. Comparison of theory and experiment for elastic-plastic plane-strain crack growth. [AISI 4140 steel

    Energy Technology Data Exchange (ETDEWEB)

    Hermann, L.; Rice, J.R.

    1980-08-01

    Recent theoretical results on elastic-plastic plane-strain crack growth are reviewed and experimental results for crack growth in a 4140 steel are discussed in terms of the theoretical concepts. The theory is based on a recent asymptotic analysis of crack surface opening and strain distributions at a quasistatically advancing crack tip in an ideally plastic solid. The analysis is incomplete in that some of the parameters which appear in it are known only approximately, especially at large-scale yielding. Nevertheless, it is sufficient for the derivation of a relation between the imposed loading and amount of crack growth prior to general yielding, based on the assumption that a geometrically similar near-tip crack profile is maintained during growth. The resulting predictions for the variation of J with crack growth are found to fit well to the experimental results obtained on deeply cracked compact specimens.

  6. EBSD-based techniques for characterization of microstructural restoration processes during annealing of metals deformed to large plastic strains

    DEFF Research Database (Denmark)

    Godfrey, A.; Mishin, Oleg; Yu, Tianbo

    2012-01-01

    Some methods for quantitative characterization of the microstructures deformed to large plastic strains both before and after annealing are discussed and illustrated using examples of samples after equal channel angular extrusion and cold-rolling. It is emphasized that the microstructures...... in such deformed samples exhibit a heterogeneity in the microstructural refinement by high angle boundaries. Based on this, a new parameter describing the fraction of regions containing predominantly low angle boundaries is introduced. This parameter has some advantages over the simpler high angle boundary...... on mode of the distribution of dislocation cell sizes is outlined, and it is demonstrated how this parameter can be used to investigate the uniformity, or otherwise, of the restoration processes occurring during annealing of metals deformed to large plastic strains. © (2012) Trans Tech Publications...

  7. Texture, residual strain, and plastic deformation around scratches in alloy 600 using synchrotron X-ray Laue micro-diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Suominen Fuller, M.L. [Surface Science Western, Room G-1, Western Science Centre, University of Western Ontario, London, Ontario, N6A 5B7 (Canada)], E-mail: mfuller@uwo.ca; Klassen, R.J. [Department of Mechanical and Materials Engineering, Room 3002 Spencer Engineering Building, University of Western Ontario, London, Ontario, N6A 5B9 (Canada); McIntyre, N.S. [Surface Science Western, Room G-1, Western Science Centre, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Gerson, A.R. [Applied Centre for Structural and Synchrotron Studies, Mawson Lakes Campus, University of South Australia, Adelaide, South Australia 5095 (Australia); Ramamurthy, S. [Surface Science Western, Room G-1, Western Science Centre, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); King, P.J. [Babcock and Wilcox Canada, 581 Coronation Blvd., Cambridge, Ontario, N1R5V3 (Canada); Liu, W. [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)

    2008-03-15

    Deformation around two scratches in Alloy 600 (A600) was studied nondestructively using synchrotron Laue differential aperture X-ray microscopy. The orientation of grains and elastic strain distribution around the scratches were measured. A complex residual deviatoric elastic strain state was found to exist around the scratches. Heavy plastic deformation was observed up to a distance of 20 {mu}m from the scratches. In the region 20-30 {mu}m from the scratches the diffraction spots were heavily streaked and split indicating misoriented dislocation cell structures.

  8. Assessment of stress-strain data suitable for finite-element elastic--plastic analysis of shipping containers

    International Nuclear Information System (INIS)

    Rack, H.J.; Knorovsky, G.A.

    1978-09-01

    Stress-strain data which describes the influence of strain rate and temperature on the mechanical response of materials presently being used for light water reactor fuel shipping containers have been assembled. Selection of data has been limited to that which is suitable for use in finite-element elastic--plastic analysis of shipping containers (e.g., they must include complete material history profiles). Based on this information, recommendations have been made for further work which is required to complete the necessary data base

  9. A model for plasticity kinetics and its role in simulating the dynamic behavior of Fe at high strain rates

    Energy Technology Data Exchange (ETDEWEB)

    Colvin, J D; Minich, R W; Kalantar, D H

    2007-03-29

    The recent diagnostic capability of the Omega laser to study solid-solid phase transitions at pressures greater than 10 GPa and at strain rates exceeding 10{sup 7} s{sup -1} has also provided valuable information on the dynamic elastic-plastic behavior of materials. We have found, for example, that plasticity kinetics modifies the effective loading and thermodynamic paths of the material. In this paper we derive a kinetics equation for the time-dependent plastic response of the material to dynamic loading, and describe the model's implementation in a radiation-hydrodynamics computer code. This model for plasticity kinetics incorporates the Gilman model for dislocation multiplication and saturation. We discuss the application of this model to the simulation of experimental velocity interferometry data for experiments on Omega in which Fe was shock compressed to pressures beyond the {alpha}-to-{var_epsilon} phase transition pressure. The kinetics model is shown to fit the data reasonably well in this high strain rate regime and further allows quantification of the relative contributions of dislocation multiplication and drag. The sensitivity of the observed signatures to the kinetics model parameters is presented.

  10. Microstructure and annealing behavior of a modified 9Cr-1Mo steel after dynamic plastic deformation to different strains

    DEFF Research Database (Denmark)

    Zhang, Zhenbo; Mishin, Oleg; Tao, N.R.

    2015-01-01

    The microstructure, hardness and tensile properties of a modified 9Cr-1Mo steel processed by dynamic plastic deformation (DPD) to different strains (0.5 and 2.3) have been investigated in the as-deformed and annealed conditions. It is found that significant structural refinement and a high level...... in a loss of strength with only a small gain in ductility, coarsening combined with pronounced partial recrystallization enables a combination of appreciably increased ductility and comparatively high strength....

  11. A Finite Strain Model of Stress, Diffusion, Plastic Flow and Electrochemical Reactions in a Lithium-ion Half-cell

    OpenAIRE

    Bower, Allan F.; Guduru, Pradeep R.; Sethuraman, Vijay A.

    2011-01-01

    We formulate the continuum field equations and constitutive equations that govern deformation, stress, and electric current flow in a Li-ion half-cell. The model considers mass transport through the system, deformation and stress in the anode and cathode, electrostatic fields, as well as the electrochemical reactions at the electrode/electrolyte interfaces. It extends existing analyses by accounting for the effects of finite strains and plastic flow in the electrodes, and by exploring in deta...

  12. Fiscal 1999 leading research report. High strain-rate super-plasticity (Leading research); 1999 nendo kosoku chososei kenkyu hokokusho. Sendo kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    For solving the global warming problem and constructing the resource recycling society, a demand for highly recyclable light-weight Mg alloys is increasing for energy saving and recycling improvement, in particular, for automobiles and electrical appliances. However, use of Mg materials is limited because its poor workability. This research targets development of the material with a rich recyclability and a rich workability for forming complex shapes, and its working technology. Leading research was made on development of the continuous high-strain rate (more than 10{sup -2}/s) super- plasticity material forming process from raw materials to products of Mg alloys, and establishment of the production technology free from technological barriers. The research result showed that for the recognition of Mg alloy as low- environment load super light-weight industrial material, establishment of the composite resource-saving energy-saving production process including recycling and reusing is necessary at the same time as establishment of the high- strain rate super-plasticity material forming process. (NEDO)

  13. Pyrolysis of plastic waste for liquid fuel production as prospective energy resource

    Science.gov (United States)

    Sharuddin, S. D. A.; Abnisa, F.; Daud, W. M. A. W.; Aroua, M. K.

    2018-03-01

    The worldwide plastic generation expanded over years because of the variety applications of plastics in numerous sectors that caused the accumulation of plastic waste in the landfill. The growing of plastics demand definitely affected the petroleum resources availability as non-renewable fossil fuel since plastics were the petroleum-based material. A few options that have been considered for plastic waste management were recycling and energy recovery technique. Nevertheless, several obstacles of recycling technique such as the needs of sorting process that was labour intensive and water pollution that lessened the process sustainability. As a result, the plastic waste conversion into energy was developed through innovation advancement and extensive research. Since plastics were part of petroleum, the oil produced through the pyrolysis process was said to have high calorific value that could be used as an alternative fuel. This paper reviewed the thermal and catalytic degradation of plastics through pyrolysis process and the key factors that affected the final end product, for instance, oil, gaseous and char. Additionally, the liquid fuel properties and a discussion on several perspectives regarding the optimization of the liquid oil yield for every plastic were also included in this paper.

  14. Determining the amount of waste plastics in the feed of Austrian waste-to-energy facilities.

    Science.gov (United States)

    Schwarzböck, Therese; Van Eygen, Emile; Rechberger, Helmut; Fellner, Johann

    2017-02-01

    Although thermal recovery of waste plastics is widely practiced in many European countries, reliable information on the amount of waste plastics in the feed of waste-to-energy plants is rare. In most cases the amount of plastics present in commingled waste, such as municipal solid waste, commercial, or industrial waste, is estimated based on a few waste sorting campaigns, which are of limited significance with regard to the characterisation of plastic flows. In the present study, an alternative approach, the so-called Balance Method, is used to determine the total amount of plastics thermally recovered in Austria's waste incineration facilities in 2014. The results indicate that the plastics content in the waste feed may vary considerably among different plants but also over time. Monthly averages determined range between 8 and 26 wt% of waste plastics. The study reveals an average waste plastics content in the feed of Austria's waste-to-energy plants of 16.5 wt%, which is considerably above findings from sorting campaigns conducted in Austria. In total, about 385 kt of waste plastics were thermally recovered in all Austrian waste-to-energy plants in 2014, which equals to 45 kg plastics cap -1 . In addition, the amount of plastics co-combusted in industrial plants yields a total thermal utilisation rate of 70 kg cap -1  a -1 for Austria. This is significantly above published rates, for example, in Germany reported rates for 2013 are in the range of only 40 kg of waste plastics combusted per capita.

  15. Greenhouse gas mitigation for U.S. plastics production: energy first, feedstocks later

    Science.gov (United States)

    Posen, I. Daniel; Jaramillo, Paulina; Landis, Amy E.; Griffin, W. Michael

    2017-03-01

    Plastics production is responsible for 1% and 3% of U.S. greenhouse gas (GHG) emissions and primary energy use, respectively. Replacing conventional plastics with bio-based plastics (made from renewable feedstocks) is frequently proposed as a way to mitigate these impacts. Comparatively little research has considered the potential for green energy to reduce emissions in this industry. This paper compares two strategies for reducing greenhouse gas emissions from U.S. plastics production: using renewable energy or switching to renewable feedstocks. Renewable energy pathways assume all process energy comes from wind power and renewable natural gas derived from landfill gas. Renewable feedstock pathways assume that all commodity thermoplastics will be replaced with polylactic acid (PLA) and bioethylene-based plastics, made using either corn or switchgrass, and powered using either conventional or renewable energy. Corn-based biopolymers produced with conventional energy are the dominant near-term biopolymer option, and can reduce industry-wide GHG emissions by 25%, or 16 million tonnes CO2e/year (mean value). In contrast, switching to renewable energy cuts GHG emissions by 50%-75% (a mean industry-wide reduction of 38 million tonnes CO2e/year). Both strategies increase industry costs—by up to 85/tonne plastic (mean result) for renewable energy, and up to 3000 tonne-1 plastic for renewable feedstocks. Overall, switching to renewable energy achieves greater emission reductions, with less uncertainty and lower costs than switching to corn-based biopolymers. In the long run, producing bio-based plastics from advanced feedstocks (e.g. switchgrass) and/or with renewable energy can further reduce emissions, to approximately 0 CO2e/year (mean value).

  16. Application of Strain Energy on BIW Mode Optimization

    Directory of Open Access Journals (Sweden)

    Chang Guangbao

    2015-01-01

    Full Text Available This paper takes the BIW model as the research object, completes modal analysis, and verifies the finite element model by comparing the simulation results with the test results. In order to improve the frequency of BIW, the weak structure of D pillar is found and then optimized by the method of strain energy, and the frequency of BIW is changed from 28.80Hz to 32.15Hz. Finally, the method of strain energy has great positive effects on modal optimization.

  17. A neutron diffraction study of residual stress and plastic strain in welded beryllium rings

    Energy Technology Data Exchange (ETDEWEB)

    Brown, D.W.; Varma, R.; Bourke, M.A.M.; Holden, T.M. [Los Alamos National Lab., Los Alamos, NM (United States); Ely, T.; Spooner, S. [Oak Ridge National Lab., Oak Ridge, TN (United States)

    2002-07-01

    We present a study of residual stresses associated with the welding of beryllium rings. Using novel analysis techniques, information about residual stresses and plastic deformation of the base metal were obtained. In the post-welded state, the rings have a strong tensile circumferential residual stress and show evidence of significant plastic deformation. (orig.)

  18. Energy dependent response of plastic scintillation detectors to photon radiation of low to medium energy.

    Science.gov (United States)

    Ebenau, Melanie; Radeck, Désirée; Bambynek, Markus; Sommer, Holger; Flühs, Dirk; Spaan, Bernhard; Eichmann, Marion

    2016-08-01

    Plastic scintillation detectors are promising candidates for the dosimetry of low- to medium-energy photons but quantitative knowledge of their energy response is a prerequisite for their correct use. The purpose of this study was to characterize the energy dependent response of small scintillation detectors (active volume <1 mm(3)) made from the commonly used plastic scintillator BC400. Different detectors made from BC400 were calibrated at a number of radiation qualities ranging from 10 to 280 kV and at a (60)Co beam. All calibrations were performed at the Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany. The energy response in terms of air kerma, dose to water, and dose to the scintillator was determined. Conversion factors from air kerma to dose to water and to dose to the scintillator were derived from Monte Carlo simulations. In order to quantitatively describe the energy dependence, a semiempirical model known as unimolecular quenching or Birks' formula was fitted to the data and from this the response to secondary electrons generated within the scintillator material BC400 was derived. The detector energy response in terms of air kerma differs for different scintillator sizes and different detector casings. It is therefore necessary to take attenuation within the scintillator and in the casing into account when deriving the response in terms of dose to water from a calibration in terms of air kerma. The measured energy response in terms of dose to water for BC400 cannot be reproduced by the ratio of mean mass energy-absorption coefficients for polyvinyl toluene to water but shows evidence of quenching. The quenching parameter kB in Birks' formula was determined to be kB = (12.3 ± 0.9) mg MeV(-1) cm(-2). The energy response was quantified relative to the response to (60)Co which is the common radiation quality for the calibration of therapy dosemeters. The observed energy dependence could be well explained with the

  19. Energy dependent response of plastic scintillation detectors to photon radiation of low to medium energy

    Energy Technology Data Exchange (ETDEWEB)

    Ebenau, Melanie, E-mail: melanie.ebenau@tu-dortmunde.de; Sommer, Holger; Spaan, Bernhard; Eichmann, Marion [Fakultät Physik, Technische Universität Dortmund, Otto-Hahn Str. 4a, 44221 Dortmund (Germany); Radeck, Désirée; Bambynek, Markus [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Flühs, Dirk [Universitätsklinikum Essen, Hufelandstr. 55, 45147 Essen (Germany)

    2016-08-15

    Purpose: Plastic scintillation detectors are promising candidates for the dosimetry of low- to medium-energy photons but quantitative knowledge of their energy response is a prerequisite for their correct use. The purpose of this study was to characterize the energy dependent response of small scintillation detectors (active volume <1 mm{sup 3}) made from the commonly used plastic scintillator BC400. Methods: Different detectors made from BC400 were calibrated at a number of radiation qualities ranging from 10 to 280 kV and at a {sup 60}Co beam. All calibrations were performed at the Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany. The energy response in terms of air kerma, dose to water, and dose to the scintillator was determined. Conversion factors from air kerma to dose to water and to dose to the scintillator were derived from Monte Carlo simulations. In order to quantitatively describe the energy dependence, a semiempirical model known as unimolecular quenching or Birks’ formula was fitted to the data and from this the response to secondary electrons generated within the scintillator material BC400 was derived. Results: The detector energy response in terms of air kerma differs for different scintillator sizes and different detector casings. It is therefore necessary to take attenuation within the scintillator and in the casing into account when deriving the response in terms of dose to water from a calibration in terms of air kerma. The measured energy response in terms of dose to water for BC400 cannot be reproduced by the ratio of mean mass energy-absorption coefficients for polyvinyl toluene to water but shows evidence of quenching. The quenching parameter kB in Birks’ formula was determined to be kB = (12.3 ± 0.9) mg MeV{sup −1} cm{sup −2}. Conclusions: The energy response was quantified relative to the response to {sup 60}Co which is the common radiation quality for the calibration of therapy dosemeters. The

  20. Constitutive modelling and identification of parameters of the plastic strain-induced martensitic transformation in 316L stainless steel at cryogenic temperatures

    CERN Document Server

    Garion, C; Sgobba, Stefano

    2006-01-01

    The present paper is focused on constitutive modelling and identification of parameters of the relevant model of plastic strain- induced martensitic transformation in austenitic stainless steels at low temperatures. The model used to describe the FCCrightward arrow BCC phase transformation in austenitic stainless steels is based on the assumption of linearization of the most intensive part of the transformation curve. The kinetics of phase transformation is described by three parameters: transformation threshold (p/sub xi/), slope (A) and saturation level (xi/sub L/). It is assumed that the phase transformation is driven by the accumulated plastic strain p. In addition, the intensity of plastic deformation is strongly coupled to the phase transformation via the description of mixed kinematic /isotropic linear plastic hardening based on the Mori-Tanaka homogenization. The theory of small strains is applied. Small strain fields, corresponding to phase transformation, are decomposed into the volumic and the shea...

  1. Potential of Electronic Plastic Waste as a Source of Raw Material and Energy Recovery

    International Nuclear Information System (INIS)

    Norazli Othman; Nor Ezlin Ahmad Basri; Lariyah Mohd Sidek

    2009-01-01

    Nowadays, the production of electronic equipment is one of the fastest growing industrial activities in this world. The increase use of plastic in this sector resulted in an increase of electronic plastic waste. Basically, electronic plastic material contains various chemical elements which act as a flame retardant when electronic equipment is operated. In general, the concept of recycling electronic plastic waste should be considered in order to protect the environment. For this purpose, research has been conducted to different resins of electronic plastic waste to identify the potential of electronic plastic waste as a source of raw material and energy recovery. This study was divided into two part for example determination of physical and chemical characteristics of plastic resins and calculation of heating value for plastic resins based on Dulong formula. Results of this research show that the average calorific value of electronic waste is 30,872.42 kJ/ kg (7,375 kcal/ kg). The emission factor analysis showed that the concentration of emission value that might occur during waste management activities is below the standard set by the Environment Quality Act 1974. Basically, this research shows that electronic plastic waste has the potential to become the source of raw material and energy recovery. (author)

  2. Genome Plasticity and Polymorphisms in Critical Genes Correlate with Increased Virulence of Dutch Outbreak-Related Coxiella burnetii Strains

    Directory of Open Access Journals (Sweden)

    Runa Kuley

    2017-08-01

    in all Dutch outbreak strains compared to the NM reference strain and other strains of the CbNL12 genotype. The presence of large numbers of transposable elements and mutated genes, thereof most likely resulted in high level of genome rearrangements and genotype-specific pathogenicity of outbreak strains. Thus, the epidemic potential of Dutch outbreak strains could be linked to increased genome plasticity and mutations in critical genes involved in virulence and the evasion of the host immune system.

  3. Microstructure and annealing behavior of a modified 9Cr−1Mo steel after dynamic plastic deformation to different strains

    International Nuclear Information System (INIS)

    Zhang, Z.B.; Mishin, O.V.; Tao, N.R.; Pantleon, W.

    2015-01-01

    The microstructure, hardness and tensile properties of a modified 9Cr−1Mo steel processed by dynamic plastic deformation (DPD) to different strains (0.5 and 2.3) have been investigated in the as-deformed and annealed conditions. It is found that significant structural refinement and a high level of strength can be achieved by DPD to a strain of 2.3, and that the microstructure at this strain contains a large fraction of high angle boundaries. The ductility of the DPD processed steel is however low. Considerable structural coarsening of the deformed microstructure without pronounced recrystallization takes place during annealing of the low-strain and high-strain samples for 1 h at 650 °C and 600 °C, respectively. Both coarsening and partial recrystallization occur in the high-strain sample during annealing at 650 °C for 1 h. For this sample, it is found that whereas coarsening alone results in a loss of strength with only a small gain in ductility, coarsening combined with pronounced partial recrystallization enables a combination of appreciably increased ductility and comparatively high strength

  4. Relaxation of the single-slip condition in strain-gradient plasticity.

    Science.gov (United States)

    Anguige, Keith; Dondl, Patrick W

    2014-09-08

    We consider the variational formulation of both geometrically linear and geometrically nonlinear elasto-plasticity subject to a class of hard single-slip conditions. Such side conditions typically render the associated boundary-value problems non-convex. We show that, for a large class of non-smooth plastic distortions, a given single-slip condition (specification of Burgers vectors) can be relaxed by introducing a microstructure through a two-stage process of mollification and lamination. The relaxed model can be thought of as an aid to simulating macroscopic plastic behaviour without the need to resolve arbitrarily fine spatial scales.

  5. Representative Stress-Strain Curve by Spherical Indentation on Elastic-Plastic Materials

    Directory of Open Access Journals (Sweden)

    Chao Chang

    2018-01-01

    Full Text Available Tensile stress-strain curve of metallic materials can be determined by the representative stress-strain curve from the spherical indentation. Tabor empirically determined the stress constraint factor (stress CF, ψ, and strain constraint factor (strain CF, β, but the choice of value for ψ and β is still under discussion. In this study, a new insight into the relationship between constraint factors of stress and strain is analytically described based on the formation of Tabor’s equation. Experiment tests were performed to evaluate these constraint factors. From the results, representative stress-strain curves using a proposed strain constraint factor can fit better with nominal stress-strain curve than those using Tabor’s constraint factors.

  6. Characterization of plastic strains and crystallographic properties surrounding defects in steam generator tubes by orientation imaging microscopy

    International Nuclear Information System (INIS)

    Lehockey, E.M.; Brennenstuhl, A.M.

    2002-01-01

    Orientation Imaging Microscopy (OIM) has become a valuable technique for characterizing grain boundary structure, texture, and grain size distribution, which govern material susceptibility to degenerative effects (e.g. IGSCC). Methods recently developed, by Kinectrics, have extended OIM capabilities toward mapping and quantifying residual plastic strains in materials. OIM is applied in the present work to characterize the distribution of plastic strains, that accumulate in CANDU steam generator tubing during installation and service potentially undermining the performance, reliability, and fitness-for-service of these components. Plastic strain that evolves in response to roller-expansion was characterized in simulated roll joints constructed from Alloy 600 tubing. Results underscore the effect of over-rolling in generating intense gradients with broad variations in strain that extend significant distances through the wall thickness. Of greater relevance is the orientation of these gradients in the transverse direction, relative to the tube axis and potential for the development of abnormal grain growth during post-expansion heat treatments. The magnitude and distribution of strain measured by OIM are remarkably consistent with Finite Element Analysis (FEA) predictions offering compelling evidence as to the reliability of the OIM technique. OIM offers superior resolution than can be practically achieved with FEA having particular relevance in identifying highly localized concentrations of strain surrounding metallurgical defects that can serve as precursors to stress-related degenerative effects (e.g. IGSCC). The spatial distribution of residual plastic strain was also characterized within the context of localized texture, and grain size morphology surrounding (OD) 'pits' and indentations found in ex-service Monel 400 and Alloy 800 SG tubes, respectively. An absence of strain surrounding these surface defects suggests their propensity for promoting more deleterious

  7. Spatial-structural interaction and strain energy structural optimisation

    NARCIS (Netherlands)

    Hofmeyer, H.; Davila Delgado, J.M.; Borrmann, A.; Geyer, P.; Rafiq, Y.; Wilde, de P.

    2012-01-01

    A research engine iteratively transforms spatial designs into structural designs and vice versa. Furthermore, spatial and structural designs are optimised. It is suggested to optimise a structural design by evaluating the strain energy of its elements and by then removing, adding, or changing the

  8. Cellular basis of morphological variation and temperature-related plasticity in Drosophila melanogaster strains with divergent wing shapes.

    Science.gov (United States)

    Torquato, Libéria Souza; Mattos, Daniel; Matta, Bruna Palma; Bitner-Mathé, Blanche Christine

    2014-12-01

    Organ shape evolves through cross-generational changes in developmental patterns at cellular and/or tissue levels that ultimately alter tissue dimensions and final adult proportions. Here, we investigated the cellular basis of an artificially selected divergence in the outline shape of Drosophila melanogaster wings, by comparing flies with elongated or rounded wing shapes but with remarkably similar wing sizes. We also tested whether cellular plasticity in response to developmental temperature was altered by such selection. Results show that variation in cellular traits is associated with wing shape differences, and that cell number may play an important role in wing shape response to selection. Regarding the effects of developmental temperature, a size-related plastic response was observed, in that flies reared at 16 °C developed larger wings with larger and more numerous cells across all intervein regions relative to flies reared at 25 °C. Nevertheless, no conclusive indication of altered phenotypic plasticity was found between selection strains for any wing or cellular trait. We also described how cell area is distributed across different intervein regions. It follows that cell area tends to decrease along the anterior wing compartment and increase along the posterior one. Remarkably, such pattern was observed not only in the selected strains but also in the natural baseline population, suggesting that it might be canalized during development and was not altered by the intense program of artificial selection for divergent wing shapes.

  9. Micromechanical analysis of martensite distribution on strain localization in dual phase steels by scanning electron microscopy and crystal plasticity simulation

    Energy Technology Data Exchange (ETDEWEB)

    Jafari, M. [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Ziaei-Rad, S., E-mail: szrad@cc.iut.ac.ir [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Saeidi, N. [Department of Materials Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Jamshidian, M. [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)

    2016-07-18

    The morphology and distribution of the dispersed martensite islands in the ferrite matrix plays a key role in the formation of shear bands in dual phase steels. In this study, we investigate the relationship between the martensite dispersion and the strain localization regions due to the formation of shear bands in fine-grained DP 780 steel, employing experimental observations as well as numerical simulations. SEM studies of the deformed microstructure showed that voids nucleated at ferrite-martensite interface within larger ferrite grains and regions with low local martensite fraction. The experimental results were precisely analyzed by finite element simulations based on the theory of crystal plasticity. A parametric study was then performed to obtain a deeper insight in to the effect of martensite dispersion on the strain localization of the neighboring ferrite. Crystal plasticity simulation results revealed that in a more regular structure compared to a random structure, a greater region of the ferrite phase contributes to accommodate plasticity. In addition, these regions limit the formation of main shear bands by creating barriers against stress concentration regions, results in lower growth and interaction of stress concentration regions with each others.

  10. A new approach for elasto-plastic finite strain analysis of cantilever ...

    Indian Academy of Sciences (India)

    GЦKHAN T TAYYAR

    mental kinematic theories are not well selected according to the expected deflection. ... elasto-plastic behavior to curvature-based kinematic dis- placement theory (KDT) [11]. In KDT ..... transportation and exploitation of sea resources. London:.

  11. Plastic Flow Characteristics of Uranium-Niobium as a Function of Strain Rate and Temperature

    International Nuclear Information System (INIS)

    Cady, C.M.; Gray, G.T. III; Hecker, S.S; Thoma, D.J.; Korzekwa, D.R.; Patterson, R.A.; Dunn, P.S.; Bingert, J.F.

    1999-01-01

    The stress-strain response of uranium-niobium alloys as a function of temperature, strain-rate and stress-state was investigated. The yield and flow stresses of the U-Nb alloys were found to exhibit a pronounced strain rate sensitivity, while the hardening rates were found to be insensitive to strain rate and temperature. The overall stress-strain response of the U-6Nb exhibits a sinusoidal hardening response, which is consistent with multiple deformation modes and is thought to be related to shape-memory behavior

  12. Simulation of finite-strain inelastic phenomena governed by creep and plasticity

    Science.gov (United States)

    Li, Zhen; Bloomfield, Max O.; Oberai, Assad A.

    2017-11-01

    Inelastic mechanical behavior plays an important role in many applications in science and engineering. Phenomenologically, this behavior is often modeled as plasticity or creep. Plasticity is used to represent the rate-independent component of inelastic deformation and creep is used to represent the rate-dependent component. In several applications, especially those at elevated temperatures and stresses, these processes occur simultaneously. In order to model these process, we develop a rate-objective, finite-deformation constitutive model for plasticity and creep. The plastic component of this model is based on rate-independent J_2 plasticity, and the creep component is based on a thermally activated Norton model. We describe the implementation of this model within a finite element formulation, and present a radial return mapping algorithm for it. This approach reduces the additional complexity of modeling plasticity and creep, over thermoelasticity, to just solving one nonlinear scalar equation at each quadrature point. We implement this algorithm within a multiphysics finite element code and evaluate the consistent tangent through automatic differentiation. We verify and validate the implementation, apply it to modeling the evolution of stresses in the flip chip manufacturing process, and test its parallel strong-scaling performance.

  13. Hydrogen-induced strain localisation in oxygen-free copper in the initial stage of plastic deformation

    Science.gov (United States)

    Yagodzinskyy, Yuriy; Malitckii, Evgenii; Tuomisto, Filip; Hänninen, Hannu

    2018-03-01

    Single crystals of oxygen-free copper oriented to easy glide of dislocations were tensile tested in order to study the hydrogen effects on the strain localisation in the form of slip bands appearing on the polished specimen surface under tensile straining. It was found that hydrogen increases the plastic flow stress in Stage I of deformation. The dislocation slip localisation in the form of slip bands was observed and analysed using an online optical monitoring system and atomic force microscopy. The fine structure of the slip bands observed with AFM shows that they consist of a number of dislocation slip offsets which spacing in the presence of hydrogen is markedly reduced as compared to that in the hydrogen-free specimens. The tensile tests and AFM observations were accompanied with positron annihilation lifetime measurements showing that straining of pure copper in the presence of hydrogen results in free volume generation in the form of vacancy complexes. Hydrogen-enhanced free-volume generation is discussed in terms of hydrogen interactions with edge dislocation dipoles forming in double cross-slip of screw dislocations in the initial stage of plastic deformation of pure copper.

  14. Plastic strains during stent deployment have a critical influence on the rate of corrosion in absorbable magnesium stents.

    Science.gov (United States)

    Galvin, Emmet; Cummins, Christy; Yoshihara, Shoichiro; Mac Donald, Bryan J; Lally, Caitríona

    2017-08-01

    Magnesium stents are a promising candidate in the emerging field of absorbable metallic stents (AMSs). In this study, the mechanical and corrosion performance of dog-bone specimens and a specific stent design of a magnesium alloy, WE43, are assessed experimentally in terms of their corrosion behaviour and mechanical integrity. It is shown that plastic strains that are induced in the struts of the stent during stent deployment have a critical influence in directing subsequent corrosion behaviour within the material. In addition, the deployment and scaffolding characteristics of the magnesium stent are elucidated and contrasted with those of a commercial stainless steel stent. The magnesium stent is found to support higher levels of cyclic strain amplitude than the stainless steel stent, even prior to degradation, and this may play a role in reducing in-stent restenosis. This study provides new insights into the experimental performance of a current AMS design and material whilst demonstrating the critical influence of plastic strain on the corrosion performance and scaffolding ability of an AMS.

  15. Mechanisms of strain accommodation in plastically-deformed zircon under simple shear deformation conditions during amphibolite-facies metamorphism

    Science.gov (United States)

    Kovaleva, Elizaveta; Klötzli, Urs; Wheeler, John; Habler, Gerlinde

    2018-02-01

    This study documents the strain accommodation mechanisms in zircon under amphibolite-facies metamorphic conditions in simple shear. Microstructural data from undeformed, fractured and crystal-plastically deformed zircon crystals are described in the context of the host shear zone, and evaluated in the light of zircon elastic anisotropy. Our work challenges the existing model of zircon evolution and shows previously undescribed rheological characteristics for this important accessory mineral. Crystal-plastically deformed zircon grains have axis oriented parallel to the foliation plane, with the majority of deformed grains having axis parallel to the lineation. Zircon accommodates strain by a network of stepped low-angle boundaries, formed by switching between tilt dislocations with the slip systems {010} and {110} and rotation axis [001], twist dislocations with the rotation axis [001], and tilt dislocations with the slip system {001} and rotation axis [010]. The slip system {110} is newly described for zircon. Most misorientation axes in plastically-deformed zircon grains are parallel to the XY plane of the sample and have [001] crystallographic direction. Such behaviour of strained zircon lattice is caused by elastic anisotropy that has a direct geometric control on the rheology, deformation mechanisms and dominant slip systems in zircon. Young's modulus and P wave velocity have highest values parallel to zircon [001] axis, indicating that zircon is elastically strong along this direction. Poisson ratio and Shear modulus demonstrate that zircon is also most resistant to shearing along [001]. Thus, [001] axis is the most common rotation axis in zircon. The described zircon behaviour is important to take into account during structural and geochronological investigations of (poly)metamorphic terrains. Geometry of dislocations in zircon may help reconstructing the geometry of the host shear zone(s), large-scale stresses in the crust, and, possibly, the timing of

  16. Micro-scale measurements of plastic strain field, and local contributions of slip and twinning in TWIP steels during in situ tensile tests

    Energy Technology Data Exchange (ETDEWEB)

    Yang, H.K. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Laboratoire de Mécanique des Solides, Ecole Polytechnique, CNRS UMR7649, Université Paris-Saclay, 91128 Palaiseau (France); Doquet, V., E-mail: doquet@lms.polytechnique.fr [Laboratoire de Mécanique des Solides, Ecole Polytechnique, CNRS UMR7649, Université Paris-Saclay, 91128 Palaiseau (France); Zhang, Z.F. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2016-08-30

    In-situ tensile tests were carried out on Fe22Mn0.6C and Fe22Mn0.6C3Al (wt%) twinning-induced plasticity (TWIP) steels specimens covered with gold micro-grids. High resolution atomic force microscopy (AFM) and scanning electron microscope (SEM) images were periodically captured. The latter were used for measurements of the plastic strain field, using digital image correlation (DIC). Although no meso-scale localization bands appeared, some areas were deformed three times more than average. Plastic deformation inside the grains was more heterogeneous in Fe22Mn0.6C, but at meso-scale, the degree of strain heterogeneity was not higher, at least up to 12% strain. Plastic deformation started from grain boundaries or annealing twin boundaries in both materials, due to a high elastic anisotropy of the grains. An original method based on DIC was developed to estimate the twin fraction in grains that exhibit a single set of slip/twin bands. Deformation twinning accommodated 60–80% of the plastic strain in some favorably oriented grains, from the onset of plastic flow in Fe22Mn0.6C, but was not observed in the Al-bearing steel until 12% strain. The back stress was important in both materials, but significantly higher in Fe22Mn0.6C.

  17. Micro-scale measurements of plastic strain field, and local contributions of slip and twinning in TWIP steels during in situ tensile tests

    International Nuclear Information System (INIS)

    Yang, H.K.; Doquet, V.; Zhang, Z.F.

    2016-01-01

    In-situ tensile tests were carried out on Fe22Mn0.6C and Fe22Mn0.6C3Al (wt%) twinning-induced plasticity (TWIP) steels specimens covered with gold micro-grids. High resolution atomic force microscopy (AFM) and scanning electron microscope (SEM) images were periodically captured. The latter were used for measurements of the plastic strain field, using digital image correlation (DIC). Although no meso-scale localization bands appeared, some areas were deformed three times more than average. Plastic deformation inside the grains was more heterogeneous in Fe22Mn0.6C, but at meso-scale, the degree of strain heterogeneity was not higher, at least up to 12% strain. Plastic deformation started from grain boundaries or annealing twin boundaries in both materials, due to a high elastic anisotropy of the grains. An original method based on DIC was developed to estimate the twin fraction in grains that exhibit a single set of slip/twin bands. Deformation twinning accommodated 60–80% of the plastic strain in some favorably oriented grains, from the onset of plastic flow in Fe22Mn0.6C, but was not observed in the Al-bearing steel until 12% strain. The back stress was important in both materials, but significantly higher in Fe22Mn0.6C.

  18. Decay Time Measurement for Different Energy Depositions of Plastic Scintillator Fabricated by High Temperature Polymerization Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Cheol Ho; Son, Jaebum; Lee, Sangmin; Kim, Tae Hoon; Kim, Yong-Kyun [Hanyang University, Seoul (Korea, Republic of)

    2016-10-15

    Plastic scintillators are based on organic fluorite. They have many advantages such as fast rise and decay time, high optical transmission, ease of manufacturing, low cost, and large available size. For these reasons they are widely used for particle identification. Also, protection of people against a variety of threats (such as nuclear, radiological, and explosive) represents a true challenge along with the continuing development of science and technology. The plastic scintillator is widely used in various devise, which serves for nuclear, photonics, quantum, and high-energy physics. The plastic scintillator is probably the most widely used organic detector, and polystyrene is one of the most widely used materials in the making of the plastic scintillator detector. Thus, a styrene monomer as a solvent was used to fabricate the plastic scintillator by using high temperature polymerization reaction, and then the emission wavelength and the decay times for different energy depositions were measured by using the fabricated plastic scintillator. A plastic scintillator was fabricated to measure decay time for different energy depositions using the high temperature polymerization. Emission wavelength was measured of 426.05 nm to confirm a scintillator property using the spectrophotometer. Four gamma-ray sources (Cs-137, Co-60, Na-22, and Ba-133) were used to evaluate effect for decay time of different energy depositions. The average decay time of the fabricated plastic scintillator was measured to approximately 4.72 ns slightly higher more than commercial plastic scintillator. In future, light output and linearity will be measured to evaluate other property compared with the commercial scintillator.

  19. Decay Time Measurement for Different Energy Depositions of Plastic Scintillator Fabricated by High Temperature Polymerization Reaction

    International Nuclear Information System (INIS)

    Lee, Cheol Ho; Son, Jaebum; Lee, Sangmin; Kim, Tae Hoon; Kim, Yong-Kyun

    2016-01-01

    Plastic scintillators are based on organic fluorite. They have many advantages such as fast rise and decay time, high optical transmission, ease of manufacturing, low cost, and large available size. For these reasons they are widely used for particle identification. Also, protection of people against a variety of threats (such as nuclear, radiological, and explosive) represents a true challenge along with the continuing development of science and technology. The plastic scintillator is widely used in various devise, which serves for nuclear, photonics, quantum, and high-energy physics. The plastic scintillator is probably the most widely used organic detector, and polystyrene is one of the most widely used materials in the making of the plastic scintillator detector. Thus, a styrene monomer as a solvent was used to fabricate the plastic scintillator by using high temperature polymerization reaction, and then the emission wavelength and the decay times for different energy depositions were measured by using the fabricated plastic scintillator. A plastic scintillator was fabricated to measure decay time for different energy depositions using the high temperature polymerization. Emission wavelength was measured of 426.05 nm to confirm a scintillator property using the spectrophotometer. Four gamma-ray sources (Cs-137, Co-60, Na-22, and Ba-133) were used to evaluate effect for decay time of different energy depositions. The average decay time of the fabricated plastic scintillator was measured to approximately 4.72 ns slightly higher more than commercial plastic scintillator. In future, light output and linearity will be measured to evaluate other property compared with the commercial scintillator

  20. Transcript expression plasticity as a response to alternative larval host plants in the speciation process of corn and rice strains of Spodoptera frugiperda.

    Science.gov (United States)

    Silva-Brandão, Karina Lucas; Horikoshi, Renato Jun; Bernardi, Daniel; Omoto, Celso; Figueira, Antonio; Brandão, Marcelo Mendes

    2017-10-16

    Our main purpose was to evaluate the expression of plastic and evolved genes involved in ecological speciation in the noctuid moth Spodoptera frugiperda, the fall armyworm (FAW); and to demonstrate how host plants might influence lineage differentiation in this polyphagous insect. FAW is an important pest of several crops worldwide, and it is differentiated into host plant-related strains, corn (CS) and rice strains (RS). RNA-Seq and transcriptome characterization were applied to evaluate unbiased genetic expression differences in larvae from the two strains, fed on primary (corn) and alternative (rice) host plants. We consider that genes that are differently regulated by the same FAW strain, as a response to different hosts, are "plastic". Otherwise, differences in gene expression between the two strains fed on the same host are considered constitutive differences. Individual performance parameters (larval and pupal weight) varied among conditions (strains vs. hosts). A total of 3657 contigs was related to plastic response, and 2395 contigs were differentially regulated in the two strains feeding on preferential and alternative hosts (constitutive contigs). Three molecular functions were present in all comparisons, both down- and up-regulated: oxidoreductase activity, metal-ion binding, and hydrolase activity. Metabolization of foreign chemicals is among the key functions involved in the phenotypic variation of FAW strains. From an agricultural perspective, high plasticity in families of detoxifying genes indicates the capacity for a rapid response to control compounds such as insecticides.

  1. Optimization of the wavelength shifter ratio in a polystyrene based plastic scintillator through energy spectrum analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ye Won; Kim, Myung Soo; Yoo, Hyun Jun; Lee, Dae Hee; Cho, Gyu Seong [Dept. of Nuclear and Quantum Engineering, KAIST, Daejeon (Korea, Republic of); Moon, Myung Kook [Neutron Instrumentation Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-02-15

    The scintillation efficiency of the polystyrene based plastic scintillator depends on the ratio of the wavelength shifters, organic fluors (PPO and POPOP). Thus, 24 samples of the plastic scintillator were fabricated in order to find out the optimum ratio of the wavelength shifters in the plastic scintillator. The fabricated plastic scintillators were trimmed through a cutting and polishing process. They were used in gamma energy spectrum measurement with the {sup 137}Cs emitting monoenergy photon with 662 keV for the comparison of the scintillation efficiency. As a result, it was found out that the scintillator sample with 1.00 g of PPO (2,5-Diphenyloxazole) and 0.50 g of POPOP (1,4-Bis(5-phnyl-2oxidazolyl)benzene) dissolved in 100 g of styrene solution has the optimum ratio in terms of the light yield of the polystyrene based plastic scintillator.

  2. Fault on-off versus strain rate and earthquakes energy

    Directory of Open Access Journals (Sweden)

    C. Doglioni

    2015-03-01

    Full Text Available We propose that the brittle-ductile transition (BDT controls the seismic cycle. In particular, the movements detected by space geodesy record the steady state deformation in the ductile lower crust, whereas the stick-slip behavior of the brittle upper crust is constrained by its larger friction. GPS data allow analyzing the strain rate along active plate boundaries. In all tectonic settings, we propose that earthquakes primarily occur along active fault segments characterized by relative minima of strain rate, segments which are locked or slowly creeping. We discuss regional examples where large earthquakes happened in areas of relative low strain rate. Regardless the tectonic style, the interseismic stress and strain pattern inverts during the coseismic stage. Where a dilated band formed during the interseismic stage, this will be shortened at the coseismic stage, and vice-versa what was previously shortened, it will be dilated. The interseismic energy accumulation and the coseismic expenditure rather depend on the tectonic setting (extensional, contractional, or strike-slip. The gravitational potential energy dominates along normal faults, whereas the elastic energy prevails for thrust earthquakes and performs work against the gravity force. The energy budget in strike-slip tectonic setting is also primarily due elastic energy. Therefore, precursors may be different as a function of the tectonic setting. In this model, with a given displacement, the magnitude of an earthquake results from the coseismic slip of the deformed volume above the BDT rather than only on the fault length, and it also depends on the fault kinematics.

  3. Severe plastic deformation of copper by machining: Microstructure refinement and nanostructure evolution with strain

    International Nuclear Information System (INIS)

    Swaminathan, S.; Brown, T.L.; Chandrasekar, S.; McNelley, T.R.; Compton, W.D.

    2007-01-01

    The microstructures of copper chips created by plane strain machining at ambient temperature have been analyzed using transmission electron microscopy (TEM) and orientation imaging microscopy (OIM). The strain imposed in the chips was varied by changing the tool rake angle. Characterization of orthogonal faces of the chips showed the microstructure to be essentially uniform through the chip volume, indicative also of uniform deformation

  4. A review of higher order strain gradient theories of plasticity: Origins ...

    Indian Academy of Sciences (India)

    require higher order boundary conditions that enable us to model effects of disloca- ..... where ǫ0 is a reference strain, σ0 the yield stress and n the strain hardening exponent. The ...... Petch N J 1953 J. Iron Steel Inst. London 173: 25. Pantleon ...

  5. Plasticity-induced damage in metals : nonlocal modelling at finite strains

    NARCIS (Netherlands)

    Engelen, R.A.B.

    2005-01-01

    The plasticity models that are generally adopted to predict the response of e.g. a deforming piece of metal assume that the material behaves like a true local continuum. This implies that the evolution of a state variable in a single material point only depends on the material state of that

  6. On the existence of minimisers for strain-gradient single-crystal plasticity

    Czech Academy of Sciences Publication Activity Database

    Anguige, K.; Dondl, P.; Kružík, Martin

    (2018) ISSN 0044-2267 R&D Projects: GA ČR GA14-15264S; GA ČR(CZ) GF16-34894L Institutional support: RVO:67985556 Keywords : existence of minimizers * plasticity Subject RIV: BA - General Mathematics Impact factor: 1.332, year: 2016 http://library.utia.cas.cz/separaty/2017/MTR/kruzik-0481468.pdf

  7. Integrating a logarithmic-strain based hyper-elastic formulation into a three-field mixed finite element formulation to deal with incompressibility in finite-strain elasto-plasticity

    International Nuclear Information System (INIS)

    Dina Al Akhrass; Bruchon, Julien; Drapier, Sylvain; Fayolle, Sebastien

    2014-01-01

    This paper deals with the treatment of incompressibility in solid mechanics in finite-strain elasto-plasticity. A finite-strain model proposed by Miehe, Apel and Lambrecht, which is based on a logarithmic strain measure and its work-conjugate stress tensor is chosen. Its main interest is that it allows for the adoption of standard constitutive models established in a small-strain framework. This model is extended to take into account the plastic incompressibility constraint intrinsically. In that purpose, an extension of this model to a three-field mixed finite element formulation is proposed, involving displacements, a strain variable and pressure as nodal variables with respect to standard finite element. Numerical examples of finite-strain problems are presented to assess the performance of the formulation. To conclude, an industrial case for which the classical under-integrated elements fail is considered. (authors)

  8. Use of pultruded reinforced plastics in energy generation and energy related applications

    Science.gov (United States)

    Anderson, R.

    Applications of pultrusion-formed fiber-reinforced plastics (FRP) in the wind, oil, and coal derived energy industries are reviewed. FRP is noted to be a viable alternative to wood, aluminum, and steel for reasons of availability, price, and weight. Attention is given to the development of FRP wind turbine blades for the DOE 8 kW low cost, high reliability wind turbine program. The blades feature a NACA 23112 profile with a 15 in. chord on the system which was tested at Rocky Flats, CO. Fabricating the blades involved a plus and minus 45 deg roving orientation, a heavy fiber-glass nose piece to assure blade strength, and a separately manufactured foam core. Additional uses for FRP products have been found in the structural members of coal stack scrubbers using a vinyl ester resin in a fire retardant formulation, and as low cost, light weight sucker rods for deep well oil drilling.

  9. Perfect plasticity with damage and healing at small strains, its modeling, analysis, and computer implementation

    Czech Academy of Sciences Publication Activity Database

    Roubíček, Tomáš; Valdman, Jan

    2016-01-01

    Roč. 76, č. 1 (2016), s. 314-340 ISSN 0036-1399 R&D Projects: GA ČR GA13-18652S; GA ČR GA14-15264S Institutional support: RVO:67985556 ; RVO:61388998 Keywords : Prandtl-Reuss perfect plasticity * bounded-deformation space * incomplete damage Subject RIV: BA - General Mathematics Impact factor: 1.670, year: 2016 http://library.utia.cas.cz/separaty/2016/MTR/valdman-0458557.pdf

  10. On the formulations of higher-order strain gradient crystal plasticity models

    DEFF Research Database (Denmark)

    Kuroda, M.; Tvergaard, Viggo

    2008-01-01

    Recently, several higher-order extensions to the crystal plasticity theory have been proposed to incorporate effects of material length scales that were missing links in the conventional continuum mechanics. The extended theories are classified into work-conjugate and non-work-conjugate types. A ...... deformation. In this paper, the discussion is extended to a more general situation, i.e. the context of multiple and three-dimensional slip deformations....

  11. Studying the effect of elastic-plastic strain and hydrogen sulphide on the magnetic behaviour of pipe steels as applied to their testing

    Directory of Open Access Journals (Sweden)

    Povolotskaya Anna

    2018-01-01

    Full Text Available The paper reports results of magnetic measurements made on samples of the 12GB pipe steel (strength group X42SS designed for producing pipes to be used in media with high hydrogen sulphide content, both in the initial state and after exposure to hydrogen sulphide, for 96, 192 and 384 hours under uniaxial elastic-plastic tension. At the stage of elastic deformation there is a unique correlation between the coercive force measured on a minor hysteresis loop in weak fields and tensile stress, which enables this parameter to be used for the evaluation of elastic stresses in pipes made of the 12 GB pipe steel under different conditions, including a hydrogen sulphide containing medium. The effect of the value of preliminary plastic strain, viewed as the initial stress-strain state, on the magnetic behaviour of X70 pipe steels under elastic tension and compression is studied. Plastic strain history affects the magnetic behaviour of the material during subsequent elastic deformation since plastic strain induces various residual stresses, and this necessitates taking into account the initial stress-strain state of products when developing magnetic techniques for the determination of their stress-strain parameters during operation.

  12. Pyrolysis of fibre residues with plastic contamination from a paper recycling mill: Energy recoveries

    International Nuclear Information System (INIS)

    Brown, Logan Jeremy; Collard, François-Xavier; Görgens, Johann

    2017-01-01

    Highlights: • Pyrolysis of fibre-plastics residues from paper recycling mill into fuel products. • Product with remarkable energy content up to 42.8 MJ/kg. • Influence of temperature on the product yields and fuel properties. • Effect of plastic composition on product properties. - Abstract: Pyrolysis is a promising technology for the production of marketable energy products from waste mixtures, as it decomposes heterogeneous material into homogenous fuel products. This research assessed the ability of slow pyrolysis to convert three waste streams, composed of fibre residues contaminated with different plastic mixtures, into char and tarry phase products at three different temperatures (300, 425 and 550 °C). The products were characterised in terms of mass yield, higher heating value (HHV) and gross energy conversion (EC). Significant amounts of hydrocarbon plastics in the feed materials increased the calorific values of the char (up to 32.9 MJ/kg) and tarry phase (up to 42.8 MJ/kg) products, comparable to high volatile bituminous A coal and diesel respectively. For all three waste streams converted at 300 °C, the majority of the energy in the feedstock was recovered in the char product (>80%), while deoxygenation of fibre component resulted in char with increased calorific value (up to 31.6 MJ/kg) being produced. Pyrolysis at 425 °C for two of the waste streams containing significant amounts of plastic produced both a valuable char and tarry phase, which resulted in an EC greater than 74%. Full conversion of plastic at 550 °C increased the tarry phase yield but dramatically decreased the char HHV. The influence of temperature on product yield and HHV was discussed based on the pyrolysis mechanisms and in relation to the plastic composition of the waste streams.

  13. Reconstruction of fiber Bragg grating strain profile used to monitor the stiffness degradation of the adhesive layer in carbon fiber–reinforced plastic single-lap joint

    OpenAIRE

    Song Chunsheng; Zhang Jiaxiang; Yang Mo; Shang Erwei; Zhang Jinguang

    2017-01-01

    The adhesive-bonded joint of carbon fiber–reinforced plastic is one of the core components in aircraft structure design. It is an effective guarantee for the safety and reliability of the aerospace aircraft structure to use effective methods for monitoring and early warning of internal failure. In this article, the mapping relation model between the strain profiles of the adherend of the carbon fiber–reinforced plastic single-lap adhesive joint and the stiffness degradation evolution of adhes...

  14. Features of energy impact on a billet material when cutting with outstripping plastic deformation

    Directory of Open Access Journals (Sweden)

    V. M. Yaroslavtsev

    2014-01-01

    Full Text Available In the last decades the so-called combined machining methods based on parallel, serial or parallelserial combination of different types of energy impacts on the billet are designed and developed. Combination of two or more sources of external energy in one method of machining can be directed to the solution of different technological tasks, such as: improvement of a basic method to enhance technicaland-economic and technological indicators of machining, expansion of technological capabilities of the method, increase of reliability and stability of technological process to produce details, etc. Besides, the combined methods of machining are considered as one of the means, which enables reducing the number of operations in technological process, allows the growth of workforce productivity.When developing the combined technologies, one of the main scientific tasks is to define the general regularities of interaction and mutual influence of the energy fluxes brought to the zone of machining. The result of such mutual influence becomes apparent from the forming technological parameters of machining and determines the most rational operating conditions of technological process.In the context of conducted in BMSTU researches on the combined cutting method with outstripping plastic deformation (OPD the mutual influence of the energetic components of machining has been quantitatively assessed. The paper shows a direct relationship between the rational ratio of the two types of the mechanical energy brought in the machining zone, the machining conditions, and the optimum operating conditions.The paper offers a physical model of chip formation when machining with OPD. The essence of model is that specific works spent on material deformation of a cut-off layer are quantitatively compared at usual cutting and at cutting with OPD. It is experimentally confirmed that the final strain-deformed material states of a cut-off layer, essentially, coincide in both

  15. Strain-based plastic instability acceptance criteria for ferritic steel safety class 1 nuclear components under level D

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Su; Lee, Han Sang; Kim, Yun Jae [Dept. of Mechanical Engineering, Korea University, Seoul (Korea, Republic of); Kim, Jong Sung [Dept. of Mechanical Engineering, Sunchon National University, Suncheon (Korea, Republic of); Kim, Jin Won [Dept. of Nuclear Engineering, Chosun University, Gwangju (Korea, Republic of)

    2015-04-15

    This paper proposes strain-based acceptance criteria for assessing plastic instability of the safety class 1 nuclear components made of ferritic steel during level D service loads. The strain-based criteria were proposed with two approaches: (1) a section average approach and (2) a critical location approach. Both approaches were based on the damage initiation point corresponding to the maximum load-carrying capability point instead of the fracture point via tensile tests and finite element analysis (FEA) for the notched specimen under uni-axial tensile loading. The two proposed criteria were reviewed from the viewpoint of design practice and philosophy to select a more appropriate criterion. As a result of the review, it was found that the section average approach is more appropriate than the critical location approach from the viewpoint of design practice and philosophy. Finally, the criterion based on the section average approach was applied to a simplified reactor pressure vessel (RPV) outlet nozzle subject to SSE loads. The application shows that the strain-based acceptance criteria can consider cumulative damages caused by the sequential loads unlike the stress-based acceptance criteria and can reduce the over conservatism of the stress-based acceptance criteria, which often occurs for level D service loads.

  16. Strain-based plastic instability acceptance criteria for ferritic steel safety class 1 nuclear components under level D

    International Nuclear Information System (INIS)

    Kim, Ji Su; Lee, Han Sang; Kim, Yun Jae; Kim, Jong Sung; Kim, Jin Won

    2015-01-01

    This paper proposes strain-based acceptance criteria for assessing plastic instability of the safety class 1 nuclear components made of ferritic steel during level D service loads. The strain-based criteria were proposed with two approaches: (1) a section average approach and (2) a critical location approach. Both approaches were based on the damage initiation point corresponding to the maximum load-carrying capability point instead of the fracture point via tensile tests and finite element analysis (FEA) for the notched specimen under uni-axial tensile loading. The two proposed criteria were reviewed from the viewpoint of design practice and philosophy to select a more appropriate criterion. As a result of the review, it was found that the section average approach is more appropriate than the critical location approach from the viewpoint of design practice and philosophy. Finally, the criterion based on the section average approach was applied to a simplified reactor pressure vessel (RPV) outlet nozzle subject to SSE loads. The application shows that the strain-based acceptance criteria can consider cumulative damages caused by the sequential loads unlike the stress-based acceptance criteria and can reduce the over conservatism of the stress-based acceptance criteria, which often occurs for level D service loads.

  17. Determination of dynamic fracture initiation toughness of elastic-plastic materials at intermediate strain rates

    International Nuclear Information System (INIS)

    Fernandez-Saez, J.; Luna de, S.; Rubio, L.; Perez-Castellanos, J. L.; Navarro, C.

    2001-01-01

    An earlier paper dealt with the experimental techniques used to determine the dynamic fracture properties of linear elastic materials. Here we describe those most commonly used as elastoplastic materials, limiting the study to the initiation fracture toughness at the intermediate strain rate (of around 10''2 s''-1). In this case the inertial forces are negligible and it is possible to apply the static solutions. With this stipulation, the analysis can be based on the methods of testing in static conditions. The dynamic case differs basically, from the static one, in the influence of the strain rate on the properties of the material. (Author) 57 refs

  18. Formation Energies of Native Point Defects in Strained-Layer Superlattices (Postprint)

    Science.gov (United States)

    2017-06-05

    potential; bulk materials; total energy calculations; entropy; strained- layer superlattice (SLS) 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...AFRL-RX-WP-JA-2017-0217 FORMATION ENERGIES OF NATIVE POINT DEFECTS IN STRAINED- LAYER SUPERLATTICES (POSTPRINT) Zhi-Gang Yu...2016 Interim 11 September 2013 – 5 November 2016 4. TITLE AND SUBTITLE FORMATION ENERGIES OF NATIVE POINT DEFECTS IN STRAINED- LAYER SUPERLATTICES

  19. First-principles investigation of strain effects on the energy gaps in silicon nanoclusters

    International Nuclear Information System (INIS)

    Peng, X-H; Alizadeh, A; Bhate, N; Varanasi, K K; Kumar, S K; Nayak, S K

    2007-01-01

    First-principles density functional calculations were performed to study strain effects on the energy gaps in silicon nanoclusters with diameter ranging from 0.6 to 2 nm. Hydrostatic and non-hydrostatic strains have been found to affect the energy gaps differently. For the same strain energy density, non-hydrostatic strain leads to a significantly larger change in the energy gap of silicon clusters compared to that of the hydrostatic strain case. In contrast, hydrostatic and non-hydrostatic strain effects on the energy gaps of bulk Si or larger size Si quantum dots are comparable. Non-hydrostatic strains break the tetrahedral bonding symmetry in silicon, resulting in significant variation in the energy gaps due to the splitting of the degenerate orbitals in the clusters. Our results suggest that the combination of energy gaps and strains permits the engineering of photoluminescence in silicon nanoclusters and offers the possibility of designing novel optical devices and chemical sensors

  20. Thermal recycling of plastic waste using pyrolysis-gasification process for energy production

    Energy Technology Data Exchange (ETDEWEB)

    Forbit, George Teke

    2012-04-04

    The disposal of mixed waste in landfills, dump sites and open burning without material and energy recovery leads to resource loss, causes health problems, pollution and littering. Increasing energy demand for industrial and domestic application with rising costs due to scarcity motivates a constant search for alternative clean energy sources. Recovering energy from waste presents various incentives e.g. creating jobs, alleviating poverty, combating and mitigating climate change, protecting the environment and reducing dependence on traditional fuels sources. Hence, plastics end up in landfills, surface waters and ocean bed with serious negative impact on terrestrial and aquatic biodiversity. Plastic waste with high calorific value (36-46MJ/kg) occupies the greatest portion of landfill space. Hence, using an appropriate technology to transform waste plastic to a hot gaseous mixture which is burned in-situ produces enormous amount of energy without pollution. Based on this hypothesis, the study objectives accomplished were to: 1. Characterise, quantify and classify waste fractions and plastic components common in MSW by manual sorting 2. Evaluate options for sustainable plastic waste management especially for developing countries 3. Design, construct, test and optimize an appropriate technology that applies pyrolysis and gasification processes to convert non-PVC plastic waste to energy 4. Assess the efficiency of the technology based on the functioning, the engineering, mass and energy analysis including socioeconomic and environmental impacts An integrated methodology involving review of current literature, field and laboratory experiments on mixed waste and plastic waste analysis was used. In addition, the pyrolysis-gasification technology (PGT) was conceptualised, designed, constructed, tested and optimised at BTU Cottbus, Germany; Lagos, Nigeria and Dschang, Cameroon. Field studies involving natural observation, interviews, personal discussions and visits to

  1. Elastic-plastic potential functionals for rates and increments of stress and strain

    International Nuclear Information System (INIS)

    Feijoo, R.A.; Zouain, N.

    1990-03-01

    In this work attention is focused in the derivation of variational formulations of the constutive relationship in the form of conjugate potential functionals from which stress and strain rates are derived as elements of the corresponding sub-differential sets. The main result obtained is a pair of potential functionals. (A.C.A.S.) [pt

  2. Numerical simulation of elasto-plastic electro-osmosis consolidation at large strain

    NARCIS (Netherlands)

    Yuan, J.; Hicks, M.A.

    2015-01-01

    n this paper, a numerical solution for the electro-osmosis consolidation of clay in multi-dimensional domains at large strains is presented, with the coupling of the soil mechanical behaviour, pore water transport and electrical fields being considered. In particular, the Modified Cam Clay model is

  3. A modified Gurson-type plasticity model at finite strains: formulation, numerical analysis and phase-field coupling

    Science.gov (United States)

    Aldakheel, Fadi; Wriggers, Peter; Miehe, Christian

    2017-12-01

    The modeling of failure in ductile materials must account for complex phenomena at the micro-scale, such as nucleation, growth and coalescence of micro-voids, as well as the final rupture at the macro-scale, as rooted in the work of Gurson (J Eng Mater Technol 99:2-15, 1977). Within a top-down viewpoint, this can be achieved by the combination of a micro-structure-informed elastic-plastic model for a porous medium with a concept for the modeling of macroscopic crack discontinuities. The modeling of macroscopic cracks can be achieved in a convenient way by recently developed continuum phase field approaches to fracture, which are based on the regularization of sharp crack discontinuities, see Miehe et al. (Comput Methods Appl Mech Eng 294:486-522, 2015). This avoids the use of complex discretization methods for crack discontinuities, and can account for complex crack patterns. In this work, we develop a new theoretical and computational framework for the phase field modeling of ductile fracture in conventional elastic-plastic solids under finite strain deformation. It combines modified structures of Gurson-Tvergaard-Needelman GTN-type plasticity model outlined in Tvergaard and Needleman (Acta Metall 32:157-169, 1984) and Nahshon and Hutchinson (Eur J Mech A Solids 27:1-17, 2008) with a new evolution equation for the crack phase field. An important aspect of this work is the development of a robust Explicit-Implicit numerical integration scheme for the highly nonlinear rate equations of the enhanced GTN model, resulting with a low computational cost strategy. The performance of the formulation is underlined by means of some representative examples, including the development of the experimentally observed cup-cone failure mechanism.

  4. Strain energy storage and dissipation rate in active cell mechanics

    Science.gov (United States)

    Agosti, A.; Ambrosi, D.; Turzi, S.

    2018-05-01

    When living cells are observed at rest on a flat substrate, they can typically exhibit a rounded (symmetric) or an elongated (polarized) shape. Although the cells are apparently at rest, the active stress generated by the molecular motors continuously stretches and drifts the actin network, the cytoskeleton of the cell. In this paper we theoretically compare the energy stored and dissipated in this active system in two geometric configurations of interest: symmetric and polarized. We find that the stored energy is larger for a radially symmetric cell at low activation regime, while the polar configuration has larger strain energy when the active stress is beyond a critical threshold. Conversely, the dissipation of energy in a symmetric cell is always larger than that of a nonsymmetric one. By a combination of symmetry arguments and competition between surface and bulk stress, we argue that radial symmetry is an energetically expensive metastable state that provides access to an infinite number of lower-energy states, the polarized configurations.

  5. δ-hydride habit plane determination in α-zirconium by strain energy minimization technique at 25 and 300 deg C

    International Nuclear Information System (INIS)

    Singh, R.N.; Stahle, P.; Sairam, K.; Ristmana, Matti; Banerjee, S.

    2008-01-01

    The objective of the present investigation is to predict the habit plane of δ-hydride precipitating in α-Zr at 25 and 300 deg C using strain energy minimization technique. The δ-hydride phase is modeled to undergo isotropic elastic and plastic deformation. The α-Zr phase was modeled to undergo transverse isotropic elastic deformation. Both isotropic plastic and transverse isotropic plastic deformations of α-Zr were considered. Further, both perfect and linear work-hardening plastic behaviors of zirconium and its hydride were considered. Accommodation strain energy of δ-hydrides forming in α-Zr crystal was computed using initial strain method as a function of hydride nuclei orientation. Hydride was modeled as disk with circular edge. The simulation was carried out using materials properties reported at 25 and 300 deg C. Contrary to several habit planes reported in literature for δ-hydrides precipitating in α-Zr crystal the total accommodation energy minima suggests only basal plane i.e. (0001) as the habit plane. (author)

  6. Dual energy CT inspection of a carbon fibre reinforced plastic composite combined with metal components

    Czech Academy of Sciences Publication Activity Database

    Vavřík, Daniel; Jakůbek, J.; Kumpová, Ivana; Pichotka, M.

    6, Part B, November (2016), s. 47-55 ISSN 2214-6571 R&D Projects: GA MŠk(CZ) LO1219; GA ČR(CZ) GA15-07210S Keywords : dual energy computed tomography * carbon fibre reinforced plastic composite * metal artefact suppression Subject RIV: JI - Composite Material s http://www.sciencedirect.com/science/article/pii/S2214657116300107

  7. The Strain Energy, Seismic Moment and Magnitudes of Large Earthquakes

    Science.gov (United States)

    Purcaru, G.

    2004-12-01

    The strain energy Est, as potential energy, released by an earthquake and the seismic moment Mo are two fundamental physical earthquake parameters. The earthquake rupture process ``represents'' the release of the accumulated Est. The moment Mo, first obtained in 1966 by Aki, revolutioned the quantification of earthquake size and led to the elimination of the limitations of the conventional magnitudes (originally ML, Richter, 1930) mb, Ms, m, MGR. Both Mo and Est, not in a 1-to-1 correspondence, are uniform measures of the size, although Est is presently less accurate than Mo. Est is partitioned in seismic- (Es), fracture- (Eg) and frictional-energy Ef, and Ef is lost as frictional heat energy. The available Est = Es + Eg (Aki and Richards (1980), Kostrov and Das, (1988) for fundamentals on Mo and Est). Related to Mo, Est and Es, several modern magnitudes were defined under various assumptions: the moment magnitude Mw (Kanamori, 1977), strain energy magnitude ME (Purcaru and Berckhemer, 1978), tsunami magnitude Mt (Abe, 1979), mantle magnitude Mm (Okal and Talandier, 1987), seismic energy magnitude Me (Choy and Boatright, 1995, Yanovskaya et al, 1996), body-wave magnitude Mpw (Tsuboi et al, 1998). The available Est = (1/2μ )Δ σ Mo, Δ σ ~=~average stress drop, and ME is % \\[M_E = 2/3(\\log M_o + \\log(\\Delta\\sigma/\\mu)-12.1) ,\\] % and log Est = 11.8 + 1.5 ME. The estimation of Est was modified to include Mo, Δ and μ of predominant high slip zones (asperities) to account for multiple events (Purcaru, 1997): % \\[E_{st} = \\frac{1}{2} \\sum_i {\\frac{1}{\\mu_i} M_{o,i} \\Delta\\sigma_i} , \\sum_i M_{o,i} = M_o \\] % We derived the energy balance of Est, Es and Eg as: % \\[ E_{st}/M_o = (1+e(g,s)) E_s/M_o , e(g,s) = E_g/E_s \\] % We analyzed a set of about 90 large earthquakes and found that, depending on the goal these magnitudes quantify differently the rupture process, thus providing complementary means of earthquake characterization. Results for some

  8. Strain hardening behavior and microstructural evolution during plastic deformation of dual phase, non-grain oriented electrical and AISI 304 steels

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Guilherme Corrêa; Gonzalez, Berenice Mendonça; Arruda Santos, Leandro de, E-mail: leandro.arruda@demet.ufmg.br

    2017-01-27

    Strain hardening behavior and microstructural evolution of non-grain oriented electrical, dual phase, and AISI 304 steels, subjected to uniaxial tensile tests, were investigated in this study. Tensile tests were performed at room temperature and the strain hardening behavior of the steels was characterized by three different parameters: modified Crussard–Jaoul stages, strain hardening rate and instantaneous strain hardening exponent. Optical microscopic analysis, X-ray diffraction measurements, phase quantification by Rietveld refinement and hardness tests were also carried out in order to correlate the microstructural and mechanical responses to plastic deformation. Distinct strain hardening stages were observed in the steels in terms of the instantaneous strain hardening exponent and the strain hardening rate. The dual phase and non-grain oriented steels exhibited a two-stage strain hardening behavior while the AISI 304 steel displayed multiple stages, resulting in a more complex strain hardening behavior. The dual phase steels showed a high work hardening capacity in stage 1, which was gradually reduced in stage 2. On the other hand, the AISI 304 steel showed high strain hardening capacity, which continued to increase up to the tensile strength. This is a consequence of its additional strain hardening mechanism, based on a strain-induced martensitic transformation, as shown by the X-ray diffraction and optical microscopic analyses.

  9. The impact of elastic and plastic strain on relaxation and crystallization of Pd–Ni–P-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Mitrofanov, Yu.P.; Peterlechner, M.; Binkowski, I.; Zadorozhnyy, M.Yu.; Golovin, I.S.; Divinski, S.V.; Wilde, G.

    2015-01-01

    The effects of deformation and subsequent heat treatment on the low-temperature heat capacity, enthalpy relaxation rate and mechanical losses of two Pd–Ni–P-based bulk metallic glasses of slightly different compositions and different thermal stabilities have been investigated. It was found that the crystallization temperatures decreased significantly with imposed strain and the effect was more pronounced for the alloy with a higher thermal stability. The boson heat capacity peak increases with increasing strain in both alloys. However, after annealing treatments above room temperature, it relaxes to a lower enthalpy state as compared to that of the as-quenched state for the alloy with a lower thermal stability. The existence of two counteracting processes that might be related to different shear band structures within one homogeneously deformed sample is suggested. These results agree with the internal friction data, which indicate different regimes of mechanical damping as a function of the strain amplitude, while the critical amplitude of a transition between the regimes depends on the imposed strain. The results are interpreted within the energy landscape approach and advocate that the composition-dependent local atomic configurations affect significantly the response of the glass to an applied strain

  10. Dynamic Strength and Accumulated Plastic Strain Development Laws and Models of the Remolded Red Clay under Long-Term Cyclic Loads: Laboratory Test Results

    Directory of Open Access Journals (Sweden)

    Li Jian

    2015-09-01

    Full Text Available The dynamic strength and accumulated plastic strain are two important parameters for evaluating the dynamic response of soil. As a special clay, the remolded red clay is often used as the high speed railway subgrade filling, but studies on its dynamic characteristics are few. For a thorough analysis of the suitability of the remolded red clay as the subgrade filling, a series of long-term cyclic load triaxial test under different load histories are carried out. Considering the influence of compactness, confining pressure, consolidation ratio, vibration frequency and dynamic load to the remolded red clay dynamic property, the tests obtain the development curves of the dynamic strength and accumulated plastic strain under different test conditions. Then, through curve fitting method, two different hyperbolic models respectively for the dynamic strength and accumulated plastic strain are built, which can match the test datum well. By applying the dynamic strength model, the critical dynamic strength of the remolded red clay are gained. Meanwhile, for providing basic datum and reference for relevant projects, all key parameters for the dynamic strength and accumulated plastic strain of the remolded red clay are given in the paper.

  11. Energy Payback Time of a Solar Photovoltaic Powered Waste Plastic Recyclebot System

    Directory of Open Access Journals (Sweden)

    Shan Zhong

    2017-06-01

    Full Text Available The growth of both plastic consumption and prosumer 3-D printing are driving an interest in producing 3-D printer filaments from waste plastic. This study quantifies the embodied energy of a vertical DC solar photovoltaic (PV powered recyclebot based on life cycle energy analysis and compares it to horizontal AC recyclebots, conventional recycling, and the production of a virgin 3-D printer filament. The energy payback time (EPBT is calculated using the embodied energy of the materials making up the recyclebot itself and is found to be about five days for the extrusion of a poly lactic acid (PLA filament or 2.5 days for the extrusion of an acrylonitrile butadiene styrene (ABS filament. A mono-crystalline silicon solar PV system is about 2.6 years alone. However, this can be reduced by over 96% if the solar PV system powers the recyclebot to produce a PLA filament from waste plastic (EPBT is only 0.10 year or about a month. Likewise, if an ABS filament is produced from a recyclebot powered by the solar PV system, the energy saved is 90.6–99.9 MJ/kg and 26.33–29.43 kg of the ABS filament needs to be produced in about half a month for the system to pay for itself. The results clearly show that the solar PV system powered recyclebot is already an excellent way to save energy for sustainable development.

  12. Effects of surface roughness on plastic strain localization in polycrystalline aggregates

    Directory of Open Access Journals (Sweden)

    Guilhem Yoann

    2014-06-01

    Full Text Available The surface state of mechanical components differs according to applied loadings. Industrial processes may produce specific features at the surface, such as roughness, local hardening, residual stresses or recrystallization. Under fatigue loading, all these parameters will affect the component lifetime, but in different manner. A better understanding of each surface state parameter, separately first and then all combined, will provide a better prediction of fatigue life. The study focuses on the effect of surface roughness. Crystal plasticity finite element computations have been carried out on three-dimensional polycrystalline aggregates with different roughness levels. Local mechanical fields have been analyzed both at the surface and inside the bulk to highlight the competition between crystallography and roughness to impose localization patterns. As soon as surface roughness is strong enough, classical localization bands driven by grains orientation are replaced by localizations patterns driven by the local roughness topology. Nevertheless, this effect tends to decrease gradually under the surface, and it becomes usually negligible after the first layer of grains. The discussion allows us to characterize the influence of the surface state on the local mechanical fields.

  13. Production of high-calorie energy briquettes from bark waste, plastic and oil

    Science.gov (United States)

    Suwinarti, W.; Amirta, R.; Yuliansyah

    2018-04-01

    Bark is the waste generated from the utilization of plantation timber, while plastics and oil waste are produced from daily human activity. These waste has the potential to be used as energy briquettes raw materials, especially for fuel in power plants. It would be worth very strategic for the environment and the welfare of society, considering that at this time we are not yet fully capable of well managing all three waste types. On the other hands most of the power plants that operate today still use diesel and coal as fuel. Therefore, the best composition of mixing bark, plastic and oil will be studied as well as its influence on the physical and chemical quality of the briquettes produced. The results show that the addition of the oil waste (70%) and used plastic (30%) as additive give effect to the performance of the briquette formation with the highest calorific value of 33.56 MJ/kg.

  14. Microcrystalline silicon growth by low laser energy crystallization on a plastic substrate

    International Nuclear Information System (INIS)

    Kim, D. Y.; Seo, C. K.; Shim, M. S.; Kim, C. H.; Yi, J.

    2004-01-01

    We are reporting the crystallization of amorphous silicon (a-Si) using a XeCl excimer laser treatment. Although polycarbonate (PC) plastic substrates are very weak at high temperatures of more than 150 .deg. C, they are very useful for applications to microelectronics because of light weight, high transmittance, and flexibility. In order to crystallize a-Si films on plastic substrates, we suggest that a CeO 2 seed layer will be very helpful at a low laser energy density. The seed layer is deposited at room temperature by rf using magnetron sputtering. A seed layer deposition method will be also presented in detail in this article. We compare a-Si crytallization without a seed layer with one with a seed layer deposited between the a-Si and the plastic substrate. The a-Si was deposited on the plastic substrate by using inductively coupled plasma Chemical-Vapor Deposition (ICPCVD) at the room temperature. In this paper, we will present the crystallization properties of a-Si with and without a CeO 2 seed layer on the plastic substrate.

  15. Internal state variable plasticity-damage modeling of AISI 4140 steel including microstructure-property relations: temperature and strain rate effects

    Science.gov (United States)

    Nacif el Alaoui, Reda

    Mechanical structure-property relations have been quantified for AISI 4140 steel. under different strain rates and temperatures. The structure-property relations were used. to calibrate a microstructure-based internal state variable plasticity-damage model for. monotonic tension, compression and torsion plasticity, as well as damage evolution. Strong stress state and temperature dependences were observed for the AISI 4140 steel. Tension tests on three different notched Bridgman specimens were undertaken to study. the damage-triaxiality dependence for model validation purposes. Fracture surface. analysis was performed using Scanning Electron Microscopy (SEM) to quantify the void. nucleation and void sizes in the different specimens. The stress-strain behavior exhibited. a fairly large applied stress state (tension, compression dependence, and torsion), a. moderate temperature dependence, and a relatively small strain rate dependence.

  16. Processing and properties of a solid energy fuel from municipal solid waste (MSW) and recycled plastics.

    Science.gov (United States)

    Gug, JeongIn; Cacciola, David; Sobkowicz, Margaret J

    2015-01-01

    Diversion of waste streams such as plastics, woods, papers and other solid trash from municipal landfills and extraction of useful materials from landfills is an area of increasing interest especially in densely populated areas. One promising technology for recycling municipal solid waste (MSW) is to burn the high-energy-content components in standard coal power plant. This research aims to reform wastes into briquettes that are compatible with typical coal combustion processes. In order to comply with the standards of coal-fired power plants, the feedstock must be mechanically robust, free of hazardous contaminants, and moisture resistant, while retaining high fuel value. This study aims to investigate the effects of processing conditions and added recyclable plastics on the properties of MSW solid fuels. A well-sorted waste stream high in paper and fiber content was combined with controlled levels of recyclable plastics PE, PP, PET and PS and formed into briquettes using a compression molding technique. The effect of added plastics and moisture content on binding attraction and energy efficiency were investigated. The stability of the briquettes to moisture exposure, the fuel composition by proximate analysis, briquette mechanical strength, and burning efficiency were evaluated. It was found that high processing temperature ensures better properties of the product addition of milled mixed plastic waste leads to better encapsulation as well as to greater calorific value. Also some moisture removal (but not complete) improves the compacting process and results in higher heating value. Analysis of the post-processing water uptake and compressive strength showed a correlation between density and stability to both mechanical stress and humid environment. Proximate analysis indicated heating values comparable to coal. The results showed that mechanical and moisture uptake stability were improved when the moisture and air contents were optimized. Moreover, the briquette

  17. Machined and plastic copings in three-element prostheses with different types of implantabutment joints: a strain gauge comparative analysis

    Directory of Open Access Journals (Sweden)

    Renato Sussumu Nishioka

    2010-06-01

    Full Text Available OBJECTIVE: Using strain gauge (SG analysis, the aim of this in vitro study was quantify the strain development during the fixation of three-unit screw implant-supported fixed partial dentures, varying the types of implant-abutment joints and the type of prosthetic coping. The hypotheses were that the type of hexagonal connection would generate different microstrains and the type of copings would produce similar microstrains after prosthetic screws had been tightened onto microunit abutments. MATERIALS AND METHODS: Three dental implants with external (EH and internal (IH hexagonal configurations were inserted into two polyurethane blocks. Microunit abutments were screwed onto their respective implant groups, applying a torque of 20 Ncm. Machined Co-Cr copings (M and plastic prosthetic copings (P were screwed onto the abutments, which received standard wax patterns. The wax patterns were cast in Co-Cr alloy (n=5, forming four groups: G1 EH/M; G2 EH/P; G3 IH/M and G4 IH/P. Four SGs were bonded onto the surface of the block tangentially to the implants, SG 1 mesially to implant 1, SG 2 and SG 3 mesially and distally to implant 2, respectively, and SG 4 distally to implant 3. The superstructure's occlusal screws were tightened onto microunit abutments with 10 Ncm torque using a manual torque driver. The magnitude of microstrain on each SG was recorded in units of microstrain (µε. The data were analyzed statistically by ANOVA and Tukey's test (p0.05. The hypotheses were partially accepted. CONCLUSIONS: It was concluded that the type of hexagonal connection and coping presented similar mechanical behavior under tightening conditions.

  18. Coefficient of restitution and plastic strain for impact of elements welded with micro-jet cooling

    Directory of Open Access Journals (Sweden)

    Damian HADRYŚ

    2014-06-01

    Full Text Available The main purpose of investigations is the qualification how post-accident repair of model car body parts influence on the value of coefficient of restitution. Evaluation of impact energy absorption by model car body parts repaired with MIG welding (with and without micro-jet cooling was carried out. The results of investigations present that the value of coefficient of restitution changes with speed of impact. Coefficient of restitution is bigger for elements welded with micro-jet cooling than for element welded with ordinary method. This could have influence on passive safety of vehicle.

  19. A quantitative approach to study the effect of local texture and heterogeneous plastic strain on the deformation micromechanism in RR1000 nickel-based superalloy

    International Nuclear Information System (INIS)

    Birosca, S.; Di Gioacchino, F.; Stekovic, S.; Hardy, M.

    2014-01-01

    In a weakly textured material with relatively pore-free and homogeneous microstructure, the local texture can influence primary crack propagation and secondary crack initiation, depending on specific microtexture cluster size. Moreover, the plastic strain assessment and strain quantity within individual grains are essential for understanding the material susceptibility to crack initiation and propagation at various loading conditions and temperature ranges. In the current study, electron backscatter diffraction (EBSD) is applied to measure the plastic strain present in RR1000 nickel-based superalloy microstructure following thermo-mechanical fatigue tests. The EBSD plastic strain measurements are evaluated to identify the distinctive deformation mode within individual grains. It was evident from the overall statistical analyses carried out for over 2000 grains that cube (〈0 0 1〉//loading direction) and near cube orientations (φ 1 , Φ, φ 2 : 0, 0–15, 0) behaved as “soft” grains with a high Schmid factor and contained low geometrically necessary dislocation (GND) density as a result of low strain hardening at the early stage of deformation for such grains. The near cube orientation (typically φ 1 , Φ, φ 2 : 0, 9, 0) was the softest orientation among the cube family. While the brass grains (〈1 1 1〉//loading direction) acted as “hard” grains that have the lowest Schmid factor with the highest Taylor factor and GND density compared with other oriented grains. A high GND content was found in the vicinity of the grain boundaries in the soft grains and on slip plane traces within the hard grains. It is concluded that GND absolute value for each grain can vary, as it is interrelated with deformation degree, but the GND locations within the grains give indications of the strain hardening state and deformation stages in hard and soft grains. Furthermore, the areas with random local texture contained high strain incompatibilities between neighbouring

  20. A unified model of hydride cracking based on elasto-plastic energy release rate over a finite crack extension

    International Nuclear Information System (INIS)

    Zheng, X.J.; Metzger, D.R.; Sauve, R.G.

    1995-01-01

    A fracture criterion based on energy balance is proposed for elasto-plastic cracking at hydrides in zirconium, assuming a finite length of crack advance. The proposed elasto-plastic energy release rate is applied to the crack initiation at hydrides in smooth and notched surfaces, as well as the subsequent delayed hydride cracking (DHC) considering limited crack-tip plasticity. For a smooth or notched surface of an elastic body, the fracture parameter is related to the stress intensity factor for the initiated crack. For DHC, a unique curve relates the non-dimensionalized elasto-plastic energy release rate with the length of crack extension relative to the plastic zone size. This fracture criterion explains experimental observations concerning DHC in a qualitative manner. Quantitative comparison with experiments is made for fracture toughness and DHC tests on specimens containing certain hydride structures; very good agreement is obtained. ((orig.))

  1. Influence of dynamic strain ageing on tensile strain energy of type 316L(N) austenitic stainless steel

    International Nuclear Information System (INIS)

    Isaac Samuel, B.; Choudhary, B.K.; Bhanu Sankara Rao, K.

    2010-01-01

    Tensile tests were conducted on type 316 L(N) stainless steel over a wide temperature range of 300-1123 K employing strain rates ranging from 3.16 X 10 -5 to 3.16 X 10 -3/s . The variation of strain energy in terms of modulus of resilience and modulus of toughness over the wide range of temperatures and strain rates were examined. The variation in modulus of resilience with temperature and strain rate did not show the signatures of dynamic strain ageing (DSA). However, the modulus of toughness exhibited a plateau at the intermediate temperatures of 523-1023 K. Further, the distribution of energy absorbed till necking and energy absorbed from necking till fracture were found to characterise the deformation and damage processes, respectively, and exhibited anomalous variations in the temperature range 523-823 K and 823-1023 K, respectively. In addition to the observed manifestations of DSA such as serrated load-elongation curve, peaks/plateaus in flow stress, ultimate tensile strength and work hardening rate, negative strain rate sensitivity and ductility minima, the observed anomalous variations in modulus of toughness at intermediate temperatures (523-1023 K) can be regarded as yet another key manifestation of DSA. At temperatures above 1023 K, a sharp decrease in the modulus of toughness and also in the strain energies up to necking and from necking to fracture observed, with increasing temperature and decreasing strain rate, reveal the onset of dynamic recovery leading to early cross slip and climb processes. (author)

  2. Reconstruction of fiber Bragg grating strain profile used to monitor the stiffness degradation of the adhesive layer in carbon fiber–reinforced plastic single-lap joint

    Directory of Open Access Journals (Sweden)

    Song Chunsheng

    2017-01-01

    Full Text Available The adhesive-bonded joint of carbon fiber–reinforced plastic is one of the core components in aircraft structure design. It is an effective guarantee for the safety and reliability of the aerospace aircraft structure to use effective methods for monitoring and early warning of internal failure. In this article, the mapping relation model between the strain profiles of the adherend of the carbon fiber–reinforced plastic single-lap adhesive joint and the stiffness degradation evolution of adhesive layer was achieved by finite element software ABAQUS. The fiber Bragg grating was embedded in the adherend between the first and second layers at the end of the adhesive layer to calculate the reflection spectrum of fiber Bragg grating sensor region with improved T-matrix method for reconstruction of the adherend strain profile of fiber Bragg grating sensing area with the help of genetic algorithm. According to the reconstruction results, the maximum error between the ideal and reconstructed strain profile under different tension loads did not exceed 7.43%, showing a good coincidence degree. The monitoring method of the stiffness degradation evolution of adhesive layer of the carbon fiber–reinforced plastic single-lap joint based on the reconstruction of the adherend strain profile of fiber Bragg grating sensing area thus was figured out.

  3. Processing and properties of a solid energy fuel from municipal solid waste (MSW) and recycled plastics

    International Nuclear Information System (INIS)

    Gug, JeongIn; Cacciola, David; Sobkowicz, Margaret J.

    2015-01-01

    Highlights: • Briquetting was used to produce solid fuels from municipal solid waste and recycled plastics. • Optimal drying, processing temperature and pressure were found to produce stable briquettes. • Addition of waste plastics yielded heating values comparable with typical coal feedstocks. • This processing method improves utilization of paper and plastic diverted from landfills. - Abstract: Diversion of waste streams such as plastics, woods, papers and other solid trash from municipal landfills and extraction of useful materials from landfills is an area of increasing interest especially in densely populated areas. One promising technology for recycling municipal solid waste (MSW) is to burn the high-energy-content components in standard coal power plant. This research aims to reform wastes into briquettes that are compatible with typical coal combustion processes. In order to comply with the standards of coal-fired power plants, the feedstock must be mechanically robust, free of hazardous contaminants, and moisture resistant, while retaining high fuel value. This study aims to investigate the effects of processing conditions and added recyclable plastics on the properties of MSW solid fuels. A well-sorted waste stream high in paper and fiber content was combined with controlled levels of recyclable plastics PE, PP, PET and PS and formed into briquettes using a compression molding technique. The effect of added plastics and moisture content on binding attraction and energy efficiency were investigated. The stability of the briquettes to moisture exposure, the fuel composition by proximate analysis, briquette mechanical strength, and burning efficiency were evaluated. It was found that high processing temperature ensures better properties of the product addition of milled mixed plastic waste leads to better encapsulation as well as to greater calorific value. Also some moisture removal (but not complete) improves the compacting process and results in

  4. Processing and properties of a solid energy fuel from municipal solid waste (MSW) and recycled plastics

    Energy Technology Data Exchange (ETDEWEB)

    Gug, JeongIn, E-mail: Jeongin_gug@student.uml.edu; Cacciola, David, E-mail: david_cacciola@student.uml.edu; Sobkowicz, Margaret J., E-mail: Margaret_sobkowiczkline@uml.edu

    2015-01-15

    Highlights: • Briquetting was used to produce solid fuels from municipal solid waste and recycled plastics. • Optimal drying, processing temperature and pressure were found to produce stable briquettes. • Addition of waste plastics yielded heating values comparable with typical coal feedstocks. • This processing method improves utilization of paper and plastic diverted from landfills. - Abstract: Diversion of waste streams such as plastics, woods, papers and other solid trash from municipal landfills and extraction of useful materials from landfills is an area of increasing interest especially in densely populated areas. One promising technology for recycling municipal solid waste (MSW) is to burn the high-energy-content components in standard coal power plant. This research aims to reform wastes into briquettes that are compatible with typical coal combustion processes. In order to comply with the standards of coal-fired power plants, the feedstock must be mechanically robust, free of hazardous contaminants, and moisture resistant, while retaining high fuel value. This study aims to investigate the effects of processing conditions and added recyclable plastics on the properties of MSW solid fuels. A well-sorted waste stream high in paper and fiber content was combined with controlled levels of recyclable plastics PE, PP, PET and PS and formed into briquettes using a compression molding technique. The effect of added plastics and moisture content on binding attraction and energy efficiency were investigated. The stability of the briquettes to moisture exposure, the fuel composition by proximate analysis, briquette mechanical strength, and burning efficiency were evaluated. It was found that high processing temperature ensures better properties of the product addition of milled mixed plastic waste leads to better encapsulation as well as to greater calorific value. Also some moisture removal (but not complete) improves the compacting process and results in

  5. Direct strain energy harvesting in automobile tires using piezoelectric PZT-polymer composites

    NARCIS (Netherlands)

    Ende, D.A. van den; Wiel, H.J. van de; Groen, W.A.; Zwaag, S. van der

    2012-01-01

    Direct piezoelectric strain energy harvesting can be used to power wireless autonomous sensors in environments where low frequency, high strains are present, such as in automobile tires during operation. However, these high strains place stringent demands on the materials with respect to mechanical

  6. Direct strain energy harvesting in automobile tires using piezoelectric PZT–polymer composites

    NARCIS (Netherlands)

    Van den Ende, D.A.; Van de Wiel, H.J.; Groen, W.A.; Van der Zwaag, S.

    2011-01-01

    Direct piezoelectric strain energy harvesting can be used to power wireless autonomous sensors in environments where low frequency, high strains are present, such as in automobile tires during operation. However, these high strains place stringent demands on the materials with respect to mechanical

  7. Thermal recycling of plastic waste using pyrolysis-gasification process for energy production

    Energy Technology Data Exchange (ETDEWEB)

    Forbit, George Teke

    2012-04-04

    The disposal of mixed waste in landfills, dump sites and open burning without material and energy recovery leads to resource loss, causes health problems, pollution and littering. Increasing energy demand for industrial and domestic application with rising costs due to scarcity motivates a constant search for alternative clean energy sources. Recovering energy from waste presents various incentives e.g. creating jobs, alleviating poverty, combating and mitigating climate change, protecting the environment and reducing dependence on traditional fuels sources. Hence, plastics end up in landfills, surface waters and ocean bed with serious negative impact on terrestrial and aquatic biodiversity. Plastic waste with high calorific value (36-46MJ/kg) occupies the greatest portion of landfill space. Hence, using an appropriate technology to transform waste plastic to a hot gaseous mixture which is burned in-situ produces enormous amount of energy without pollution. Based on this hypothesis, the study objectives accomplished were to: 1. Characterise, quantify and classify waste fractions and plastic components common in MSW by manual sorting 2. Evaluate options for sustainable plastic waste management especially for developing countries 3. Design, construct, test and optimize an appropriate technology that applies pyrolysis and gasification processes to convert non-PVC plastic waste to energy 4. Assess the efficiency of the technology based on the functioning, the engineering, mass and energy analysis including socioeconomic and environmental impacts An integrated methodology involving review of current literature, field and laboratory experiments on mixed waste and plastic waste analysis was used. In addition, the pyrolysis-gasification technology (PGT) was conceptualised, designed, constructed, tested and optimised at BTU Cottbus, Germany; Lagos, Nigeria and Dschang, Cameroon. Field studies involving natural observation, interviews, personal discussions and visits to

  8. Fatigue Crack Propagation Under Variable Amplitude Loading Analyses Based on Plastic Energy Approach

    Directory of Open Access Journals (Sweden)

    Sofiane Maachou

    2014-04-01

    Full Text Available Plasticity effects at the crack tip had been recognized as “motor” of crack propagation, the growth of cracks is related to the existence of a crack tip plastic zone, whose formation and intensification is accompanied by energy dissipation. In the actual state of knowledge fatigue crack propagation is modeled using crack closure concept. The fatigue crack growth behavior under constant amplitude and variable amplitude loading of the aluminum alloy 2024 T351 are analyzed using in terms energy parameters. In the case of VAL (variable amplitude loading tests, the evolution of the hysteretic energy dissipated per block is shown similar with that observed under constant amplitude loading. A linear relationship between the crack growth rate and the hysteretic energy dissipated per block is obtained at high growth rates. For lower growth rates values, the relationship between crack growth rate and hysteretic energy dissipated per block can represented by a power law. In this paper, an analysis of fatigue crack propagation under variable amplitude loading based on energetic approach is proposed.

  9. An application of the recrystallization method for the observation of plastic strain distribution around SCC cracks in sensitized SUS 304 stainless steels

    International Nuclear Information System (INIS)

    Tokiwai, Moriyasu

    1981-01-01

    Various types of stress corrosion cracking (SCC) testing methods have been developed since the SCC was discovered in type 304 stainless steel of BWR cooling pipes. With regard to the countermeasures for SCC, it is essential to evaluate the SCC susceptibility under the simulated or accelerated testing conditions. Among various acceleration SCC tests, the slow strain rate technique (SSRT) test has been used most widely. The SCC susceptibility, in almost cases, has been evaluated not on the base of the crack behavior but of the reduction of stress or strain under the corrosive environment. It is well known that the intensively deformed zone (plastic zone) is formed at the crack tip in fatigue and creep phenomena, but such plastic zone related with the resistance of crack extention has not been studied in SCC phenomenon. The objective of this study is to confirm the existence of the plastic zone at tips of SCC cracks by the application of the recrystallization method. The shape and the distribution of the plastic zone was measured by use of optical and scanning electron microscope in sensitized specimens SSRT tested in high temperature water containing various concentrations of dissolved oxygen. Results obtained are discussed in relation to the susceptibility of SCC. (author)

  10. Avalanches and plastic flow in crystal plasticity: an overview

    Science.gov (United States)

    Papanikolaou, Stefanos; Cui, Yinan; Ghoniem, Nasr

    2018-01-01

    Crystal plasticity is mediated through dislocations, which form knotted configurations in a complex energy landscape. Once they disentangle and move, they may also be impeded by permanent obstacles with finite energy barriers or frustrating long-range interactions. The outcome of such complexity is the emergence of dislocation avalanches as the basic mechanism of plastic flow in solids at the nanoscale. While the deformation behavior of bulk materials appears smooth, a predictive model should clearly be based upon the character of these dislocation avalanches and their associated strain bursts. We provide here a comprehensive overview of experimental observations, theoretical models and computational approaches that have been developed to unravel the multiple aspects of dislocation avalanche physics and the phenomena leading to strain bursts in crystal plasticity.

  11. High density polyethylene (HDPE-2) and polystyrene (PS-6) waste plastic mixture turns into valuable fuel energy

    Energy Technology Data Exchange (ETDEWEB)

    Sarker, Moinuddin; Rashid, Mohammad Mamunor; Rahman, Md. Sadikur; Molla, Mohammed [Department of Research and Development, Natural State Research Inc, Stamford, (United States)

    2011-07-01

    Disposal of waste plastic is a serious concern in USA. Waste plastic generated from different cities and towns is a part of municipal solid waste. It is a matter of concern that disposal of waste plastic is causing many problems such as leaching impact on land and ground water, choking of drains, making land infertile, indiscriminate burning causes environmental hazards etc. Waste plastics being nonbiodegradable it can remain as a long period of landfill. Over 48 million tons of synthetic polymer material is produced in the United States every year. Plastic are made from limited resources such as petroleum. When waste plastic come in contact with light and starts photo degrading, it starts releasing harmful such as carbon, chlorine and sulfur causing the soil around them to decay, contributing many complications for cultivation. Waste plastics also end up in the ocean, where it becomes small particles due to the reaction caused by the sun ray and salt from the ocean. Million of ocean habitants die from consuming these small plastic particles when they mistake them for food. To solve this problem countries are resorting to dumping the waste plastics, which requires a lot of effort and money yet they are only able to recycle a fraction of waste plastics. This developed a new technology which will remove these waste plastics form landfill and ocean and convert them into useful liquid fuels. The fuels show high potential for commercialization due to the fact, its influence to the environment. Keywords: waste plastics, fuel, energy, polystyrene, high density polyethylene, thermal, environmental.

  12. The elastic plastic behaviour of a 1/2% Cr Mo V steam turbine steel during high strain thermal fatigue

    International Nuclear Information System (INIS)

    Murphy, M.C.; Batte, A.D.; Stringer, M.B.

    1979-01-01

    High strain fatigue problem in steam turbine. Cyclic stress strain hysteresis loops and stress relaxation behaviour in 16 h dwell period tests. Variation of stress and strain during tests under nominally strain controlled conditions. Definition of test conditions and of criteria for crack initiation and failure. Comparison of reverse bend and push pull failure data. (orig.) 891 RW/orig. 892 RKD [de

  13. Using Omega and NIF to Advance Theories of High-Pressure, High-Strain-Rate Tantalum Plastic Flow

    Science.gov (United States)

    Rudd, R. E.; Arsenlis, A.; Barton, N. R.; Cavallo, R. M.; Huntington, C. M.; McNaney, J. M.; Orlikowski, D. A.; Park, H.-S.; Prisbrey, S. T.; Remington, B. A.; Wehrenberg, C. E.

    2015-11-01

    Precisely controlled plasmas are playing an important role as both pump and probe in experiments to understand the strength of solid metals at high energy density (HED) conditions. In concert with theory, these experiments have enabled a predictive capability to model material strength at Mbar pressures and high strain rates. Here we describe multiscale strength models developed for tantalum and vanadium starting with atomic bonding and extending up through the mobility of individual dislocations, the evolution of dislocation networks and so on up to full scale. High-energy laser platforms such as the NIF and the Omega laser probe ramp-compressed strength to 1-5 Mbar. The predictions of the multiscale model agree well with the 1 Mbar experiments without tuning. The combination of experiment and theory has shown that solid metals can behave significantly differently at HED conditions; for example, the familiar strengthening of metals as the grain size is reduced has been shown not to occur in the high pressure experiments. Work performed under the auspices of the U.S. Dept. of Energy by Lawrence Livermore National Lab under contract DE-AC52-07NA273.

  14. Structural Analysis of Shipping Casks, Vol. 9. Energy Absorption Capabilities of Plastically Deformed Struts Under Specified Impact Loading Conditions (Thesis)

    International Nuclear Information System (INIS)

    Davis, F.C.

    2001-01-01

    The purpose of this investigation was to determine the energy absorption characteristics of plastically deformed inclined struts under impact loading. This information is needed to provide a usable method by which designers and analysts of shipping casks for radioactive or fissile materials can determine the energy absorption capabilities of external longitudinal fins on cylindrical casks under specified impact conditions. A survey of technical literature related to experimental determination of the dynamic plastic behavior of struts revealed no information directly applicable to the immediate problem, especially in the impact velocity ranges desired, and an experimental program was conducted to obtain the needed data. Mild-steel struts with rectangular cross sections were impacted by free-falling weights dropped from known heights. These struts or fin specimens were inclined at five different angles to simulate different angles of impact that fins on a shipping cask could experience under certain accident conditions. The resisting force of the deforming strut was measured and recorded as a function of time by using load cells instrumented with resistance strain gage bridges, signal conditioning equipment, an oscilloscope, and a Polaroid camera. The acceleration of the impacting weight was measured and recorded as a function of time during the latter portion of the testing program by using an accelerometer attached to the drop hammer, appropriate signal conditioning equipment, the oscilloscope, and the camera. A digital computer program was prepared to numerically integrate the force-time and acceleration-time data recorded during the tests to obtain deformation-time data. The force-displacement relationships were then integrated to obtain values of absorbed energy with respect to deformation or time. The results for various fin specimen geometries and impact angles are presented graphically, and these curves may be used to compute the energy absorption capacity of

  15. Contribution to the theoretical study of the plastic strain localization in porous materials; Contribution a l'etude theorique de la localisation plastique dans les poreux

    Energy Technology Data Exchange (ETDEWEB)

    Willot, F

    2007-01-15

    This work presents a study in theoretical mechanics, in the classical framework of homogenization of heterogeneous media. It addresses a notoriously problematical situation of non-linear behavior and infinite contrast between two phases, one of which is a plastic solid phase and the other one, the porosity of the medium. Its aim is to investigate how plastic strain localization manifests itself at the level of the overall effective behavior of the medium in presence of pores, and in particular in the non-trivial limit of small porosity. This question, important to the understanding of ductile damage, is examined both numerically and theoretically, in the restricted situation of bi-dimensional systems, and using a deformation theory approach of plasticity. The numerical investigations consist of quasi-exact computations of the strain and stress fields in the voided medium, by means of a Fast Fourier Transform method, and using a particular Green function. The theoretical approach makes use of exact solutions, which can be obtained in particular cases of a periodic void lattice, as well as of a recent 'second-order' nonlinear homogenization approach. The virtues of the latter are evaluated in two steps, first by studying the underlying linear anisotropic homogenization step (an essential ingredient), then by studying the nonlinear step itself. The nature and significance of the singularities of the theory which appear in the limit of small porosity, confirmed by numerical computations, are partly elucidated. Finally, original observations are presented as to the relation between plastic deformation patterns in an ideal disordered medium, and some features of the macroscopic strain/stress curve. (author)

  16. An elasto-plastic self-consistent model with hardening based on dislocation density, twinning and de-twinning: Application to strain path changes in HCP metals

    International Nuclear Information System (INIS)

    Zecevic, Milovan; Knezevic, Marko; Beyerlein, Irene J.; Tomé, Carlos N.

    2015-01-01

    In this work, we develop a polycrystal mean-field constitutive model based on an elastic–plastic self-consistent (EPSC) framework. In this model, we incorporate recently developed subgrain models for dislocation density evolution with thermally activated slip, twin activation via statistical stress fluctuations, reoriented twin domains within the grain and associated stress relaxation, twin boundary hardening, and de-twinning. The model is applied to a systematic set of strain path change tests on pure beryllium (Be). Under the applied deformation conditions, Be deforms by multiple slip modes and deformation twinning and thereby provides a challenging test for model validation. With a single set of material parameters, determined using the flow-stress vs. strain responses during monotonic testing, the model predicts well the evolution of texture, lattice strains, and twinning. With further analysis, we demonstrate the significant influence of internal residual stresses on (1) the flow stress drop when reloading from one path to another, (2) deformation twin activation, (3) de-twinning during a reversal strain path change, and (4) the formation of additional twin variants during a cross-loading sequence. The model presented here can, in principle, be applied to other metals, deforming by multiple slip and twinning modes under a wide range of temperature, strain rate, and strain path conditions

  17. Safe Disposal of Medical and Plastic Waste and Energy Recovery Possibilities using Plasma Pyrolysis Technology

    International Nuclear Information System (INIS)

    Nema, S.K.; Mukherjee, S.

    2010-01-01

    Plasma pyrolysis and plasma gasification are emerging technologies that can provide complete solution to organic solid waste disposal. In these technologies plasma torch is used as a workhorse to convert electrical energy into heat energy. These technologies dispose the organic waste in an environment friendly manner. Thermal plasma provides extremely high temperature in oxygen free or controlled air environment which is required for pyrolysis or gasification reactions. Plasma based medical waste treatment is an extremely complex technology since it has to contend with extreme temperatures and corrosion-prone environment, complex pyro-chemistry resulting in toxic and dangerous products, if not controlled. In addition, one has to take care of complete combustion of pyrolyzed gases followed by efficient scrubbing to meet the emission standards set by US EPA and Central Pollution Control Board, India. In medical waste, high volume and low packing density waste with nonstandard composition consisting of a variety of plastics, organic material and liquids used to be present. The present paper describes the work carried out at Institute for Plasma Research, India, on plasma pyrolysis of (i) medical waste disposal and the results of emission measurement done at various locations in the system and (ii) energy recovery from cotton and plastic waste. The process and system development has been done in multiple steps. Different plasma pyrolysis models were made and each subsequent model was improved upon to meet stringent emission norms and to make the system energy efficient and user friendly. FCIPT, has successfully demonstrated up to 50 kg/ hr plasma pyrolysis systems and have installed plasma pyrolysis facilities at various locations in India . Plastic Waste disposal along with energy recovery in 15 kg/ hr model has also been developed and demonstrated at FCIPT. In future, this technology has great potential to dispose safely different waste streams such as biomass

  18. Morphological plasticity in the tropical sponge Anthosigmella varians: responses to predators and wave energy.

    Science.gov (United States)

    Hill, Malcolm S; Hill, April L

    2002-02-01

    The goal of the research presented here was to examine phenotypic plasticity exhibited by three morphotypes of the common Caribbean sponge Anthosigmella varians (Duchassaing & Michelotti). We were interested in examining the biotic (and, to a lesser extent, abiotic) factors responsible for branch production in this species. We also tested the hypothesis that the skeleton may serve an antipredator function in this sponge, focusing on vertebrate fish predators (i.e., angelfish) in this work. In transplant and caging experiments, unprotected forma varians replicates were immediately consumed by angelfish, while caged replicates persisted on the reef for several months. These findings support the hypothesis that predators (and not wave energy) restrict forma varians to lagoonal habitats. Branch production was not observed in A. varians forma incrustans when sponges were protected from predators or placed in predator-free, low-wave-energy environments. It is not clear from our work whether forma incrustans is capable of producing branches (i.e., whether branch production is a plastic trait in this morph). Additional field experiments demonstrated that A. varians forma varians increased spicule concentrations, compared to uninjured sponges, in response to artificial predation events, and A. varians forma rigida reduced spicule concentrations, compared to uncaged controls, when protected from predators. These findings indicate that spicule concentration is a plastic morphological trait that can be induced by damage, and that A. varians may be able to reduce spicule concentrations when environmental conditions change (e.g., in the absence of predators). The potential significance of inducible defenses and structural anti-predator defenses in sponges is discussed in relation to recent work on sponge chemical defenses.

  19. Study of the evolution of the boundary of the elastic field with strain hardening, and elastic-plastic behaviour relationships of cubic metals

    International Nuclear Information System (INIS)

    Bui, Huy Duong

    1969-01-01

    In this research thesis on metal strain hardening, the author first discusses the issue of passing from microscopic values to corresponding macroscopic values. If there is generally a correspondence between them, it is not the case for plastic strain. Thus, the author studies the general properties of the boundary of the macroscopic plastic field with respect to single-crystal elastic boundaries. In the second part, the author reports an experimental study of the evolution of the elastic field boundary. In the third part, he develops elastic-plastic behaviour laws for an aggregate of cubic crystals. The objectives are to report experimental results in a more satisfying way than previous studies, and to obtain acceptable physical laws while keeping some properties of conventional laws in order to ensure the solution uniqueness, and to establish minimum principles similar to those of Nodge-Prager and of Greenberg. In order to do so, he introduces a new hypothesis: there is a statistic scattering in initial thresholds of crystals

  20. Crack tip stress and strain

    International Nuclear Information System (INIS)

    Francois, D.

    1975-01-01

    The study of potential energy variations in a loaded elastic solid containing a crack leads to determination of the crack driving force G. Generalization of this concept to cases other than linear elasticity leads to definition of the integral J. In a linear solid, the crack tip stress field is characterized by a single parameter: the stress-intensity factor K. When the crack tip plastic zone size is confined to the elastic singularity J=G, it is possible to establish relationship between these parameters and plastic strain (and in particular the crack tip opening displacement delta). The stress increases because of the triaxiality effect. This overload rises with increasing strain hardening. When the plastic zone size expands, using certain hypotheses, delta can be calculated. The plastic strain intensity is exclusively dependent on parameter J [fr

  1. Energy and angular responses of the criticality accident detector using a plastic scintillator

    International Nuclear Information System (INIS)

    Tsujimura, Norio; Yoshida, Tadayoshi

    2006-01-01

    The Japan Atomic Energy Agency (JAEA), Nuclear Fuel Cycle Engineering Laboratories, operates a spent fuel reprocessing plant and MOX (Plutonium-Uranium Mixed Oxide) fuel fabrication plants. Criticality accident detectors have been installed in these facilities. The detector, the Toshiba RD120, is composed of a plastic scintillator coupled to a photomultiplier tube, and an operational amplifier. The alarm triggering point is set to 1.0-3.6 mGy·h -1 in photon dose rate to detect the minimum accident of concern. However, a plastic scintillator is principally sensitive not only to primary photons but also to neutrons by secondary photons and heavy charged particles produced in the detector itself. The authors calculated energy and angular responses of the RD120 criticality accident detector to photons and neutrons using Monte Carlo computer codes. The response to primary photons was evaluated with the MCNP-4B and EGS4 calculations, and photon and X-ray irradiation experiments. The response to neutrons that produce secondary photons and heavy charged particles from neutron interactions was computed using the MCNP-4B and SCINFUL, respectively. As a result, reliable response functions were obtained. These results will be a great help in reassessing the coverage area and in determining the appropriate triggering dose rate level in criticality accidents. (author)

  2. Energy efficient microwave heating of carbon fibre reinforced plastic; Energieeffiziente Mikrowellentemperierung von kohlenstofffaserverstaerkten Duroplasten

    Energy Technology Data Exchange (ETDEWEB)

    Danilov, Maksim

    2013-07-01

    The polymerization of carbon fiber reinforced thermosetting composites (CFRP) is a dull process step with high energy requirements within the production chain. His improvement would affect the economic and ecological balance of the fiber reinforced materials in a positive way. One possible approach investigated here is tempering of raw materials in a microwave oven. In this work the material to be processed - a carbon fiber-reinforced plastic laminate - is being characterized in the microwave field through electromagnetic and thermal parameters. The relationship between its design parameters (fiber orientation and number of layers), the energy levels (reflection, absorption and transmittance) and the thermal process parameters (temperature gradient achievable) will be established. Afterwards, constructive options will be examined and evaluated which are suitable to install a low-loss (both by means of wave reflections and heat losses) industrial process.

  3. Energy recycling: an innovative solution for unrecyclable plastic; Reciclagem energetica: uma solucao inovadora para o plastico nao reciclavel

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Julyane Carolina; Oliveira, Magno Andre de; Pires, Pedro Henrique; Silva, Thuanye Peixoto; Rodrigues, Marcia [Centro Universitario de Belo Horizonte (UnBH), MG (Brazil)], e-mails: juhlorah@hotmail.com, marromar2004@yahoo.com.br

    2011-07-01

    This paper shows a new technology that is already used in over 35 countries with more than 750 plants in total and is still under study in Brazil: the energy recycling of plastic. Through studies, tables, comparisons and observations, have to analyze the plastic, chemical composition, the steps of material recycling and energy production, the final products obtained by recycling and gases released during the process. Thus, after highlighting how this technology is advantageous, it is expected to awaken to the reflection that it is feasible to use the recycling energy due to its great benefits environmental, social and economic shown the course of research. (author)

  4. Strain Energy Density in the Elastodynamics of the Spacetime Continuum and the Electromagnetic Field

    Directory of Open Access Journals (Sweden)

    Millette P. A.

    2013-04-01

    Full Text Available We investigate the strain energy density of the spacetime continuum in the Elasto- dynamics of the Spacetime Continuum by applying continuum m echanical results to strained spacetime. The strain energy density is a scalar. W e find that it is separated into two terms: the first one expresses the dilatation energy density (the “mass” longitu- dinal term while the second one expresses the distortion en ergy density (the “massless” transverse term. The quadratic structure of the energy rel ation of Special Relativity is found to be present in the theory. In addition, we find that the kinetic energy pc is car- ried by the distortion part of the deformation, while the dil atation part carries only the rest-mass energy. The strain energy density of the electrom agnetic energy-momentum stress tensor is calculated. The dilatation energy density (the rest-mass energy density of the photon is found to be 0 as expected. The transverse dis tortion energy density is found to include a longitudinal electromagnetic energy fl ux term, from the Poynting vector, that is massless as it is due to distortion, not dilatation, of the spacetime con- tinuum. However, because this energy flux is along the direct ion of propagation (i.e. longitudinal, it gives rise to the particle aspect of the el ectromagnetic field, the photon.

  5. Demonstrations of the Action and Reaction Law and the Energy Conservation Law Using Fine Spherical Plastic Beads

    Science.gov (United States)

    Khumaeni, A.; Tanaka, S.; Kobayashi, A.; Lee, Y. I.; Kurniawan, K. H.; Ishii, K.; Kagawa, K.

    2008-01-01

    Equipment for demonstrating Newton's third law and the energy conservation law in mechanics have successfully been constructed utilizing fine spherical plastic beads in place of metal ball bearings. To demonstrate Newton's third law, special magnetized Petri dishes were employed as objects, while to examine the energy conservation law, a…

  6. Deformation mechanism study of a hot rolled Zr-2.5Nb alloy by transmission electron microscopy. I. Dislocation microstructures in as-received state and at different plastic strains

    Energy Technology Data Exchange (ETDEWEB)

    Long, Fei; Daymond, Mark R., E-mail: mark.daymond@queensu.ca; Yao, Zhongwen [Department of Mechanical and Materials Engineering, Queen' s University Kingston, Ontario K7L 3N6 (Canada)

    2015-03-07

    Thin foil dog bone samples prepared from a hot rolled Zr-2.5Nb alloy have been deformed by tensile deformation to different plastic strains. The development of slip traces during loading was observed in situ through SEM, revealing that deformation starts preferentially in certain sets of grains during the elastic-plastic transition region. TEM characterization showed that sub-grain boundaries formed during hot rolling consisted of screw 〈a〉 dislocations or screw 〈c〉 and 〈a〉 dislocations. Prismatic 〈a〉 dislocations with large screw or edge components have been identified from the sample with 0.5% plastic strain. Basal 〈a〉 and pyramidal 〈c + a〉 dislocations were found in the sample that had been deformed with 1.5% plastic strain, implying that these dislocations require larger stresses to be activated.

  7. Clinical dosimetry with plastic scintillators - Almost energy independent, direct absorbed dose reading with high resolution

    Energy Technology Data Exchange (ETDEWEB)

    Quast, U; Fluehs, D [Department of Radiotherapy, Essen (Germany). Div. of Clinical Radiation Physics; Fluehs, D; Kolanoski, H [Dortmund Univ. (Germany). Inst. fuer Physik

    1996-08-01

    Clinical dosimetry is still far behind the goal to measure any spatial or temporal distribution of absorbed dose fast and precise without disturbing the physical situation by the dosimetry procedure. NE 102A plastic scintillators overcome this border. These tissue substituting dosemeter probes open a wide range of new clinical applications of dosimetry. This versatile new dosimetry system enables fast measurement of the absorbed dose to water in water also in regions with a steep dose gradient, close to interfaces, or in partly shielded regions. It allows direct reading dosimetry in the energy range of all clinically used external photon and electron beams, or around all branchytherapy sources. Thin detector arrays permit fast and high resolution measurements in quality assurance, such as in-vivo dosimetry or even afterloading dose monitoring. A main field of application is the dosimetric treatment planning, the individual optimization of brachytherapy applicators. Thus, plastic scintillator dosemeters cover optimally all difficult fields of clinical dosimetry. An overview about its characteristics and applications is given here. 20 refs, 1 fig.

  8. Intersubband energies in strain-compensated InGaN/AlInN quantum well structures

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seoung-Hwan, E-mail: shpark@cu.ac.kr [Department of Electronics Engineering, Catholic University of Daegu, Hayang, Kyeongsan, Kyeongbuk, 712-702 (Korea, Republic of); Ahn, Doyeol [Institute of Quantum Information Processing and Systems, University of Seoul, 90 Jeonnong, Tongdaimoon-Gu, Seoul, Korea 130-743 (Korea, Republic of)

    2016-01-15

    Intersubband transition energies in the conduction band for strain-compensated InGaN/AlInN quantum well (QW) structures were investigated as a function of strain based on an effective mass theory with the nonparabolicity taken into account. In the case of an InGaN/AlInN QW structure lattice-matched to GaN, the wavelength is shown to be longer than 1.55 μm. On the other hand, strain-compensated QW structures show that the wavelength of 1.55 μm can be reached even for the QW structure with a relatively small strain of 0.3 %. Hence, the strain-compensated QW structures can be used for telecommunication applications at 1.55 μm with a small strain, compared to conventional GaN/AlN QW structure.

  9. A systematic characterization of the low-energy photon response of plastic scintillation detectors

    Science.gov (United States)

    Boivin, Jonathan; Beddar, Sam; Bonde, Chris; Schmidt, Daniel; Culberson, Wesley; Guillemette, Maxime; Beaulieu, Luc

    2016-08-01

    To characterize the low energy behavior of scintillating materials used in plastic scintillation detectors (PSDs), 3 PSDs were developed using polystyrene-based scintillating materials emitting in different wavelengths. These detectors were exposed to National Institute of Standards and Technology (NIST)-matched low-energy beams ranging from 20 kVp to 250 kVp, and to 137Cs and 60Co beams. The dose in polystyrene was compared to the dose in air measured by NIST-calibrated ionization chambers at the same location. Analysis of every beam quality spectrum was used to extract the beam parameters and the effective mass energy-absorption coefficient. Monte Carlo simulations were also performed to calculate the energy absorbed in the scintillators’ volume. The scintillators’ expected response was then compared to the experimental measurements and an energy-dependent correction factor was identified to account for low-energy quenching in the scintillators. The empirical Birks model was then compared to these values to verify its validity for low-energy electrons. The clear optical fiber response was below 0.2% of the scintillator’s light for x-ray beams, indicating that a negligible amount of fluorescence contamination was produced. However, for higher-energy beams (137Cs and 60Co), the scintillators’ response was corrected for the Cerenkov stem effect. The scintillators’ response increased by a factor of approximately 4 from a 20 kVp to a 60Co beam. The decrease in sensitivity from ionization quenching reached a local minimum of about 11%+/- 1% between 40 keV and 60 keV x-ray beam mean energy, but dropped by 20% for very low-energy (13 keV) beams. The Birks model may be used to fit the experimental data, but it must take into account the energy dependence of the kB quenching parameter. A detailed comprehension of intrinsic scintillator response is essential for proper calibration of PSD dosimeters for radiology.

  10. Quasi-plane-hypothesis of strain coordination for RC beams seismically strengthened with externally-bonded or near-surface mounted fiber reinforced plastic

    Science.gov (United States)

    Ren, Zhenhua; Zeng, Xiantao; Liu, Hanlong; Zhou, Fengjun

    2013-03-01

    The application of fiber reinforced plastic (FRP), including carbon FRP and glass FRP, for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement (EBR) and near-surface mounted (NSM) strengthening techniques. This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods, including externally-bonded and near-surface mounted FRP, to study the strain coordination of the FRP and steel rebar of the RC beam. Since there is relative slipping between the RC beam and the FRP, the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis; that is, the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height ( h 0) of the cross section is in direct proportion to the distance from the fiber to the neutral axis. The strain of the FRP and steel rebar satisfies the equation: ɛ FRP= βɛ steel, and the value of β is equal to 1.1-1.3 according to the test results.

  11. Correlation between residual stress and plastic strain amplitude during low cycle fatigue of mechanically surface treated austenitic stainless steel AISI 304 and ferritic-pearlitic steel SAE 1045

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, I. [Institute of Materials Engineering, University of Kassel, 34125 Kassel, Hessen (Germany)], E-mail: Ivan.Nikitin@infineon.com; Besel, M. [Institute of Materials Engineering, University of Kassel, 34125 Kassel, Hessen (Germany)

    2008-09-15

    Mechanical surface treatments such as deep rolling are known to affect the near-surface microstructure and induce, e.g. residual stresses and/or increase the surface hardness. It is well known that, e.g. compressive residual stress states usually increase the lifetime under fatigue loading. The stress relaxation behaviour and the stability of the residual stress during fatigue loading depend on the mechanical surface treatment method. In this paper three different surface treatments are used and their effects on the low cycle fatigue behaviour of austenitic stainless steel (AISI 304) and ferritic-pearlitic steel (SAE 1045) are investigated. X-ray diffraction is applied for the non-destructive evaluation of the stress state and the microstructure. It is found that consecutive deep rolling and annealing as well as high temperature deep rolling produce more stable near-surface stress states than conventional deep rolling at room temperature. The plastic strain amplitudes during fatigue loading are measured and it is shown that they correlate well with the induced residual stress and its relaxation, respectively. Furthermore, Coffin-Manson plots are presented which clearly show the correlation between the plastic strain amplitude and the fatigue lifetime.

  12. A phase field study of strain energy effects on solute–grain boundary interactions

    International Nuclear Information System (INIS)

    Heo, Tae Wook; Bhattacharyya, Saswata; Chen Longqing

    2011-01-01

    We have studied strain-induced solute segregation at a grain boundary and the solute drag effect on boundary migration using a phase field model integrating grain boundary segregation and grain structure evolution. The elastic strain energy of a solid solution due to the atomic size mismatch and the coherency elastic strain energy caused by the inhomogeneity of the composition distribution are obtained using Khachaturyan’s microelasticity theory. Strain-induced grain boundary segregation at a static planar boundary is studied numerically and the equilibrium segregation composition profiles are validated using analytical solutions. We then systematically studied the effect of misfit strain on grain boundary migration with solute drag. Our theoretical analysis based on Cahn’s analytical theory shows that enhancement of the drag force with increasing atomic size mismatch stems from both an increase in grain boundary segregation due to the strain energy reduction and misfit strain relaxation near the grain boundary. The results were analyzed based on a theoretical analysis in terms of elastic and chemical drag forces. The optimum condition for solute diffusivity to maximize the drag force under a given driving force was identified.

  13. Linking Scales in Plastic Deformation and Fracture

    DEFF Research Database (Denmark)

    Martinez-Paneda, Emilio; Niordson, Christian Frithiof; S. Deshpande, Vikram

    2017-01-01

    We investigate crack growth initiation and subsequent resistance in metallic materials by means of an implicit multi-scale approach. Strain gradient plasticity is employed to model the mechanical response of the solid so as to incorporate the role of geometrically necessary dislocations (GNDs......) and accurately capture plasticity at the small scales involved in crack tip deformation. The response ahead of the crack is described by means of a traction-separation law, which is characterized by the cohesive strength and the fracture energy. Results reveal that large gradients of plastic strain accumulatein...... the vicinity of the crack, elevating the dislocation density and the local stress. This stress elevation enhances crack propagation and significantly lowers the steady state fracture toughness with respect to conventional plasticity. Important insight is gained into fracture phenomena that cannot be explained...

  14. The elastic strain energy of crystallographic shear planes in reduced tungsten trioxide

    International Nuclear Information System (INIS)

    Iguchi, E.; Tilley, R.J.D.

    1977-01-01

    Calculations of the elastic strain energy due to crystallographic shear (c.s.) planes lying upon 102, 103 and 001 planes in reduced tungsten trioxide crystals have been made. The cases analysed in detail are for both isolated c.s. planes and for pairs of c.s. planes. These results are used to determine the elastic strain energy per unit volume for crystals containing ordered arrays of c.s. planes. It was found that the magnitude of the elastic strain energy was in the sequence 001 < 102 < 103 and that at relatively small inter-c.s. spacings the curves of elastic strain energy against c.s. plane separation take the form of a series of peaks and valleys. These results are compared with experimental observations of c.s. plane spacings in substantially reduced crystals containing quasi-ordered arrays of c.s. planes and with observations of c.s. plane nucleation and growth in both slightly and more appreciably reduced crystals. It was found that the elastic strain energy plays a significant part in controlling the microstructure of c.s. plane arrays in such cases. (author)

  15. A new approach to film dosimetry for high-energy photon beams using organic plastic scintillators

    International Nuclear Information System (INIS)

    Yeo, I.J.; Wang, C.-K.C.; Burch, S.E.

    1999-01-01

    Successful radiotherapy relies on accurate dose measurement. Traditional dosimeters such as ion chambers, TLDs and diodes have disadvantages such as relatively long measurement time and poor spatial resolution. These drawbacks become more serious problems for dynamic beams (i.e. with the use of dynamic wedges or even the intensity modulation technique). X-ray film, an integrating dosimeter, may not be associated with the above disadvantages and problems. However, there are several major issues regarding use of x-ray film for routine dosimetry, including the over-response of the film to low-energy photons, variations in the dose response curve (nonlinearity), lack of reproducibility due to variation in processing, etc. This paper addresses the first problem. That is, x-ray film over-responds to low-energy photons (energies below 400 keV), and thus generates unacceptably inaccurate dosimetric data compared with ion-chamber data. To overcome the over-response problem of x-ray film in a phantom, a scintillation method has been investigated. In this method, a film is sandwiched by two plastic scintillation screens to enhance the film response to upstream electrons, and therefore minimize the over-response caused by low-energy photons. The sandwiched system was tested with a 4 MV linac beam. The result shows that, depending on the uniformity of the scintillation screens, the depth-dose distribution obtained from the sandwich system can be made to agree well with that obtained from ion chambers. However, the required high degree of uniformity remains a challenge for the scintillation screen manufacturers. (author)

  16. The pulverization and handling of soft plastics for energy recovery; Soenderdelning och hantering av mjuka plaster foer energiutvinning

    Energy Technology Data Exchange (ETDEWEB)

    Wiklund, Sven-Erik

    2000-10-01

    The purpose of the project has primarily been to investigate suitable equipment (mills, crushers, shredders) for the pulverization of different types of soft plastics from the agricultural sector (large sacks and silage plastic) and the peat extraction industry (plastic covers) with the aim of being able to use the plastic material as fuel in conventional solid waste-fired plants. Many of the mills that are used for pulverizing different types of biofuel have proved not to be particularly suitable for soft plastics. The project has comprised the following: * Contact with a number of plant owners with different types of plants (grate, CFB and BFB boilers) for a review of existing fuel handling and fuel feed equipment as well as the demands they make on the fuel that is to be fired. * Contact with Trio Plast concerning previous tests carried out in connection with the collection, baling, handling, pulverization and combustion of plastics from the agricultural sector. * Contact with mill suppliers for participation in the tests and for feedback on experience gained in connection with the pulverization of soft plastics. * Choice of a suitable plant for practical trials based on contact with the above plant owners as a reference group. * Practical trials in 5 mills with the pulverization of soft plastics from agriculture (silage plastic and large sacks) as well as plastic from peat extraction (plastic covers) and * Evaluation of technical, economic, energy-related and environmental preconditions. Following contact with several owners of solid waste-fired combustion plants, and after hearing their opinions, it became clear that many of them were doubtful about the combustion of plastic. They are primarily afraid of tripping superheaters, etc. Consequently, two plants without superheaters, one in Oestersund and the other in Malmoe, were chosen for the tests. The mills that were tested were: * A SIM mill from WahIkvist, Oedeshoeg Plant - a mobile slow-action pulverizer for

  17. The exponentiated Hencky-logarithmic strain energy. Part II: Coercivity, planar polyconvexity and existence of minimizers

    Science.gov (United States)

    Neff, Patrizio; Lankeit, Johannes; Ghiba, Ionel-Dumitrel; Martin, Robert; Steigmann, David

    2015-08-01

    We consider a family of isotropic volumetric-isochoric decoupled strain energies based on the Hencky-logarithmic (true, natural) strain tensor log U, where μ > 0 is the infinitesimal shear modulus, is the infinitesimal bulk modulus with the first Lamé constant, are dimensionless parameters, is the gradient of deformation, is the right stretch tensor and is the deviatoric part (the projection onto the traceless tensors) of the strain tensor log U. For small elastic strains, the energies reduce to first order to the classical quadratic Hencky energy which is known to be not rank-one convex. The main result in this paper is that in plane elastostatics the energies of the family are polyconvex for , extending a previous finding on its rank-one convexity. Our method uses a judicious application of Steigmann's polyconvexity criteria based on the representation of the energy in terms of the principal invariants of the stretch tensor U. These energies also satisfy suitable growth and coercivity conditions. We formulate the equilibrium equations, and we prove the existence of minimizers by the direct methods of the calculus of variations.

  18. Mixed-waste pyrolysis of biomass and plastics waste – A modelling approach to reduce energy usage

    International Nuclear Information System (INIS)

    Oyedun, Adetoyese Olajire; Gebreegziabher, Tesfaldet; Ng, Denny K.S.; Hui, Chi Wai

    2014-01-01

    Thermal co-processing of waste mixtures had gained a lot of attention in the last decade. This is largely due to certain synergistic effects such as higher quantity and better quality of oil, limited supply of certain feedstock and improving the overall pyrolysis process. Many experiments have been conducted via TGA analysis and different reactors to achieve the stated synergistic effects in co-pyrolysis of biomass and plastic wastes. The thermal behaviour of plastics during pyrolysis is different from that of biomass because its decomposition happens at a high temperature range with sudden release of volatile compared to biomass which have a wide range of thermal decomposition. A properly designed recipe and operational strategy of mixing feedstock can ease the operational difficulties and at the same time decrease energy consumption and/or improve the product yield. Therefore it is worthwhile to study the possible synergistic effects on the overall energy used during co-pyrolysis process. In this work, two different modelling approaches were used to study the energy related synergistic effect between polystyrene (PS) and bamboo waste. The mass loss and volatile generation profiles show that significant interactions between the two feedstocks exist. The results also show that both modelling approaches give an appreciable synergy effect of reduction in overall energy when PS and bamboo are co-pyrolysed together. However, the second approach which allows interaction between the two feedstocks gives a more reduction in overall energy usage up to 6.2% depending on the ratio of PS in the mixed blend. - Highlights: • Proposed the mixed-waste pyrolysis modelling via two modelling approaches. • Study the energy related synergistic effects when plastics and biomass are pyrolysed together. • Mass loss and volatile generation profiles show the existence of significant interactions. • Energy usage can be reduced by up to 6.2% depending on the percentage of the plastic

  19. Energy absorption at high strain rate of glass fiber reinforced mortars

    Directory of Open Access Journals (Sweden)

    Fenu Luigi

    2015-01-01

    Full Text Available In this paper, the dynamic behaviour of cement mortars reinforced with glass fibers was studied. The influence of the addition of glass fibers on energy absorption and tensile strength at high strain-rate was investigated. Static tests in compression, in tension and in bending were first performed. Dynamic tests by means of a Modified Hopkinson Bar were then carried out in order to investigate how glass fibers affected energy absorption and tensile strength at high strain-rate of the fiber reinforced mortar. The Dynamic Increase Factor (DIF was finally evaluated.

  20. Size dependence of energy storage and dissipation in a discrete dislocation plasticity analysis of static friction

    NARCIS (Netherlands)

    Deshpande, VS; Needleman, A; Van der Giessen, E; Deshpande, V.S.

    2005-01-01

    The initiation of frictional sliding between a flat-bottomed indenter and a planar single crystal substrate is analyzed using discrete dislocation plasticity. Plastic deformation is modeled through the motion of edge dislocations in an elastic solid with the lattice resistance to dislocation motion,

  1. A compact cyclic plasticity model with parameter evolution

    DEFF Research Database (Denmark)

    Krenk, Steen; Tidemann, L.

    2017-01-01

    The paper presents a compact model for cyclic plasticity based on energy in terms of external and internal variables, and plastic yielding described by kinematic hardening and a flow potential with an additive term controlling the nonlinear cyclic hardening. The model is basically described by five...... parameters: external and internal stiffness, a yield stress and a limiting ultimate stress, and finally a parameter controlling the gradual development of plastic deformation. Calibration against numerous experimental results indicates that typically larger plastic strains develop than predicted...

  2. Finite strain anisotropic elasto-plastic model for the simulation of the forming and testing of metal/short fiber reinforced polymer clinch joints at room temperature

    Science.gov (United States)

    Dean, A.; Rolfes, R.; Behrens, A.; Bouguecha, A.; Hübner, S.; Bonk, C.; Grbic, N.

    2017-10-01

    There is a strong trend in the automotive industry to reduce car body-, chassis- and power-train mass in order to lower carbon emissions. More wide spread use of lightweight short fiber reinforced polymer (SFRP) is a promising approach to attain this goal. This poses the challenge of how to integrate new SFRP components by joining them to traditional sheet metal structures. Recently (1), the clinching technique has been successfully applied as a suitable joining method for dissimilar material such as SFRP and Aluminum. The material pairing PA6GF30 and EN AW 5754 is chosen for this purpose due to their common application in industry. The current contribution presents a verification and validation of a finite strain anisotropic material model for SFRP developed in (2) for the FE simulation of the hybrid clinching process. The finite fiber rotation during forming and separation, and thus the change of the preferential material direction, is represented in this model. Plastic deformations in SFRP are considered in this model via an invariant based non-associated plasticity formulation following the multiplicative decomposition approach of the deformation gradient where the stress-free intermediate configuration is introduced. The model allows for six independent characterization curves. The aforementioned material model allows for a detailed simulation of the forming process as well as a simulative prediction of the shear test strength of the produced joint at room temperature.

  3. 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.

  4. Foraging plasticity of breeding Northern Rockhopper Penguins, Eudyptes moseleyi, in response to changing energy requirements

    KAUST Repository

    Booth, Jenny Marie

    2018-04-02

    During the breeding season, seabirds must balance the changing demands of self- and off-spring provisioning with the constraints imposed by central-place foraging. Recently, it was shown that Northern Rockhopper Penguins at Tristan da Cunha in the South Atlantic Ocean switch diet from lower to higher trophic level prey throughout their breeding cycle. Here, we investigated if this switch is reflected in their foraging behaviour, using time-depth recorders to study the diving behaviour of 27 guard and 10 crèche birds during the breeding season 2010 at Tristan da Cunha and obtaining complementary stomach contents of 20 birds. While no significant effects of breeding stage were detected on any foraging trip or dive parameters, stage/prey had a significant effect on feeding dive parameters, with dive duration, bottom time, and maximum depth explaining the majority of the dissimilarity amongst categories. We verified the previously shown dietary shift from zooplankton and cephalopods during the guard stage to a higher-energy fish-based diet during the crèche stage, which was reflected in a change in dive behaviour from shorter, shallower to longer, deeper dives. This prey switching behaviour may reflect preferential selection to account for the increased physiological needs of chicks or simply mirror changes in local prey abundance. Nonetheless, we show that Northern Rockhopper Penguins demonstrate behavioural plasticity as a response to their changing energy requirements, which is a critical trait when living in a spatio-temporally heterogeneous environment. This ability is likely to be particularly important under extrinsic constraints such as long-term environmental change.

  5. Influence of a preliminary tensile plastic strain on the first stages of oxidation of a Ni80-Cr20 alloy

    International Nuclear Information System (INIS)

    Schmitt, Jean-Francois

    1992-01-01

    This research thesis reports the study of the influence of surface, and maybe also volume, defects created by a uniaxial mechanical strain on the chemical reactivity of metal and alloy surface (adsorption, desorption, segregation, surface chemical reaction), and more particularly on their early stages of oxidation. A tensile micro-machine has been designed and manufactured to study the influence of a mechanical strain on the first stages of oxidation of sample ribbons of Ni80-Cr20 alloy. Tests have been performed under low oxygen pressures. In order to analyze the surface, each reaction is monitored by Auger electron spectrometry, and many samples are transferred to another apparatus to examine the oxide distribution. Results are interpreted in terms of evolution of nickel, chromium and oxygen Auger signals which have been recorded during oxidation experiments. The first layers of the sample alloy are simply modelled and some theoretical calculations are developed which correlate with experimental values [fr

  6. Controlling the exciton energy of a nanowire quantum dot by strain fields

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yan; Zhang, Jiaxiang; Ding, Fei, E-mail: f.ding@ifw-dresden.de [Institute for Integrative Nanosciences, IFW Dresden, Helmholtz Strasse 20, 01069 Dresden (Germany); Zadeh, Iman Esmaeil; Jöns, Klaus D.; Fognini, Andreas; Zwiller, Val [Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft (Netherlands); Reimer, Michael E. [Institute for Quantum Computing and Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, N2L 3G1 (Canada); Dalacu, Dan; Poole, Philip J. [National Research Council, Ottawa, Ontario K1A 0R6 (Canada); Schmidt, Oliver G. [Institute for Integrative Nanosciences, IFW Dresden, Helmholtz Strasse 20, 01069 Dresden (Germany); Material Systems for Nanoelectronics, Chemnitz University of Technology, Reichenhainer Strasse 70, 09107 Chemnitz (Germany)

    2016-05-02

    We present an experimental route to engineer the exciton energies of single quantum dots in nanowires. By integrating the nanowires onto a piezoelectric crystal, we controllably apply strain fields to the nanowire quantum dots. Consequently, the exciton energy of a single quantum dot in the nanowire is shifted by several meVs without degrading its optical intensity and single-photon purity. Second-order autocorrelation measurements are performed at different strain fields on the same nanowire quantum dot. The suppressed multi-photon events at zero time delay clearly verify that the quantum nature of single-photon emission is well preserved under external strain fields. The work presented here could facilitate on-chip optical quantum information processing with the nanowire based single photon emitters.

  7. Robust piezoelectric composites for energy harvesting in high-strain environments

    NARCIS (Netherlands)

    Ende, D.A. van der; Groen, W.A.; Zwaag, S. van der

    2013-01-01

    High-strain environments, such as are found in automobile tires, provide deformation energy that can be harvested using piezoelectric materials, for instance, for powering electronics such as wireless sensors. Despite numerous efforts, none of the present devices easily satisfy the stringent

  8. Prediction of strain energy-based liquefaction resistance of sand-silt mixtures: An evolutionary approach

    Science.gov (United States)

    Baziar, Mohammad H.; Jafarian, Yaser; Shahnazari, Habib; Movahed, Vahid; Amin Tutunchian, Mohammad

    2011-11-01

    Liquefaction is a catastrophic type of ground failure, which usually occurs in loose saturated soil deposits under earthquake excitations. A new predictive model is presented in this study to estimate the amount of strain energy density, which is required for the liquefaction triggering of sand-silt mixtures. A wide-ranging database containing the results of cyclic tests on sand-silt mixtures was first gathered from previously published studies. Input variables of the model were chosen from the available understandings evolved from the previous studies on the strain energy-based liquefaction potential assessment. In order to avoid overtraining, two sets of validation data were employed and a particular monitoring was made on the behavior of the evolved models. Results of a comprehensive parametric study on the proposed model are in accord with the previously published experimental observations. Accordingly, the amount of strain energy required for liquefaction onset increases with increase in initial effective overburden pressure, relative density, and mean grain size. The effect of nonplastic fines on strain energy-based liquefaction resistance shows a more complicated behavior. Accordingly, liquefaction resistance increases with increase in fines up to about 10-15% and then starts to decline for a higher increase in fines content. Further verifications of the model were carried out using the valuable results of some downhole array data as well as centrifuge model tests. These verifications confirm that the proposed model, which was derived from laboratory data, can be successfully utilized under field conditions.

  9. Vibration based structural health monitoring in fibre reinforced composites employing the modal strain energy method

    NARCIS (Netherlands)

    Loendersloot, Richard; Ooijevaar, T.H.; Warnet, Laurent; Akkerman, Remko; de Boer, Andries; Meguid, S.A.; Gomes, J.F.S.

    2009-01-01

    The feasibility of a vibration based damage identification method is investigated. The Modal Strain Energy method is applied to a T–beam structure. The dynamic response of an intact structure and a damaged, delaminated structure is analysed employing a commercially available Finite Element package.

  10. Introduction to Computational Plasticity

    International Nuclear Information System (INIS)

    Hartley, P

    2006-01-01

    The focus of the book on computational plasticity embodies techniques of relevance not only to academic researchers, but also of interest to industrialists engaged in the production of components using bulk or sheet forming processes. Of particular interest is the guidance on how to create modules for use with the commercial system Abaqus for specific types of material behaviour. The book is in two parts, the first of which contains six chapters, starting with microplasticity, but predominantly on continuum plasticity. The first chapter on microplasticty gives a brief description of the grain structure of metals and the existence of slip systems within the grains. This provides an introduction to the concept of incompressibility during plastic deformation, the nature of plastic yield and the importance of the critically resolved shear stress on the slip planes (Schmid's law). Some knowledge of the notation commonly used to describe slip systems is assumed, which will be familiar to students of metallurgy, but anyone with a more general engineering background may need to undertake additional reading to understand the various descriptions. Chapter two introduces one of several yield criteria, that normally attributed to von Mises (though historians of mechanics might argue over who was first to develop the theory of yielding associated with strain energy density), and its two or three-dimensional representation as a yield surface. The expansion of the yield surface during plastic deformation, its translation due to kinematic hardening and the Bauschinger effect in reversed loading are described with a direct link to the material stress-strain curve. The assumption, that the increment of strain is normal to the yield surface, the normality principle, is introduced. Uniaxial loading of an elastic-plastic material is used as an example in which to develop expressions to describe increments in stress and strain. The full presentation of numerous expressions, tensors and

  11. Improved incorporation of strain gradient elasticity in the flexoelectricity based energy harvesting from nanobeams

    Science.gov (United States)

    Zhou, Yarong; Yang, Xu; Pan, Dongmei; Wang, Binglei

    2018-04-01

    Flexoelectricity, the coupling of strain gradient and polarization, exists in all the dielectric materials and numerous models have been proposed to study this mechanism. However, the contribution of strain gradient elasticity has typically been underestimated. In this work, inspired by the one-length scale parameter model developed by Deng et al. [19], we incorporate three length-scale parameters to carefully capture the contribution of the purely mechanical strain gradients on flexoelectricity. This three-parameter model is more flexible and could be applied to investigate the flexoelectricity in a wide range of complicated deformations. Accordingly, we carry out our analysis by studying a dielectric nanobeam under different boundary conditions. We show that the strain gradient elasticity and flexoelectricity have apparent size effects and significant influence on the electromechanical response. In particular, the strain gradient effects could significantly reduce the energy efficiency, indicating their importance and necessity. This work may be helpful in understanding the mechanism of flexoelectricity at the nanoscale and sheds light on the flexoelectricity energy harvesting.

  12. Formosa Plastics Corporation: Plant-Wide Assessment of Texas Plant Identifies Opportunities for Improving Process Efficiency and Reducing Energy Costs

    Energy Technology Data Exchange (ETDEWEB)

    None

    2005-01-01

    At Formosa Plastics Corporation's plant in Point Comfort, Texas, a plant-wide assessment team analyzed process energy requirements, reviewed new technologies for applicability, and found ways to improve the plant's energy efficiency. The assessment team identified the energy requirements of each process and compared actual energy consumption with theoretical process requirements. The team estimated that total annual energy savings would be about 115,000 MBtu for natural gas and nearly 14 million kWh for electricity if the plant makes several improvements, which include upgrading the gas compressor impeller, improving the vent blower system, and recovering steam condensate for reuse. Total annual cost savings could be $1.5 million. The U.S. Department of Energy's Industrial Technologies Program cosponsored this assessment.

  13. A general approach for defining the macroscopic free energy density of saturated porous media at finite strains under non-isothermal conditions

    International Nuclear Information System (INIS)

    Gajo, A.

    2011-01-01

    A general approach is proposed for defining the macroscopic free energy density function (and its complement, the free enthalpy) of a saturated porous medium submitted to finite deformations under non-isothermal conditions, in the case of compressible fluid and solid constituents. Reference is made to an elementary volume treated as an 'open system', moving with the solid skeleton. The proposed free energy depends on the generalised strains (namely an appropriate measure of the strain of the solid skeleton and the variation in fluid mass content) and the absolute temperatures of the solid and fluid phases (which are assumed to differ from each other for the sake of generality). This macroscopic energy proves to be a potential for the generalised stresses (namely the associated measure of the total stress and the free enthalpy of the pore fluid per unit mass) and the entropies of the solid and fluid phases. In contrast with mixture theories, the resulting free energy is not the simple sum of the free energies of the single constituents. Two simplified cases are examined in detail, i.e. the semi-linear theory (originally proposed for isothermal conditions and extended here to non-isothermal problems) and the linear theory. The proposed approach paves the way to the consistent non-isothermal-hyper-elastic-plastic modelling of saturated porous media with a compressible fluid and solid constituents. (authors)

  14. Energy generation by air gasification of two industrial plastic wastes in a pilot scale fluidized bed reactor

    International Nuclear Information System (INIS)

    Arena, Umberto; Di Gregorio, Fabrizio

    2014-01-01

    Two plastic wastes obtained as co-products from an industrial process were fed in a pilot-scale bubbling fluidized bed gasifier, having an internal diameter of 0.38 m and a maximum thermal output of about 400 kW. The experimental runs were carried out by reaching a condition of thermal and chemical steady state under values of equivalence ratio ranging from 0.2 to 0.3. Olivine, a neo-silicate of Fe and Mg, already tested as a good catalyst for tar removal during gasification of polyolefin plastic wastes, was used as bed material. The results provide the complete composition of the syngas, including the tar, particulate and acid/basic gas contents as well as the chemical and physical characterization of the bed material and entrained fines. The gasification process appears technically feasible, yielding a producer gas of valuable quality for energy applications in an appropriate plant configuration. On the other hand, under the experimental conditions tested, olivine particles show a strongly reduced catalytic activity in all the runs. The differences in the gasification behaviour of the two industrial plastics are explained on the basis of the structure and composition of the wastes, taking also into account the results of a combined material and substance flow analysis. - Highlights: • Pilot-scale investigation of fluidized bed gasification of two industrial plastic wastes. • Tests under conditions of thermal/chemical steady state at various equivalence ratios. • Complete composition of the producer gas, including tar, particulate and acid/basic gases. • Differences in the gasification behaviour of plastic wastes. • Material, substance, and feedstock energy flow analysis for different gasification tests

  15. MD simulations to evaluate effects of applied tensile strain on irradiation-induced defect production at various PKA energies

    International Nuclear Information System (INIS)

    Miyashiro, S.; Fujita, S.; Okita, T.; Okuda, H.

    2012-01-01

    Highlights: ► Strain effects on defect formation were evaluated at various PKA energies by MD. ► Radiation-induced defects were increased numerically by external strain. ► Enhanced formation of larger clusters causes the numerical increase of defects. ► Strain influence on the number of defects was greatest at about 20 keV PKA. ► Cluster size, which is mostly affected by strain, was greater with higher PKA energy. - Abstract: Molecular Dynamics (MD) simulations were conducted to investigate the influence of applied tensile strain on defect production during cascade damages at various Primary Knock-on Atom (PKA) energies of 1–30 keV. When 1% strain was applied, the number of surviving defects increased at PKA energies higher than 5 keV, although they did not increase at 1 keV. The rate of increase by strain application was higher with higher PKA energy, and attained the maximum at 20 keV PKA energy with a subsequent gradual decrease at 30 keV PKA energy The cluster size, mostly affected by strain, was larger with higher PKA energy, although clusters with fewer than seven interstitials did not increase in number at any PKA energy.

  16. Direct strain energy harvesting in automobile tires using piezoelectric PZT–polymer composites

    International Nuclear Information System (INIS)

    Van den Ende, D A; Van de Wiel, H J; Groen, W A; Van der Zwaag, S

    2012-01-01

    Direct piezoelectric strain energy harvesting can be used to power wireless autonomous sensors in environments where low frequency, high strains are present, such as in automobile tires during operation. However, these high strains place stringent demands on the materials with respect to mechanical failure or depolarization, especially at elevated temperatures. In this work, three kinds of ceramic–polymer composite piezoelectric materials were evaluated and compared against state-of-the-art piezoelectric materials. The new composites are unstructured and structured composites containing granular lead zirconate titanate (PZT) particles or PZT fibers in a polyurethane matrix. The composites were used to build energy harvesting patches which were attached to a tire and tested under simulated rolling conditions. The energy density of the piezoelectric ceramic–polymer composite materials is initially not as high as that of the reference materials (a macro-fiber composite and a polyvinylidene fluoride polymer). However, the area normalized power output of the composites after temperature and strain cycling is comparable to that of the reference devices because the piezoelectric ceramic–polymer composites did not degrade during operation. (paper)

  17. A Comparison of Quantum and Molecular Mechanical Methods to Estimate Strain Energy in Druglike Fragments.

    Science.gov (United States)

    Sellers, Benjamin D; James, Natalie C; Gobbi, Alberto

    2017-06-26

    Reducing internal strain energy in small molecules is critical for designing potent drugs. Quantum mechanical (QM) and molecular mechanical (MM) methods are often used to estimate these energies. In an effort to determine which methods offer an optimal balance in accuracy and performance, we have carried out torsion scan analyses on 62 fragments. We compared nine QM and four MM methods to reference energies calculated at a higher level of theory: CCSD(T)/CBS single point energies (coupled cluster with single, double, and perturbative triple excitations at the complete basis set limit) calculated on optimized geometries using MP2/6-311+G**. The results show that both the more recent MP2.X perturbation method as well as MP2/CBS perform quite well. In addition, combining a Hartree-Fock geometry optimization with a MP2/CBS single point energy calculation offers a fast and accurate compromise when dispersion is not a key energy component. Among MM methods, the OPLS3 force field accurately reproduces CCSD(T)/CBS torsion energies on more test cases than the MMFF94s or Amber12:EHT force fields, which struggle with aryl-amide and aryl-aryl torsions. Using experimental conformations from the Cambridge Structural Database, we highlight three example structures for which OPLS3 significantly overestimates the strain. The energies and conformations presented should enable scientists to estimate the expected error for the methods described and we hope will spur further research into QM and MM methods.

  18. Multi-layered controllable stiffness beams for morphing: energy, actuation force, and material strain considerations

    International Nuclear Information System (INIS)

    Murray, Gabriel; Gandhi, Farhan

    2010-01-01

    Morphing aerospace structures could benefit from the ability of structural elements to transition from a stiff load-bearing state to a relatively compliant state that can undergo large deformation at low actuation cost. The present paper focuses on multi-layered beams with controllable flexural stiffness—comprising polymer layers affixed to the surfaces of a base beam and cover layers, in turn, affixed to the surfaces of the polymer layers. Heating the polymer through the glass transition reduces its shear modulus, decouples the cover layers from the base beam and reduces the overall flexural stiffness. Although the stiffness and actuation force required to bend the beam reduce, the energy required to heat the polymer layer must also be considered. Results show that for beams with low slenderness ratios, relatively thick polymer layers, and cover layers whose extensional stiffness is high, the decoupling of the cover layers through softening of the polymer layers can result in flexural stiffness reductions of over 95%. The energy savings are also highest for these configurations, and will increase as the deformation of the beam increases. The decoupling of the cover layers from the base beam through the softening of the polymer reduces the axial strains in the cover layers significantly; otherwise material failure would prevent large deformation. Results show that when the polymer layer is stiff, the cover layers are the dominant contributors to the total energy in the beam, and the energy in the polymer layers is predominantly axial strain energy. When the polymer layers are softened the energy in the cover layers is a small contributor to the total energy which is dominated by energy in the base beam and shear strain energy in the polymer layer

  19. Plastic collapse and energy absorption of circular filled tubes under quasi-static loads by computational analysis

    Energy Technology Data Exchange (ETDEWEB)

    Beng, Yeo Kiam; Tzeng, Woo Wen [Universiti Malaysia Sabah, Sabah (Malaysia)

    2017-02-15

    This study presents the finite element analysis of plastic collapse and energy absorption of polyurethane-filled aluminium circular tubes under quasi-static transverse loading. Increasing focuses were given to impact damage of structures where energy absorbed during impact could be controlled to avoid total structure collapse of energy absorbers and devices designed to dissipate energy. ABAQUS finite element analysis application was utilized for modelling and simulating the polyurethane-filled aluminium tubes, different set of diameterto- thickness ratios and span lengths, subjected to transverse three-point-bending load. Different sets of polyurethane-filled aluminium tubes subjected to the transverse loading were modelled and simulated. The failure modes and mechanisms of filled tubes and its capabilities as energy absorbers to further improve and strengthening of empty tube were also identified. The results showed that plastic deformation response was affected by the geometric constraints and parameters of the specimens. The diameter-to-thickness ratio and span lengths had shown to play crucial role in optimizing the PU-filled tube as energy absorber.

  20. A study on synthesis of energy fuel from waste plastic and assessment of its potential as an alternative fuel for diesel engines.

    Science.gov (United States)

    Kaimal, Viswanath K; Vijayabalan, P

    2016-05-01

    The demand for plastic is ever increasing and has produced a huge amount of plastic waste. The management and disposal of plastic waste have become a major concern, especially in developing cities. The idea of waste to energy recovery is one of the promising techniques used for managing the waste plastic. This paper assesses the potential of using Waste Plastic Oil (WPO), synthesized using pyrolysis of waste plastic, as an alternative for diesel fuel. In this research work, the performance and emission characteristics of a single cylinder diesel engine fuelled with WPO and its blends with diesel are studied. In addition to neat plastic oil, three blends (PO25, PO50 and PO75) were prepared on a volumetric basis and the engine was able to run on neat plastic oil. Brake thermal efficiency of blends was lower compared to diesel, but PO25 showed similar performance to that of diesel. The emissions were reduced considerably while using blends when compared to neat plastic oil. The smoke and NOX were reduced by 22% and 17.8% respectively for PO25 than that of plastic oil. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. A Conservative Formulation for Plasticity

    Science.gov (United States)

    1992-01-01

    concepts that apply to a broad class of macroscopic models: plastic deformation and plastic flow rule. CONSERVATIVE PLASTICITY 469 3a. Plastic Defrrnation...temperature. We illustrate these concepts with a model that has been used to describe high strain-rate plastic flow in metals [11, 31, 32]. In the case...JOURDREN, AND P. VEYSSEYRE. Un Modele ttyperelastique- Plastique Euldrien Applicable aux Grandes Dtformations: Que/ques R~sultats 1-D. preprint, 1991. 2. P

  2. Composite of wood-plastic and micro-encapsulated phase change material (MEPCM) used for thermal energy storage

    International Nuclear Information System (INIS)

    Jamekhorshid, A.; Sadrameli, S.M.; Barzin, R.; Farid, M.M.

    2017-01-01

    Highlights: • A composite of wood–plastic-MEPCM has been produced. • Compression molding has been used for the composite preparation. • Thermal and properties were investigated using DSC analysis and cycling test. • Leakage test has been performed for the encapsulated PCM. • The composites can be used as a building material for thermal energy management. - Abstract: Application of phase change materials (PCMs) in lightweight building is growing due to the high latent heat of fusion of PCMs and their ability to control temperature by absorbing and releasing heat efficiently. Wood-plastic composites (WPC) are materials used in the interior parts of buildings that have improved properties compared to conventional materials. However, these materials have low energy storage capacity, which can be improved by incorporating PCM in them. Leakage of PCM is a major obstacle to the industrial applications, which can be solved through the use of microencapsulated PCM (MEPCM). This paper presents the performance tests conducted for a composite of wood-plastic-MEPCM for using in buildings for thermal storage. The wood-plastic-MEPCM composites were produced in this project using compression molding and their thermal and mechanical properties were investigated using DSC analysis, cycling test, leakage test, and three point bending analysis. The results showed that there is no leakage of PCM during phase change. The results also indicated that the composite has reasonable thermal properties, but its mechanical properties need to be improved by increasing the pressure during the molding process or by using extrusion method. The produced composites can be used as a building material for thermal energy management of building.

  3. Organophosphate flame retardants and plasticizers in indoor dust, air and window wipes in newly built low-energy preschools.

    Science.gov (United States)

    Persson, Josefin; Wang, Thanh; Hagberg, Jessika

    2018-07-01

    The construction of extremely airtight and energy efficient low-energy buildings is achieved by using functional building materials, such as age-resistant plastics, insulation, adhesives, and sealants. Additives such as organophosphate flame retardants (OPFRs) can be added to some of these building materials as flame retardants and plasticizers. Some OPFRs are considered persistent, bioaccumulative and toxic. Therefore, in this pilot study, the occurrence and distribution of nine OPFRs were determined for dust, air, and window wipe samples collected in newly built low-energy preschools with and without environmental certifications. Tris(1,3-dichloroisopropyl) phosphate (TDCIPP) and triphenyl phosphate (TPHP) were detected in all indoor dust samples at concentrations ranging from 0.014 to 10μg/g and 0.0069 to 79μg/g, respectively. Only six OPFRs (predominantly chlorinated OPFRs) were detected in the indoor air. All nine OPFRs were found on the window surfaces and the highest concentrations, which occurred in the reference preschool, were measured for 2-ethylhexyl diphenyl phosphate (EHDPP) (maximum concentration: 1500ng/m 2 ). Interestingly, the OPFR levels in the environmental certified low-energy preschools were lower than those in the reference preschool and the non-certified low-energy preschool, probably attributed to the usage of environmental friendly and low-emitting building materials, interior decorations, and consumer products. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Experimental investigation of the quality characteristics of agricultural plastic wastes regarding their recycling and energy recovery potential

    International Nuclear Information System (INIS)

    Briassoulis, D.; Hiskakis, M.; Babou, E.; Antiohos, S.K.; Papadi, C.

    2012-01-01

    Highlights: ► Definition of parameters characterising agricultural plastic waste (APW) quality. ► Analysis of samples to determine APW quality for recycling or energy recovery. ► Majority of APW samples from various countries have very good quality for recycling. ► Upper limit of 50% w/w soil contamination in APW acceptable for energy recovery. ► Chlorine and heavy metals content in APW below the lowest limit for energy recovery. - Abstract: A holistic environmentally sound waste management scheme that transforms agricultural plastic waste (APW) streams into labelled guaranteed quality commodities freely traded in open market has been developed by the European research project LabelAgriWaste. The APW quality is defined by the APW material requirements, translated to technical specifications, for recycling or energy recovery. The present work investigates the characteristics of the APW quality and the key factors affecting it from the introduction of the virgin product to the market to the APW stream reaching the disposer. Samples of APW from different countries were traced from their application to the field through their storage phase and transportation to the final destination. The test results showed that the majority of APW retained their mechanical properties after their use preserving a “very good quality” for recycling in terms of degradation. The degree of soil contamination concerning the APW recycling and energy recovery potential fluctuates depending on the agricultural plastic category and application. The chlorine and heavy metal content of the tested APW materials was much lower than the maximum acceptable limits for their potential use in cement industries.

  5. Energy metabolism after U.V.-irradiation in a sensitive yeast strain

    International Nuclear Information System (INIS)

    Kiefer, J.

    1976-01-01

    Stationary-phase cells of an excision-repair deficient diploid yeast (strain 2094) were UV-irradiated at exposures of up to 440 erg mm -2 and then resuspended in fresh medium. Measurements of energy metabolism per cell at periods of up to 6 hours after irradiation showed that cellular respiration was increased for all doses tested from about 3 hours after exposure, whereas fermentation did not start before about 2 hours after irradiation, never significantly exceeded control values and was markedly inhibited by the higher doses. The results suggest that respiration is under nuclear control, since a mutation in one gene is thought to be the only difference between this strain and the wild-type. The D 0 value of about 360 erg mm -2 found for the relative cellular fermentation at 2 hours after irradiation was used to give an estimate of the size of the structural gene involved, of about 3000 nucleotides, or a protein with 1000 amino-acid residues, compatible with the molecular weight of alcohol dehydrogenase. Fermentation can therefore be inhibited in this sensitive strain by lesions in the structural gene of a key enzyme. Since respiration was increased even more in repair-deficient than in repair-proficient strains, it must be assumed that higher energy metabolism is not linked to the repair process, but rather reflects a general disturbance in cellular regulation. (U.K.)

  6. Analysis of stress-strain relationship in materials containing voids by means of plastic finite element method

    International Nuclear Information System (INIS)

    Shiraishi, Haruki; Tabuchi, Masaaki

    2000-01-01

    Applying the finite element method in two dimensions, an analysis is performed to derive the stress-strain relationship of material containing voids in matrix, and which is subjected to large deformation. The conditions assumed for the analysis are applicability of continuum body mechanics, Mises yield criterion, J2 flow theory, power work-hardening, plane stress in two-dimensional system and uniform cyclically recurring void distribution. Taking as example a case of material presenting 0.3 work-hardening, it is indicated from the analysis that: With voids arrayed in square lattice, total elongation would be little affected by change in void size; With a void spacing in lattice of 10 μ m, a uniform elongation 12-14% should be obtained in a wide range of void sizes from 0.01 to 8.0 μm; Tensile strength should start to lower at a void areal fraction of around 1%; A sharply lowered uniform elongation of a level far below 1% should be presented by material of low work-hardening exponent. The severe decline of ductility seen with 316 stainless steel upon neutron irradiation at temperatures around 600 K is interpreted as resulting from a combination of low work-hardening and the presence of voids in matrix. (author)

  7. Modeling plasticity by non-continuous deformation

    Science.gov (United States)

    Ben-Shmuel, Yaron; Altus, Eli

    2017-10-01

    Plasticity and failure theories are still subjects of intense research. Engineering constitutive models on the macroscale which are based on micro characteristics are very much in need. This study is motivated by the observation that continuum assumptions in plasticity in which neighbour material elements are inseparable at all-time are physically impossible, since local detachments, slips and neighbour switching must operate, i.e. non-continuous deformation. Material microstructure is modelled herein by a set of point elements (particles) interacting with their neighbours. Each particle can detach from and/or attach with its neighbours during deformation. Simulations on two- dimensional configurations subjected to uniaxial compression cycle are conducted. Stochastic heterogeneity is controlled by a single "disorder" parameter. It was found that (a) macro response resembles typical elasto-plastic behaviour; (b) plastic energy is proportional to the number of detachments; (c) residual plastic strain is proportional to the number of attachments, and (d) volume is preserved, which is consistent with macro plastic deformation. Rigid body displacements of local groups of elements are also observed. Higher disorder decreases the macro elastic moduli and increases plastic energy. Evolution of anisotropic effects is obtained with no additional parameters.

  8. Reliability assessment of a bi-material notch: Strain energy density factor approach

    Czech Academy of Sciences Publication Activity Database

    Klusák, Jan; Knésl, Zdeněk

    2010-01-01

    Roč. 53, č. 2 (2010), s. 89-93 ISSN 0167-8442 R&D Projects: GA ČR GAP108/10/2049; GA ČR GA101/08/0994 Institutional research plan: CEZ:AV0Z20410507 Keywords : crack initiation * bi-material notch * strain energy density factor Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.073, year: 2010

  9. Comminution of solids caused by kinetic energy of high shear strain rate, with implications for impact, shock, and shale fracturing.

    Science.gov (United States)

    Bazant, Zdenek P; Caner, Ferhun C

    2013-11-26

    Although there exists a vast literature on the dynamic comminution or fragmentation of rocks, concrete, metals, and ceramics, none of the known models suffices for macroscopic dynamic finite element analysis. This paper outlines the basic idea of the macroscopic model. Unlike static fracture, in which the driving force is the release of strain energy, here the essential idea is that the driving force of comminution under high-rate compression is the release of the local kinetic energy of shear strain rate. The density of this energy at strain rates >1,000/s is found to exceed the maximum possible strain energy density by orders of magnitude, making the strain energy irrelevant. It is shown that particle size is proportional to the -2/3 power of the shear strain rate and the 2/3 power of the interface fracture energy or interface shear stress, and that the comminution process is macroscopically equivalent to an apparent shear viscosity that is proportional (at constant interface stress) to the -1/3 power of this rate. A dimensionless indicator of the comminution intensity is formulated. The theory was inspired by noting that the local kinetic energy of shear strain rate plays a role analogous to the local kinetic energy of eddies in turbulent flow.

  10. Distribution of Energy Deposited in Plastic Tubing and Copper-Wire Insulation by Electron Beam Irradiation

    DEFF Research Database (Denmark)

    Pedersen, Walther Batsberg; Miller, Arne; Pejtersen, K.

    1978-01-01

    chloride insulation. Radiochromic dye films equivalent to the insulating materials were used as accurate dosimeters having a response independent of dose rate. Irradiations were in various geometries, wire and plastic thicknesses, positions along the beam scan, and with different backing materials near...

  11. Calculation of efficiency of high-energy neutron detection by plastic scintillators

    International Nuclear Information System (INIS)

    Telegin, Yu.N.

    1977-01-01

    A computer was used to calculate neutron (5-30O MeV) registration effeciencies with plastic scintillators 2,5,10, 20,30,40 and 50 cm thick. The results are shown in the form of tables. The contributions to efficiency of various processes have been analysed. The calculation results may be used in planning experiments with neutron counters

  12. Enhancing inhibition-induced plasticity in tinnitus--spectral energy contrasts in tailor-made notched music matter.

    Directory of Open Access Journals (Sweden)

    Alwina Stein

    Full Text Available Chronic tinnitus seems to be caused by reduced inhibition among frequency selective neurons in the auditory cortex. One possibility to reduce tinnitus perception is to induce inhibition onto over-activated neurons representing the tinnitus frequency via tailor-made notched music (TMNM. Since lateral inhibition is modifiable by spectral energy contrasts, the question arises if the effects of inhibition-induced plasticity can be enhanced by introducing increased spectral energy contrasts (ISEC in TMNM. Eighteen participants suffering from chronic tonal tinnitus, pseudo randomly assigned to either a classical TMNM or an ISEC-TMNM group, listened to notched music for three hours on three consecutive days. The music was filtered for both groups by introducing a notch filter centered at the individual tinnitus frequency. For the ISEC-TMNM group a frequency bandwidth of 3/8 octaves on each side of the notch was amplified, additionally, by about 20 dB. Before and after each music exposure, participants rated their subjectively perceived tinnitus loudness on a visual analog scale. During the magnetoencephalographic recordings, participants were stimulated with either a reference tone of 500 Hz or a test tone with a carrier frequency representing the individual tinnitus pitch. Perceived tinnitus loudness was significantly reduced after TMNM exposure, though TMNM type did not influence the loudness ratings. Tinnitus related neural activity in the N1m time window and in the so called tinnitus network comprising temporal, parietal and frontal regions was reduced after TMNM exposure. The ISEC-TMNM group revealed even enhanced inhibition-induced plasticity in a temporal and a frontal cortical area. Overall, inhibition of tinnitus related neural activity could be strengthened in people affected with tinnitus by increasing spectral energy contrast in TMNM, confirming the concepts of inhibition-induced plasticity via TMNM and spectral energy contrasts.

  13. Is gastrointestinal plasticity in king quail (Coturnix chinensis) elicited by diet-fibre or diet-energy dilution?

    Science.gov (United States)

    Williamson, Sean A; Jones, Stephanie K Courtney; Munn, Adam J

    2014-06-01

    Phenotypic plasticity of organ size allows some animals to manage fluctuations of resource quality or availability. Here, we examined the phenotypic plasticity of the gastrointestinal tract of king quail (Coturnix chinensis) in a diet-fibre manipulation study. Quail were offered either a control low-fibre (high-quality) food (8.5% neutral-detergent fibre; NDF), or one of two experimental diets of higher fibre contents of 16% NDF (i.e. low-quality food). To examine whether phenotypic plasticity of organ size was associated with the fibre content per se, or as a consequence of diluting the diet energy contents by adding fibre, one of the high-fibre feeds was 'balanced' with additional energy to match that of the low-fibre control diet. Total empty dry mass of the gastrointestinal tract was significantly heavier among birds offered the unbalanced high-fibre diet as compared with those offered the control diet, with birds offered the fibrous but energy-balanced diet having guts of intermediate size. The heavier entire-gut mass (dry) of quail offered the unbalanced high-fibre diet was associated mainly with these birds having significantly heavier gizzards. Notably, the larger gizzard in the birds offered the unbalanced high-fibre diet was associated with marked increases in their metabolisability (digestion) of diet fibre. Our findings suggest that the available energy in the diet may be more important for eliciting phenotypic changes in the gut of these herbivorous birds rather than simple physical effects of diet fibre on feed intakes or on muscular compensation to fibrous ingesta. © 2014. Published by The Company of Biologists Ltd.

  14. Strengths and strain energies of volcanic edifices: implications for eruptions, collapse calderas, and landslides

    Directory of Open Access Journals (Sweden)

    A. Gudmundsson

    2012-07-01

    Full Text Available Natural hazards associated with volcanic edifices depend partly on how fracture resistant the edifices are, i.e. on their strengths. Observations worldwide indicate that large fluid-driven extension fractures (dikes, inclined sheets, shear fractures (landslides, and mixed-mode fractures (ring dikes and ring faults normally propagate more easily in a basaltic edifice (shield volcano than in a stratovolcano. For example, dike-fed eruptions occur once every few years in many basaltic edifices but once every 102-3 yr in many stratovolcanoes. Large landslides and caldera collapses also appear to be more common in a typical basaltic edifice/shield volcano than in a typical stratovolcano. In contrast to a basaltic edifice, a stratovolcano is composed of mechanically dissimilar rock layers, i.e. layers with mismatching elastic properties (primarily Young's modulus. Elastic mismatch encourages fracture deflection and arrest at contacts and increases the amount of energy needed for a large-scale edifice failure. Fracture-related hazards depend on the potential energy available to propagate the fractures which, in turn, depends on the boundary conditions during fracture propagation. Here there are two possible scenarios: one in which the outer boundary of the volcanic edifice or rift zone does not move during the fracture propagation (constant displacement; the other in which the boundary moves (constant load. In the former, the total potential energy is the strain energy stored in the volcano before fracture formation; in the latter, the total potential energy is the strain energy plus the work done by the forces moving the boundary. Constant-displacement boundary conditions favor small eruptions, landslides, and caldera collapses, whereas constant-load conditions favor comparatively large eruptions, landslides, and collapses. For a typical magma chamber (sill-like with a diameter of 8 km, the strain energy change due to magma-chamber inflation

  15. Nondestructive strain depth profiling with high energy X-ray diffraction: System capabilities and limitations

    Science.gov (United States)

    Zhang, Zhan; Wendt, Scott; Cosentino, Nicholas; Bond, Leonard J.

    2018-04-01

    Limited by photon energy, and penetration capability, traditional X-ray diffraction (XRD) strain measurements are only capable of achieving a few microns depth due to the use of copper (Cu Kα1) or molybdenum (Mo Kα1) characteristic radiation. For deeper strain depth profiling, destructive methods are commonly necessary to access layers of interest by removing material. To investigate deeper depth profiles nondestructively, a laboratory bench-top high-energy X-ray diffraction (HEXRD) system was previously developed. This HEXRD method uses an industrial 320 kVp X-Ray tube and the Kα1 characteristic peak of tungsten, to produces a higher intensity X-ray beam which enables depth profiling measurement of lattice strain. An aluminum sample was investigated with deformation/load provided using a bending rig. It was shown that the HEXRD method is capable of strain depth profiling to 2.5 mm. The method was validated using an aluminum sample where both the HEXRD method and the traditional X-ray diffraction method gave data compared with that obtained using destructive etching layer removal, performed by a commercial provider. The results demonstrate comparable accuracy up to 0.8 mm depth. Nevertheless, higher attenuation capabilities in heavier metals limit the applications in other materials. Simulations predict that HEXRD works for steel and nickel in material up to 200 µm, but experiment results indicate that the HEXRD strain profile is not practical for steel and nickel material, and the measured diffraction signals are undetectable when compared to the noise.

  16. Folding and Boudinage As the Same Fundamental Energy Bifurcation in Elasto-Visco-Plastic Rocks

    Science.gov (United States)

    Peters, M.; Paesold, M.; Veveakis, M.; Poulet, T.; Herwegh, M.; Regenauer-Lieb, K.

    2014-12-01

    Folding or boudinage are commonly thought to develop due to viscosity contrasts induced by either geometric interactions or material imperfections. However, there exists an additional localization phenomenon, i.e. strain localization out of steady state in homogeneous materials at a critical material parameter (set) or deformation rate. This study focuses on imperfections in terms of grain size variations, using the paleowattmeter relationship [Austin and Evans, 2007; 2009, Herwegh et al., 2014]. We identify the parameters for bifurcation, which is the critical amount of dissipation, expressed by the Gruntfest number [Gruntfest, 1963], incorporating flow stress, the Arrhenius number (Q/RT) and the layer dimensions. We verify the robustness of the solution through a method, developed to analyze such material instabilities [Rudnicki and Rice, 1975]. The second step is to identify the natural mode shapes and frequencies of the geometric structure and material parameters, including geometric imperfections. In a third step, the eigenmodes are perturbed and superposed to the initial conditions. We then subject the composite structure to natural deformation conditions. Grain sizes within the layer relatively quickly equilibrate to a homogeneous state, which is in response to energy optimization following the paleowattmeterrelationship. Upon continued loading, localization in terms of a necking or folding instability consequently arises out of this steady state. We obtain the criteria for the onset of localization from theory and numerical simulation, i.e. the critical Gruntfest number. Boudinage and folding instabilities occur when heat produced by dissipative work overcomes the diffusive capacity of the system. Both instabilities develop for the exact same Arrhenius and Gruntfestnumbers. Consequently, folding and boudinage instabilities can be seen as the same energy bifurcation triggered by dissipative work out of homogeneous state. Austin, N.J. and Evans, B. (2007

  17. Tuning the energy gap of bilayer α-graphyne by applying strain and electric field

    Science.gov (United States)

    Yang, Hang; Wu, Wen-Zhi; Jin, Yu; Wan-Lin, Guo

    2016-02-01

    Our density functional theory calculations show that the energy gap of bilayer α-graphyne can be modulated by a vertically applied electric field and interlayer strain. Like bilayer graphene, the bilayer α-graphyne has electronic properties that are hardly changed under purely mechanical strain, while an external electric field can open the gap up to 120 meV. It is of special interest that compressive strain can further enlarge the field induced gap up to 160 meV, while tensile strain reduces the gap. We attribute the gap variation to the novel interlayer charge redistribution between bilayer α-graphynes. These findings shed light on the modulation of Dirac cone structures and potential applications of graphyne in mechanical-electric devices. Project supported by the National Key Basic Research Program of China (Grant Nos. 2013CB932604 and 2012CB933403), the National Natural Science Foundation of China (Grant Nos. 51472117 and 51535005), the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures, China (Grant No. 0414K01), the Nanjing University of Aeronautics and Astronautics (NUAA) Fundamental Research Funds, China (Grant No. NP2015203), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

  18. The role of chemical free energy and elastic strain in the nucleation of zirconium hydride

    International Nuclear Information System (INIS)

    Barrow, A.T.W.; Toffolon-Masclet, C.; Almer, J.; Daymond, M.R.

    2013-01-01

    In this work a combination of synchrotron X-ray diffraction and thermodynamic modelling has been used to study the dissolution and precipitation of zirconium hydride in α-Zr establishing the role of elastic misfit strain and chemical free energy in the α → α + δ phase transformation. The nucleation of zirconium hydride is dominated by the chemical free energy where the chemical driving force for hydride precipitation is proportional to the terminal-solid solubility for precipitation and can be predicted by a function that is analogous to the universal nucleation parameter for the bainite transformation in ferrous alloys. The terminal-solid solubility for precipitation was found to be kinetically limited ⩾287 °C at a cooling rate of 5 °C min −1 or greater. The terminal solubilities were established using an offset method applied to the lattice strain data where a resolution of ∼10 wppm H can be achieved in the 〈c〉-direction. This is aided by the introduction of intra-granular strains in the 〈c〉-direction during cooling as a result of the thermal expansion anisotropy which increases the anisotropy associated with the misfitting H atoms within the α-Zr lattice

  19. Direct measurement of conformational strain energy in protofilaments curling outward from disassembling microtubule tips.

    Science.gov (United States)

    Driver, Jonathan W; Geyer, Elisabeth A; Bailey, Megan E; Rice, Luke M; Asbury, Charles L

    2017-06-19

    Disassembling microtubules can generate movement independently of motor enzymes, especially at kinetochores where they drive chromosome motility. A popular explanation is the 'conformational wave' model, in which protofilaments pull on the kinetochore as they curl outward from a disassembling tip. But whether protofilaments can work efficiently via this spring-like mechanism has been unclear. By modifying a previous assay to use recombinant tubulin and feedback-controlled laser trapping, we directly demonstrate the spring-like elasticity of curling protofilaments. Measuring their mechanical work output suggests they carry ~25% of the energy of GTP hydrolysis as bending strain, enabling them to drive movement with efficiency similar to conventional motors. Surprisingly, a β-tubulin mutant that dramatically slows disassembly has no effect on work output, indicating an uncoupling of disassembly speed from protofilament strain. These results show the wave mechanism can make a major contribution to kinetochore motility and establish a direct approach for measuring tubulin mechano-chemistry.

  20. Study of the Elasto-plastic Properties of Mineralized Biomaterials via Synchrotron High-energy X-ray Diffraction

    Science.gov (United States)

    Deymier-Black, Alix Christine

    Synchrotron high-energy X-ray diffraction was employed to investigate the strains in the hydroxyapatite (HAP) platelets and mineralized collagen fibrils in bovine dentin and cortical bone. The HAP and the fibrillar apparent moduli, defined as the applied stress divided by the phase strain, in dentin were measured as 27+/-7.2 and 16+/-4.9 GPa. The HAP apparent modulus ( EHAPapp ) is less than the lower bound calculated for EHAPapp from the Voigt model. This discrepancy is probably due to stress concentrators or decreases in the HAP Young's modulus due to size or composition effects. EHAPapp and Efibapp in dentin vary significantly within a single tooth in both the apical-cervical direction and the buccal-lingual direction. However, the variation between teeth is minimal. The HAP and fibrillar apparent moduli are not affected by freezing in dentin or by X-ray irradiation in bone and dentin. X-ray irradiation causes a decrease in HAP residual strain in bone. This decrease suggests the presence of HAP-collagen interfacial damage. It was determined from the HAP 00.2 peak broadening that irradiation damage mostly affects the HAP unit cells which are under the highest strain. From this it was theorized that irradiation may damage highly-strained bonds at stress concentrators and/or calcium-mediated electrostatic bonds. The fact that the apparent modulus does not change with irradiation suggests that the interfacial damage must be reversible. Bone and dentin both undergo creep when loaded to high stresses. At low irradiation doses, both the fibrillar and HAP strains increase with creep time indicating that load is being transferred from the matrix to the HAP. However, at high doses, the strain on the HAP decreases with creep time. This supports the interfacial damage theory which would allow the HAP to release its elastic load upon interfacial debonding. At -80 MPa, beyond a dose of 50 kGy, the rate of change in HAP strain with time begins to increase, becoming positive at

  1. The internal strain parameter of gallium arsenide measured by energy-dispersive X-ray diffraction

    International Nuclear Information System (INIS)

    Cousins, C.S.G.; Sheldon, B.J.; Webster, G.E.; Gerward, L.; Selsmark, B.; Staun Olsen, J.

    1989-01-01

    The internal strain parameter of GaAs has been measured by observing the stress-dependence of the integrated intensity of the weak 006 reflection, with the compressive stress along the [1anti 10] axis. An energy-dispersive technique was employed so that the reflection could be obtained at a photon energy close to the minimum in the structure factor, thereby approaching closely the strictly-forbidden condition that applies at any energy in the diamond structure. A value anti A=-0.138±0.005, equivalent to a bond-bending parameter ζ=0.55=0.02, has been found. This is in good agreement with recent theoretical calculations and indirect determinations related to the bandstructure of GaAs. (orig.)

  2. Final Report: Development of Renewable Microbial Polyesters for Cost Effective and Energy-Efficient Wood-Plastic Composites

    Energy Technology Data Exchange (ETDEWEB)

    David N. Thompson, Robert W. Emerick, Alfred B. England, James P. Flanders, Frank J. Loge, Katherine A. Wiedeman, Michael P. Wolcott

    2010-04-08

    The forestry, wood and paper industries in the United States provide thousands of productive well-paying jobs; however, in the face of the recent economic downturn it faces significant challenges in remaining economically viable and competitive. To compete successfully on a global market that is increasingly driven by the need for sustainable products and practices, the industry must improve margins and diversify product lines while continuing to produce the staple products. One approach that can help to accomplish this goal sustainably is the forest biorefinery. In the forest biorefinery, traditional waste streams are utilized singly or in combination to manufacture additional products in a profitable and environmentally sustainable manner. In this project, we proposed to produce wood fiber reinforced thermoplastic composites (WFRTCs) using microbial thermoplastic polyesters in place of petroleum-derived plastic. WFRTCs are a rapidly growing product area, averaging a 38% growth rate since 1997. Their production is dependent on substantial quantities of petroleum based thermoplastics, increasing their overall energy costs by over 230% when compared to traditional Engineered Wood Products (EWP). Utilizing bio-based thermoplastics for these materials can reduce our dependence on foreign petroleum. Renewable microbial polyesters are not currently used in WFRTCs primarily because their production costs are several times higher than those of conventional petrochemical-derived plastics, limiting their use to small specialty markets. The strategy for this project was to economically produce WFRTCs using microbial polyesters by reducing or eliminating the most costly steps in the bio-plastic production. This would be achieved by producing them in and from waste effluents from the municipal and forest products sectors, and by eliminating the costly purification steps. After production the plasticladen biosolids would be dried and used directly to replace petroleum

  3. Anisotropic Lithium Insertion Behavior in Silicon Nanowires: Binding Energy, Diffusion Barrier, and Strain Effect

    KAUST Repository

    Zhang, Qianfan; Cui, Yi; Wang, Enge

    2011-01-01

    Silicon nanowires (SiNWs) have recently been shown to be promising as high capacity lithium battery anodes. SiNWs can be grown with their long axis along several different crystallographic directions. Due to distinct atomic configuration and electronic structure of SiNWs with different axial orientations, their lithium insertion behavior could be different. This paper focuses on the characteristics of single Li defects, including binding energy, diffusion barriers, and dependence on uniaxial strain in [110], [100], [111], and [112] SiNWs. Our systematic ab initio study suggests that the Si-Li interaction is weaker when the Si-Li bond direction is aligned close to the SiNW long axis. This results in the [110] and [111] SiNWs having the highest and lowest Li binding energy, respectively, and it makes the diffusion barrier along the SiNW axis lower than other pathways. Under external strain, it was found that [110] and [001] SiNWs are the most and least sensitive, respectively. For diffusion along the axial direction, the barrier increases (decreases) under tension (compression). This feature results in a considerable difference in the magnitude of the energy barrier along different diffusion pathways. © 2011 American Chemical Society.

  4. Anisotropic Lithium Insertion Behavior in Silicon Nanowires: Binding Energy, Diffusion Barrier, and Strain Effect

    KAUST Repository

    Zhang, Qianfan

    2011-05-19

    Silicon nanowires (SiNWs) have recently been shown to be promising as high capacity lithium battery anodes. SiNWs can be grown with their long axis along several different crystallographic directions. Due to distinct atomic configuration and electronic structure of SiNWs with different axial orientations, their lithium insertion behavior could be different. This paper focuses on the characteristics of single Li defects, including binding energy, diffusion barriers, and dependence on uniaxial strain in [110], [100], [111], and [112] SiNWs. Our systematic ab initio study suggests that the Si-Li interaction is weaker when the Si-Li bond direction is aligned close to the SiNW long axis. This results in the [110] and [111] SiNWs having the highest and lowest Li binding energy, respectively, and it makes the diffusion barrier along the SiNW axis lower than other pathways. Under external strain, it was found that [110] and [001] SiNWs are the most and least sensitive, respectively. For diffusion along the axial direction, the barrier increases (decreases) under tension (compression). This feature results in a considerable difference in the magnitude of the energy barrier along different diffusion pathways. © 2011 American Chemical Society.

  5. Exploring the tensile strain energy absorption of hybrid modified epoxies containing soft particles

    International Nuclear Information System (INIS)

    Abadyan, M.; Bagheri, R.; Kouchakzadeh, M.A.; Hosseini Kordkheili, S.A.

    2011-01-01

    Research highlights: → Two epoxy systems have been modified by combination of fine and coarse modifiers. → While both hybrid systems reveal synergistic K IC , no synergism is observed in tensile test. → It is found that coarse particles induce stress concentration in hybrid samples. → Stress concentration leads to fracture of samples at lower energy absorption levels. -- Abstract: In this paper, tensile strain energy absorption of two different hybrid modified epoxies has been systematically investigated. In one system, epoxy has been modified by amine-terminated butadiene acrylonitrile (ATBN) and hollow glass spheres as fine and coarse modifiers, respectively. The other hybrid epoxy has been modified by the combination of ATBN and recycled Tire particles. The results of fracture toughness measurement of blends revealed synergistic toughening for both hybrid systems in some formulations. However, no evidence of synergism is observed in tensile test of hybrid samples. Scanning electron microscope (SEM), transmission optical microscope (TOM) and finite element (FEM) simulation were utilized to study deformation mechanisms of hybrid systems in tensile test. It is found that coarse particles induce stress concentration in hybrid samples. This produces non-uniform strain localized regions which lead to fracture of hybrid samples at lower tensile loading and energy absorption levels.

  6. Experimental investigation of the quality characteristics of agricultural plastic wastes regarding their recycling and energy recovery potential.

    Science.gov (United States)

    Briassoulis, D; Hiskakis, M; Babou, E; Antiohos, S K; Papadi, C

    2012-06-01

    A holistic environmentally sound waste management scheme that transforms agricultural plastic waste (APW) streams into labelled guaranteed quality commodities freely traded in open market has been developed by the European research project LabelAgriWaste. The APW quality is defined by the APW material requirements, translated to technical specifications, for recycling or energy recovery. The present work investigates the characteristics of the APW quality and the key factors affecting it from the introduction of the virgin product to the market to the APW stream reaching the disposer. Samples of APW from different countries were traced from their application to the field through their storage phase and transportation to the final destination. The test results showed that the majority of APW retained their mechanical properties after their use preserving a "very good quality" for recycling in terms of degradation. The degree of soil contamination concerning the APW recycling and energy recovery potential fluctuates depending on the agricultural plastic category and application. The chlorine and heavy metal content of the tested APW materials was much lower than the maximum acceptable limits for their potential use in cement industries. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Study on the unified constraint parameter for characterizing in-plane and out-of-plane constraint based on the equivalent plastic strain

    International Nuclear Information System (INIS)

    Yang Jie; Wang Guozhen; Xuan Fuzhen; Tu Shandong

    2013-01-01

    Background: Constraint can significantly alter the material's fracture toughness. Purpose: In order to increase accuracy of the structural integrity assessment. It needs to consider the effect of constraint on the fracture toughness of nuclear power materials and structures. A unified measure which can reflect both in-plane and out-of-plane constraint is needed. Methods: In this paper, the finite element numerical simulation method was used, a unified measure and characterization parameter of in-plane and out-of-plane constraint based on crack-tip equivalent plastic strain have been investigated. Results: The results show that the area surrounded by ε p isoline has a good relevance with the material's fracture toughness on different constraint conditions, so it may be a suitable parameter. Based on the area A PEEQ , a unified constraint characterization parameter √A p is defined. It was found that there exists a sole linear relation between the normalized fracture toughness J IC /J re f and √A p regardless of the in-plane, out-of-plane constraint and the selection of the p isolines. The sole J IC /J re f-√A p line exists for a certain material. For different materials, the slope of J IC /J re f-√A p reference line is different. The material whose slope is larger has a higher J IC /J re f and is more sensitive to constraint at the same magnitude of normalized unified parameter. Conclusions: The unified J IC /J re f -√A p reference line may be used to assess the safety of a cracked component with any constraint levels regardless of in-plane or out-of-plane constraint or both. (authors)

  8. A high energy microscope for local strain measurements within bulk materials

    DEFF Research Database (Denmark)

    Lienert, U.; Poulsen, H.F.; Martins, R.V.

    2000-01-01

    A novel diffraction technique for local, three dimensional strain scanning within bulk materials is presented. The technique utilizes high energy, micro-focussed synchrotron radiation which can penetrate several millimeters into typical metals. The spatial resolution can be as narrow as 1 mum...... in one dimension and in three dimensions about 5x10x100 mum(3) Bulk properties are probed non-destructively and in-situ measurements during thermo-mechanical processing are feasible. A dedicated experimental station has been constructed at the ID11 beamline of the European Synchrotron Radiation Facility...

  9. Strain relaxation of CdTe on Ge studied by medium energy ion scattering

    Energy Technology Data Exchange (ETDEWEB)

    Pillet, J.C., E-mail: jean-christophe.pillet@cea.fr [Univ. Grenoble Alpes, CEA, LETI, MINATEC campus, F38000 Grenoble (France); CEA, LETI, Département Optique et Photonique, F38054 Grenoble (France); Pierre, F. [Univ. Grenoble Alpes, CEA, LETI, MINATEC campus, F38000 Grenoble (France); CEA, LETI, Service de Caractérisation des Matériaux et Composants, F38054 Grenoble (France); Jalabert, D. [Univ. Grenoble Alpes, CEA, LETI, MINATEC campus, F38000 Grenoble (France); CEA-INAC/UJF-Grenoble 1 UMR-E, SP2M, LEMMA, Minatec Grenoble F-38054 (France)

    2016-10-01

    We have used the medium energy ion scattering (MEIS) technique to assess the strain relaxation in molecular-beam epitaxial (MBE) grown CdTe (2 1 1)/Ge (2 1 1) system. A previous X-ray diffraction study, on 10 samples of the same heterostructure having thicknesses ranging from 25 nm to 10 μm has allowed the measurement of the strain relaxation on a large scale. However, the X-ray diffraction measurements cannot achieve a stress measurement in close proximity to the CdTe/Ge interface at the nanometer scale. Due to the huge lattice misfit between the CdTe and Ge, a high degree of disorder is expected at the interface. The MEIS in channeling mode is a good alternative in order to profile defects with a high depth resolution. For a 21 nm thick CdTe layer, we observed, at the interface, a high density of Cd and/or Te atoms moved from their expected crystallographic positions followed by a rapid recombination of defects. Strain relaxation mechanisms in the vicinity of the interface are discussed.

  10. Strain-Induced Enhancement of the Electron Energy Relaxation in Strongly Correlated Superconductors

    Directory of Open Access Journals (Sweden)

    C. Gadermaier

    2014-03-01

    Full Text Available We use femtosecond optical spectroscopy to systematically measure the primary energy relaxation rate Γ_{1} of photoexcited carriers in cuprate and pnictide superconductors. We find that Γ_{1} increases monotonically with increased negative strain in the crystallographic a axis. Generally, the Bardeen-Shockley deformation potential theorem and, specifically, pressure-induced Raman shifts reported in the literature suggest that increased negative strain enhances electron-phonon coupling, which implies that the observed direct correspondence between a and Γ_{1} is consistent with the canonical assignment of Γ_{1} to the electron-phonon interaction. The well-known nonmonotonic dependence of the superconducting critical temperature T_{c} on the a-axis strain is also reflected in a systematic dependence T_{c} on Γ_{1}, with a distinct maximum at intermediate values (∼16  ps^{−1} at room temperature. The empirical nonmonotonic systematic variation of T_{c} with the strength of the electron-phonon interaction provides us with unique insight into the role of electron-phonon interaction in relation to the mechanism of high-T_{c} superconductivity as a crossover phenomenon.

  11. Energy use in the rubber, and linoleum and plastics floor-covering sectors

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    Visits were made to 77 establishments producing linoleum and 16 establishments producing coated substrates to gather information on energy consumption, fuel types, and attitudes to energy management. Data are presented on percentages of electricity, wastes, fuel oil, gas, and coal consumed totally for plants visited and percentages consumed for establishments grouped under the following categories: new tires, remolded tires, solid rubber base, latex rubber base, and coated substrate industries. Data on energy consumed per employee and by size of buildings were determined. About 760 opportunities for saving energy within the 93 sites visited were identified with the greatest potential for saving energy identified as recovery of waste heat. (MCW)

  12. Thermoelectric energy conversion in layered structures with strained Ge quantum dots grown on Si surfaces

    Science.gov (United States)

    Korotchenkov, Oleg; Nadtochiy, Andriy; Kuryliuk, Vasyl; Wang, Chin-Chi; Li, Pei-Wen; Cantarero, Andres

    2014-03-01

    The efficiency of the energy conversion devices depends in many ways on the materials used and various emerging cost-effective nanomaterials have promised huge potentials in highly efficient energy conversion. Here we show that thermoelectric voltage can be enhanced by a factor of 3 using layer-cake growth of Ge quantum dots through thermal oxidation of SiGe layers stacked in SiO2/Si3N4 multilayer structure. The key to achieving this behavior has been to strain the Ge/Si interface by Ge dots migrating to Si substrate. Calculations taking into account the carrier trapping in the dot with a quantum transmission into the neighboring dot show satisfactory agreement with experiments above ≈200 K. The results may be of interest for improving the functionality of thermoelectric devices based on Ge/Si.

  13. Strain control of Urbach energy in Cr-doped PrFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Anil; Warshi, M.K.; Mishra, Vikash; Saxena, Shailendra K.; Kumar, Rajesh; Sagdeo, Pankaj R. [Indian Institute of Technology Indore, Material Research Laboratory, Discipline of Physics and MEMS, Indore (India)

    2017-09-15

    Polycrystalline samples of PrFe{sub 1-x}Cr{sub x}O{sub 3} having average particle size of ∝90 nm have been prepared by wet chemical route. The structural phase purity of the prepared samples is confirmed by powder X-ray diffraction followed by Rietveld refinements. It is observed that with Cr doping, the Urbach energy (E{sub u}) increases. The E{sub u} is measure of the various disorders present in the sample, such as chemical and structural. To understand the contribution to the E{sub u} due to chemical and structural disorders, we have probed the chemical and structural disorders in the samples by elemental mappings and through X-ray diffraction experiments, respectively. Elemental mapping confirms chemical homogeneity of prepared samples. It is observed that with Cr doping the crystallographic strain increases and Urbach energy shows the similar scaling. (orig.)

  14. Community challenges when using large plastic bottles for Solar Energy Disinfection of Water (SODIS

    Directory of Open Access Journals (Sweden)

    Preeti Borde

    2016-09-01

    Full Text Available Abstract Background Communities living in developing countries as well as populations affected by natural or man-made disasters can be left at great risk from water related diseases, especially those spread through the faecal-oral route. Conventional water treatments such as boiling and chlorination can be effective but may prove costly for impoverished communities. Solar water disinfection (SODIS has been shown to be a cheap and effective way for communities to treat their water. The exposure to sunlight is typically carried out in small volume plastic beverage bottles (up to 2 l. Given the water requirements of consumption and basic personal hygiene, this may not always meet the needs of communities. Recent work has shown 19-L plastic water dispenser containers to be effective SODIS reactors, comparable in efficacy to PET bottles. In this paper we outline the need for studying SODIS in large volumes and discuss 4 main associated challenges. Discussion Apart from clean water needed for consumption, access to adequate water is essential for sanitation and hygiene. Contamination of treated water through unwashed hands or vessels contributes heavily to the spread of water borne pathogens in communities. Traditional water treatments such as boiling and chlorination can be effective but may prove financially burdensome for low income communities. SODIS in large vessels could be used as a simple method to meet water requirements in low income and disaster affected populations. However, there have been some concerns associated with the conventional SODIS method; we identify the main ones to be: (1 cold or cloudy weather; (2 the fear of leaching in plastic bottles; (3 water turbidity, and; (4 community acceptance. Summary The application of SODIS in large bottles like WDCs has the potential to be an efficient and cost effective method of disinfecting water, either for consumption until more rigorous water treatments can be put in place, or for

  15. Cyclic plastic hinges with degradation effects for frame structures

    DEFF Research Database (Denmark)

    Tidemann, Lasse; Krenk, Steen

    2017-01-01

    A model of cyclic plastic hinges in frame structures including degradation effects for stiffness and strength is developed. The model is formulated via potentials in terms of section forces. It consists of a yield surface, described in a generic format permitting representation of general convex...... shapes including corners, and a set of evolution equations based on an internal energy potential and a plastic flow potential. The form of these potentials is specified by five parameters for each generalized stress-strain component describing yield level, ultimate stress capacity, elastic...... and stiffness parameters. The cyclic plastic hinges are introduced into a six-component equilibrium-based beam element, using additive element and hinge flexibilities. When converted to stiffness format the plastic hinges are incorporated into the element stiffness matrix. The cyclic plastic hinge model...

  16. Conversion of light-energy into molecular strain in the photocycle of the photoactive yellow protein.

    Science.gov (United States)

    Gamiz-Hernandez, Ana P; Kaila, Ville R I

    2016-01-28

    The Photoactive Yellow Protein (PYP) is a light-driven photoreceptor, responsible for the phototaxis of halophilic bacteria. Recently, a new short-lived intermediate (pR0) was characterized in the PYP photocycle using combined time-resolved X-ray crystallography and density functional theory calculations. The pR0 species was identified as a highly contorted cis-intermediate, which is stabilized by hydrogen bonds with protein residues. Here we show by hybrid quantum mechanics/classical mechanics (QM/MM) molecular dynamics simulations, and first-principles calculations of optical properties, that the optical shifts in the early steps of the PYP photocycle originate from the conversion of light energy into molecular strain, stored in the pR0 state, and its relaxation in subsequent reaction steps. Our calculations quantitatively reproduce experimental data, which enables us to identify molecular origins of the optical shifts. Our combined approach suggests that the short-lived pR0 intermediate stores ∼1/3 of the photon energy as molecular strain, thus providing the thermodynamic driving force for later conformational changes in the protein.

  17. Preparation of plastic-cellulose compounds by high energy gamma radiation

    International Nuclear Information System (INIS)

    Rosa, M.C.F.

    1978-01-01

    The use of high intensity sources of ionizing radiation for inducing polymer cross-linking was studied and the feasibility of its application in making plastic and cellulose combined compounds, particularly plates formed by paper sheets aglutinated with polyester resin, was analyzed. Several types of paper capable of being used in the plate composition were tested. It was verified that with the preparation technique used in this work the ordinary filter paper gave the best results. By different material testing techniques it was found that the chemical and mechanical properties of plates cured with radiation doses of about 1.5 Mrad are favorably compared with those exhibited by plates of equal composition, cured by the classic method (adding chemical initiator and accelerator) [pt

  18. Scaling of brain metabolism with a fixed energy budget per neuron: implications for neuronal activity, plasticity and evolution.

    Science.gov (United States)

    Herculano-Houzel, Suzana

    2011-03-01

    It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodents and primates (including humans). The estimated average glucose use per neuron does not correlate with neuronal density in any structure. This suggests that the energy budget of the whole brain per neuron is fixed across species and brain sizes, such that total glucose use by the brain as a whole, by the cerebral cortex and also by the cerebellum alone are linear functions of the number of neurons in the structures across the species (although the average glucose consumption per neuron is at least 10× higher in the cerebral cortex than in the cerebellum). These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons. Because synaptic activity is considered the major determinant of metabolic cost, a conserved energy budget per neuron has several profound implications for synaptic homeostasis and the regulation of firing rates, synaptic plasticity, brain imaging, pathologies, and for brain scaling in evolution.

  19. Scaling of brain metabolism with a fixed energy budget per neuron: implications for neuronal activity, plasticity and evolution.

    Directory of Open Access Journals (Sweden)

    Suzana Herculano-Houzel

    Full Text Available It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodents and primates (including humans. The estimated average glucose use per neuron does not correlate with neuronal density in any structure. This suggests that the energy budget of the whole brain per neuron is fixed across species and brain sizes, such that total glucose use by the brain as a whole, by the cerebral cortex and also by the cerebellum alone are linear functions of the number of neurons in the structures across the species (although the average glucose consumption per neuron is at least 10× higher in the cerebral cortex than in the cerebellum. These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons. Because synaptic activity is considered the major determinant of metabolic cost, a conserved energy budget per neuron has several profound implications for synaptic homeostasis and the regulation of firing rates, synaptic plasticity, brain imaging, pathologies, and for brain scaling in evolution.

  20. Scaling of Brain Metabolism with a Fixed Energy Budget per Neuron: Implications for Neuronal Activity, Plasticity and Evolution

    Science.gov (United States)

    Herculano-Houzel, Suzana

    2011-01-01

    It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodents and primates (including humans). The estimated average glucose use per neuron does not correlate with neuronal density in any structure. This suggests that the energy budget of the whole brain per neuron is fixed across species and brain sizes, such that total glucose use by the brain as a whole, by the cerebral cortex and also by the cerebellum alone are linear functions of the number of neurons in the structures across the species (although the average glucose consumption per neuron is at least 10× higher in the cerebral cortex than in the cerebellum). These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons. Because synaptic activity is considered the major determinant of metabolic cost, a conserved energy budget per neuron has several profound implications for synaptic homeostasis and the regulation of firing rates, synaptic plasticity, brain imaging, pathologies, and for brain scaling in evolution. PMID:21390261

  1. Photoswitchable Dihydroazulene Macrocycles for Solar Energy Storage: The Effects of Ring Strain.

    Science.gov (United States)

    Vlasceanu, Alexandru; Frandsen, Benjamin N; Skov, Anders B; Hansen, Anne Schou; Rasmussen, Mads Georg; Kjaergaard, Henrik G; Mikkelsen, Kurt V; Nielsen, Mogens Brøndsted

    2017-10-06

    Efficient energy storage and release are two major challenges of solar energy harvesting technologies. The development of molecular solar thermal systems presents one approach to address these issues by tuning the isomerization reactions of photo/thermoswitches. Here we show that the incorporation of photoswitches into macrocyclic structures is a particularly attractive solution for increasing the storage time. We present the synthesis and properties of a series of macrocycles incorporating two dihydroazulene (DHA) photoswitching subunits, bridged by linkers of varying chain length. Independent of ring size, all macrocycles exhibit stepwise, light-induced, ring-opening reactions (DHA-DHA to DHA-VHF to VHF-VHF; VHF = vinylheptafulvene) with the first DHA undergoing isomerization with a similar efficiency as the uncyclized parent system while the second (DHA-VHF to VHF-VHF) is significantly slower. The energy-releasing, VHF-to-DHA, ring closures also occur in a stepwise manner and are systematically found to proceed slower in the more strained (smaller) cycles, but in all cases with a remarkably slow conversion of the second VHF to DHA. We managed to increase the half-life of the second VHF-to-DHA conversion from 65 to 202 h at room temperature by simply decreasing the ring size. A computational study reveals the smallest macrocycle to have the most energetic VHF-VHF state and hence highest energy density.

  2. Scintillating plastic optical fiber radiation detectors in high energy particle physics

    International Nuclear Information System (INIS)

    Bross, A.D.

    1991-01-01

    We describe the application of scintillating optical fiber in instrumentation for high energy particle physics. The basic physics of the scintillation process in polymers is discussed first and then we outline the fundamentals of scintillating fiber technology. Fiber performance, optimization, and characterization measurements are given. Detector applications in the areas of particle tracking and particle energy determination are then described. 13 refs., 12 figs

  3. Life cycle of the plastics in the wastes. Energy development analysis of the PET disposal

    International Nuclear Information System (INIS)

    Rubini, L.; Carlini, M.

    2001-01-01

    The work is directed to an energy-environmental evaluation, through the LCA methodology, of the life cycle of the containers for liquids in PET, particularly to the phase post use. Applied the italian decree with the force of law (Decreto Ronchi), the methodology LCA has been described in the basic points. Then such methodology has been applied to the containers for liquids in PET. Several disposal systems have been studied and it was found out the most suitable system from the energy and environmental point of view. The recycling turned out to be the best solution either from the energy point of view or environmental. The incineration with energy saving has found out better than the conferring in disposal (with biogas recovery) from the energy point of view, on the contrary the conferring in disposal has found out better than the environmental one [it

  4. Determination of the light response of BC-404 plastic scintillator for protons and deuterons with energies between 1 and 11 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Saraf, S.K.; Brient, C.E.; Egun, P.M.; Grimes, S.M.; Mishra, V.; Pedroni, R.S.

    1988-05-10

    The response of BC-404 plastic scintillator is measured up to 11 MeV for protons and up to 8 MeV for deuterons using a time-of-flight spectrometer. It is shown that the response is nonlinear in this energy range and can be described very well using a four-term polynomial in energy. Earlier response curves which were extrapolated from high energy data and from interpolation of low energy data at widely separated energies are nearly linear in the low energy region. A comparison has been made between our new measured data and the existing curves.

  5. Plastic Surgery

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Plastic Surgery KidsHealth / For Teens / Plastic Surgery What's in ... her forehead lightened with a laser? What Is Plastic Surgery? Just because the name includes the word " ...

  6. The elasto plastic fracture mechanics in ductile metal sheets

    International Nuclear Information System (INIS)

    Khan, M.A.; Malik, M.N.; Naeem, A.; Haq, A.U.; Atkins, A.G.

    1999-01-01

    The crack initiation of propagation in ductile metal sheets are caused by various micro and macro changes taking place due to material properties, applied loads, shape of the indenter (tool geometry) and the environmental conditions. These microstructural failures are directly related to the atomic bonding, crystal lattices, grain boundary status, material flaws in matrix, inhomogeneities and anisotropy in the metal sheets. The Elasto-Plastic related energy based equations are applied to these Rigid Plastic materials to determine the onset of fracture in metal forming. The combined stress and strain criterion of a critical plastic work per unit volume is no more considered as a universal ductile fracture criterion, rather a critical plastic work per unit volume dependence on all sort of stresses (hydrostatic) are the required features for the sheet metal failure (fracture). In this present study, crack initiation and propagation are related empirically with fracture toughness and the application of the theory in industry to save energy. (author)

  7. Energy dissipation during an explosion in a porous elasto-plastic medium

    Energy Technology Data Exchange (ETDEWEB)

    Lovetskii, E.E.; Maslennikov, A.M.; Fetisov, V.S.

    1979-01-01

    A study is made of the redistribution of energy from camouflage blasting in a saturated porous medium. The study is undertaken with the aid of a numerical solution to a system of hydrodynamic equations, that account for shear strength of the substance under investigation. A study is made of the energy characteristics of explosion, their dynamic development, the influence of strength parameters of the medium, and porosity on these characteristics. A mechanism that is associated with the impact compression of matter is identified as the basic mechanism of energy dissipation for dry porous media. Water saturation of pores brings the energy characteristics of the explosion close to the explosion in a monolith. 12 references, 5 figures, 1 table.

  8. Tear energy and strain-induced crystallization of natural rubber/styrene-butadiene rubber blend

    International Nuclear Information System (INIS)

    Noguchi, F; Akabori, K; Yamamoto, Y; Kawahara, S; Kawazura, T

    2009-01-01

    Strain-induced crystallization of natural rubber (NR), dispersed in styrene-butadiene rubber (SBR), was investigated in relation to dimensional feature of a dispersoid and crosslink density of NR by measuring tear energy (G) of crosslinked NR/SBR blends. The crosslinked NR/SBR blends in ratios of 1/9 and 3/7 by weight were prepared by mixing masticated NR and SBR with an internal mixer at a rotor speed of 30 rpm, followed by crosslinking with dicumyl peroxide on a hot press at 444 K for 60 min. The G, measured in wide-ranges of temperature and tear rate, was superposed into a master curve with a Williams-Landel-Ferry shift factor. The G of the NR/SBR(3/7) blend abruptly decreased to a level comparable to that of SBR at about melting temperature of NR crystals formed on straining. The temperature, at which the dramatic decrease in the G occurred, was associated with the dimensional feature of the NR dispersoid and the crosslink density.

  9. Decreasing Distortion Energies without Strain: Diazo-Selective 1,3-Dipolar Cycloadditions.

    Science.gov (United States)

    Gold, Brian; Aronoff, Matthew R; Raines, Ronald T

    2016-07-15

    The diazo group has attributes that complement those of the azido group for applications in chemical biology. Here, we use computational analyses to provide insights into the chemoselectivity of the diazo group in 1,3-dipolar cycloadditions. Dipole distortion energies are responsible for ∼80% of the overall energetic barrier for these reactions. Here, we show that diazo compounds, unlike azides, provide an opportunity to decrease that barrier substantially without introducing strain into the dipolarophile. The ensuing rate enhancement is due to the greater nucleophilic character of a diazo group compared to that of an azido group, which can accommodate decreased distortion energies without predistortion. The tuning of distortion energies with substituents in a diazo compound or dipolarophile can enhance reactivity and selectivity in a predictable manner. Notably, these advantages of diazo groups are amplified in water. Our findings provide a theoretical framework that can guide the design and application of both diazo compounds and azides in "orthogonal" contexts, especially for biological investigations.

  10. The Breeding of a Pigment Mutant Strain of Steroid Hydroxylation Aspergillus Flavus by Low Energy Ion Implantation

    International Nuclear Information System (INIS)

    Ye Hui; Ma Jingming; Feng Chun; Cheng Ying; Zhu Suwen; Cheng Beijiu

    2009-01-01

    In the process of the fermentation of steroid C 11 α-hydroxylgenation strain Aspergillus flavus AF-ANo208, a red pigment is derived, which will affect the isolation and purification of the target product. Low energy ion beam implantation is a new tool for breeding excellent mutant strains. In this study, the ion beam implantation experiments were performed by infusing two different ions: argon ion (Ar + ) and nitrogen ion (N + ). The results showed that the optimal ion implantation was N + with an optimum dose of 2.08 x 10 15 ions/cm 2 , with which the mutant strain AF-ANm16 that produced no red pigment was obtained. The strain had high genetic stability and kept the strong capacity of C11α-hydroxylgenation, which could be utilized in industrial fermentation. The differences between the original strain and the mutant strain at a molecular level were analyzed by randomly amplified polymorphic DNA (RAPD). The results indicated that the frequency of variation was 7.00%, which would establish the basis of application investigation into the breeding of pigment mutant strains by low energy ion implantation. (ion beam bioengineering)

  11. Remaining stress-state and strain-energy in tempered glass fragments

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    2016-01-01

    to the fragmentation process and some authors e.g. Barsom (J Am Ceram Soc 51(2):75, 1968), Gulati (Glass processing days, Tamglass Engineering Oy, Tampere, 1997), Warren (Fractography of glasses and ceramics IV, Alfred University, Alfred, 2001) and Tandon and Glass (Fracture mechanics of ceramics—active materials......When tempered glass breaks, it shatters into relatively small pieces depending on the residual stress state in the glass. This has been known for centuries and is currently used in standards for classifying whether a piece of glass is tempered or not. However, the process of fragmentation...... is complex and only a few, relatively simple, models have been suggested for predicting the fragment size. The full theoretical explanation is still to be found and this work aims at providing another brick to the puzzle. The strain-energy present in tempered glass is obviously contributing...

  12. Final Report: Development of Renewable Microbial Polyesters for Cost Effective and Energy- Efficient Wood-Plastic Composites

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, David N.; Emerick, Robert W.; England, Alfred B.; Flanders, James P.; Loge, Frank J.; Wiedeman, Katherine A.; Wolcott, Michael P.

    2010-03-31

    In this project, we proposed to produce wood fiber reinforced thermoplastic composites (WFRTCs) using microbial thermoplastic polyesters in place of petroleum-derived plastic. WFRTCs are a rapidly growing product area, averaging a 38% growth rate since 1997. Their production is dependent on substantial quantities of petroleum based thermoplastics, increasing their overall energy costs by over 230% when compared to traditional Engineered Wood Products (EWP). Utilizing bio-based thermoplastics for these materials can reduce our dependence on foreign petroleum. We have demonstrated that biopolymers (polyhydroxyalkanoates, PHA) can be successfully produced from wood pulping waste streams and that viable wood fiber reinforced thermoplastic composite products can be produced from these materials. The results show that microbial polyester (PHB in this study) can be extruded together with wastewater-derived cell mass and wood flour into deck products having performance properties comparable to existing commercial HDPE/WF composite products. This study has thus proven the underlying concept that the microbial polyesters produced from waste effluents can be used to make cost-effective and energy-efficient wood-plastic composites. The cost of purified microbial polyesters is about 5-20 times that of HDPE depending on the cost of crude oil, due to high purification (40%), carbon substrate (40%) and sterilized fermentation (20%) costs for the PHB. Hence, the ability to produce competitive and functional composites with unpurified PHA-biomass mixtures from waste carbon sources in unsterile systems—without cell debris removal—is a significant step forward in producing competitive value-added structural composites from forest products residuals using a biorefinery approach. As demonstrated in the energy and waste analysis for the project, significant energy savings and waste reductions can also be realized using this approach. We recommend that the next step for development of

  13. Spectral Modeling of Residual Stress and Stored Elastic Strain Energy in Thermal Barrier Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Donegan, Sean; Rolett, Anthony

    2013-12-31

    Solutions to the thermoelastic problem are important for characterizing the response under temperature change of refractory systems. This work extends a spectral fast Fourier transform (FFT) technique to analyze the thermoelastic behavior of thermal barrier coatings (TBCs), with the intent of probing the local origins of failure in TBCs. The thermoelastic FFT (teFFT) approach allows for the characterization of local thermal residual stress and strain fields, which constitute the origins of failure in TBC systems. A technique based on statistical extreme value theory known as peaks-over-threshold (POT) is developed to quantify the extreme values ("hot spots") of stored elastic strain energy (i.e., elastic energy density, or EED). The resolution dependence of the teFFT method is assessed through a sensitivity study of the extreme values in EED. The sensitivity study is performed both for the local (point-by-point) eld distributions as well as the grain scale eld distributions. A convergence behavior to a particular distribution shape is demonstrated for the local elds. The grain scale fields are shown to exhibit a possible convergence to a maximum level of EED. To apply the teFFT method to TBC systems, 3D synthetic microstructures are created to approximate actual TBC microstructures. The morphology of the grains in each constituent layer as well as the texture is controlled. A variety of TBC materials, including industry standard materials and potential future materials, are analyzed using the teFFT. The resulting hot spots are quantified using the POT approach. A correlation between hot spots in EED and interface rumpling between constituent layers is demonstrated, particularly for the interface between the bond coat (BC) and the thermally grown oxide (TGO) layer.

  14. Static and dynamic strain energy release rates in toughened thermosetting composite laminates

    Science.gov (United States)

    Cairns, Douglas S.

    1992-01-01

    In this work, the static and dynamic fracture properties of several thermosetting resin based composite laminates are presented. Two classes of materials are explored. These are homogeneous, thermosetting resins and toughened, multi-phase, thermosetting resin systems. Multi-phase resin materials have shown enhancement over homogenous materials with respect to damage resistance. The development of new dynamic tests are presented for composite laminates based on Width Tapered Double Cantilevered Beam (WTDCB) for Mode 1 fracture and the End Notched Flexure (ENF) specimen. The WTDCB sample was loaded via a low inertia, pneumatic cylinder to produce rapid cross-head displacements. A high rate, piezo-electric load cell and an accelerometer were mounted on the specimen. A digital oscilloscope was used for data acquisition. Typical static and dynamic load versus displacement plots are presented. The ENF specimen was impacted in three point bending with an instrumented impact tower. Fracture initiation and propagation energies under static and dynamic conditions were determined analytically and experimentally. The test results for Mode 1 fracture are relatively insensitive to strain rate effects for the laminates tested in this study. The test results from Mode 2 fracture indicate that the toughened systems provide superior fracture initiation and higher resistance to propagation under dynamic conditions. While the static fracture properties of the homogeneous systems may be relatively high, the apparent Mode 2 dynamic critical strain energy release rate drops significantly. The results indicate that static Mode 2 fracture testing is inadequate for determining the fracture performance of composite structures subjected to conditions such as low velocity impact. A good correlation between the basic Mode 2 dynamic fracture properties and the performance is a combined material/structural Compression After Impact (CAI) test is found. These results underscore the importance of

  15. Role of stacking fault energy on the deformation characteristics of copper alloys processed by plane strain compression

    International Nuclear Information System (INIS)

    El-Danaf, Ehab A.; Al-Mutlaq, Ayman; Soliman, Mahmoud S.

    2011-01-01

    Highlights: → Different compositions of Cu-Zn and Cu-Al alloys are plane strain compressed. → Strain hardening rates, microstructure and texture evolution are documented. → SFE has an indirect effect rather a critical dislocation density controls twinning. → Cu-Al exhibited the need for higher dislocation density for twin initiation. → Onset of twinning occurs in the copper alloys tested with a normalized SFE ≤ 10-3. - Abstract: Samples of Cu-Al and Cu-Zn alloys with different compositions were subjected to large strains under plane strain compression (PSC), a process that simulates the rolling operation. Four compositions in the Cu-Al system, namely 1, 2, 4.7 and 7 wt.% Al and three compositions in the Cu-Zn system of 10, 20 and 30 wt.% Zn, were investigated. Adding Al or Zn to Cu effectively lowers the stacking fault energy (SFE) of the alloy and changes the deformation mechanism from dislocation slipping to dislocation slipping and deformation twinning. True stress-true strain responses in PSC were documented and the strain hardening rates were calculated and correlated to the evolved microstructure. The onset of twinning in low SFE alloys was not directly related to the low value of SFE, but rather to build up of a critical dislocation density during strain hardening in the early stage of deformation (ε < 0.1). The evolution of texture was documented for the Cu-Al samples using X-ray diffraction for samples plane strain compressed to true axial strains of 0.25, 0.5, 0.75 and 1.0. Orientation distribution function (ODF) plots were generated and quantitative information on the volume fraction of ideal rolling orientations were depicted and correlated with the stacking fault energy.

  16. Industrial energy thrift scheme. Report No. 27. Energy use in the rubber, and linoleum and plastics floor-covering sectors

    Energy Technology Data Exchange (ETDEWEB)

    1981-05-01

    A total of 374 establishments manufacturing rubber products and 42 establishments producing linoleum or other coated substrates were invited to take part in the scheme, leading to 77 and 16 visits respectively. Both sectors manufacture products which contain as a main ingredient polymers of high molecular weight. For purposes of comparison, the different types of products have been grouped under five product headings: new tires, remoulded tires, solid rubber based products, latex based products, and coated substrates. Five sources of energy were used at the sites visited. Fuel oil was the main source, supplying 49 percent of the total, followed by gas with 25 percent. Coal, supplying only 10 percent of the total, contributed much less than it did in the past. Process wastes and reject products, used as fuels, contributed only 1.5 percent to the total supply of energy - but could supply much more. Within the 93 sites visited 760 opportunities for saving energy were noted; nineteen different types of opportunity were observed in at least 20 percent of the sites. Opportunities for saving energy, in descending order of significance, lay in the recovery of waste heat from manufacturing processes, in the reduction of heat loss from process equipment, in the improvement of insulation of buildings, in better control of space heating, and in the recovery of heat from the blowdown of boilers.

  17. Evolution of the Deep-space Galactic Cosmic Ray Lineal Energy Transfer Spectrum through Tissue Equivalent Plastic

    Science.gov (United States)

    Case, A. W.; Kasper, J. C.; Spence, H. E.; Golightly, M. J.; Schwadron, N. A.; Mazur, J. E.; Blake, J. B.; Looper, M. D.; Townsend, L.; Zeitlin, C. J.

    2011-12-01

    The Cosmic Ray Telescope for the Effects of Radiation is an energetic particle telescope that resides on the Lunar Reconnaissance Orbiter spacecraft, currently in a 50 km circular lunar polar orbit. The telescope consists of 6 silicon semi-conductor detectors placed in pairs that surround two pieces of Tissue Equivalent Plastic (TEP), which serve to absorb energy from particles as they transit through the instrument. Particles with energies greater than 12 MeV/nucleon can penetrate the outermost shield and be measured by the instrument. The primary measurement made by the instrument is of the Linear Energy Transfer (LET) of energetic particles as they transit through the telescope. CRaTER measures the LET spectrum with unprecedented energy resolution and has done so during a period of historically low solar activity that led to record high intensities of Galactic Cosmic Rays (GCR). These LET spectra are used to study changes in the properties of the incoming particles, and to make detailed measurements of the radiation doses human explorers will experience in deep space on missions to the moon, to asteroids, or to Mars. We present LET spectra accumulated during 2009 and 2010. We show how the LET spectrum evolves through the instrument as the GCR interact with the TEP. Due to the importance of these measurements for human effects, our extensive absolute calibration procedures are presented. Of particular note is a significant reduction in the flux of particles with LET greater than 10 keV/um for detectors that lie deeper within the telescope stack, due to the attenuation of high LET particles within the TEP. By measuring this attenuation we can estimate the depth in human tissue where the highest LET particles that are most likely to cause genetic damage pose the greatest threat to humans in space.

  18. Influence of plastic strain localization on the stress corrosion cracking of austenitic stainless steels; Influence de la localisation de la deformation plastique sur la CSC d'aciers austenitiques inoxydables

    Energy Technology Data Exchange (ETDEWEB)

    Cisse, S.; Tanguy, B. [CEA Saclay, DEN, SEMI, 91 - Gif-sur-Yvette (France); Andrieu, E.; Laffont, L.; Lafont, M.Ch. [Universite de Toulouse. CIRIMAT, UPS/INPT/CNRS, 31 - Toulous (France)

    2010-03-15

    The authors present a research study of the role of strain localization on the irradiation-assisted stress corrosion cracking (IASCC) of vessel steel in PWR-type (pressurized water reactor) environment. They study the interaction between plasticity and intergranular corrosion and/or oxidation mechanisms in austenitic stainless steels with respect to sublayer microstructure transformations. The study is performed on three austenitic stainless grades which have not been sensitized by any specific thermal treatment: the A286 structurally hardened steel, and the 304L and 316L austenitic stainless steels

  19. Size effects in crystal plasticity

    DEFF Research Database (Denmark)

    Borg, Ulrik

    2007-01-01

    Numerical analyses of plasticity size effects have been carried out for different problems using a developed strain gradient crystal plasticiy theory. The theory employs higher order stresses as work conjugates to slip gradients and uses higher order boundary conditions. Problems on localization...... of plastic flow in a single crystal, grain boundary effects in a bicrystal, and grain size effects in a polycrystal are studied. Single crystals containing micro-scale voids have also been analyzed at different loading conditions with focus on the stress and deformation fields around the voids, on void...... growth and interaction between neighboring voids, and on a comparison between the developed strain gradient crystal plasticity theory and a discrete dislocation plasticity theory. Furthermore, voids and rigid inclusions in isotropic materials have been studied using a strain gradient plasticity theory...

  20. Plasticity theory

    CERN Document Server

    Lubliner, Jacob

    2008-01-01

    The aim of Plasticity Theory is to provide a comprehensive introduction to the contemporary state of knowledge in basic plasticity theory and to its applications. It treats several areas not commonly found between the covers of a single book: the physics of plasticity, constitutive theory, dynamic plasticity, large-deformation plasticity, and numerical methods, in addition to a representative survey of problems treated by classical methods, such as elastic-plastic problems, plane plastic flow, and limit analysis; the problem discussed come from areas of interest to mechanical, structural, and

  1. Energy harvesting from vibration of Timoshenko nanobeam under base excitation considering flexoelectric and elastic strain gradient effects

    Science.gov (United States)

    Managheb, S. A. M.; Ziaei-Rad, S.; Tikani, R.

    2018-05-01

    The coupling between polarization and strain gradients is called flexoelectricity. This phenomenon exists in all dielectrics with any symmetry. In this paper, energy harvesting from a Timoshenko beam is studied by considering the flexoelectric and strain gradient effects. General governing equations and related boundary conditions are derived using Hamilton's principle. The flexoelectric effects are defined by gradients of normal and shear strains which lead to a more general model. The developed model also covers the classical Timoshenko beam theory by ignoring the flexoelectric effect. Based on the developed model, flexoelectricity effect on dielectric beams and energy harvesting from cantilever beam under harmonic base excitation is investigated. A parametric study was conducted to evaluate the effects of flexoelectric coefficients, strain gradient constants, base acceleration and the attaching tip mass on the energy harvested from a cantilever Timoshenko beam. Results show that the flexoelectricity has a significant effect on the energy harvester performance, especially in submicron and nano scales. In addition, this effect makes the beam to behave softer than before and also it changes the harvester first resonance frequency. The present study provides guidance for flexoelectric nano-beam analysis and a method to evaluate the performance of energy harvester in nano-dielectric devices.

  2. Constitutive model of discontinuous plastic flow at cryogenic temperatures

    CERN Document Server

    Skoczen, B; Bielski, J; Marcinek, D

    2010-01-01

    FCC metals and alloys are frequently used in cryogenic applications, nearly down to the temperature of absolute zero, because of their excellent physical and mechanical properties including ductility. Some of these materials, often characterized by the low stacking fault energy (LSFE), undergo at low temperatures three distinct phenomena: dynamic strain ageing (DSA), plastic strain induced transformation from the parent phase (gamma) to the secondary phase (alpha) and evolution of micro-damage. The constitutive model presented in the paper is focused on the discontinuous plastic flow (serrated yielding) and takes into account the relevant thermodynamic background. The discontinuous plastic flow reflecting the DSA effect is described by the mechanism of local catastrophic failure of Lomer-Cottrell (LC) locks under the stress fields related to the accumulating edge dislocations (below the transition temperature from the screw dislocations to the edge dislocations mode T-1). The failure of LC locks leads to mass...

  3. Calculated performance of iron--argon and iron--plastic calorimeters for incident hadrons with energies of 5 to 75 GeV

    International Nuclear Information System (INIS)

    Gabriel, T.A.; Schmidt, W.

    1976-02-01

    The calculated responses of iron--argon and iron--plastic calorimeters for incident hadrons with energies of 5 to 75 GeV are presented. The responses calculated are energy resolution vs energy, energy resolution vs the thickness of the sampling plates, the angular and spatial root-mean-square deviations (i.e., the ability to determine the incident particle's entrance angle and impact point), and the spatial properties of the average and individual hadronic cascades. Some comparisons are made with experimental data; however, the main purpose of this paper is to provide specific design information for these types of calorimeters

  4. Fracture Assessment of PEEK under Static Loading by Means of the Local Strain Energy Density

    Directory of Open Access Journals (Sweden)

    Mirco Peron

    2017-12-01

    Full Text Available Polyetheretherketone (PEEK has gained interest in many industrial applications due to its high strength-to-weight ratio, excellent heat tolerance and high corrosion resistance. Stress concentrators such as notches and geometrical discontinuities are present in many such components necessitating the reliable assessment of notch sensitivity of PEEK in monotonic tension. Here we evaluate the applicability of the strain energy density (SED approach for the assessment of the fracture strength of experimentally tested notched geometries subject to corrosion. The fracture behavior of neat, circumferentially razor-grooved dog-bone specimens and circumferentially U-notched specimens with different notch radii can be predicted with a discrepancy lower than ±10%. Reliable predictions are shown on two previously published datasets employing both computed and published mechanical properties as inputs for the SED calculations. This report presents the first successful application of SED for PEEK as well as the successful prediction of tensile behavior in corrosive environments. This opens the road towards future applications of PEEK in fields its compliant use is of growing popularity.

  5. New perspectives in plastic biodegradation.

    Science.gov (United States)

    Sivan, Alex

    2011-06-01

    During the past 50 years new plastic materials, in various applications, have gradually replaced the traditional metal, wood, leather materials. Ironically, the most preferred property of plastics--durability--exerts also the major environmental threat. Recycling has practically failed to provide a safe solution for disposal of plastic waste (only 5% out of 1 trillion plastic bags, annually produced in the US alone, are being recycled). Since the most utilized plastic is polyethylene (PE; ca. 140 million tons/year), any reduction in the accumulation of PE waste alone would have a major impact on the overall reduction of the plastic waste in the environment. Since PE is considered to be practically inert, efforts were made to isolate unique microorganisms capable of utilizing synthetic polymers. Recent data showed that biodegradation of plastic waste with selected microbial strains became a viable solution. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Global Existence Results for Viscoplasticity at Finite Strain

    Science.gov (United States)

    Mielke, Alexander; Rossi, Riccarda; Savaré, Giuseppe

    2018-01-01

    We study a model for rate-dependent gradient plasticity at finite strain based on the multiplicative decomposition of the strain tensor, and investigate the existence of global-in-time solutions to the related PDE system. We reveal its underlying structure as a generalized gradient system, where the driving energy functional is highly nonconvex and features the geometric nonlinearities related to finite-strain elasticity as well as the multiplicative decomposition of finite-strain plasticity. Moreover, the dissipation potential depends on the left-invariant plastic rate, and thus depends on the plastic state variable. The existence theory is developed for a class of abstract, nonsmooth, and nonconvex gradient systems, for which we introduce suitable notions of solutions, namely energy-dissipation-balance and energy-dissipation-inequality solutions. Hence, we resort to the toolbox of the direct method of the calculus of variations to check that the specific energy and dissipation functionals for our viscoplastic models comply with the conditions of the general theory.

  7. Plastic flow and preferred orientation in molybdenum and zirconium films

    International Nuclear Information System (INIS)

    Window, B.

    1989-01-01

    X-ray diffraction measurements on samples of molybdenum and zirconium growth with ion assistance at low temperatures support the occurrence of plastic flow during growth, provided the level of bombardment is high enough. As the energy of the argon ions was increased, the lattice strain in the growth direction increased to a maximum before decreasing slowly. That this is a plastic flow transition is shown by the independence of the maximum strain on preparation conditions and by the changes in microstructure. In particular, the grain size in the growth direction decreased and the preferred orientation favored the usual wire drawing textures of these metals. For the zirconium films this involved a change in preferred orientation from a (00.2) to a (10.0) texture. A reduction in strain is observed at high bombardment levels

  8. Strain improvement and optimization for β-glucosidase production in Aspergillus niger by low-energy N+ implantation

    International Nuclear Information System (INIS)

    Diao Jinshan; Wang Li; Chen Zhen; Liu Hui; Nie Guangjun; Zheng Zhiming

    2010-01-01

    Low-energy N + implantation was employed to mutate Aspergillus niger Au to enhance productivity of β-glucosidase. Effects of N + on strains, survival and mutation rate were studied. After several rounds of implantation, activity of β-glucosidase of the final mutant Au 0847 reached 13.75 U/mL, which is higher by 106.8% than that of original strain Au, and its heritability was stabilized. Activity of β-glucosidase of Au 0847 reached 30.53 U/mL after further fermentation condition optimization. (authors)

  9. Mechanical stresses and strains in superconducting dipole magnets for high energy accelerators

    International Nuclear Information System (INIS)

    Greben, L.I.; Mironov, E.S.; Moustafin, H.H.

    1979-01-01

    Stress and strain distributions in superconducting dipole magnets were investigated numerically. A finite element computer program was developed to calculate stresses and displacements due to thermal stress, electromagnetic forces and prestressing of structural elements. Real mechanical and thermal properties of superconducting dipole elements are taken into account. Numerical results of stress and strain patterns in dipole magnets are presented

  10. Plastics and environment

    International Nuclear Information System (INIS)

    Avenas, P.

    1996-01-01

    Synthetic organic polymers, such as plastics, PVC, polyamides etc are considered less ecological than natural materials such as wood. Other artificial materials such as metals, glass or biodegradable plastics have also a better image than petroleum products. This short paper demonstrates that the manufacturing or the transport of every material uses energy and that the complete energy balance sheet of a plastic bottle, for instance, is more favourable than the one of a glass bottle. Plastic materials are also easily valorized and recycled and part of the energy spent during manufacturing can be recovered during incineration for district heating. During the life-cycle of such a synthetic material, the same petroleum quantity can be used twice which leads to less negative effects on the environment. Finally, the paper focusses on the problem of biodegradable materials which are not degradable when buried under several meters of wastes and which are a nuisance to recycling. (J.S.)

  11. An experimental study of plastic deformation of materials

    DEFF Research Database (Denmark)

    Knudsen, Tine

    The thesis falls in three parts, focusing on different aspects of plastic deformation of metals. Part I investigates the dislocation structures induced by hot deformation and compares these with the structures after cold deformation. In particular, it is shown that the dislocation structures...... after cold deformation by calorimetry and by analysis of the dislocation structure. The stored energy measured by calorimetry is found to be larger than that determined from the dislocation structure by a factor between 1.9 and 2.7, and this factor decreases with the plastic strain. Part III aimed...

  12. The waste-to-energy framework for integrated multi-waste utilization: Waste cooking oil, waste lubricating oil, and waste plastics

    Energy Technology Data Exchange (ETDEWEB)

    Singhabhandhu, Ampaitepin; Tezuka, Tetsuo [Energy Economics Laboratory, Department of Socio-Environmental Energy Science, Graduate School of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501 (Japan)

    2010-06-15

    Energy generation by wastes is considered one method of waste management that has the benefit of energy recovery. From the waste-to-energy point of view, waste cooking oil, waste lubricating oil, and waste plastics have been considered good candidates for feedstocks for energy conversion due to their high heating values. Compared to the independent management of these three wastes, the idea of co-processing them in integration is expected to gain more benefit. The economies of scale and the synergy of co-processing these wastes results in higher quality and higher yield of the end products. In this study, we use cost-benefit analysis to evaluate the integrated management scenario of collecting the three wastes and converting them to energy. We report the total heat of combustion of pyrolytic oil at the maximum and minimum conversion rates, and conduct a sensitivity analysis in which the parameters of an increase of the electricity cost for operating the process and increase of the feedstock transportation cost are tested. We evaluate the effects of economy of scale in the case of integrated waste management. We compare four cases of waste-to-energy conversion with the business as usual (BAU) scenario, and our results show that the integrated co-processing of waste cooking oil, waste lubricating oil, and waste plastics is the most profitable from the viewpoints of energy yield and economics. (author)

  13. Beam model for seismic analysis of complex shear wall structure based on the strain energy equivalence

    International Nuclear Information System (INIS)

    Reddy, G.R.; Mahajan, S.C.; Suzuki, Kohei

    1997-01-01

    A nuclear reactor building structure consists of shear walls with complex geometry, beams and columns. The complexity of the structure is explained in the section Introduction. Seismic analysis of the complex reactor building structure using the continuum mechanics approach may produce good results but this method is very difficult to apply. Hence, the finite element approach is found to be an useful technique for solving the dynamic equations of the reactor building structure. In this approach, the model which uses finite elements such as brick, plate and shell elements may produce accurate results. However, this model also poses some difficulties which are explained in the section Modeling Techniques. Therefore, seismic analysis of complex structures is generally carried out using a lumped mass beam model. This model is preferred because of its simplicity and economy. Nevertheless, mathematical modeling of a shear wall structure as a beam requires specialized skill and a thorough understanding of the structure. For accurate seismic analysis, it is necessary to model more realistically the stiffness, mass and damping. In linear seismic analysis, modeling of the mass and damping may pose few problems compared to modeling the stiffness. When used to represent a complex structure, the stiffness of the beam is directly related to the shear wall section properties such as area, shear area and moment of inertia. Various beam models which are classified based on the method of stiffness evaluation are also explained under the section Modeling Techniques. In the section Case Studies the accuracy and simplicity of the beam models are explained. Among various beam models, the one which evaluates the stiffness using strain energy equivalence proves to be the simplest and most accurate method for modeling the complex shear wall structure. (author)

  14. Work of plastic deformation in local zone of crack apex

    International Nuclear Information System (INIS)

    Gol'tsev, V.Yu.; Matvienko, Yu.G.; Rivkin, E.Yu.

    1981-01-01

    For substantiating application of criteria of viscous fracture and deeoer understanding of this. process one should know strain distribution and energy consumption for plastic deformation in crack top zone. For this purpose plane samples of 300x70x1.5 mm dimension with central notch of 23, 36 and 46 mm length have been subjected to tensile testing. The samples have been cut out from sheet steel 1Kh18N9T perpendicularly to the rolling direction. It is shown that the suggested viscous fracture conception ensures general approach to the viscous and elastoplastic fracture based on the concept on specific work of plastic deformation in the localized zone νsub(l). The νsub(l) value characterizes maximum plastic material energy consumption and may serve as criterion of viscous material fracture parallel to the critical opening of the deltasub(c) crack top

  15. Energy-efficient strain gauges for the wireless condition monitoring systems in mechanical engineering

    Energy Technology Data Exchange (ETDEWEB)

    Berndt, Michael; Fellner, Thomas; Zeiser, Roderich; Wilde, Juergen [Freiburg Univ. (Germany). Dept. for Microsystems Engineering (IMTEK)

    2012-07-01

    This work focuses on the development of novel strain gauges, which are suited for the operation in autonomous wireless condition monitoring systems. For this purpose, capacitive as well as highly resistive strain gauges were designed and fabricated. The C- and R-sensors were utilised in combination with demonstration circuits, which integrate the circuits for instrumentation, A/D-conversion and furthermore comprise a microcontroller with a wireless transceiver system, all on a small separate printed wiring board. (orig.)

  16. The pan-genome of the animal pathogen Corynebacterium pseudotuberculosis reveals differences in genome plasticity between the biovar ovis and equi strains

    DEFF Research Database (Denmark)

    Soares, Siomar C; Silva, Artur; Trost, Eva

    2013-01-01

    , Corynebacterium pseudotuberculosis infections pose a rising worldwide economic problem in ruminants. The complete genome sequences of 15 C. pseudotuberculosis strains isolated from different hosts and countries were comparatively analyzed using a pan-genomic strategy. Phylogenomic, pan-genomic, core genomic...

  17. Conformational locking by design: relating strain energy with luminescence and stability in rigid metal-organic frameworks.

    Science.gov (United States)

    Shustova, Natalia B; Cozzolino, Anthony F; Dincă, Mircea

    2012-12-05

    Minimization of the torsional barrier for phenyl ring flipping in a metal-organic framework (MOF) based on the new ethynyl-extended octacarboxylate ligand H(8)TDPEPE leads to a fluorescent material with a near-dark state. Immobilization of the ligand in the rigid structure also unexpectedly causes significant strain. We used DFT calculations to estimate the ligand strain energies in our and all other topologically related materials and correlated these with empirical structural descriptors to derive general rules for trapping molecules in high-energy conformations within MOFs. These studies portend possible applications of MOFs for studying fundamental concepts related to conformational locking and its effects on molecular reactivity and chromophore photophysics.

  18. Density scaling and quasiuniversality of flow-event statistics for athermal plastic flows

    NARCIS (Netherlands)

    Lerner, E.; Bailey, N.P.; Dyre, J.C.

    2014-01-01

    Athermal steady-state plastic flows were simulated for the Kob-Andersen binary Lennard-Jones system and its repulsive version in which the sign of the attractive terms is changed to a plus. Properties evaluated include the distributions of energy drops, stress drops, and strain intervals between the

  19. Unified creep-plasticity model for halite

    International Nuclear Information System (INIS)

    Krieg, R.D.

    1980-11-01

    There are two national energy programs which are considering caverns in geological salt (NaCl) as a storage repository. One is the disposal of nuclear wastes and the other is the storage of oil. Both short-time and long-time structural deformations and stresses must be predictable for these applications. At 300K, the nominal initial temperature for both applications, the salt is at 0.28 of the melting temperature and exhibits a significant time dependent behavior. A constitutive model has been developed which describes the behavior observed in an extensive set of triaxial creep tests. Analysis of these tests showed that a single deformation mechanism seems to be operative over the stress and temperature range of interest so that the secondary creep data can be represented by a power of the stress over the entire test range. This simple behavior allowed a new unified creep-plasticity model to be applied with some confidence. The resulting model recognizes no inherent difference between plastic and creep strains yet models the total inelastic strain reasonably well including primary and secondary creep and reverse loadings. A multiaxial formulation is applied with a back stress. A Bauschinger effect is exhibited as a consequence and is present regardless of the time scale over which the loading is applied. The model would be interpreted as kinematic hardening in the sense of classical plasticity. Comparisons are made between test data and model behavior

  20. Effect of Plastic Pre-straining on Residual Stress and Composition Profiles in Low-Temperature Surface-Hardened Austenitic Stainless Steel

    DEFF Research Database (Denmark)

    Bottoli, Federico; Christiansen, Thomas Lundin; Winther, Grethe

    2016-01-01

    The present work deals with the evaluation of the residual stress profiles in expanded austenite by applying grazing incidence X-ray diffraction (GI-XRD) combined with successive sublayer removal. Annealed and deformed (εeq=0.5) samples of stable stainless steel EN 1.4369 were nitrided...... or nitrocarburized. The residual stress profiles resulting from the thermochemical low-temperature surface treatment were measured. The results indicate high-residual compressive stresses of several GPa’s in the nitrided region, while lower-compressive stresses are produced in the carburized case. Plastic...... deformation in the steel prior to thermochemical treatment has a hardly measurable influence on the nitrogen-rich zone, while it has a measurable effect on the stresses and depth of the carbon-rich zone....

  1. Bacterial production of the biodegradable plastics polyhydroxyalkanoates.

    Science.gov (United States)

    Urtuvia, Viviana; Villegas, Pamela; González, Myriam; Seeger, Michael

    2014-09-01

    Petroleum-based plastics constitute a major environmental problem due to their low biodegradability and accumulation in various environments. Therefore, searching for novel biodegradable plastics is of increasing interest. Microbial polyesters known as polyhydroxyalkanoates (PHAs) are biodegradable plastics. Life cycle assessment indicates that PHB is more beneficial than petroleum-based plastics. In this report, bacterial production of PHAs and their industrial applications are reviewed and the synthesis of PHAs in Burkholderia xenovorans LB400 is described. PHAs are synthesized by a large number of microorganisms during unbalanced nutritional conditions. These polymers are accumulated as carbon and energy reserve in discrete granules in the bacterial cytoplasm. 3-hydroxybutyrate and 3-hydroxyvalerate are two main PHA units among 150 monomers that have been reported. B. xenovorans LB400 is a model bacterium for the degradation of polychlorobiphenyls and a wide range of aromatic compounds. A bioinformatic analysis of LB400 genome indicated the presence of pha genes encoding enzymes of pathways for PHA synthesis. This study showed that B. xenovorans LB400 synthesize PHAs under nutrient limitation. Staining with Sudan Black B indicated the production of PHAs by B. xenovorans LB400 colonies. The PHAs produced were characterized by GC-MS. Diverse substrates for the production of PHAs in strain LB400 were analyzed. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Strain energy density-distance criterion for the initiation of stress corrosion cracking of alloy X-750

    Energy Technology Data Exchange (ETDEWEB)

    Hall, M.M. Jr.; Symons, D.M.

    1996-05-01

    A strain energy density-distance criterion was previously developed and used to correlate rising-load K{sub c} initiation data for notched and fatigue precracked specimens of hydrogen precharged Alloy X-750. This criterion, which was developed for hydrogen embrittlement (HE) cracking, is used here to correlate static-load stress corrosion cracking (SCC) initiation times obtained for smooth geometry, notched and fatigue precracked specimens. The onset of SCC crack growth is hypothesized to occur when a critical strain, which is due to environment-enhanced creep, is attained within the specimen interior. For notched and precracked specimens, initiation is shown by analysis to occur at a variable distance from notch and crack tips. The initiation site varies from very near the crack tip, for highly loaded sharp cracks, to a site that is one grain diameter from the notch, for lower loaded, blunt notches. The existence of hydrogen gradients, which are due to strain-induced hydrogen trapping in the strain fields of notch and crack tips, is argued to be controlling the site for initiation of cracking. By considering the sources of the hydrogen, these observations are shown to be consistent with those from the previous HE study, in which the characteristic distance for crack initiation was found to be one grain diameter from the notch tip, independent of notch radius, applied stress intensity factor and hydrogen level.

  3. Strain gradient effects in surface roughening

    DEFF Research Database (Denmark)

    Borg, Ulrik; Fleck, N.A.

    2007-01-01

    evidence for strain gradient effects. Numerical analyses of a bicrystal undergoing in-plane tensile deformation are also studied using a strain gradient crystal plasticity theory and also by using a strain gradient plasticity theory for an isotropic solid. Both theories include an internal material length...

  4. Development of Process for Disposal of Plastic Waste Using Plasma Pyrolysis Technology and Option for Energy Recovery

    Czech Academy of Sciences Publication Activity Database

    Punčochář, Miroslav; Ruj, B.; Chatterj, P.K.

    2012-01-01

    Roč. 42, SI (2012), s. 420-430 E-ISSN 1877-7058. [International Congress of Chemical and Process Engineering CHISA 2012 and 15th Conference PRES 2012 /20./. Prague, 25.08.2012-29.08.2012] Institutional support: RVO:67985858 Keywords : plastic waste * plasma pyrolysis * syngas Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  5. High-energy x-ray scattering quantification of in-situ-loading-related strain gradients spanning the dentinoenamel junction (DEJ) in bovine tooth specimens

    International Nuclear Information System (INIS)

    Almer, J.D.; Stock, S.R.

    2010-01-01

    High energy X-ray scattering (80.7keV photons) at station 1-ID of the Advanced Photon Source quantified internal strains as a function of applied stress in mature bovine tooth. These strains were mapped from dentin through the dentinoenamel junction (DEJ) into enamel as a function of applied compressive stress in two small parallelepiped specimens. One specimen was loaded perpendicular to the DEJ and the second parallel to the DEJ. Internal strains in enamel and dentin increased and, as expected from the relative values of the Young's modulus, the observed strains were much higher in dentin than in enamel. Large strain gradients were observed across the DEJ, and the data suggest that the mantle dentin-DEJ-aprismatic enamel structure may shield the near-surface volume of the enamel from large strains. In the enamel, drops in internal strain for applied stresses above 40MPa also suggest that this structure had cracked.

  6. Self-adaptive strain-relaxation optimization for high-energy lithium storage material through crumpling of graphene.

    Science.gov (United States)

    Zhao, Yunlong; Feng, Jiangang; Liu, Xue; Wang, Fengchao; Wang, Lifen; Shi, Changwei; Huang, Lei; Feng, Xi; Chen, Xiyuan; Xu, Lin; Yan, Mengyu; Zhang, Qingjie; Bai, Xuedong; Wu, Hengan; Mai, Liqiang

    2014-08-01

    High-energy lithium battery materials based on conversion/alloying reactions have tremendous potential applications in new generation energy storage devices. However, these applications are limited by inherent large volume variations and sluggish kinetics. Here we report a self-adaptive strain-relaxed electrode through crumpling of graphene to serve as high-stretchy protective shells on metal framework, to overcome these limitations. The graphene sheets are self-assembled and deeply crumpled into pinecone-like structure through a contraction-strain-driven crumpling method. The as-prepared electrode exhibits high specific capacity (2,165 mAh g(-1)), fast charge-discharge rate (20 A g(-1)) with no capacity fading in 1,000 cycles. This kind of crumpled graphene has self-adaptive behaviour of spontaneous unfolding-folding synchronized with cyclic expansion-contraction volumetric variation of core materials, which can release strain and maintain good electric contact simultaneously. It is expected that such findings will facilitate the applications of crumpled graphene and the self-adaptive materials.

  7. On the rank 1 convexity of stored energy functions of physically linear stress-strain relations

    Czech Academy of Sciences Publication Activity Database

    Šilhavý, Miroslav; Bertram, A.; Böhlke, T.

    2007-01-01

    Roč. 86, č. 3 (2007), s. 235-243 ISSN 0374-3535 Institutional research plan: CEZ:AV0Z10190503 Keywords : generalized linear elastic law s * generalized strain measures * rank 1 convexity Subject RIV: BA - General Mathematics Impact factor: 0.743, year: 2007

  8. The exponentiated Hencky-logarithmic strain energy. Improvement of planar polyconvexity

    Czech Academy of Sciences Publication Activity Database

    Ghiba, I.-D.; Neff, P.; Šilhavý, Miroslav

    2015-01-01

    Roč. 71, May (2015), s. 48-51 ISSN 0020-7462 Institutional support: RVO:67985840 Keywords : finite isotropis elasticity * polyconvexity * logarithmic strain Subject RIV: BA - General Mathematics Impact factor: 1.920, year: 2015 http://www.sciencedirect.com/science/article/pii/S0020746215000190

  9. Track detection on the cells exposed to high Linear Energy Transfer heavy-ions by Cr-39 plastic and terminal deoxynucleotidyl transferase(Td T)

    International Nuclear Information System (INIS)

    Mehnati, P.; Keshtkar, A.; Mesbahi, A.; Sasaki, H.

    2006-01-01

    The fatal effect of ionizing radiation on cells depends on Linear Energy Transfer level. The distribution of ionizing radiation is sparse and homogeneous for low Linear Energy Transfer radiations such as X or y, but it is dense and concentrated for high Linear Energy Transfer radiation such as heavy-ions radiation. Materials and Methods: Chinese hamster ovary cells (CHO-K1) were exposed to 4 Gy Fe-ion 2000 keV/μm. The Cr-39 is a special and sensitive plastic used to verify exact position of heavy-ions traversal. Terminal deoxynucleotidyl transferase is an enzyme labeled with [3 H ] d ATP for detection of cellular DNA damage by autoradiography assay. Results: The track of heavy ions traversals presented by pit size was almost similar for all different doses of radiation. No pits to show the track of traversal were found in 20% of the cell nuclei of the irradiation. Apparently these fractions of cells wave not hit by heavy ions. Conclusion: This study indicated the possible usefulness of both the Cr-39 plastics and DNA labeling with Terminal deoxynucleotidyl transferase method for evaluating the biological effect of heavy-ions in comparison with low Linear Energy Transfer ionizing radiation

  10. Improved optical properties of InAs quantum dots for intermediate band solar cells by suppression of misfit strain relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Xie, H. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287-6106 (United States); Prioli, R. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Departamento de Física, Pontificia Universidade Católica do Rio de Janeiro, Marques de São Vicente 225, Rio de Janeiro 22452-900 RJ (Brazil); Fischer, A. M.; Ponce, F. A., E-mail: ponce@asu.edu [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Kawabata, R. M. S.; Pinto, L. D.; Souza, P. L. [LabSem, CETUC, Pontificia Universidade Católica do Rio de Janeiro, Marques de São Vicente 225, Rio de Janeiro 22452-900 RJ (Brazil); Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutores – DISSE – PUC-Rio, RJ (Brazil); Jakomin, R. [Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutores – DISSE – PUC-Rio, RJ (Brazil); Campus de Xerem, UFRJ, Duque de Caxias-RJ (Brazil); Pires, M. P. [Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutores – DISSE – PUC-Rio, RJ (Brazil); Instituto de Física, UFRJ, Rio de Janeiro-RJ (Brazil)

    2016-07-21

    The properties of InAs quantum dots (QDs) have been studied for application in intermediate band solar cells. It is found that suppression of plastic relaxation in the QDs has a significant effect on the optoelectronic properties. Partial capping plus annealing is shown to be effective in controlling the height of the QDs and in suppressing plastic relaxation. A force balancing model is used to explain the relationship between plastic relaxation and QD height. A strong luminescence has been observed from strained QDs, indicating the presence of localized states in the desired energy range. No luminescence has been observed from plastically relaxed QDs.

  11. Tensile-strain effect of inducing the indirect-to-direct band-gap transition and reducing the band-gap energy of Ge

    Energy Technology Data Exchange (ETDEWEB)

    Inaoka, Takeshi, E-mail: inaoka@phys.u-ryukyu.ac.jp; Furukawa, Takuro; Toma, Ryo; Yanagisawa, Susumu [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213 (Japan)

    2015-09-14

    By means of a hybrid density-functional method, we investigate the tensile-strain effect of inducing the indirect-to-direct band-gap transition and reducing the band-gap energy of Ge. We consider [001], [111], and [110] uniaxial tensility and (001), (111), and (110) biaxial tensility. Under the condition of no normal stress, we determine both normal compression and internal strain, namely, relative displacement of two atoms in the primitive unit cell, by minimizing the total energy. We identify those strain types which can induce the band-gap transition, and evaluate the critical strain coefficient where the gap transition occurs. Either normal compression or internal strain operates unfavorably to induce the gap transition, which raises the critical strain coefficient or even blocks the transition. We also examine how each type of tensile strain decreases the band-gap energy, depending on its orientation. Our analysis clearly shows that synergistic operation of strain orientation and band anisotropy has a great influence on the gap transition and the gap energy.

  12. Metamorphosis of strain/stress on optical band gap energy of ZAO thin films via manipulation of thermal annealing process

    International Nuclear Information System (INIS)

    Malek, M.F.; Mamat, M.H.; Musa, M.Z.; Soga, T.; Rahman, S.A.; Alrokayan, Salman A.H.; Khan, Haseeb A.; Rusop, M.

    2015-01-01

    We report on the growth of Al-doped ZnO (ZAO) thin films prepared by the sol–gel technique associated with dip-coating onto Corning 7740 glass substrates. The influence of varying thermal annealing (T a ) temperature on crystallisation behaviour, optical and electrical properties of ZAO films has been systematically investigated. All films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction 〈0 0 2〉. The metamorphosis of strain/stress effects in ZAO thin films has been investigated using X-ray diffraction. The as growth films have a large compressive stress of 0.55 GPa, which relaxed to 0.25 GPa as the T a was increased to 500 °C. Optical parameters such as optical transmittance, absorption coefficient, refractive index and optical band gap energy have been studied and discussed with respect to T a . All films exhibit a transmittance above 80–90% along the visible–NIR range up to 1500 nm and a sharp absorption onset below 400 nm corresponding to the fundamental absorption edge of ZnO. Experimental results show that the tensile stress in the films reveals an incline pattern with the optical band gap energy, while the compressive stress shows opposite relation. - Highlights: • Minimum stress of highly c-axis oriented ZAO was grown at suitable T a temperature. • The ZAO crystal orientation was influenced by strain/stress of the film. • Minimum stress/strain of ZAO film leads to lower defects. • Bandgap and defects were closely intertwined with strain/stress. • We report additional optical and electrical properties based on T a temperature

  13. Metamorphosis of strain/stress on optical band gap energy of ZAO thin films via manipulation of thermal annealing process

    Energy Technology Data Exchange (ETDEWEB)

    Malek, M.F., E-mail: firz_solarzelle@yahoo.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA UiTM, 40450 Shah Alam, Selangor (Malaysia); Mamat, M.H. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Musa, M.Z. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM) Pulau Pinang, Jalan Permatang Pauh, 13500 Permatang Pauh, Pulau Pinang (Malaysia); Soga, T. [Department of Frontier Materials, Nagoya Institute of Technology (NITech), Nagoya 466-8555 (Japan); Rahman, S.A. [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, Universiti Malaya (UM), 50603 Kuala Lumpur (Malaysia); Alrokayan, Salman A.H.; Khan, Haseeb A. [Department of Biochemistry, College of Science, King Saud University (KSU), Riyadh 11451 (Saudi Arabia); Rusop, M. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA UiTM, 40450 Shah Alam, Selangor (Malaysia)

    2015-04-15

    We report on the growth of Al-doped ZnO (ZAO) thin films prepared by the sol–gel technique associated with dip-coating onto Corning 7740 glass substrates. The influence of varying thermal annealing (T{sub a}) temperature on crystallisation behaviour, optical and electrical properties of ZAO films has been systematically investigated. All films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction 〈0 0 2〉. The metamorphosis of strain/stress effects in ZAO thin films has been investigated using X-ray diffraction. The as growth films have a large compressive stress of 0.55 GPa, which relaxed to 0.25 GPa as the T{sub a} was increased to 500 °C. Optical parameters such as optical transmittance, absorption coefficient, refractive index and optical band gap energy have been studied and discussed with respect to T{sub a}. All films exhibit a transmittance above 80–90% along the visible–NIR range up to 1500 nm and a sharp absorption onset below 400 nm corresponding to the fundamental absorption edge of ZnO. Experimental results show that the tensile stress in the films reveals an incline pattern with the optical band gap energy, while the compressive stress shows opposite relation. - Highlights: • Minimum stress of highly c-axis oriented ZAO was grown at suitable T{sub a} temperature. • The ZAO crystal orientation was influenced by strain/stress of the film. • Minimum stress/strain of ZAO film leads to lower defects. • Bandgap and defects were closely intertwined with strain/stress. • We report additional optical and electrical properties based on T{sub a} temperature.

  14. Effect of Strain Restored Energy on Abnormal Grain Growth in Mg Alloy Simulated by Phase Field Methods

    Science.gov (United States)

    Wu, Yan; Huang, Yuan-yuan

    2018-03-01

    Abnormal grain growth of single phase AZ31 Mg alloy in the spatio-temporal process has been simulated by phase field models, and the influencing factors of abnormal grain growth are studied in order to find the ways to control secondary recrystallization in the microstructure. The study aims to find out the mechanisms for abnormal grain growth in real alloys. It is shown from the simulated results that the abnormal grain growth can be controlled by the strain restored energy. Secondary recrystallization after an annealing treatment can be induced if there are grains of a certain orientation in the microstructure with local high restored energy. However, if the value of the local restored energy at a certain grain orientation is not greater than 1.1E 0, there may be no abnormal grain growth in the microstructure.

  15. Strain Limits within the Scope of the Integrity Assessment of Piping Systems

    International Nuclear Information System (INIS)

    Mutz, Alexander

    2008-01-01

    Allowable stresses in nuclear power plant piping resulting from loading conditions to be considered in Germany are determined on the basis of the German Safety Standards of the Nuclear Safety Standards Commission, KTA. The limitation of the different stress categories within the analysis of the mechanical behaviour is based on a linear elastic material behaviour. Because of the ductile material used in high energy nuclear piping, a more realistic assessment can be performed on the basis of allowable strains using elastic plastic material behaviour. In the present work comparison between the analysis of piping systems considering the elastic material model and the actual elastic plastic material behaviour is performed. The possibilities of allocating plastic strains to calculated elastic stresses is discussed. A parametric study on straight pipes with the actual elastic plastic material model under pure bending is the basis of deriving the elastic plastic strains for the calculated elastic stresses. Strain limits are suggested which correspond to the different stress categories. The aim is to utilize the deformation possibilities of ductile materials used in German nuclear piping and the allocation of maximum strains to different load categories. Keywords: strain limit, ductile material, stress category. (author)

  16. Strain Limits within the Scope of the Integrity Assessment of Piping Systems

    Energy Technology Data Exchange (ETDEWEB)

    Mutz, Alexander [EnBW, Durlacher Allee 93, Karlsruhe 76131 (Germany)

    2008-07-01

    Allowable stresses in nuclear power plant piping resulting from loading conditions to be considered in Germany are determined on the basis of the German Safety Standards of the Nuclear Safety Standards Commission, KTA. The limitation of the different stress categories within the analysis of the mechanical behaviour is based on a linear elastic material behaviour. Because of the ductile material used in high energy nuclear piping, a more realistic assessment can be performed on the basis of allowable strains using elastic plastic material behaviour. In the present work comparison between the analysis of piping systems considering the elastic material model and the actual elastic plastic material behaviour is performed. The possibilities of allocating plastic strains to calculated elastic stresses is discussed. A parametric study on straight pipes with the actual elastic plastic material model under pure bending is the basis of deriving the elastic plastic strains for the calculated elastic stresses. Strain limits are suggested which correspond to the different stress categories. The aim is to utilize the deformation possibilities of ductile materials used in German nuclear piping and the allocation of maximum strains to different load categories. Keywords: strain limit, ductile material, stress category. (author)

  17. Effects of Sex, Strain, and Energy Intake on Hallmarks of Aging in Mice

    DEFF Research Database (Denmark)

    Mitchell, Sarah J.; Madrigal-Matute, Julio; Scheibye-Knudsen, Morten

    2016-01-01

    Calorie restriction (CR) is the most robust non-genetic intervention to delay aging. However, there are a number of emerging experimental variables that alter CR responses. We investigated the role of sex, strain, and level of CR on health and survival in mice. CR did not always correlate with li...... of outcomes related to health and survival, highlighting complexities of translation of CR into human interventions....

  18. Tangent moduli of the Hencky material model derived from the stored energy function at finite strains

    Czech Academy of Sciences Publication Activity Database

    Poživilová, Alena; Plešek, Jiří

    2005-01-01

    Roč. 482, č. 482 (2005), s. 327-330 ISSN 0255-5476 R&D Projects: GA ČR(CZ) GA101/03/0331; GA ČR(CZ) GP106/03/D038 Institutional research plan: CEZ:AV0Z20760514 Keywords : acoustoelasticity * large strains * third order elastic moduli Subject RIV: JG - Metallurgy Impact factor: 0.399, year: 2005

  19. Elastic and plastic strains and the stress corrosion cracking of austenitic stainless steels. Progress report, April 30, 1975--December 30, 1975

    International Nuclear Information System (INIS)

    Troiano, A.R.

    1975-12-01

    Homogeneous deformation of type 310 austenitic stainless steel only slightly influenced the corrosion potential in a boiling 3 percent NaCl aqueous environment. The difference in a deaerated solution was of the order of 25 mV and somewhat more for an aerated solution. Elastic strains appeared to have little or no influence on the corrosion potential for fully annealed as well as 10 percent and 25 percent homogeneously deformed 310 steel. Oxygen in the environment shifted the corrosion potential several hundred millivolts in the less active direction. The critical cracking potential in a deaerated 3 percent NaCl solution was approximately the same for the annealed and homogeneously deformed specimens at approximately -125 mV SCE

  20. Strain rate dependent energy absorption capacity of reinforced concrete members under aircraft impact

    International Nuclear Information System (INIS)

    Brandes, K.; Limberger, E.; Herter, J.

    1983-01-01

    The safety analysis of nuclear power plants includes the impact of an aircraft on the reinforced concrete containment structure. The load characteristics of this event are more or less standardized. In order to reduce the construction costs and to come to a realistic design of anti-impact structures, it is of interest to take advantage of the potential plastic behaviour of reinforced concrete structural members under impact and impulsive loading. But up to now gaps in the knowledge in this field restrain a realistic design. To close these gaps a R and D-programme supported by the governments has been initiated in the Federal Republic of Germany. Some work in this respect carried out since 1977 in BAM is part of this programme. (orig./WL)

  1. A correlative approach to segmenting phases and ferrite morphologies in transformation-induced plasticity steel using electron back-scattering diffraction and energy dispersive X-ray spectroscopy.

    Science.gov (United States)

    Gazder, Azdiar A; Al-Harbi, Fayez; Spanke, Hendrik Th; Mitchell, David R G; Pereloma, Elena V

    2014-12-01

    Using a combination of electron back-scattering diffraction and energy dispersive X-ray spectroscopy data, a segmentation procedure was developed to comprehensively distinguish austenite, martensite, polygonal ferrite, ferrite in granular bainite and bainitic ferrite laths in a thermo-mechanically processed low-Si, high-Al transformation-induced plasticity steel. The efficacy of the ferrite morphologies segmentation procedure was verified by transmission electron microscopy. The variation in carbon content between the ferrite in granular bainite and bainitic ferrite laths was explained on the basis of carbon partitioning during their growth. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Constructing a Plastic Bottle Wind Turbine as a Practical Aid for Learning about Using Wind Energy to Generate Electricity

    Science.gov (United States)

    Appleyard, S. J.

    2009-01-01

    A simple horizontal axis wind turbine can be easily constructed using a 1.5 l PET plastic bottle, a compact disc and a small dynamo. The turbine operates effectively at low wind speeds and has a rotational speed of 500 rpm at a wind speed of about 14 km h[superscript -1]. The wind turbine can be used to demonstrate the relationship between open…

  3. Plastic dosimeter

    International Nuclear Information System (INIS)

    Nagai, Shiro; Matsuda, Kohji.

    1988-01-01

    The report outlines major features and applications of plastic dosimeters. Some plastic dosimeters, including the CTA and PVC types, detect the response of the plastic material itself to radiations while others, such as pigment-added plastic dosimeters, contain additives as radiation detecting material. Most of these dosimeters make use of color centers produced in the dosimeter by radiations. The PMMA dosimeter is widely used in the field of radiation sterilization of food, feed and medical apparatus. The blue cellophane dosimeter is easy to handle if calibrated appropriately. The rad-color dosimeter serves to determine whether products have been irradiated appropriately. The CTA dosimeter has better damp proofing properties than the blue cellophane type. The pigment-added plastic dosimeter consists of a resin such as nylon, CTA or PVC that contains a dye. Some other plastic dosimeters are also described briefly. Though having many advantages, these plastic dosimeter have disadvantages as well. Some of their major disadvantages, including fading as well as large dependence on dose, temperature, humidity and anviroment, are discussed. (Nogami, K.)

  4. Grain Interactions in Crystal Plasticity

    International Nuclear Information System (INIS)

    Boyle, K.P.; Curtin, W.A.

    2005-01-01

    The plastic response of a sheet metal is governed by the collective response of the underlying grains. Intragranular plasticity depends on intrinsic variables such as crystallographic orientation and on extrinsic variables such as grain interactions; however, the role of the latter is not well understood. A finite element crystal plasticity formulation is used to investigate the importance of grain interactions on intragranular plastic deformation in initially untextured polycrystalline aggregates. A statistical analysis reveals that grain interactions are of equal (or more) importance for determining the average intragranular deviations from the applied strain as compared to the orientation of the grain itself. Furthermore, the influence of the surrounding grains is found to extend past nearest neighbor interactions. It is concluded that the stochastic nature of the mesoscale environment must be considered for a proper understanding of the plastic response of sheet metals at the grain-scale

  5. Correlation Among the Variant Group, Effective Grain Size, and Elastic Strain Energy During the Phase Transformation in 9Ni Steels

    Science.gov (United States)

    Terasaki, Hidenori; Moriguchi, Koji; Tomio, Yusaku; Yamagishi, Hideki; Morito, Shigekazu

    2017-12-01

    The effect of carbon content on the density of variant-pair boundaries was investigated in 9Ni steel using an electron backscatter diffraction patterns method. The changes in the density of variant-pair boundaries were correlated with the nondestructive measured values of shear modulus of the austenite phase at the phase transformation point. Furthermore, the effective grain size was correlated with the shear modulus and the density of variant-pair boundaries. These relations are discussed from the viewpoint of self-accommodation of elastic strain energy and the nucleation event in the bainite and martensitic transformations.

  6. Local strain energy density for the fatigue assessment of hot dip galvanized welded joints: some recent outcomes

    Directory of Open Access Journals (Sweden)

    M. Peron

    2017-10-01

    Full Text Available Since in literature only data about the effect of the hot-dip galvanizing coating on fatigue behavior of unnotched specimens are available, whereas very few for notched components and none for welded joints, the aim of this paper is to partially fill this lack of knowledge comparing fatigue strength of uncoated and hot-dip galvanized fillet welded cruciform joints made of structural steel S355 welded joints, subjected to a load cycle R = 0. 34. The results are shown in terms of stress range ?s and of the averaged strain energy density range DW in a control volume of radius R0 = 0.28 mm

  7. Methodology for plastic fracture. A progress report

    International Nuclear Information System (INIS)

    Wilkinson, J.P.D.; Hahn, G.T.; Smith, R.E.E.

    1977-01-01

    The initiation and growth of flaws in pressure vessels under overload conditions is distinguished by a number of unique features, such as large scale yielding, three-dimensional structural and flaw configurations, and failure instabilities that may be controlled by either toughness or plastic flow. In order to develop a broadly applicable methodology of plastic fracture, these features require the following analytical and experimental studies: development of criteria for crack initiation and growth under large scale yielding; the use of the finite element method to describe elastic-plastic behavior of both the structure and the crack tip region; and extensive experimental studies on laboratory scale and large scale specimens, which attempt to reproduce the pertinent plastic flow and crack growth phenomena. A variety of candidate criteria for crack initiation and growth are examined. For the case of crack initiation, these criteria include the J-integral, crack opening displacement, and strain amplitude. In the case of crack growth, the criteria examined include in addition the strain amplitude at the crack tip, work done in a crack tip process zone, and a generalized energy release-rate approach. Each test specimen configuration is analyzed through the finite element method in order to predict its experimental behavior. Specimens include the compact tension specimen and center cracked panels. The basic materials used in the program are a single heat of reactor grade A533 Grade B Class 1 steel, purchased in the form of a plate of size 4.5 m (178 in.) square and 0.2 m (8 in.) thick, and two alloys with yield strength-to-roughness ratios about five times

  8. Joined application of a multiaxial critical plane criterion and a strain energy density criterion in low-cycle fatigue

    Directory of Open Access Journals (Sweden)

    Andrea Carpinteri

    2017-07-01

    Full Text Available In the present paper, the multiaxial fatigue life assessment of notched structural components is performed by employing a strain-based multiaxial fatigue criterion. Such a criterion, depending on the critical plane concept, is extended by implementing the control volume concept reated to the Strain Energy Density (SED approach: a material point located at a certain distance from the notch tip is assumed to be the verification point where to perform the above assessment. Such a distance, measured along the notch bisector, is a function of both the biaxiality ratio (defined as the ratio between the applied shear stress amplitude and the normal stress amplitude and the control volume radii under Mode I and Mode III. Once the position of the verification point is determined, the fatigue lifetime is assessed through an equivalent strain amplitude, acting on the critical plane, together with a unique material reference curve (i.e. the Manson-Coffin curve. Some uniaxial and multiaxial fatigue data related to V-notched round bars made of titanium grade 5 alloy (Ti-6Al-4V are examined to validate the present criterion.

  9. Seaweed as source of energy. 1: effect of a specific bacterial strain on biogas production

    Energy Technology Data Exchange (ETDEWEB)

    Sreenivasa R.P.; Tarwade, S.J.; Sarma, K.S.R.

    1980-09-01

    Only certain marine bacteria capable of digesting the special type of polysaccharide - agar and alginic acid can bring about the biodegradation of these substances and utilise them as carbon source to produce the organics which will be utilised by the methane bacteria to produce methane. When bacterial strain was used in conjunction with cowdung as a source of methane bacteria in seaweed digester, production of biogas from seaweed was accelerated. Adding of small amount of Ulva to seaweed digester increased the output of gas. (Refs. 4).

  10. PLASTIC SURGERY

    African Journals Online (AJOL)

    Department of Plastic and Reconstructive Surgery Sefako Makgatho Health Science University, ... We report on a pilot study on the use of a circumareolar excision and the use of .... and 1 gynecomastia patient) requested reduction in NAC size.

  11. Plastic Fishes

    CERN Multimedia

    Trettnak, Wolfgang

    2015-01-01

    In terms of weight, the plastic pollution in the world’s oceans is estimated to be around 300,000 tonnes. This plastic comes from both land-based and ocean-based sources. A lecture at CERN by chemist Wolfgang Trettnak addressed this issue and highlighted the role of art in raising people’s awareness. The slideshow below gives you a taste of the artworks by Wolfgang Trettnak and Margarita Cimadevila.

  12. Study of combustion and emission characteristics of fuel derived from waste plastics by various waste to energy (W-t-E) conversion processes

    Science.gov (United States)

    Hazrat, M. A.; Rasul, M. G.; Khan, M. M. K.

    2016-07-01

    Reduction of plastic wastes by means of producing energy can be treated as a good investment in the waste management and recycling sectors. In this article, conversion of plastics into liquid fuel by two thermo-chemical processes, pyrolysis and gasification, are reviewed. The study showed that the catalytic pyrolysis of homogenous waste plastics produces better quality and higher quantity of liquefied fuel than that of non-catalytic pyrolysis process at a lower operating temperature. The syngas produced from gasification process, which occurs at higher temperature than the pyrolysis process, can be converted into diesel by the Fischer-Tropsch (FT) reaction process. Conducive bed material like Olivine in the gasification conversion process can remarkably reduce the production of tar. The waste plastics pyrolysis oil showed brake thermal efficiency (BTE) of about 27.75%, brake specific fuel consumption (BSFC) of 0.292 kg/kWh, unburned hydrocarbon emission (uHC) of 91 ppm and NOx emission of 904 ppm in comparison with the diesel for BTE of 28%, BSFC of 0.276 kg/kWh, uHC of 57 ppm and NOx of 855 ppm. Dissolution of Polystyrene (PS) into biodiesel also showed the potential of producing alternative transport fuel. It has been found from the literature that at higher engine speed, increased EPS (Expanded Polystyrene) quantity based biodiesel blends reduces CO, CO2, NOx and smoke emission. EPS-biodiesel fuel blend increases the brake thermal efficiency by 7.8%, specific fuel consumption (SFC) by 7.2% and reduces brake power (Pb) by 3.2%. More study using PS and EPS with other thermoplastics is needed to produce liquid fuel by dissolving them into biodiesel and to assess their suitability as a transport fuel. Furthermore, investigation to find out most suitable W-t-E process for effective recycling of the waste plastics as fuel for internal combustion engines is necessary to reduce environmental pollution and generate revenue which will be addressed in this article.

  13. Mutation breeding and submerged fermentation of a Pleurotus polysaccharide high-yield strain with low-energy heavy ions implantation

    International Nuclear Information System (INIS)

    Chen Henglei; Wan Honggui; Lv Changwu; Zeng Xianxian

    2010-01-01

    Pleurotus polysaccharide high-yield strains were selected through a method of auxotrophic primary screening and Shake-flask fermentation re-screening after low-energy heavy ions (the fluence of 1.2 x 10 16 N + /cm 2 at the energy of 15 keV) stepwise implantation. Two Pleurotus polysaccharide high-yield strains, PFPH-1 and PFPH-2, were selected with stable mycelium polysaccharide yield. The mycelium polysaccharide yield of PFPH-1 and PFPH-2 increased by 46.55% and 75.14%, respectively, compared to the original strain. The accumulation of mycelium biomass and intracellular polysaccharides were monitored in the submerged fermentation of Pleurotus ferulae by supplementation of various carbon and nitrogen sources as well as inorganic salts and pH alteration. The optima1 submerged fermentation medium favoring the accumulation of mycelium biomass and intracellular polysaccharides of PFPH-2 consisted of 1.0% wheat flour, 2.0% sucrose, 2.0% soybean flour, 1.5% bran extract, 0.2% K 2 HPO 4 , and 0.15% MgSO 4 ·7H 2 O, with a fittest pH value of 5.64. The orthogonal combination of the optimal carbon and nitrogen sources with inorganic salts indicates a synergistic effect on the accumulation of mycelium biomass and intracellular polysaccharides in the submerged fermentation of PFPH-2. The yield of mycelium polysaccharides of PFPH-2 increased to 903.73 ± 1.23 mg·L -1 by the end of fermentation. (authors)

  14. 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)

  15. A portable organic plastic scintillator dosimetry system for low energy X-rays: a feasibility study using an intraoperative X-ray unit as the radiation source

    International Nuclear Information System (INIS)

    Williams, Kerry; Robinson, Neil; Trapp, Jamie; Geso, Moshi; Ackerly, Trevor; Das, Ram; Kemp, Penny

    2007-01-01

    The effective use of near water equivalent organic plastic scintillators (OPS) for radiation dosimetry with high-energy sources under laboratory conditions is recognized. In this work, an OPS-based dosimeter using a photodiode combined with improved solid state detection and signal processing techniques has been developed; it offers the potential for the construction of a stable and fully portable dosimeter which will extend the useful range of measurement beyond the usual MeV area and provide reliable readings down to sub-100 keV X-ray energy levels. In these experiments, the instrument described has been used for the dosimetry of INTRABEAM intraoperative radiotherapy (IORT) equipment at distances as low as 1.8 mm from the effective source, i.e., 0.2 mm from the X-ray probe surface. Comparison is shown with dosimetry measurements made using the calibrated reference ion chamber supplied by the IORT equipment manufacturer. (author)

  16. Phyllosphere yeasts rapidly break down biodegradable plastics.

    Science.gov (United States)

    Kitamoto, Hiroko K; Shinozaki, Yukiko; Cao, Xiao-Hong; Morita, Tomotake; Konishi, Masaaki; Tago, Kanako; Kajiwara, Hideyuki; Koitabashi, Motoo; Yoshida, Shigenobu; Watanabe, Takashi; Sameshima-Yamashita, Yuka; Nakajima-Kambe, Toshiaki; Tsushima, Seiya

    2011-11-29

    The use of biodegradable plastics can reduce the accumulation of environmentally persistent plastic wastes. The rate of degradation of biodegradable plastics depends on environmental conditions and is highly variable. Techniques for achieving more consistent degradation are needed. However, only a few microorganisms involved in the degradation process have been isolated so far from the environment. Here, we show that Pseudozyma spp. yeasts, which are common in the phyllosphere and are easily isolated from plant surfaces, displayed strong degradation activity on films made from poly-butylene succinate or poly-butylene succinate-co-adipate. Strains of P. antarctica isolated from leaves and husks of paddy rice displayed strong degradation activity on these films at 30°C. The type strain, P. antarctica JCM 10317, and Pseudozyma spp. strains from phyllosphere secreted a biodegradable plastic-degrading enzyme with a molecular mass of about 22 kDa. Reliable source of biodegradable plastic-degrading microorganisms are now in our hands.

  17. New plastic recycling technology

    Science.gov (United States)

    Greater than 60% of the total plastic content of municipal solid waste is comprised of polyolefins (high-density, low-density, and linear polyethylene and polypropylene. Polyethylene (PE) is the largest-volume component but presents a challenge due to the absence of low-energy de...

  18. Seaweed as source of energy. I: effect of a specific bacterial strain on biogas production

    Energy Technology Data Exchange (ETDEWEB)

    Rao, P.S.; Tarwade, S.J.; Sarma, K.S.R.

    1980-01-01

    Biogas was produced from seaweed by making use of alginate-digesting marine bacteria that were isolated from decomposing seaweed and can digest seaweed carbohydrates (agar and alginic acid). Laboratory digesters containing 100 g seaweed were inoculated with 50 mL broth cultures of different seaweed-derived bacterial strains, and the maximum amount of degradation obtained was 28% (compared with 13% for a bacteria-free digestion). Cow dung was added as a source of methanogenic bacteria, and the amount of biogas produced was more than double the amount obtained when seaweed and cow dung were digested in the absence of the seaweed-derived bacteria. Adding a small amount of Ulva to the seaweed digester increased the production of biogas.

  19. GREEN PLASTIC: A NEW PLASTIC FOR PACKAGING

    OpenAIRE

    Mr. Pankaj Kumar*, Sonia

    2016-01-01

    This paper gives a brief idea about a new type of plastic called as bio-plastic or green plastic. Plastic is used as a packaging material for various products, but this plastic is made up of non renewable raw materials. There are various disadvantages of using conventional plastic like littering, CO2 production, non-degradable in nature etc. To overcome these problems a new type of plastic is discovered called bio-plastic or green plastic. Bio-plastic is made from renewable resources and also...

  20. Exposure of clinical MRSA heterogeneous strains to β-lactams redirects metabolism to optimize energy production through the TCA cycle.

    Directory of Open Access Journals (Sweden)

    Mignon A Keaton

    adaptation that HeR-MRSA clinical strains undergo when exposed to β-lactam pressure, indicating that the energy production is redirected to supply the cell wall synthesis/metabolism, which in turn contributes to the survival response in the presence of β-lactam antibiotics.

  1. Exposure of clinical MRSA heterogeneous strains to β-lactams redirects metabolism to optimize energy production through the TCA cycle.

    Science.gov (United States)

    Keaton, Mignon A; Rosato, Roberto R; Plata, Konrad B; Singh, Christopher R; Rosato, Adriana E

    2013-01-01

    R-MRSA clinical strains undergo when exposed to β-lactam pressure, indicating that the energy production is redirected to supply the cell wall synthesis/metabolism, which in turn contributes to the survival response in the presence of β-lactam antibiotics.

  2. Evaluation of initiation behavior of stress corrosion cracking for type 316L stainless steel in high temperature water. Behavior of crack initiation and effects of distribution of plastic strain on crack initiation

    International Nuclear Information System (INIS)

    Miura, Yasufumi; Miyahara, Yuichi; Kako, Kenji; Sato, Masaru

    2011-01-01

    It is known that the initiation of stress corrosion cracking (SCC) in components such as the reactor core shroud and primary loop re-circulation piping made of L-grade stainless steel is affected by the properties of surface work hardened layer. Therefore, it is important to clarify the effect of the hardened layer on SCC initiation behavior. In this study, creviced bent beam (CBB) test using specimens made of Type 316L stainless steel with controlled distribution of surface work hardened layer was conducted in a simulated BWR environment in order to evaluate the effect of the controlled layer on SCC initiation behavior. The results obtained are as follows; (1) Micro intergranular SCC of low carbon stainless steel was initiated in 50 hours. (2) In this SCC test, it was found that only micro cracks whose depths were smaller than 50 μm were observed until 250 hours and cracks whose depths were larger than 50 μm were observed after 500 hours. (3) SCC was initiated preferentially on the region with high plastic strain gradient in the specimen with controlled distribution of work hardened layer. (author)

  3. Thermal image analysis of plastic deformation and fracture behavior by a thermo-video measurement system

    International Nuclear Information System (INIS)

    Ohbuchi, Yoshifumi; Sakamoto, Hidetoshi; Nagatomo, Nobuaki

    2016-01-01

    The visualization of the plastic region and the measurement of its size are necessary and indispensable to evaluate the deformation and fracture behavior of a material. In order to evaluate the plastic deformation and fracture behavior in a structural member with some flaws, the authors paid attention to the surface temperature which is generated by plastic strain energy. The visualization of the plastic deformation was developed by analyzing the relationship between the extension of the plastic deformation range and the surface temperature distribution, which was obtained by an infrared thermo-video system. Furthermore, FEM elasto-plastic analysis was carried out with the experiment, and the effectiveness of this non-contact measurement system of the plastic deformation and fracture process by a thermography system was discussed. The evaluation method using an infrared imaging device proposed in this research has a feature which does not exist in the current evaluation method, i.e. the heat distribution on the surface of the material has been measured widely by noncontact at 2D at high speed. The new measuring technique proposed here can measure the macroscopic plastic deformation distribution on the material surface widely and precisely as a 2D image, and at high speed, by calculation from the heat generation and the heat propagation distribution. (paper)

  4. Candidate genes in ocular dominance plasticity

    NARCIS (Netherlands)

    Rietman, M.L.; Sommeijer, J.-P.; Levelt, C.N.; Heimel, J.A.; Brussaard, A.B.; Borst, J.G.G.; Elgersma, Y.; Galjart, N.; van der Horst, G.T.; Pennartz, C.M.; Smit, A.B.; Spruijt, B.M.; Verhage, M.; de Zeeuw, C.I.

    2012-01-01

    Many studies have been devoted to the identification of genes involved in experience-dependent plasticity in the visual cortex. To discover new candidate genes, we have reexamined data from one such study on ocular dominance (OD) plasticity in recombinant inbred BXD mouse strains. We have correlated

  5. A linear model of ductile plastic damage

    International Nuclear Information System (INIS)

    Lemaitre, J.

    1983-01-01

    A three-dimensional model of isotropic ductile plastic damage based on a continuum damage variable on the effective stress concept and on thermodynamics is derived. As shown by experiments on several metals and alloys, the model, integrated in the case of proportional loading, is linear with respect to the accumulated plastic strain and shows a large influence of stress triaxiality [fr

  6. Deformations and strain energy in fragments of tempered glass: experimental and numerical investigation

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Bjarrum, Marie

    2017-01-01

    energy and thereby the stress in a fragment post failure. The FE-model have been established in previous work Nielsen (Glass Struct Eng, 2016. doi: 10.1007/s40940-016-0036-z) and is applied here on the specific geometry and initial state of the investigated fragments. This is done by measuring...

  7. Plastic condoms.

    Science.gov (United States)

    1968-01-01

    Only simple equipment, simple technology and low initial capital investment are needed in their manufacture. The condoms can be made by people who were previously unskilled or only semi-skilled workers. Plastic condoms differ from those made of latex rubber in that the nature of the plastic film allows unlimited shelf-life. Also, the plastic has a higher degree of lubricity than latex rubber; if there is a demand for extra lubrication in a particular market, this can be provided. Because the plastic is inert, these condoms need not be packaged in hermetically sealed containers. All these attributes make it possible to put these condoms on the distributors' shelves in developing countries competitively with rubber condoms. The shape of the plastic condom is based on that of the lamb caecum, which has long been used as luxury-type condom. The plastic condom is made from plastic film (ethylene ethyl acrilate) of 0.001 inch (0.0254 mm.) thickness. In addition, a rubber ring is provided and sealed into the base of the condom for retention during coitus. The advantage of the plastic condom design and the equipment on which it is made is that production can be carried out either in labour-intensive economy or with varying degrees of mechanization and automation. The uniform, finished condom if made using previously untrained workers. Training of workers can be done in a matter of hours on the two machines which are needed to produce and test the condoms. The plastic film is provided on a double wound roll, and condom blanks are prepared by means of a heat-sealing die on the stamping machine. The rubber rings are united to the condom blanks on an assembly machine, which consists of a mandrel and heat-sealing equipment to seal the rubber ring to the base of the condom. Built into the assembly machine is a simple air-testing apparatus that can detect the smallest pinhole flaw in a condom. The manufacturing process is completed by unravelling the condom from the assembly

  8. Magical Engineering Plastic

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gwang Ung

    1988-01-15

    This book introduces engineering plastic about advantage of engineering plastic, plastic material from processing method, plastic shock, plastic until now, background of making of engineering plastic, wonderful engineering plastic science such as a high molecule and molecule, classification of high molecule, difference between metal and high molecule, heat and high molecule materials, and property of surface, engineering plastic of dream like from linseed oil to aramid, small dictionary of engineering plastic.

  9. Magical Engineering Plastic

    International Nuclear Information System (INIS)

    Kim, Gwang Ung

    1988-01-01

    This book introduces engineering plastic about advantage of engineering plastic, plastic material from processing method, plastic shock, plastic until now, background of making of engineering plastic, wonderful engineering plastic science such as a high molecule and molecule, classification of high molecule, difference between metal and high molecule, heat and high molecule materials, and property of surface, engineering plastic of dream like from linseed oil to aramid, small dictionary of engineering plastic.

  10. Monolithic, multi-bandgap, tandem, ultra-thin, strain-counterbalanced, photovoltaic energy converters with optimal subcell bandgaps

    Science.gov (United States)

    Wanlass, Mark W [Golden, CO; Mascarenhas, Angelo [Lakewood, CO

    2012-05-08

    Modeling a monolithic, multi-bandgap, tandem, solar photovoltaic converter or thermophotovoltaic converter by constraining the bandgap value for the bottom subcell to no less than a particular value produces an optimum combination of subcell bandgaps that provide theoretical energy conversion efficiencies nearly as good as unconstrained maximum theoretical conversion efficiency models, but which are more conducive to actual fabrication to achieve such conversion efficiencies than unconstrained model optimum bandgap combinations. Achieving such constrained or unconstrained optimum bandgap combinations includes growth of a graded layer transition from larger lattice constant on the parent substrate to a smaller lattice constant to accommodate higher bandgap upper subcells and at least one graded layer that transitions back to a larger lattice constant to accommodate lower bandgap lower subcells and to counter-strain the epistructure to mitigate epistructure bowing.

  11. Effect of plastic straining on the F and M centres kinetics in {gamma}-irradiated NaCl; Efecto de la deformacion plastica sobre la Cinetica de Centro de color F y M en NaCl, irradiado con rayos {gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Agullo Lopez, F

    1966-07-01

    The effect of plastic straining on the room-temperature F and H growth curves in a {gamma}-radiation field has been analyzed. Cristal are strained after F-saturation is reached and then irradiation is continued. The new F growth curve consists of an initial fast growing stage due to additional vacancies created by deformation being turned into F centre, followed by a linear stage. Its slope is higher than that prior to straining. Also the role of straining on M centre thermal decay as well as on the F{yields}M reaction under F light, has been investigated. This reaction has been shown to preferentially occur where intense gliding has developed. (Author) 44 refs.

  12. Influence of ceramic dental crown coating substrate thickness ratio on strain energy release rate

    Science.gov (United States)

    Khasnulhadi, K.; Daud, R.; Mat, F.; Noor, S. N. F. M.; Basaruddin, K. S.; Sulaiman, M. H.

    2017-10-01

    This paper presents the analysis of coating substrate thickness ratio effect on the crown coating fracture behaviour. The bi-layer material is examined under four point bending with pre-crack at the bottom of the core material by using finite element. Three different coating thickness of core/substrate was tested which is 1:1, 1:2 and 2:1. The fracture parameters are analysed based on bilayer and homogenous elastic interaction. The result shows that the ratio thickness of core/veneer provided a significant effect on energy release rate.

  13. Formation Energies of Native Point Defects in Strained layer Superlattices (Postprint)

    Science.gov (United States)

    2017-06-05

    1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law , no...Hamiltonian, tight-binding Hamiltonian, and Green’s function techniques to obtain energy levels arising from native point defects (NPDs) in InAs-GaSb and...GaSb systems and 2 designs of InAs-InAs 0.7 Sb 0.3 systems lattice matched to GaSb substrate. The calculated defect levels not only agree well with

  14. Mixed plastics recycling technology

    CERN Document Server

    Hegberg, Bruce

    1995-01-01

    Presents an overview of mixed plastics recycling technology. In addition, it characterizes mixed plastics wastes and describes collection methods, costs, and markets for reprocessed plastics products.

  15. Pervasive plastic

    Science.gov (United States)

    2018-05-01

    Human manipulation of hydrocarbons — as fuel and raw materials for modern society — has changed our world and the indelible imprint we will leave in the rock record. Plastics alone have permeated our lives and every corner of our planet.

  16. Plastic fish

    CERN Multimedia

    Antonella Del Rosso

    2015-01-01

    In terms of weight, the plastic pollution in the world’s oceans is estimated to be around 300,000 tonnes. This plastic comes from both land-based and ocean-based sources. A lecture at CERN by chemist Wolfgang Trettnak addressed this issue and highlighted the role of art in raising people’s awareness.   Artwork by Wolfgang Trettnak. Packaging materials, consumer goods (shoes, kids’ toys, etc.), leftovers from fishing and aquaculture activities… our oceans and beaches are full of plastic litter. Most of the debris from beaches is plastic bottles. “PET bottles have high durability and stability,” explains Wolfgang Trettnak, a chemist by education and artist from Austria, who gave a lecture on this topic organised by the Staff Association at CERN on 26 May. “PET degrades very slowly and the estimated lifetime of a bottle is 450 years.” In addition to the beach litter accumulated from human use, rivers bring several ki...

  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. Plastics recycling: challenges and opportunities.

    Science.gov (United States)

    Hopewell, Jefferson; Dvorak, Robert; Kosior, Edward

    2009-07-27

    Plastics are inexpensive, lightweight and durable materials, which can readily be moulded into a variety of products that find use in a wide range of applications. As a consequence, the production of plastics has increased markedly over the last 60 years. However, current levels of their usage and disposal generate several environmental problems. Around 4 per cent of world oil and gas production, a non-renewable resource, is used as feedstock for plastics and a further 3-4% is expended to provide energy for their manufacture. A major portion of plastic produced each year is used to make disposable items of packaging or other short-lived products that are discarded within a year of manufacture. These two observations alone indicate that our current use of plastics is not sustainable. In addition, because of the durability of the polymers involved, substantial quantities of discarded end-of-life plastics are accumulating as debris in landfills and in natural habitats worldwide. Recycling is one of the most important actions currently available to reduce these impacts and represents one of the most dynamic areas in the plastics industry today. Recycling provides opportunities to reduce oil usage, carbon dioxide emissions and the quantities of waste requiring disposal. Here, we briefly set recycling into context against other waste-reduction strategies, namely reduction in material use through downgauging or product reuse, the use of alternative biodegradable materials and energy recovery as fuel. While plastics have been recycled since the 1970s, the quantities that are recycled vary geographically, according to plastic type and application. Recycling of packaging materials has seen rapid expansion over the last decades in a number of countries. Advances in technologies and systems for the collection, sorting and reprocessing of recyclable plastics are creating new opportunities for recycling, and with the combined actions of the public, industry and governments it

  19. Plastics recycling: challenges and opportunities

    Science.gov (United States)

    Hopewell, Jefferson; Dvorak, Robert; Kosior, Edward

    2009-01-01

    Plastics are inexpensive, lightweight and durable materials, which can readily be moulded into a variety of products that find use in a wide range of applications. As a consequence, the production of plastics has increased markedly over the last 60 years. However, current levels of their usage and disposal generate several environmental problems. Around 4 per cent of world oil and gas production, a non-renewable resource, is used as feedstock for plastics and a further 3–4% is expended to provide energy for their manufacture. A major portion of plastic produced each year is used to make disposable items of packaging or other short-lived products that are discarded within a year of manufacture. These two observations alone indicate that our current use of plastics is not sustainable. In addition, because of the durability of the polymers involved, substantial quantities of discarded end-of-life plastics are accumulating as debris in landfills and in natural habitats worldwide. Recycling is one of the most important actions currently available to reduce these impacts and represents one of the most dynamic areas in the plastics industry today. Recycling provides opportunities to reduce oil usage, carbon dioxide emissions and the quantities of waste requiring disposal. Here, we briefly set recycling into context against other waste-reduction strategies, namely reduction in material use through downgauging or product reuse, the use of alternative biodegradable materials and energy recovery as fuel. While plastics have been recycled since the 1970s, the quantities that are recycled vary geographically, according to plastic type and application. Recycling of packaging materials has seen rapid expansion over the last decades in a number of countries. Advances in technologies and systems for the collection, sorting and reprocessing of recyclable plastics are creating new opportunities for recycling, and with the combined actions of the public, industry and governments it

  20. Plasticity - a limiting case of creep

    International Nuclear Information System (INIS)

    Cords, H.; Kleist, G.; Zimmermann, R.

    1986-11-01

    The present work is an attempt to develop further the so-called unified theory for viscoplastic constitutive equations as used for metals or metal alloys. Typically, in similar approaches creep strains and plastic strains are derived from one common stress-strain relationship for inelastic strain rates employing an internal stress function as a back stress. Some novel concepts concerning the definition of the internal stress, plastic yielding and material hardening have been introduced, formulated mathematically and tested for correspondence with a standard type of materials behaviour. As a result of the investigations a system of simultaneous differential equations is defined which has been used to elaborate a common view on a number of different material effects observed in creep and plasticity i.e. normal and inverted primary creep, recoverable creep, incubation time and anelasticity in stress reduction, negative stress relaxation, plastic yielding, perfect plasticity, negative strain rate sensitivity, serrated flow, strain hardening in monotonic and cyclic loading. The theoretical approach is mainly based on a lateral contraction movement not following rigidly the longitudinal extension of the material specimen by a prescribed constant value of Poisson's ratio as usual, but following the axial extension in a process of drag which allows for retardation and which simultaneously impedes the longitudinal straining. (orig.) [de

  1. SU-E-T-782: Using Light Output From Doped Plastic Scintillators to Resolve the Linear Energy Transfer Spectrum of Clinical Electron Beams

    International Nuclear Information System (INIS)

    Nusrat, H; Pang, G; Ahmad, S; Keller, B; Sarfehnia, A

    2015-01-01

    Purpose: This research seeks to develop a portable, clinically-suitable linear energy transfer (LET) detector. In radiotherapy, absorbed dose is commonly used to measure the amount of delivered radiation, though, it is not a good indicator of actual biological damage. LET is the energy absorbed per unit length by a medium along charged particle’s pathway; studies have shown that LET correlates well with relative biological effectiveness (RBE). Methods: According to Birks’ law, light output of plastic scintillators is stopping-power dependent. This dependency can be varied through doping by various high-Z elements. By measuring light output signals of differently doped plastic scintillators (represented by column vector S, where each row corresponds to different scintillator material), the fluence of charged particles of a given LET (represented by column vector Φ, where each row corresponds to different LET bins) can be unfolded by S=R*Φ where R is system response matrix (each row represents a different scintillator, each column corresponds to different electron LET). Monte Carlo (MC) GEANT4.10.1 was used to evaluate ideal detector response of BC408 scintillating material doped with various concentrations of several high Z dopants. Measurements were performed to validate MC. Results: Signal for 1%-lead doped BC408 and the non-doped scintillator was measured experimentally by guiding light emitted by the scintillator (via in-house made taper, fiber system) to a PMT and then an electrometer. Simulations of 1%Pb-doped scintillator to non-doped scintillator revealed 9.3% reduction in light output for 6 MeV electrons which compared well (within uncertainty) with measurements showing 10% reduction (6MeV electrons). Conclusion: Measurements were used to validate MC simulation of light output from doped scintillators. The doping of scintillators is a viable technique to induce LET dependence. Our goal is to use this effect to resolve the LET spectrum of an incident

  2. Single-shot full strain tensor determination with microbeam X-ray Laue diffraction and a two-dimensional energy-dispersive detector.

    Science.gov (United States)

    Abboud, A; Kirchlechner, C; Keckes, J; Conka Nurdan, T; Send, S; Micha, J S; Ulrich, O; Hartmann, R; Strüder, L; Pietsch, U

    2017-06-01

    The full strain and stress tensor determination in a triaxially stressed single crystal using X-ray diffraction requires a series of lattice spacing measurements at different crystal orientations. This can be achieved using a tunable X-ray source. This article reports on a novel experimental procedure for single-shot full strain tensor determination using polychromatic synchrotron radiation with an energy range from 5 to 23 keV. Microbeam X-ray Laue diffraction patterns were collected from a copper micro-bending beam along the central axis (centroid of the cross section). Taking advantage of a two-dimensional energy-dispersive X-ray detector (pnCCD), the position and energy of the collected Laue spots were measured for multiple positions on the sample, allowing the measurement of variations in the local microstructure. At the same time, both the deviatoric and hydrostatic components of the elastic strain and stress tensors were calculated.

  3. Recrystallization induced plasticity in austenite and ferrite

    International Nuclear Information System (INIS)

    Huang Mingxin; Pineau, André; Bouaziz, Olivier; Vu, Trong-Dai

    2012-01-01

    Highlights: ► Plasticity can be induced by recrystallization in austenite and ferrite. ► Strain rate is proportional to recrystallization kinetics. ► Overall atomic flux selects a preferential direction may be the origin. - Abstract: New experimental evidences are provided to demonstrate that plastic strain can be induced by recrystallization in austenite and ferrite under an applied stress much smaller than their yield stresses. Such Recrystallization Induced Plasticity (RIP) phenomenon occurs because the overall atomic flux during recrystallization follows a preferential direction imposed by the applied stress.

  4. On generalization uniaxial stress-strain relation

    International Nuclear Information System (INIS)

    Sahay, C.; Dubey, R.N.

    1980-01-01

    Different forms of constitutive relations have been advanced for elastic, plastic and elastic-plastic behaviour of materials. It is shown that the various forms of the stress-strain relationship are specialized forms of generalization of a single stress-strain relation. For example, it is shown how the laws of elastic deformation, and the incremental and total deformation relationship for plastic behaviour are derivable from the Ramberg-Osgood relation. (orig.)

  5. Quasi-static responses and variational principles in gradient plasticity

    Science.gov (United States)

    Nguyen, Quoc-Son

    2016-12-01

    Gradient models have been much discussed in the literature for the study of time-dependent or time-independent processes such as visco-plasticity, plasticity and damage. This paper is devoted to the theory of Standard Gradient Plasticity at small strain. A general and consistent mathematical description available for common time-independent behaviours is presented. Our attention is focussed on the derivation of general results such as the description of the governing equations for the global response and the derivation of related variational principles in terms of the energy and the dissipation potentials. It is shown that the quasi-static response under a loading path is a solution of an evolution variational inequality as in classical plasticity. The rate problem and the rate minimum principle are revisited. A time-discretization by the implicit scheme of the evolution equation leads to the increment problem. An increment of the response associated with a load increment is a solution of a variational inequality and satisfies also a minimum principle if the energy potential is convex. The increment minimum principle deals with stables solutions of the variational inequality. Some numerical methods are discussed in view of the numerical simulation of the quasi-static response.

  6. Density scaling and quasiuniversality of flow-event statistics for athermal plastic flows

    DEFF Research Database (Denmark)

    Lerner, Edan; Bailey, Nicholas; Dyre, J. C.

    2014-01-01

    Athermal steady-state plastic flows were simulated for the Kob-Andersen binary Lennard-Jones system and its repulsive version in which the sign of the attractive terms is changed to a plus. Properties evaluated include the distributions of energy drops, stress drops, and strain intervals between...... the flow events. We show that simulations at a single density in conjunction with an equilibrium-liquid simulation at the same density allow one to predict the plastic flow-event statistics at other densities. This is done by applying the recently established “hidden scale invariance” of simple liquids...

  7. plastic waste recycling

    African Journals Online (AJOL)

    Dr Ahmed

    incinerators is increasing around the world. Discarded plastic products ... Agency (EPA) estimated that the amount of plastics throw away is. 50 % greater in the ... The waste plastics were identified using the Society of the Plastic. Industry (SPI) ...

  8. The effect of martensite plasticity on the cyclic deformation of super-elastic NiTi shape memory alloy

    International Nuclear Information System (INIS)

    Song, Di; Kang, Guozheng; Kan, Qianhua; Yu, Chao; Zhang, Chuanzeng

    2014-01-01

    Based on stress-controlled cyclic tension–unloading experiments with different peak stresses, the effect of martensite plasticity on the cyclic deformation of super-elastic NiTi shape memory alloy micro-tubes is investigated and discussed. The experimental results show that the reverse transformation from the induced martensite phase to the austenite phase is gradually restricted by the plastic deformation of the induced martensite phase caused by an applied peak stress that is sufficiently high (higher than 900 MPa), and the extent of such restriction increases with further increasing the peak stress. The residual and peak strains of super-elastic NiTi shape memory alloy accumulate progressively, i.e., transformation ratchetting occurs during the cyclic tension–unloading with peak stresses from 600 to 900 MPa, and the transformation ratchetting strain increases with the increase of the peak stress. When the peak stress is higher than 900 MPa, the peak strain becomes almost unchanged, but the residual strain accumulates and the dissipation energy per cycle decreases very quickly with the increasing number of cycles due to the restricted reverse transformation by the martensite plasticity. Furthermore, a quantitative relationship between the applied stress and the stabilized residual strain is obtained to reasonably predict the evolution of the peak strain and the residual strain. (paper)

  9. BOOK REVIEW: Introduction to Computational Plasticity

    Science.gov (United States)

    Hartley, P.

    2006-04-01

    . Chapter two introduces one of several yield criteria, that normally attributed to von Mises (though historians of mechanics might argue over who was first to develop the theory of yielding associated with strain energy density), and its two or three-dimensional representation as a yield surface. The expansion of the yield surface during plastic deformation, its translation due to kinematic hardening and the Bauschinger effect in reversed loading are described with a direct link to the material stress-strain curve. The assumption, that the increment of strain is normal to the yield surface, the normality principle, is introduced. Uniaxial loading of an elastic-plastic material is used as an example in which to develop expressions to describe increments in stress and strain. The full presentation of numerous expressions, tensors and matrices with a clear explanation of their development, is a recurring, and commendable, feature of the book, which provides an invaluable introduction for those new to the subject. The chapter moves on from time-independent behaviour to introduce viscoplasticity and creep. Chapter three takes the theories of deformation another stage further to consider the problems associated with large deformation in which an important concept is the separation of the phenomenon into material stretch and rotation. The latter is crucial to allow correct measures of strain and stress to be developed in which the effects of rigid body rotation do not contribute to these variables. Hence, the introduction of 'objective' measures for stress and strain. These are described with reference to deformation gradients, which are clearly explained; however, the introduction of displacement gradients passes with little comment, although velocity gradients appear later in the chapter. The interpretation of different strain measures, e.g. Green--Lagrange and Almansi, is covered briefly, followed by a description of the spin tensor and its use in developing the objective

  10. Upper and lower bounds on the set of recoverable strains and on effective energies in cubic-to-monoclinic martensitic phase transformations

    Directory of Open Access Journals (Sweden)

    Schlömerkemper Anja

    2015-01-01

    Full Text Available A major open problem in the mathematical analysis of martensitic phase transformations is the derivation of explicit formulae for the set of recoverable strains and for the relaxed energy of the system. These are governed by the mathematical notion of quasiconvexity. Here we focus on bounds on these quasiconvex hulls and envelopes in the setting of geometrically-linear elasticity. Firstly, we will present mathematical results on triples of transformation strains. This yields further insight into the quasiconvex hull of the twelve transformation strains in cubic-to-monoclinic phase transformations. Secondly, we consider bounds on the energy of such materials based on the so-called energy of mixing thus obtaining a lamination upper bound on the quasiconvex envelope of the energy. Here we present a new algorithm that yields improved upper bounds and allows us to relate numerical results for the lamination upper bound on the energy with theoretical inner bounds on the quasiconvex hull of triples of transformation strains.

  11. Influence of Strain Rate on Heat Release under Quasi-Static Stretching of Metals. Experiment

    Science.gov (United States)

    Zimin, B. A.; Sventitskaya, V. E.; Smirnov, I. V.; Sud'enkov, Yu. V.

    2018-04-01

    The paper presents the results of experimental studies of energy dissipation during a quasi-static stretching of metals and alloys at room temperature. The strain rates varied in the range of 10-3-10-2 s-1. Samples of M1 copper, AZ31B magnesium alloy, BT6 titanium, 12Cr18Ni10Ti steel, and D16AM aluminum alloy were analyzed. The experimental results demonstrated a significant dependence of the heat release on the strain rate in the absence of its influence on stress-strain diagrams for all the metals studied in this range of strain rates. The correlation of the changes in the character of heat release with the processes of structural transformations at various stages of plastic flow is shown on the qualitative level. A difference in the nature of the processes of heat release in materials with different ratios of the plasticity and strength is noted.

  12. Crystallization-induced plasticity of Cu-Zr containing bulk amorphous alloys

    International Nuclear Information System (INIS)

    Lee, Seok-Woo; Huh, Moo-Young; Fleury, Eric; Lee, Jae-Chul

    2006-01-01

    This study examined the parameter governing the plasticity observed in various Cu-Zr containing monolithic amorphous alloys. All the alloys were fully amorphous in their as-cast condition but exhibited different plastic strains. Microscopic observations of the quasi-statically compressed alloys showed abundant nanocrystallites in the amorphous matrices in the alloys that exhibited pronounced plasticity. On the other hand, insignificant changes in the microstructure were observed in the alloy that did not show plasticity. The mechanism for the formation of these deformation-induced nanocrystallites was examined from the viewpoints of thermodynamics and kinetics. The role of the deformation-induced nanocrystallites on the plasticity of the amorphous alloy was examined using high-resolution transmission electron microscopy. The results demonstrate that compressive loading facilitates nanocrystallization in monolithic Cu-Zr containing amorphous alloys, resulting in plasticity. The parameter governing the plasticity in these monolithic Cu-Zr containing amorphous alloys lies in the activation energy for the overall crystallization process

  13. Research on geometrical model and mechanism for metal deformation based on plastic flow

    International Nuclear Information System (INIS)

    An, H P; Li, X; Rui, Z Y

    2015-01-01

    Starting with general conditions of metal plastic deformation, it analyses the relation between the percentage spread and geometric parameters of a forming body with typical machining process are studied. A geometrical model of deforming metal is set up according to the characteristic of a flowing metal particle. Starting from experimental results, the effect of technological parameters and friction between workpiece and dies on plastic deformation of a material were studied and a slippage deformation model of mass points within the material was proposed. Finally, the computing methods for strain and deformation energy and temperature rise are derived from homogeneous deformation. The results can be used to select technical parameters and compute physical quantities such as strain, deformation energy, and temperature rise. (paper)

  14. Modelling of elasto-plastic material behaviour

    International Nuclear Information System (INIS)

    Halleux, J.P.

    1981-01-01

    The present report describes time-independent elasto-plastic material behaviour modelling techniques useful for implementation in fast structural dynamics computer programs. Elasto-plastic behaviour is characteristic for metallic materials such as steel and is thus of particular importance in the study of reactor safety-related problems. The classical time-independent elasto-plastic flow theory is recalled and the fundamental incremental stress-strain relationships are established for strain rate independent material behaviour. Some particular expressions useful in practice and including reversed loading are derived and suitable computational schemes are shwon. Modelling of strain rate effects is then taken into account, according to experimental data obtained from uniaxial tension tests. Finally qualitative strain rate history effects are considered. Applications are presented and illustrate both static and dynamic material behaviour

  15. Inspection of small multi-layered plastic tubing during extrusion, using low-energy X-ray beams

    International Nuclear Information System (INIS)

    Armentrout, C.; Basinger, T.; Beyer, J.; Colesa, B.; Olsztyn, P.; Smith, K.; Strandberg, C.; Sullivan, D.; Thomson, J.

    1999-01-01

    The automotive industry uses nylon tubing with a thin ETFE (ethylene-tetrafluroethylene) inner layer to carry fuel from the tank to the engine. This fluorocarbon inner barrier layer is important to reduce the migration of hydrocarbons into the environment. Pilot Industries has developed a series of real-time inspection stations for dimensional measurements and flaw detection during the extrusion of this tubing. These stations are named LERA TM (low-energy radioscopic analysis), use a low energy X-ray source, a special high-resolution image converter and intensifier (ICI) stage, image capture hardware, a personal computer, and software that was specially designed to meet this task. Each LERA TM station operates up to 20 h a day, 6 days a week and nearly every week of the year. The tubing walls are 1-2 mm thick and the outer layer is nylon and the inner 0.2 mm thick layer is ethylene-tetrafluroethylene

  16. Scaling of Brain Metabolism with a Fixed Energy Budget per Neuron: Implications for Neuronal Activity, Plasticity and Evolution

    OpenAIRE

    Herculano-Houzel, Suzana

    2011-01-01

    It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodent...

  17. Characterization of plastic blends made from mixed plastics waste of different sources.

    Science.gov (United States)

    Turku, Irina; Kärki, Timo; Rinne, Kimmo; Puurtinen, Ari

    2017-02-01

    This paper studies the recyclability of construction and household plastic waste collected from local landfills. Samples were processed from mixed plastic waste by injection moulding. In addition, blends of pure plastics, polypropylene and polyethylene were processed as a reference set. Reference samples with known plastic ratio were used as the calibration set for quantitative analysis of plastic fractions in recycled blends. The samples were tested for the tensile properties; scanning electron microscope-energy-dispersive X-ray spectroscopy was used for elemental analysis of the blend surfaces and Fourier transform infrared (FTIR) analysis was used for the quantification of plastics contents.

  18. Experimental evaluation of the interaction effect between plastic and creep deformation

    International Nuclear Information System (INIS)

    Ikegami, K.; Niitsu, Y.

    1985-01-01

    An experimental study of plasticity-creep interaction effects is reported. The combined stress tests are performed on thin wall tubular specimens of SUS 304 stainless steel at room temperature and high temperature (600 0 C). The plastic behaviors subsequent to creep pre-strain and creep behaviors subsequent to plastic pre-strain are obtained for loading along straight stress paths with a corner. The inelastic behaviors including both plastic and creep deformations are experimentally investigated. The interaction effects between plastic and creep deformations are quantitatively estimated with the equi-plastic strain surface. (author)

  19. RELEASE OF ELASTIC STRAIN ENERGY AS ACOUSTIC EMISSION DURING THE REVERSE THERMOELASTIC PHASE TRANSFORMATION IN Au-47.5 at.percent Cd ALLOY

    Energy Technology Data Exchange (ETDEWEB)

    Baram, J.; Avissar, J.; Gefen, Y.; Rosen, M.

    1980-05-01

    The objective of this paper is to present experimental evidence concerning the acoustic energy evolved during the heating and cooling phase changes in Au-47.5 at.% Cd polycrystals. The results are examined from the point of view of the stored elastic strain energy during the martensite formation, and the frictional work that is dissipated by the movement of martensite interfaces in either direction, upon heating and cooling.

  20. Phenomenology of the plastic flow of amorphous solids induced by heavy-ion bombardment

    International Nuclear Information System (INIS)

    Klaumuenzer, S.; Benyagoub, A.

    1991-01-01

    Amorphous solids exhibit at temperatures far below the glass transition plastic flow when bombarded with fast heavy ions (kinetic energy ∼1 MeV/u). The dimensions perpendicular to the ion beam grow whereas the sample dimension parallel to the ion beam shrinks. The strain tensor describing phenomenologically these dimensional changes is derived from symmetry considerations and compared with experiment. Particular attention is devoted to angular changes, which have not been discussed in this context so far

  1. Energetic reuse: the use of energy from organic material from urban waste for plastics recycling; Reaproveitamento energetico: uso de energia proveniente de material organico dos residuos urbanos para reciclar plasticos

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, Priscila Alves; Rocha, Carlos Roberto [Universidade Federal de Itajuba (EXCEN/UNIFEI), MG (Brazil). Centro de Excelencia em Eficiencia Energetica

    2008-07-01

    The population growth and the elevation of the purchasing status due to economic development impel the gradual increase of residues produced a year. The discarding of these residues represents a great economic and environmental challenge, mainly because of discarded plastic concentration with no energetic and economic use, a also because of the organic material that, after decomposing, produces methane, one of the most responsible for global heating when in contact with atmosphere with no control. The recycling of plastic residues is a solution to minimize its discard and to guarantee an environmental improvement for saving raw matter, however the high consumption of energy endears the process, making it difficult its economic viability. This takes the search of new alternatives for attainment of low cost energy. In the problem of discard of the organic matter it can be the solution for the recycling of these residues. The decomposition of the organic matter produces fuel (biogas) useful as power plant for the generation of necessary electricity to the recycling process. The present study analyses an alternative to recycle plastic residues, after being consumed, in some places for discarding and using energy from biogas produced in landfills or biodigestors. Initially it was carried through a data-collecting and analysis of the physical composition of the residues, indispensable to the development of the study, which allowed to daily find the average percentage of plastics (12,9%) and organic matter (41,9%) made use by the involved population. On the basis of the data of organic matter the determination in such a way of the potential of generation of the biogas as of the electric power 'recycled' was possible to leave of that they would be discarded without any use. Data-collecting on equipment used in the plastic recycling had been essential for attainment of the necessary average energy demand to the process in such a way not only for soft plastic and

  2. Averaged strain energy density-based synthesis of crack initiation life in notched steel bars under torsional fatigue

    Directory of Open Access Journals (Sweden)

    Filippo Berto

    2016-10-01

    Full Text Available The torsional fatigue behaviour of circumferentially notched specimens made of austenitic stainless steel, SUS316L, and carbon steel, SGV410, characterized by different notch root radii has been recently investigated by Tanaka. In that contribution, it was observed that the total fatigue life of the austenitic stainless steel increases with increasing stress concentration factor for a given applied nominal shear stress amplitude. By using the electrical potential drop method, Tanaka observed that the crack nucleation life was reduced with increasing stress concentration, on the other hand the crack propagation life increased. The experimental fatigue results, originally expressed in terms of nominal shear stress amplitude, have been reanalysed by means of the local strain energy density (SED averaged over a control volume having radius R0 surrounding the notch tip. To exclude all extrinsic effects acting during the fatigue crack propagation phase, such as sliding contact and/or friction between fracture surfaces, crack initiation life has been considered in the present work. In the original paper, initiation life was defined in correspondence of a 0.1÷0.4-mm-deep crack. The control radius R0 for fatigue strength assessment of notched components, thought of as a material property, has been estimated by imposing the constancy of the averaged SED for both smooth and cracked specimens at NA = 2 million loading cycles

  3. Dynamic Optimization of Constrained Layer Damping Structure for the Headstock of Machine Tools with Modal Strain Energy Method

    Directory of Open Access Journals (Sweden)

    Yakai Xu

    2017-01-01

    Full Text Available Dynamic stiffness and damping of the headstock, which is a critical component of precision horizontal machining center, are two main factors that influence machining accuracy and surface finish quality. Constrained Layer Damping (CLD structure is proved to be effective in raising damping capacity for the thin plate and shell structures. In this paper, one kind of high damping material is utilized on the headstock to improve damping capacity. The dynamic characteristic of the hybrid headstock is investigated analytically and experimentally. The results demonstrate that the resonant response amplitudes of the headstock with damping material can decrease significantly compared to original cast structure. To obtain the optimal configuration of damping material, a topology optimization method based on the Evolutionary Structural Optimization (ESO is implemented. Modal Strain Energy (MSE method is employed to analyze the damping and to derive the sensitivity of the modal loss factor. The optimization results indicate that the added weight of damping material decreases by 50%; meanwhile the first two orders of modal loss factor decrease by less than 23.5% compared to the original structure.

  4. Elastic-plastic analysis of AS4/PEEK composite laminate using a one-parameter plasticity model

    Science.gov (United States)

    Sun, C. T.; Yoon, K. J.

    1992-01-01

    A one-parameter plasticity model was shown to adequately describe the plastic deformation of AS4/PEEK (APC-2) unidirectional thermoplastic composite. This model was verified further for unidirectional and laminated composite panels with and without a hole. The elastic-plastic stress-strain relations of coupon specimens were measured and compared with those predicted by the finite element analysis using the one-parameter plasticity model. The results show that the one-parameter plasticity model is suitable for the analysis of elastic-plastic deformation of AS4/PEEK composite laminates.

  5. 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.

  6. Special Features of Strain Localization and Nanodipoles of Partial Disclinations in the Region of Elastic Distortions

    Science.gov (United States)

    Tyumentsev, A. N.; Ditenberg, I. A.; Sukhanov, I. I.

    2018-02-01

    In the zones of strain localization in the region of elastic distortions and nanodipoles of partial disclinations representing the defects of elastically deformed medium, a theoretical analysis of the elastically stressed state and the energy of these defects, including the cases of their transformation into more complex ensembles of interrelated disclinations, is performed. Using the analytical results, the mechanisms of strain localization are discussed in the stages of nucleation and propagation of the bands of elastic and plastic strain localization formed in these zones (including the cases of nanocrystalline structure formation).

  7. Theoretical analysis, infrared and structural investigations of energy dissipation in metals under cyclic loading

    International Nuclear Information System (INIS)

    Plekhov, O.A.; Saintier, N.; Palin-Luc, T.; Uvarov, S.V.; Naimark, O.B.

    2007-01-01

    The infrared and structural investigations of energy dissipation processes in metals subjected to cyclic loading have given impetus to the development of a new thermodynamic model with the capability of describing the energy balance under plastic deformation. The model is based on the statistical description of the mesodefect ensemble evolution and its influence on the dissipation ability of the material. Constitutive equations have been formulated for plastic and structural strains, which allow us to describe the stored and dissipated parts of energy under plastic flow. Numerical results indicate that theoretical predictions are in good agreement with the experimentally observed temperature data

  8. Theoretical determination of molecular structure and conformation. 20. Reevaluation of the strain energies of cyclopropane and cyclobutane - CC and CH bond energies, 1,3 interactions, and sigma-aromaticity

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, D.; Gauss, J.

    1986-11-26

    In order to rationalize the striking similarity of the strain energies (SE) of cyclopropane (1, 28 kcal/mol) and cyclobutane (2, 27 kcal/mol), the energetic consequences of Pitzer strain, Baeyer strain, hybridization effects (CH bond strengthening), Dunitz-Schomaker strain (1,3 CC interactions), and bond stretching effects have been quantitatively assessed at the HF/6-31G** level of theory. Calculations have been based on chemically meaningful definitions of bond length, bond angle, bond energy, and bending force constant in strained molecules. Results reveal that Pitzer strain in both 1 and 2 is just 4 kcal/mol and that CH bond strengthening stabilizes 1 by 6 kcal/mol (2 by 3 kcal/mol), far less than has been assumed previously. The calculated Baeyer strain of 1 and 2 is 41 and 13 kcal/mol, respectively. SE(1) and SE(2) can only be compared if a correction term of 9 kcal/mol due to Dunitz-Schomaker strain (present in 2, but absent in 1) is taken into account. The analysis of the various energy contributions to the SEs of 1 and 2 reveals that 1 is stabilized by at least 17 kcal/mol. Both MO and electron density analysis suggest that 1 is totally different from the other cycloalkanes in being stabilized by 3-center 2-electron delocalization. sigma-Electrons are delocalized in the surface of the three-membered ring, a phenomenon which may be described by the term sigma-aromaticity.

  9. Bend strain tolerances of a Nb3Sn conductor proposed for use in the magnetic fusion energy program

    International Nuclear Information System (INIS)

    Luhman, T.; Welch, D.O.; Suenaga, M.

    1980-01-01

    Bend strain tolerances were studied on a 2869 filament bronze-processed Nb 3 Sn wire conductor in magnetic fields to 8 T. Relative values of the wire's current transfer length to twist pitch were shown to influence the bend-strain tolerance. Low matrix resistivities, associated with Sn-depleted bronzes following heat-treatments of 48 h at 725 0 C, produce current transfer lengths less than the twist pitch, 10 mm. The resulting bend-strain tolerances, at 10 -12 ohm.cm, are improved over those found for shorter heat-treatment times. Results from bend-fatigue experiments were divided into two domains separated by the strain value required to produce compound cracking, epsilon/sub f//sup B/. Applied bending strains less than epsilon/sub f//sup B/ were found to increase zero strain critical current values and this increase was independent of the number of fatigue cycles. When applying strains large enough to produce cracking in the compounds critical currents decreased from their asreacted values tending to reach a minimum after several fatigue cycles. Evidence exists for a neutral axis shift during bending and slight differences between tensile and bend strain tolerances are accounted for in terms of such a shift

  10. A correlative approach to segmenting phases and ferrite morphologies in transformation-induced plasticity steel using electron back-scattering diffraction and energy dispersive X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gazder, Azdiar A., E-mail: azdiar@uow.edu.au [Electron Microscopy Centre, University of Wollongong, New South Wales 2500 (Australia); Al-Harbi, Fayez; Spanke, Hendrik Th. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia); Mitchell, David R.G. [Electron Microscopy Centre, University of Wollongong, New South Wales 2500 (Australia); Pereloma, Elena V. [Electron Microscopy Centre, University of Wollongong, New South Wales 2500 (Australia); School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia)

    2014-12-15

    Using a combination of electron back-scattering diffraction and energy dispersive X-ray spectroscopy data, a segmentation procedure was developed to comprehensively distinguish austenite, martensite, polygonal ferrite, ferrite in granular bainite and bainitic ferrite laths in a thermo-mechanically processed low-Si, high-Al transformation-induced plasticity steel. The efficacy of the ferrite morphologies segmentation procedure was verified by transmission electron microscopy. The variation in carbon content between the ferrite in granular bainite and bainitic ferrite laths was explained on the basis of carbon partitioning during their growth. - Highlights: • Multi-condition segmentation of austenite, martensite, polygonal ferrite and ferrite in bainite. • Ferrites in granular bainite and bainitic ferrite segmented by variation in relative carbon counts. • Carbon partitioning during growth explains variation in carbon content of ferrites in bainites. • Developed EBSD image processing tools can be applied to the microstructures of a variety of alloys. • EBSD-based segmentation procedure verified by correlative TEM results.

  11. Elastic-plastic behaviour of thick-walled containers considering plastic compressibility

    International Nuclear Information System (INIS)

    Betten, J.; Frosch, H.G.

    1983-01-01

    In this paper the elastic-plastic behaviour of thick-walled pressure vessels with internal and external pressure is studied. To describe the mechanical behaviour of isotropic, plastic compressible materials we use a plastic potential which is a single-valued function of the principle stresses. For cylinders and spheres an analytic expression for the computation of stresses and residual stresses is specified. Afterwards the strains are calculated by using the finite difference method. Some examples will high-light the influence of the plastic compressibility on the behaviour of pressure vessels. (orig.) [de

  12. Plastic scintillator

    International Nuclear Information System (INIS)

    Andreeshchev, E.A.; Kilin, S.F.; Kavyrzina, K.A.

    1978-01-01

    A plastic scintillator for ionizing radiation detectors with high time resolution is suggested. To decrease the scintillation pulse width and to maintain a high light yield, the 4 1 , 4 5 -dibromo-2 1 , 2 5 , 5 1 , 5 5 -tetramethyl-n-quinquiphenyl (Br 2 Me 4 Ph) in combination with n-terphenyl (Ph 3 ) or 2, 5-diphenyloxadiazol-1, 3, 4 (PPD) is used as a luminescent addition. Taking into consideration the results of a special study, it is shown, that the following ratio of ingradients is the optimum one: 3-4 mass% Ph 3 or 4-7 mas% PPD + 2-5 mass% Br 2 Me 4 Ph + + polymeric base. The suggested scintillator on the basis of polystyrene has the light yield of 0.23-0.26 arbitrary units and the scintillation pulse duration at half-height is 0.74-0.84 ns

  13. Applications and societal benefits of plastics.

    Science.gov (United States)

    Andrady, Anthony L; Neal, Mike A

    2009-07-27

    This article explains the history, from 1600 BC to 2008, of materials that are today termed 'plastics'. It includes production volumes and current consumption patterns of five main commodity plastics: polypropylene, polyethylene, polyvinyl chloride, polystyrene and polyethylene terephthalate. The use of additives to modify the properties of these plastics and any associated safety, in use, issues for the resulting polymeric materials are described. A comparison is made with the thermal and barrier properties of other materials to demonstrate the versatility of plastics. Societal benefits for health, safety, energy saving and material conservation are described, and the particular advantages of plastics in society are outlined. Concerns relating to littering and trends in recycling of plastics are also described. Finally, we give predictions for some of the potential applications of plastic over the next 20 years.

  14. Computer Modeling of the Dynamic Strength of Metal-Plastic Cylindrical Shells Under Explosive Loading

    Science.gov (United States)

    Abrosimov, N. A.; Novosel'tseva, N. A.

    2017-05-01

    A technique for numerically analyzing the dynamic strength of two-layer metal-plastic cylindrical shells under an axisymmetric internal explosive loading is developed. The kinematic deformation model of the layered package is based on a nonclassical theory of shells. The geometric relations are constructed using relations of the simplest quadratic version of the nonlinear elasticity theory. The stress and strain tensors in the composite macrolayer are related by Hooke's law for an orthotropic body with account of degradation of the stiffness characteristics of the multilayer package due to local failure of some its elementary layers. The physical relations in the metal layer are formulated in terms of a differential theory of plasticity. An energy-correlated resolving system of dynamic equations for the metal-plastic cylindrical shells is derived by minimizing the functional of total energy of the shells as three-dimensional bodies. The numerical method for solving the initial boundary-value problem formulated is based on an explicit variational-difference scheme. The reliability of the technique considered is verified by comparing numerical results with experimental data. An analysis of the ultimate strains and strength of one-layer basalt-and glass-fiber-reinforced plastic and two-layer metalplastic cylindrical shells is carried out.

  15. Dissipation and accumulation of energy during plastic deformation of Armco -iron and 12Cr18Ni10Ti stainless steel irradiated by neutrons

    International Nuclear Information System (INIS)

    Toktogulova, D.; Maksimkin, O.; Gusev, M.; Garner, F.

    2007-01-01

    Full text of publication follows: Much attention is currently being paid in the fusion materials community to modeling of radiation damage and its consequences in structural alloys on mechanical properties. Such activities are best guided with experimental data on the fundamental microstructural and thermodynamic processes involved. This report addresses such fundamental concerns. During plastic deformation of metals some fraction of the externally-applied mechanical energy is converted into heat and is partially accumulated in the form of crystal lattice defects. The thermal release arises from gliding dislocations, their various interactions, their annihilation etc. With respect to irradiated material, one might expect additional heat release caused by interactions of dislocation and radiation-induced defects. To explore this possibility flat mini-tensile specimens of Armco-iron and 12Cr18Ni10Ti stainless steel, both in the annealed condition, were irradiated in the range 2x10 18 to 1.3x10 20 n/cm 2 (E>0.1 MeV) in the WWR-K reactor at T≤350 K. Mechanical tests of both irradiated and non-irradiated specimens were conducted at room temperature in a facility that was a combination of a Calvet calorimeter and a micro-tensile device. This allows simultaneous measurement of mechanical properties and thermodynamic parameters such as deformation work, dissipated heat and latent energy during deformation. The authors derived the kinetics of changes in thermodynamic characteristics versus the deformation level. As the neutron fluence rises, the material's capability to accumulate energy appears to be declining. For example, 12Cr18Ni10Ti irradiated to 1.3x10 20 n/cm 2 did not show any energy accumulation under deformation. In Armco-iron at 1.4x10 19 n/cm 2 the heat release considerably exceeded the deformation work value. The authors assume that such effects might be related with annihilation of point defects and their complexes introduced during irradiation. To test this

  16. Control of protein synthesis in Escherichia coli: strain differences in control of translational initiation after energy source shift-down.

    OpenAIRE

    Jacobson, L A; Jen-Jacobson, L

    1980-01-01

    We have studied the parameters of protein synthesis in a number of Escherichia coli strains after a shift-down from glucose-minimal to succinate-minimal medium. One group of strains, including K-12(lambda) (ATCC 10798) and NF162, showed a postshift translational yield of 50 to 65% and a 2- to 2.5-fold increase in the functional lifetime of general messenger ribonucleic acid. There was no change in the lag time for beta-galactosidase induction in these strains after the shift-down. A second gr...

  17. High energy X-ray diffraction analysis of strain and residual stress in silicon nitride ceramic diffusion bonds

    International Nuclear Information System (INIS)

    Vila, M.; Prieto, C.; Miranzo, P.; Osendi, M.I.; Terry, A.E.; Vaughan, G.B.M.

    2005-01-01

    High resolution X-ray scanning diffractometry is used to study the residual stress in binary metal/ceramic (Ni/Si 3 N 4 ) diffusion bonds fabricated by simultaneous high temperature heating and uniaxial pressing. In order to diminish the experimental error on the stress determination, the method consists of three steps: (i) to measure the axial and radial strains following some selected lines at the inner volume of the ceramic; (ii) to fit the strain data using finite element method (FEM) analysis and (iii) to determinate stresses by using the results obtained from the FEM method in the strain calculation

  18. Toxicological Threats of Plastic

    Science.gov (United States)

    Plastics pose both physical (e.g., entanglement, gastrointestinal blockage, reef destruction) and chemical threats (e.g., bioaccumulation of the chemical ingredients of plastic or toxic chemicals sorbed to plastics) to wildlife and the marine ecosystem.

  19. Giant voltage manipulation of MgO-based magnetic tunnel junctions via localized anisotropic strain: A potential pathway to ultra-energy-efficient memory technology

    Science.gov (United States)

    Zhao, Zhengyang; Jamali, Mahdi; D'Souza, Noel; Zhang, Delin; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha; Wang, Jian-Ping

    2016-08-01

    Voltage control of magnetization via strain in piezoelectric/magnetostrictive systems is a promising mechanism to implement energy-efficient straintronic memory devices. Here, we demonstrate giant voltage manipulation of MgO magnetic tunnel junctions (MTJ) on a Pb(Mg1/3Nb2/3)0.7Ti0.3O3 piezoelectric substrate with (001) orientation. It is found that the magnetic easy axis, switching field, and the tunnel magnetoresistance (TMR) of the MTJ can be efficiently controlled by strain from the underlying piezoelectric layer upon the application of a gate voltage. Repeatable voltage controlled MTJ toggling between high/low-resistance states is demonstrated. More importantly, instead of relying on the intrinsic anisotropy of the piezoelectric substrate to generate the required strain, we utilize anisotropic strain produced using a local gating scheme, which is scalable and amenable to practical memory applications. Additionally, the adoption of crystalline MgO-based MTJ on piezoelectric layer lends itself to high TMR in the strain-mediated MRAM devices.

  20. Plasticity size effects in voided crystals

    DEFF Research Database (Denmark)

    Hussein, M. I.; Borg, Ulrik; Niordson, Christian Frithiof

    singularities in an elastic material. The lattice resistance to dislocation motion, dislocation nucleation, dislocation interaction with obstacles and annihilation are incorporated through a set of constitutive rules. Over the range of length scales investigated, both the discrete dislocation and strain......The shear and equi-biaxial straining responses of periodic voided single crystals are analysed using discrete dislocation plasticity and a continuum strain gradient crystal plasticity theory. In the discrete dislocation formulation the dislocations are all of edge character and are modelled as line...... predictions of the two formulations for all crystal types and void volume fractions considered when the material length scale in the non-local plasticity model chosen to be $0.325\\mu m$ (around ten times the slip plane spacing in the discrete dislocation models)....

  1. Recycling of plastics in Germany

    International Nuclear Information System (INIS)

    Thienen, N. von; Patel, M.

    1999-01-01

    This article deals with the waste management of post-consumer plastics in Germany and its potential to save fossil fuels and reduce CO 2 emissions. Since most experience is available for packaging, the paper first gives an overview of the legislative background and the material flows for this sector. Then recycling and recovery processes for plastics waste from all sectors are assessed in terms of their contribution to energy saving and CO 2 abatement. Practically all the options studied show a better performance than waste treatment in an average incinerator which has been chosen as the reference case. High ecological benefits can be achieved by mechanical recycling if virgin polymers are substituted. The paper then presents different scenarios for managing plastic waste in Germany in 1995: considerable savings can be made by strongly enhancing the efficiency of waste incinerators. Under these conditions the distribution of plastics waste among mechanical recycling, feedstock recycling and energy recovery has a comparatively mall impact on the overall results. The maximum savings amount to 74 PJ of energy, i.e, 9% of the chemical sector energy demand in 1995 and 7.0 Mt CO 2 , representing 13% of the sector's emissions. The assessment does not support a general recommendation of energy recovery due to the large difference between the German average and the best available municipal waste-to-energy facilities and also due to new technological developments in the field of mechanical recycling

  2. Impacts of Interface Energies and Transformation Strain from BCC to FCC on Massive-like δ-γ Transformation in Steel

    International Nuclear Information System (INIS)

    Yoshiya, M; Sato, M; Watanabe, M; Nakajima, K; Yokoi, T; Ueshima, N; Nagira, T; Yasuda, H

    2015-01-01

    Interface energies of δ/γ, γ/γ, δ/δ, L/δ, and L/γ interfaces, at first, as a function of misorientation were evaluated with an aid of atomistic simulations with embedded atom method. Then, under geometric constraints where grains or interfaces compete each other to minimize overall free energy, effective interface energies for those interfaces were quantified. It is found that neither the minimum nor effective δ/γ interface energies, 0.41 or 0.56 J/m 2 , respectively, is significantly higher than those of other interfaces including liquid/solid interfaces, but the δ/γ interface energy is significantly high for the small entropy change upon δ-γ massive-like transformation, resulting in significantly higher undercooling required for γ nucleation in the δ phase matrix than in solidification. Detachment of δ-phase dendrite tips away from γ-phase dendrite trunks can be explained only from a viewpoint of interface energy if small misorientationis introduced at the δ/γ interface from the perfect lattice matching between BCC and FCC crystal structures. Examining the BCC-to-FCC transformation strain on the γ nucleation in the massive-like transformation, the γ nucleation is prohibited 170 K or more undercooling is achieved unless any relaxation mechanism for the transformation strain is taken into account. (paper)

  3. Particle fracture and plastic deformation in vanadium pentoxide

    Indian Academy of Sciences (India)

    Particle fracture and plastic deformation in vanadium pentoxide powders induced by high energy vibrational ball-mill ... Keywords. X-ray diffraction; ball-milling; plastic deformation; microstrain. ... Bulletin of Materials Science | News.

  4. Source properties of dynamic rupture pulses with off-fault plasticity

    KAUST Repository

    Gabriel, A.-A.

    2013-08-01

    Large dynamic stresses near earthquake rupture fronts may induce an inelastic response of the surrounding materials, leading to increased energy absorption that may affect dynamic rupture. We systematically investigate the effects of off-fault plastic energy dissipation in 2-D in-plane dynamic rupture simulations under velocity-and-state-dependent friction with severe weakening at high slip velocity. We find that plasticity does not alter the nature of the transitions between different rupture styles (decaying versus growing, pulse-like versus crack-like, and subshear versus supershear ruptures) but increases their required background stress and nucleation size. We systematically quantify the effect of amplitude and orientation of background shear stresses on the asymptotic properties of self-similar pulse-like ruptures: peak slip rate, rupture speed, healing front speed, slip gradient, and the relative contribution of plastic strain to seismic moment. Peak slip velocity and rupture speed remain bounded. From fracture mechanics arguments, we derive a nonlinear relation between their limiting values, appropriate also for crack-like and supershear ruptures. At low background stress, plasticity turns self-similar pulses into steady state pulses, for which plastic strain contributes significantly to the seismic moment. We find that the closeness to failure of the background stress state is an adequate predictor of rupture speed for relatively slow events. Our proposed relations between state of stress and earthquake source properties in the presence of off-fault plasticity may contribute to the improved interpretation of earthquake observations and to pseudodynamic source modeling for ground motion prediction.

  5. New plastic plane stress model for concrete

    International Nuclear Information System (INIS)

    Winnicki, A.; Cichon, Cz.

    1993-01-01

    In the paper a description of concrete behaviour in the plane stress case is given on the basis of the modified bounding surface plasticity theory. Three independent plastic mechanisms have been introduced describing axiatoric and deviatoric plastic strains and their coupling. All the new analytical formulae for material functions being in agreement with experiments and loading/unloading criteria have been proposed. In addition, for the proper description of concrete behaviour in tension a new, separate function of bounding surface shrinkage has been introduced. (author)

  6. Plastic deformation of 2D crumpled wires

    International Nuclear Information System (INIS)

    Gomes, M A F; Donato, C C; Brito, V P; Coelho, A S O

    2008-01-01

    When a single long piece of elastic wire is injected through channels into a confining two-dimensional cavity, a complex structure of hierarchical loops is formed. In the limit of maximum packing density, these structures are described by several scaling laws. In this paper this packing process is investigated but using plastic wires which give rise to completely irreversible structures of different morphology. In particular, the plastic deformation from circular to oblate configurations of crumpled wires is experimentally studied, obtained by the application of an axial strain. Among other things, it is shown that in spite of plasticity, irreversibility and very large deformations, scaling is still observed.

  7. Plastics pipe couplings

    International Nuclear Information System (INIS)

    Glover, J.B.

    1980-07-01

    A method is described of making a pipe coupling of the type comprising a plastics socket and a resilient annular sealing member secured in the mouth thereof, in which the material of at least one component of the coupling is subjected to irradiation with high energy radiation whereby the material is caused to undergo cross-linking. As examples, the coupling may comprise a polyethylene or plasticised PVC socket the material of which is subjected to irradiation, and the sealing member may be moulded from a thermoplastic elastomer which is subjected to irradiation. (U.K.)

  8. Prediction of crack growth direction by Strain Energy Sih's Theory on specimens SEN under tension-compression biaxial loading employing Genetic Algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-MartInez R; Lugo-Gonzalez E; Urriolagoitia-Calderon G; Urriolagoitia-Sosa G; Hernandez-Gomez L H; Romero-Angeles B; Torres-San Miguel Ch, E-mail: rrodriguezm@ipn.mx, E-mail: urrio332@hotmail.com, E-mail: guiurri@hotmail.com, E-mail: luishector56@hotmail.com, E-mail: romerobeatriz98@hotmail.com, E-mail: napor@hotmail.com [INSTITUTO POLITECNICO NACIONAL Seccion de Estudios de Posgrado e Investigacion (SEPI), Escuela Superior de Ingenieria Mecanica y Electrica (ESIME), Edificio 5. 2do Piso, Unidad Profesional Adolfo Lopez Mateos ' Zacatenco' Col. Lindavista, C.P. 07738, Mexico, D.F. (Mexico)

    2011-07-19

    Crack growth direction has been studied in many ways. Particularly Sih's strain energy theory predicts that a fracture under a three-dimensional state of stress spreads in direction of the minimum strain energy density. In this work a study for angle of fracture growth was made, considering a biaxial stress state at the crack tip on SEN specimens. The stress state applied on a tension-compression SEN specimen is biaxial one on crack tip, as it can observed in figure 1. A solution method proposed to obtain a mathematical model considering genetic algorithms, which have demonstrated great capacity for the solution of many engineering problems. From the model given by Sih one can deduce the density of strain energy stored for unit of volume at the crack tip as dW = [1/2E({sigma}{sup 2}{sub x} + {sigma}{sup 2}{sub y}) - {nu}/E({sigma}{sub x}{sigma}{sub y})]dV (1). From equation (1) a mathematical deduction to solve in terms of {theta} of this case was developed employing Genetic Algorithms, where {theta} is a crack propagation direction in plane x-y. Steel and aluminium mechanical properties to modelled specimens were employed, because they are two of materials but used in engineering design. Obtained results show stable zones of fracture propagation but only in a range of applied loading.

  9. Prediction of crack growth direction by Strain Energy Sih's Theory on specimens SEN under tension-compression biaxial loading employing Genetic Algorithms

    International Nuclear Information System (INIS)

    Rodriguez-MartInez R; Lugo-Gonzalez E; Urriolagoitia-Calderon G; Urriolagoitia-Sosa G; Hernandez-Gomez L H; Romero-Angeles B; Torres-San Miguel Ch

    2011-01-01

    Crack growth direction has been studied in many ways. Particularly Sih's strain energy theory predicts that a fracture under a three-dimensional state of stress spreads in direction of the minimum strain energy density. In this work a study for angle of fracture growth was made, considering a biaxial stress state at the crack tip on SEN specimens. The stress state applied on a tension-compression SEN specimen is biaxial one on crack tip, as it can observed in figure 1. A solution method proposed to obtain a mathematical model considering genetic algorithms, which have demonstrated great capacity for the solution of many engineering problems. From the model given by Sih one can deduce the density of strain energy stored for unit of volume at the crack tip as dW = [1/2E(σ 2 x + σ 2 y ) - ν/E(σ x σy)]dV (1). From equation (1) a mathematical deduction to solve in terms of θ of this case was developed employing Genetic Algorithms, where θ is a crack propagation direction in plane x-y. Steel and aluminium mechanical properties to modelled specimens were employed, because they are two of materials but used in engineering design. Obtained results show stable zones of fracture propagation but only in a range of applied loading.

  10. 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

  11. Percentage depth dose calculation accuracy of model based algorithms in high energy photon small fields through heterogeneous media and comparison with plastic scintillator dosimetry.

    Science.gov (United States)

    Alagar, Ananda Giri Babu; Mani, Ganesh Kadirampatti; Karunakaran, Kaviarasu

    2016-01-08

    Small fields smaller than 4 × 4 cm2 are used in stereotactic and conformal treatments where heterogeneity is normally present. Since dose calculation accuracy in both small fields and heterogeneity often involves more discrepancy, algorithms used by treatment planning systems (TPS) should be evaluated for achieving better treatment results. This report aims at evaluating accuracy of four model-based algorithms, X-ray Voxel Monte Carlo (XVMC) from Monaco, Superposition (SP) from CMS-Xio, AcurosXB (AXB) and analytical anisotropic algorithm (AAA) from Eclipse are tested against the measurement. Measurements are done using Exradin W1 plastic scintillator in Solid Water phantom with heterogeneities like air, lung, bone, and aluminum, irradiated with 6 and 15 MV photons of square field size ranging from 1 to 4 cm2. Each heterogeneity is introduced individually at two different depths from depth-of-dose maximum (Dmax), one setup being nearer and another farther from the Dmax. The central axis percentage depth-dose (CADD) curve for each setup is measured separately and compared with the TPS algorithm calculated for the same setup. The percentage normalized root mean squared deviation (%NRMSD) is calculated, which represents the whole CADD curve's deviation against the measured. It is found that for air and lung heterogeneity, for both 6 and 15 MV, all algorithms show maximum deviation for field size 1 × 1 cm2 and gradually reduce when field size increases, except for AAA. For aluminum and bone, all algorithms' deviations are less for 15 MV irrespective of setup. In all heterogeneity setups, 1 × 1 cm2 field showed maximum deviation, except in 6MV bone setup. All algorithms in the study, irrespective of energy and field size, when any heterogeneity is nearer to Dmax, the dose deviation is higher compared to the same heterogeneity far from the Dmax. Also, all algorithms show maximum deviation in lower-density materials compared to high-density materials.

  12. The impact of nutrient density in terms of energy and/or protein on live performance, metabolism and carcass composition of female and male broiler chickens of two commercial broiler strains

    OpenAIRE

    Delezie, E.; Bruggeman, V.; SWENNEN, Quirine; Decuypere, E.; Huyghebaert, G.

    2010-01-01

    The objective of this study was to investigate the effects of diet composition on performance, slaughter yield and plasma metabolites, as different modern broiler strains show different responses to feed intake. Broilers of two commercial strains and of both sexes received one of three diets being different in energy and/or protein level [control diet, low energy/low protein diet (LM/LP) and low protein diet (LP)]. Low energy/low protein diet chickens were characterized by significantly lower...

  13. Breeding of Coenzyme Q10 Produced Strain by Low-Energy Ion Implantation and Optimization of Coenzyme Q10 Fermentation

    International Nuclear Information System (INIS)

    Xu Dejun; Zheng Zhiming; Wang Peng; Wang Li; Yuan Hang; Yu Zengliang

    2008-01-01

    In order to increase the production efficiency of coenzyme Q 10 , the original strain Agrobacterium tumefaciens ATCC 4452 was mutated by means of Nitrogen ions implantation. A mutant strain, ATX 12, with high contents of coenzyme Q 10 was selected. Subsequently, the conditions such as carbohydrate concentration, nitrogen source concentration, inoculum's size, seed age, aeration and temperature which might affect the production of CoQ 10 were investigated in detail. Under optimal conditions, the maximum concentration of the intracellular CoQ 10 reached 200.3 mg/L after 80 h fed-batch fermentation, about 245% increasing in CoQ 10 production after ion implantation, compared to the original strain. (ion beam bioengineering)

  14. Recycling of Plastic

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Fruergaard, Thilde

    2011-01-01

    Plastic is produced from fossil oil. Plastic is used for many different products. Some plastic products like, for example, wrapping foil, bags and disposable containers for food and beverage have very short lifetimes and thus constitute a major fraction of most waste. Other plastic products like...

  15. Low-temperature resistance of cyclically strained aluminum

    International Nuclear Information System (INIS)

    Segal, H.R.; Richard, T.G.

    1977-01-01

    An experimental study of the resistance changes in high-purity, reinforced aluminum due to cyclic straining is presently underway. The purpose of this work is to determine the optimum purity of aluminum to be used as a stabilizing material for superconducting magnets used for energy storage. Since pure aluminum has a low yield strength, it is not capable of supporting the stress levels in an energized magnet. Therefore, it has been bonded to a high-strength material--in this case, 6061 aluminum alloy. This bonding permits pure aluminum to be strained cyclically beyond its elastic limit with recovery of large plastic strains upon release of the load. The resistance change in this composite material is less than that of pure, unreinforced aluminum

  16. Plastic deformation and hysteresis for hydrogen storage in Pd–Rh alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cappillino, P.J., E-mail: pcappil@sandia.gov [Sandia National Laboratories, PO Box 969, Mail Stop 9292, Livermore, CA 94551 (United States); Lavernia, E.J. [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States); Ong, M.D. [Department of Physics, Whitworth University, Spokane, WA 99251 (United States); Wolfer, W.G.; Yang, N.Y. [Sandia National Laboratories, PO Box 969, Mail Stop 9292, Livermore, CA 94551 (United States)

    2014-02-15

    Highlights: • Experimental evidence of plastic work resulting from hydriding of palladium is presented. • A model of this plastic work was generated and correlated to hysteresis losses. • This hysteresis is thought to be important to the lifetime of hydrogen storage materials. • Yield strength values predicted by this model agree with measured hardness. -- Abstract: The hysteresis observed when reversibly absorbing and desorbing hydrogen in metals is currently not fully understood. In general, a hysteresis represents energy that is dissipated during a cycle, but the underlying mechanism of dissipation is still uncertain. It has been suggested that the hysteresis arises either from plastic work, or from elastic strains associated with the accommodation of the hydride phase, or from both. We present here experimental evidence that implicates plastic deformation as the cause of the hysteresis in a Pd–Rh alloy. The plastic work is evident from the increased dislocation density, from the accumulation of surface steps from slip bands, from line broadening of X-ray diffraction peaks, and from an increase in hardness with the number of hydriding cycles. A model of this plastic work is developed that depends on an effective yield strength. When this model is correlated with the measured hysteresis losses, two values are found for the effective yield strength. The lower value is shown to agree with yield strength values derived from Vickers hardness measurements. The hysteresis areas for repeated cycles of absorption and desorption decrease little with the number of cycles which is reminiscent of the plastic deformation hysteresis during low-cycle fatigue of metals. This similarity further confirms the plastic nature of the hydriding hysteresis.

  17. Strain limit criteria to predict failure

    International Nuclear Information System (INIS)

    Flanders, H.E.

    1995-01-01

    In recent years extensive effort has been expended to qualify existing structures for conditions that are beyond the original design basis. Determination of the component failure load is useful for this type of evaluation. This paper presents criteria based upon strain limits to predict the load at failure. The failure modes addressed are excessive plastic deformations, localized plastic strains, and structural instability. The effects of analytical method sophistication, as built configurations, material properties degradation, and stress state are addressed by the criteria

  18. Plastics - the sustainable way to use Oil and Gas

    Energy Technology Data Exchange (ETDEWEB)

    Siebourg, Wolfgang

    2009-07-01

    Conclusions (drawn by the author): Plastics are a sustainable use of oil and gas - Plastic products enable significant savings of energy and GHG emissions particularly in the use phase; - Plastic products help use resources in the most efficient way. Restricting plastics relative growth would result in increased energy consumption. Diversion from landfill would increase resource efficiency. Waste-to-Energy is an additional resource and is complementary to mechanical recycling. Plastics producers and the Oil and Gas industry should cooperate to produce reliable consumption data. Oil and Gas industry should develop and maintain European (world) eco-profiles (cradle to gate) for their respective industry. (author)

  19. Non-uniform plastic deformation of micron scale objects

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    Significant increases in apparent flow strength are observed when non-uniform plastic deformation of metals occurs at the scale ranging from roughly one to ten microns. Several basic plane strain problems are analyzed numerically in this paper based on a new formulation of strain gradient...... plasticity. The problems are the tangential and normal loading of a finite rectangular block of material bonded to rigid platens and having traction-free ends, and the normal loading of a half-space by a flat, rigid punch. The solutions illustrate fundamental features of plasticity at the micron scale...... that are not captured by conventional plasticity theory. These include the role of material length parameters in establishing the size dependence of strength and the elevation of resistance to plastic flow resulting from constraint on plastic flow at boundaries. Details of the finite element method employed...

  20. On the formulation of higher gradient single and polycrystal plasticity

    International Nuclear Information System (INIS)

    Menzel, A.; Steinmann, P.

    1998-01-01

    This contribution aims in a geometrically linear formulation of higher gradient plasticity of single and polycrystalline material based on the continuum theory of dislocations and incompatibilities. Thereby, general continuum dislocation densities and incompatibilities are introduced from the viewpoint of continuum mechanics by considering the spatial closure failure of arbitrary line integrals of the displacement differential. Then these findings are translated to the plastic parts of the displacement gradient, the so called plastic distortion, and the plastic strain, respectively, within an elasto-plastic solid thus defining tensor fields of plastic dislocation densities and plastic incompatibilities. Next, in the case of single crystalline material the plastic dislocation density and in the case of polycrystalline material the plastic incompatibility are considered within the exploitation of the thermodynamical principle of positive dissipation. As a result, a phenomenological but physically motivated description of hardening is obtained, which incorporates for single crystals second spatial derivatives of the plastic deformation gradient and for polycrystals fourth spatial derivatives of the plastic strains into the yield condition. Moreover, these modifications mimic the characteristic structure of kinematic hardening, whereby the backstress obeys a nonlocal evolution law. (orig.)