Sample records for maximum tensile stresses

  1. Laser-induced generation of pure tensile stresses

    Niemz, M.H.; Lin, C.P.; Pitsillides, C.; Cui, J.; Doukas, A.G.; Deutsch, T.F. [Wellman Laboratories of Photomedicine, Harvard University, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States)


    While short compressive stresses can readily be produced by laser ablation, the generation of pure tensile stresses is more difficult. We demonstrate that a 90{degree} prism made of polyethylene can serve to produce short and pure tensile stresses. A compressive wave is generated by ablating a thin layer of strongly absorbing ink on one surface of the prism with a Q-switched frequency-doubled Nd:YAG laser. The compressive wave driven into the prism is reflected as a tensile wave by the polyethylene-air interface at its long surface. The low acoustic impedance of polyethylene makes it ideal for coupling tensile stresses into liquids. In water, tensile stresses up to {minus}200bars with a rise time of the order of 20 ns and a duration of 100 ns are achieved. The tensile strength of water is determined for pure tensile stresses lasting for 100 ns only. The technique has potential application in studying the initiation of cavitation in liquids and in comparing the effect of compressive and tensile stress transients on biological media. {copyright} {ital 1997 American Institute of Physics.}

  2. First-Principles Study of Tetragonal BaTiO3 Subjected to Uniaxial Tensile Stress along the c Axis

    WANG Chun-Mei; DUAN Yi-Feng; CHEN Chang-Qing


    Tetragonal Ba TiO3 under uniaxial tensile stress along the c axis is investigated from first principles. The structural parameters and polarization show a little abrupt change near a critical stress σc of 4.57 GPa, which is related to the uniaxial tensile stress induced change of elastic constants. We also find that the ferroelectric lattice distortion increases with the increasing stress. Moreover, it is found that uniaxial tensile stress can enhance the piezoelectric strain coefficients, which reach their maximum values at the stress σc.

  3. Magnetic memory signals variation induced by applied magnetic field and static tensile stress in ferromagnetic steel

    Huang, Haihong, E-mail:; Yang, Cheng; Qian, Zhengchun; Han, Gang; Liu, Zhifeng


    Stress can induce a spontaneous magnetic field in ferromagnetic steel under the excitation of geomagnetic field. In order to investigate the impact of applied magnetic field and tensile stress on variation of the residual magnetic signals on the surface of ferromagnetic materials, static tensile tests of Q235 structural steel were carried out, with the normal component of the residual magnetic signals, H{sub p}(y), induced by applied magnetic fields with different intensities measured through the tensile tests. The H{sub p}(y), its slope coefficient K{sub S} and maximum gradient K{sub max} changing with the applied magnetic field H and tensile stress were observed. Results show that the magnitude of H{sub p}(y) and its slope coefficient K{sub S} increase linearly with the increase of stress in the elastic deformation stage. Under yield stress, H{sub p}(y) and K{sub S} reach its maximum, and then decrease slightly with further increase of stress. Applied magnetic field affects the magnitude of H{sub p}(y) instead of changing the signal curve′s profile; and the magnitude of H{sub p}(y), K{sub S}, K{sub max} and the change rate of K{sub S} increase with the increase of applied magnetic field. The phenomenon is also discussed from the viewpoint of magnetic charge in ferromagnetic materials. - Highlights: • We investigated how applied magnetic field and tensile stress impact H{sub p}(y) signals. • Magnitude of H{sub p}(y), K{sub S} and K{sub max} increase with the increase of applied magnetic field. • Both applied magnetic field and tensile stress impact material magnetic permeability. • Applied magnetic field can help to evaluate the stress distribution of components.

  4. Magnetic memory signals variation induced by applied magnetic field and static tensile stress in ferromagnetic steel

    Huang, Haihong; Yang, Cheng; Qian, Zhengchun; Han, Gang; Liu, Zhifeng


    Stress can induce a spontaneous magnetic field in ferromagnetic steel under the excitation of geomagnetic field. In order to investigate the impact of applied magnetic field and tensile stress on variation of the residual magnetic signals on the surface of ferromagnetic materials, static tensile tests of Q235 structural steel were carried out, with the normal component of the residual magnetic signals, Hp(y), induced by applied magnetic fields with different intensities measured through the tensile tests. The Hp(y), its slope coefficient KS and maximum gradient Kmax changing with the applied magnetic field H and tensile stress were observed. Results show that the magnitude of Hp(y) and its slope coefficient KS increase linearly with the increase of stress in the elastic deformation stage. Under yield stress, Hp(y) and KS reach its maximum, and then decrease slightly with further increase of stress. Applied magnetic field affects the magnitude of Hp(y) instead of changing the signal curve‧s profile; and the magnitude of Hp(y), KS, Kmax and the change rate of KS increase with the increase of applied magnetic field. The phenomenon is also discussed from the viewpoint of magnetic charge in ferromagnetic materials.


    Bing Na; Qin Zhang; Hong Yang; Qiang Fu; Yong-feng Men


    In this communication, by means of stress relaxation experiments, the viscous stress at various strains during tensile deformation of oriented polyolefin samples including high density polyethylene (HDPE), linear low density polyethylene (LLDPE) and isotactic polypropylene (iPP), has been determined. The viscous stress in the oriented samples takes up to 50%-70% of the total stress, which is unusually high compared with their isotropic counterparts. The unusual high viscous stress was discussed based on mainly the existence of shish structure in oriented polyolefins, which could enhance the inter-lamella coupling significantly.

  6. The Creep Properties of Fine Sandstone under Uniaxial Tensile Stress

    Jiang Haifei


    Full Text Available A graduated uniaxial direct tensile creep test for fine sandstone is conducted by adopting a custom-designed direct tensile test device for rock. The experiment shows that the tensile creep of fine sandstone has similar creep curve patterns to those of compression creep, while the ratios of the creep strain to the total strain obtained in the tensile tests are substantially higher than those obtained for similar compression tests, which indicates that the creep ability of rock in the tensile process is higher than that in the uniaxial compression process. Based on the elastic modulus in the approximately linear portion of the obtained isochronous stress-strain curves of the tensile creep, the time dependence of the elasticity modulus for the Kelvin model is evaluated, and a revised generalized Kelvin model is obtained by substitution into the generalized Kelvin model. A new viscousplastic model is proposed to describe the accelerated creep properties, and this model is combined in series with the revised generalized Kelvin model to form a new nonlinear viscoelastic-plastic creep model that can describe the properties of attenuation creep, steady creep, and accelerated creep. Comparison of the test and theoretical curves demonstrates that they are nearly identical, which verifies the performance of the model.


    G.Q. Jia; H.W. Shen; Y.M. Zhu


    Stress relaxation behavior of two turbine bolt steels was evaluated by the manualcontrolled tensile stress relaxation test (TSRT) at high temperature. First, feasibility and the procedure of the manual-controlled tensile stress relaxation test (TSRT) is discussed and carried out on a general creep testing machine. And then, the experimental results from such type of test were compared to the existing data provided by certain Laboratory U.K. Overall good agreement between the results of manualcontrolled TSRT method and the existing data provides confidence in the use of the proposed method in practice. Finally, the experimental results of turbine bolt steels from TSRT were compared with that of bending test. It is observed that great difference exists between the results from two different type stress relaxation tests. It is therefore suggested that the results from TSRT method be adopted in turbine bolt design in engineering.

  8. Strength criterion for rocks under compressive-tensile stresses and its application

    Mingqing You


    Full Text Available Estimating in-situ stress with hydraulic borehole fracturing involves tensile strength of rock. Several strength criteria with three parameters result in tensile strengths with great differences, although they may describe the relation between strength of rock and confining pressure with low misfits. The exponential criterion provides acceptable magnitudes of tensile strengths for granites and over-estimates that for other rocks, but the criterion with tension cut-off is applicable to all rocks. The breakdown pressure will be lower than the shut-in pressure during hydraulic borehole fracturing, when the maximum horizontal principal stress is 2 times larger than the minor one; and it is not the peak value in the first cycle, but the point where the slope of pressure-time curve begins to decline.

  9. Effect of Zirconia Thickness on the Tensile Stress of Zirconia Based All-Ceramic Restorations

    Masood Shiezadeh


    Full Text Available Introduction: The purpose of the presented study was to evaluate the effect of zirconia thickness on the tensile stress of zirconia based all-ceramic restorations. Methods: Twenty zirconia disks with 10mm diameter were prepared in two groups using CAD/CAM system. The thickness of zirconia was 0.5mm in first group and 0.3mm in second group. After sintering, 0.4mm glass ceramic porcelain was applied to each disk. Then, sintering and glazing of porcelain carried out. Instron testing machine with 1mm/min crosshead speed used to evaluate the failure load of the samples. Biaxial Flexural strength standard formula employed to calculate tensile stress of specimens. Statistical analysis performed using SPSS software. Results: Although data analysis showed more maximum tensile stress in 1st group, no significant differences were found between two groups. Conclusion: Zirconia with 0.5mm and 0.3mm thicknesses cause similar tensile stress in all-ceramic restorations and thickness of these laminates could be reduced to 0.7mm.

  10. Maximum twin shear stress factor criterion for sliding mode fracture initiation

    黎振兹; 李慧剑; 黎晓峰; 周洪彬; 郝圣旺


    Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is the maximum twin shear stress factor criterion. The authors studied a finite width plate with central slant crack, subject to a far-field uniform uniaxial tensile or compressive stress.

  11. 49 CFR 230.24 - Maximum allowable stress.


    ... 49 Transportation 4 2010-10-01 2010-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

  12. Xyloglucan for Generating Tensile Stress to Bend Tree Stem

    Kei'ichi Baba; Yong Woo Park; Tomomi Kaku; Rumi Kaida; Miyuki Takeuchi; Masato Yoshida; Yoshihiro Hosoo; Yasuhisa Ojio; Takashi Okuyama; Toru Taniguchi; Yasunori Ohmiya; Teiji Kondo; Ziv Shani; Oded Shoseyov; Tatsuya Awano; Satoshi Serada; Naoko Norioka; Shigemi Norioka; Takahisa Hayashi


    In response to environmental variation, angiosperm trees bend their stems by forming tension wood, which consists of a cellulose-rich G (gelatinous)-Iayer in the walls of fiber cells and generates abnormal tensile stress in the sec-ondary xylem. We produced transgenic poplar plants overexpressing several endoglycanases to reduce each specific poly-saccharide in the cell wall, as the secondary xylem consists of primary and secondary wall layers. When placed horizontally, the basal regions of stems of transgenic poplars overexpressing xyloglucanase alone could not bend upward due to low strain in the tension side of the xylem. In the wild-type plants, xyloglucan was found in the inner surface of G-layers during multiple layering. In situ xyloglucan endotransglucosylase (XET) activity showed that the incorporation of whole xylo-glucan, potentially for wall tightening, began at the inner surface layers S1 and S2 and was retained throughout G-layer development, while the incorporation of xyloglucan heptasaccharide (XXXG) for wall loosening occurred in the primary wall of the expanding zone. We propose that the xyloglucan network is reinforced by XET to form a further connection between wall-bound and secreted xyloglucans in order to withstand the tensile stress created within the cellulose G-layer microfibrils.

  13. Tensile stress and creep in thermally grown oxide.

    Veal, Boyd W; Paulikas, Arvydas P; Hou, Peggy Y


    Structural components that operate at high temperatures (for example, turbine blades) rely on thermally grown oxide (TGO), commonly alumina, for corrosion protection. Strains that develop in TGOs during operation can reduce the protectiveness of the TGO. However, the occurrence of growth strains in TGOs, and mechanisms that cause them, are poorly understood. It is accepted that compressive strains can develop as oxygen and metal atoms meet to form new growth within constrained oxide. More controversial is the experimental finding that large tensile stresses, close to 1 GPa, develop during isothermal growth conditions in alumina TGO formed on a FeCrAlY alloy. Using a novel technique based on synchrotron radiation, we have confirmed these previous results, and show that the tensile strain develops as the early oxide, (Fe,Cr,Al)(2)O(3), converts to alpha-Al2O3 during the growth process. This allows us to model the strain behaviour by including creep and this diffusion-controlled phase change.

  14. Direct assessment of tensile stress-crack opening behavior of Strain Hardening Cementitious Composites (SHCC)

    Pereira, Eduardo B.; Fischer, Gregor; Barros, Joaquim A.O.


    at the level of a single crack. The derived tensile stress-crack opening behavior is utilized to analyze and compare the influence of various composite parameters on the resulting tensile behavior. The deformations occurring during tensile loading are furthermore examined using a digital image...

  15. Conversion of engineering stresses to Cauchy stresses in tensile and compression tests of thermoplastic polymers

    Schümann Kerstin


    Full Text Available Thermoplastic polymers exhibit non-isochoric behaviour during tensile and compression testing as well as particular deformations like local necking (tension or buckling (compression. A method for the determination of Cauchy stresses from tensile and compression tests is presented, that considers the actual deformations of the test specimens. The exact geometry of the specimens in the respective present configuration is determined in photographs, which are taken continuously throughout the test. The engineering stresses at several time points are converted into Cauchy stresses using newly developed formulas in consideration of the actual specimen geometry. For validation finite element analyses of the tensile and compression tests are performed using the identified stress-strain curves. The numerical results show good agreement with the experiments for the tested polymers. Thus a method for conversion of engineering to Cauchy stresses in tensile and compression tests could be established considering the non-isochoric deformation in plasticity. With this method “true” stress-strain curves as input for finite element material models can be identified for arbitrary materials.

  16. Characterization of Optical Fiber Strength Under Applied Tensile Stress and Bending Stress

    P.E. Klingsporn


    Various types of tensile testing and bend radius tests were conducted on silica core/silica cladding optical fiber of different diameters with different protective buffer coatings, fabricated by different fiber manufacturers. The tensile tests were conducted to determine not only the average fiber strengths at failure, but also the distribution in fracture strengths, as well as the influence of buffer coating on fracture strength. The times-to-failure of fiber subjected to constant applied bending stresses of various magnitudes were measured to provide a database from which failure times of 20 years or more, and the corresponding minimum bend radius, could be extrapolated in a statistically meaningful way. The overall study was done to provide an understanding of optical fiber strength in tensile loading and in applied bending stress as related to applications of optical fiber in various potential coizfgurations for weapons and enhanced surveillance campaigns.

  17. A silicon microwire under a three-dimensional anisotropic tensile stress

    Ji, Xiaoyu; Poilvert, Nicolas; Liu, Wenjun; Xiong, Yihuang; Cheng, Hiu Yan; Badding, John V.; Dabo, Ismaila; Gopalan, Venkatraman


    Three-dimensional tensile stress, or triaxial tensile stress, is difficult to achieve in a material. We present the investigation of an unusual three-dimensional anisotropic tensile stress field and its influence on the electronic properties of a single crystal silicon microwire. The microwire was created by laser heating an amorphous silicon wire deposited in a 1.7 μm silica glass capillary by high pressure chemical vapor deposition. Tensile strain arises due to the thermal expansion mismatch between silicon and silica. Synchrotron X-ray micro-beam Laue diffraction (μ-Laue) microscopy reveals that the three principal strain components are +0.47% (corresponding to a tensile stress of +0.7 GPa) along the fiber axis and nearly isotropic +0.02% (corresponding to a tensile stress of +0.3 GPa) in the cross-sectional plane. This effect was accompanied with a reduction of 30 meV in the band gap energy of silicon, as predicted by the density-functional theory calculations and in close agreement with energy-dependent photoconductivity measurements. While silicon has been explored under many stress states, this study explores a stress state where all three principal stress components are tensile. Given the technological importance of silicon, the influence of such an unusual stress state on its electronic properties is of fundamental interest.

  18. Thermal residual stresses and stress distributions under tensile and compressive loadings of short fiber reinforced metal matrix composites


    The thermal residual stresses and the stress distributions of short fiber reinforced metal matrix composite under tensile and compressive loadings were studied using large strain axisymmetric elasto-plastic finite element method. It is demonstrated that the thermal residual stresses can result in asymmetrical stress distributions and matrix plasticity. The thermal residual stresses decrease the stress transfer in tension and enhance the stress transfer in compression. The fiber volume fraction has more important effects on the thermal residual stresses and the stress distributions under tensile and compressive loadings than the fiber aspect ratio and the fiber end distance.

  19. Effects of tensile stress on Cu clustering in irradiated Fe–Cu alloy

    Fujii, K., E-mail: [Institute of Nuclear Safety System, Inc., Mihama 919-1205 (Japan); Fukuya, K. [Institute of Nuclear Safety System, Inc., Mihama 919-1205 (Japan); Kasada, R.; Kimura, A. [Institute of Advanced Energy, Kyoto University, Uji 611-0011 (Japan); Ohkubo, T. [National Institute for Materials Science, Tsukuba 305-0047 (Japan)


    Effects of tensile stress on Cu clustering were explained using atom probe tomography (APT) results of Fe–0.6 wt.%Cu alloy specimens irradiated with 6.4 MeV Fe ions while applying a tensile stress of 60 MPa at room temperature (less than 50 °C) and 290 °C. The hardening under the tensile-stressed irradiation was smaller than that under the stress-free irradiation at both room temperature and 290 °C. APT results showed that well-defined Cu clusters were formed in all specimens even under the room temperature irradiation. The Cu clusters under the tensile-stressed condition were smaller and had higher densities than those under the stress-free condition. The lower Cu content in clusters and more diffuse Cu clustering were obtained for the specimens irradiated under the tensile-stressed condition. The hardening efficiency of Cu clusters was correlated with the Cu content in clusters and the coherency of interface between a cluster and the matrix. Application of tensile stress would control hardening by changing the nature of Cu clusters.

  20. Discrete fracture in quasi-brittle materials under compressive and tensile stress states

    Klerck, PA


    Full Text Available A method for modelling discrete fracture in geomaterials under tensile and compressive stress fields has been developed based on a Mohr-Coulomb failure surface in compression and three independent anisotropic rotating crack models in tension...

  1. Study and analysis of the stress state in a ceramic, button-head, tensile specimen

    Jenkins, M.G.; Ferber, M.K.; Martin, R.L.; Jenkins, V.T.; Tennery, V.J.


    The final results are reported for a study to identify and correct the causes of nongage-section failures (notably button-head failures) in ceramic tensile specimens observed in several laboratories. Numerical modeling of several candidate specimen gripping systems has shown inherent stress concentrations near the specimen button head at which the maximum stress may approach 75 to 100% of the gage-section stress for certain grip conditions. Empirical comparisons of both tapered- and straight-collet gripping systems revealed compromises in both systems. The straight-collet system, with deformable collets, is simpler to use but produces statistically significant greater average percent bending for all tests than those produced for the tapered-collet system, which is slightly more difficult to use. Empirical tensile tests of {approximately}50 aluminium oxide and {approximately}50 silicon nitride specimens were conducted to evaluate the loading capability of both gripping systems, the percent bending in each system, and the potential of consistently producing successful test results. These tests revealed that, due to variations in individuals specimens or the individual specimen/grip interfaces, neither of the gripping systems can consistently produce bending of less than 3 to 4% at failure although occasional values of {approximately}0.5% bending were attained. Refinements of grinding procedures and dimensional measurement techniques have shown critical details in both the practices and consistency of machining necessary for achieving the dimensional tolerances while minimizing subsurface damage. Numerical integration techniques indicate that up to a consistent 5.0% bending during fast- fracture tests can be tolerated before large influences are detected in the determination of the Weibull modulus and the Weibull characteristic strength.

  2. Aluminum-thin-film packaged fiber Bragg grating probes for monitoring the maximum tensile strain of composite materials.

    Im, Jooeun; Kim, Mihyun; Choi, Ki-Sun; Hwang, Tae-Kyung; Kwon, Il-Bum


    In this paper, new fiber Bragg grating (FBG) sensor probes are designed to intermittently detect the maximum tensile strain of composite materials, so as to evaluate the structural health status. This probe is fabricated by two thin Al films bonded to an FBG optical fiber and two supporting brackets, which are fixed on the surface of composite materials. The residual strain of the Al packaged FBG sensor probe is induced by the strain of composite materials. This residual strain can indicate the maximum strain of composite materials. Two types of sensor probes are prepared-one is an FBG with 18 μm thick Al films, and the other is an FBG with 36 μm thick Al films-to compare the thickness effect on the detection sensitivity. These sensor probes are bonded on the surfaces of carbon fiber reinforced plastics composite specimens. In order to determine the strain sensitivity between the residual strain of the FBG sensor probe and the maximum strain of the composite specimen, tensile tests are performed by universal testing machine, under the loading-unloading test condition. The strain sensitivities of the probes, which have the Al thicknesses of 18 and 36 μm, are determined as 0.13 and 0.23, respectively.

  3. Experimental Study on Common and Steel Fiber Reinforced Concrete Under Dynamic Tensile Stress

    董新龙; 陈江瑛; 高培正; 祁振林; 王永忠; 王永刚; 王礼立


    Split Hopkinson technique has been developed to test the strength of common concrete and steel fiber reinforced concrete under dynamic tensile stress. Two types of test methods are considered, the splitting tensile test and a modified spalling test in which a specimen is loaded under uniaxial stress. The result shows that the dynamic strength enhancement of concrete is remarkable by using the reinforcing fiber. But for the common concrete, the base of compressive strength seems to show little effect on the tensile strength under dynamic loading. The experimental results also show that the resistance to tensile fracture of the steel fiber reinforced concrete for C100-mix is higher than those of C40-mix.


    Mao-sheng Zhan


    Theoretical and experimental research has been performed on the interaction curves and stress paths of crystalline polymeric materials PE and POM under tensile-torsional stress with a linearly intensifying model and in terms of the yield points undergoing Von Mises criterion.

  5. Tensile stress generation by optical breakdown in tissue: Experimental investigations and numerical simulations

    Vogel, A. [Medizinisches Laserzentrum Luebeck (Germany); Scammon, R.J.; Godwin, R.P. [Los Alamos National Lab., NM (United States)


    Biological tissue is more susceptible to damage from tensile stress than to compressive stress. Tensile stress may arise through the thermoelastic response of laser-irradiated media. Optical breakdown, however, has to date been exclusively associated with compressive stress. The authors show that this is appropriate for water, but not for tissues for which the elastic-plastic material response needs to be considered. The acoustic transients following optical breakdown in water and cornea were measured with a fast hydrophone and the cavitation bubble dynamics, which is closely linked to the stress wave generation, was documented by flash photography. Breakdown in water produced a monopolar acoustic signal and a bubble oscillation in which the expansion and collapse phases were symmetric. Breakdown in cornea produced a bipolar acoustic signal coupled with a pronounced shortening of the bubble expansion phase and a considerable prolongation of its collapse phase. The tensile stress wave is related to the abrupt end of the bubble expansion. Numerical simulations using the MESA-2D code were performed assuming elastic-plastic material behavior in a wide range of values for the shear modulus and yield strength. The calculations revealed that consideration of the elastic-plastic material response is essential to reproduce the experimentally observed bipolar stress waves. The tensile stress evolves during the outward propagation of the acoustic transient and reaches an amplitude of 30--40% of the compressive pulse.

  6. Relating Residual Stress and Substructural Evolution During Tensile Deformation of an Aluminum-Manganese Alloy

    Lodh, Arijit; Tak, Tawqeer Nasir; Prakash, Aditya; Guruprasad, P. J.; Hutchinson, Christopher; Samajdar, Indradev


    Interrupted tensile tests were coupled with ex situ measurements of residual stress and microtexture. The residual stress quantification involved measurements of six independent Laue spots and conversion of the interplanar spacings to the residual stress tensor. A clear orientation-dependent residual stress evolution emerged from the experiments and the numerical simulations. For the orientations undergoing negligible changes in ρ GND (density of geometrically necessary dislocation), the residual stress developments appeared to be governed by the elastic stiffness of the grain clusters. For the others, the evolution of the residual stress and ρ GND exhibited a clear orientation-dependent scaling.

  7. Analysis of Friction Stir Welding of Aluminum Alloys and Optimization of Welding Parameters for Maximum Tensile Strength

    Prof. S. K. Aditya


    Full Text Available The Friction Stir Welding (FSW process is an innovative technique to join metals in the plastic state thus not reaching the liquid state as it happen in traditional welding processes. This feature of the FSW proved that a modification can be done on the fatigue behavior and strength of the welding joints so, some of the leading companies to adopted the process for the manufacturing of Automotive, Locomotive, Shipping & Aerospace. The FSW is a variant of the linear friction welding process in which the material is being welded without bulk melting. The FSW parameters such as tool Rotational speed, Welding speed, Axial Force, Tool tilt angle, Welding Tool Shoulder Diameter, and Welded Plate thickness play a major role in determining the properties like Tensile strength, hardness, residual stress, HAZ etc. of the joints. Our objective is to optimize the welding parameters to achieve Max. Tensile Strength of Aluminium Alloys (especially on AA-2xxx, AA-5xxx under FSW. We only wish to optimize (by Taguchi and ANOVA method with three variable input parameters (Rotational speed in rpm, Translation speed in mm/min & Axial force in KN considering a cylindrical pin.

  8. Soft magnetic properties of nanocrystalline Fe73B7Si16Nb3Cu1 alloy after rapid heating under tensile stress

    Nosenko, Anton; Mika, Taras; Rudenko, Olexandr; Yarmoshchuk, Yevhenii; Nosenko, Viktor


    Amorphous Fe73B7Si16Nb3Cu1 ribbon was crystallized rapidly by electric current heating under simultaneously applied tensile stress along the ribbon axis. As a result, strong transverse magnetic anisotropy was induced in the ribbon. Dynamic magnetic properties of the ribbons rapidly heated either under the tensile stress or without tensile stress were measured using toroidal cores. Optimal electric current heating regime that provides maximum improvement of the initial magnetic permeability and core loss was determined. Tensile stress increase from 0 to 180 MPa was shown to result in the decrease of the initial magnetic permeability down to 400 and core loss at frequencies from 0.4 to 200 kHz. Comparative analysis of magnetic properties of the cut core (with non-magnetic gap) and the cores heated under tensile stress was carried out. The magnetic properties of the latter cores are advantageous for manufacturing the reactors and linear chokes of switch-mode power supplies.

  9. Tensile stress-strain behavior of hybrid composite laminates

    Kennedy, J. M.


    A study was made of the stress-strain response of several hybrid laminates, and the damage was correlated with nonlinear stress-strain response and ultimate strength. The fibers used in the laminates were graphite, S-glass, and Kevlar. Some laminates with graphite fibers had perforated Mylar film between plies, which lowered the interlaminar bond strength. The laminate configurations were chosen to be like those of buffer strips in large panels and fracture coupons. Longitudinal and transverse specimens were loaded in tension to failure. Some specimens were radiographed to reveal damage due to edge effects. Stress-strain response is discussed in terms of damage shown by the radiographs. Ultimate strengths are compared with simple failure criteria, one of which account for damage.

  10. Tensile stress stimulates microtubule outgrowth in living cells

    Kaverina, Irina; Krylyshkina, Olga; Beningo, Karen; Anderson, Kurt; Wang, Yu-Li; Small, J. Victor


    Cell motility is driven by the sum of asymmetric traction forces exerted on the substrate through adhesion foci that interface with the actin cytoskeleton. Establishment of this asymmetry involves microtubules, which exert a destabilising effect on adhesion foci via targeting events. Here, we demonstrate the existence of a mechano-sensing mechanism that signals microtubule polymerisation and guidance of the microtubules towards adhesion sites under increased stress. Stress was applied either by manipulating the body of cells moving on glass with a microneedle or by stretching a flexible substrate that cells were migrating on. We propose a model for this mechano-sensing phenomenon whereby microtubule polymerisation is stimulated and guided through the interaction of a microtubule tip complex with actin filaments under tension.

  11. Dynamic tensile testing for determining the stress-strain curve at different strain rate

    Mansilla, A; Regidor, A.; García, D.; Negro, A


    A detailed discussion of high strain-rate tensile testing is presented. A comparative analysis of different ways to measure stress and strain is made. The experimental stress-strain curves have been suitably interpreted to distinguish between the real behaviour of the material and the influence of the testing methodology itself. A special two sections flat specimen design was performed through FEA computer modelling. The mechanical properties as function of strain rate were experimentally obt...

  12. A tensile stage for high-stress low-strain fibre studies

    Pauw, Brian Richard; Vigild, Martin Etchells; Mortensen, Kell;


    Determining the effects of stress on the internal structure of high-performance fibres may provide insight into their structure-property relationships. The deformation of voids inside a poly(p-phenylene terephthalamide) (PPTA) fibre upon application of stress is one such effect which may...... that the effects of the application of heat during tensile load can also be determined. Initial results show a slight but significant effect of stress and heating on the internal void structure of PPTA fibres. The effects on the void structure of heating and stress appear to be markedly different....

  13. Cell division plane orientation based on tensile stress in Arabidopsis thaliana.

    Louveaux, Marion; Julien, Jean-Daniel; Mirabet, Vincent; Boudaoud, Arezki; Hamant, Olivier


    Cell geometry has long been proposed to play a key role in the orientation of symmetric cell division planes. In particular, the recently proposed Besson-Dumais rule generalizes Errera's rule and predicts that cells divide along one of the local minima of plane area. However, this rule has been tested only on tissues with rather local spherical shape and homogeneous growth. Here, we tested the application of the Besson-Dumais rule to the divisions occurring in the Arabidopsis shoot apex, which contains domains with anisotropic curvature and differential growth. We found that the Besson-Dumais rule works well in the central part of the apex, but fails to account for cell division planes in the saddle-shaped boundary region. Because curvature anisotropy and differential growth prescribe directional tensile stress in that region, we tested the putative contribution of anisotropic stress fields to cell division plane orientation at the shoot apex. To do so, we compared two division rules: geometrical (new plane along the shortest path) and mechanical (new plane along maximal tension). The mechanical division rule reproduced the enrichment of long planes observed in the boundary region. Experimental perturbation of mechanical stress pattern further supported a contribution of anisotropic tensile stress in division plane orientation. Importantly, simulations of tissues growing in an isotropic stress field, and dividing along maximal tension, provided division plane distributions comparable to those obtained with the geometrical rule. We thus propose that division plane orientation by tensile stress offers a general rule for symmetric cell division in plants.

  14. Tensile stresses generated in pharmaceutical tablets by opposing compressive line loads.

    Drake, K R; Newton, J M; Mokhtary-Saghafi, S; Davies, P N


    The distribution of tensile stress, across the splitting plane, has been investigated for the case when circular and square tablets are subjected to opposing compressive line loads acting in the through thickness direction. This type of loading is referred to in the paper as axial compression. Analytical solutions for the two-dimensional problem of a rectangular strip have been used to investigate the variation of stress in the through thickness direction and to consider the effects of load spreading. Three-dimensional finite element analysis has been used to investigate the variation in stress across the diameter, or breadth, of the tablets. It is shown that the magnitude of the tensile stress varies significantly throughout and that load spreading has an important influence on the stress distribution in the through thickness direction. Experiments have been carried out with microcrystalline cellulose (Avicel PH102) material for circular and square tablets to determine their breaking loads when subjected to axial compression and diametral compression. The experimental results show higher breaking loads for the case of axial compression. It is concluded that the platen contact width must be known in order to evaluate the exact value of the tensile strength of the tablet material when applying this test procedure.

  15. On some method of the space elevator maximum stress reduction

    Ambartsumian S. A.


    Full Text Available The possibility of the realization and exploitation of the space elevator project is connected with a number of complicated problems. One of them are large elastic stresses arising in the space elevator ribbon body, which are considerably bigger that the limit of strength of modern materials. This note is devoted to the solution of problem of maximum stress reduction in the ribbon by the modification of the ribbon cross-section area.

  16. The Combined Effects of Stress Concentration and Tensile Stresses from Autofrettage on the Life of Pressure Vessels


    Technical Report ARWSB-TR-17011 THE COMBINED EFFECTS OF STRESS CONCENTRATION AND TENSILE STRESSES FROM AUTOFRETTAGE ON THE LIFE OF...Laboratories Watervliet, NY 12189 The views, opinions, and/or findings contained in this report are those of the author(s) and...should not be construed as an official Department of the Army position, policy, or decision, unless so designated by other documentation. The

  17. Tensile and stress-rupture behavior of hafnium carbide dispersed molybdenum and tungsten base alloy wires

    Yun, Hee Mann; Titran, Robert H.


    The tensile strain rate sensitivity and the stress-rupture strength of Mo-base and W-base alloy wires, 380 microns in diameter, were determined over the temperature range from 1200 K to 1600 K. Three molybdenum alloy wires; Mo + 1.1w/o hafnium carbide (MoHfC), Mo + 25w/o W + 1.1w/o hafnium carbide (MoHfC+25W) and Mo + 45w/o W + 1.1w/o hafnium carbide (MoHfC+45W), and a W + 0.4w/o hafnium carbide (WHfC) tungsten alloy wire were evaluated. The tensile strength of all wires studied was found to have a positive strain rate sensitivity. The strain rate dependency increased with increasing temperature and is associated with grain broadening of the initial fibrous structures. The hafnium carbide dispersed W-base and Mo-base alloys have superior tensile and stress-rupture properties than those without HfC. On a density compensated basis the MoHfC wires exhibit superior tensile and stress-rupture strengths to the WHfC wires up to approximately 1400 K. Addition of tungsten in the Mo-alloy wires was found to increase the long-term stress rupture strength at temperatures above 1400 K. Theoretical calculations indicate that the strength and ductility advantage of the HfC dispersed alloy wires is due to the resistance to recrystallization imparted by the dispersoid.

  18. Germanium under high tensile stress: nonlinear dependence of direct band gap vs. strain

    Guilloy, K.; Pauc, N.; Gassenq, A.; Niquet, Y. M.; Escalante, J. M.; Duchemin, I.; Tardif, S; Dias, G. Osvaldo; Rouchon, D.; Widiez, J.; Hartmann, J.M.; Geiger, R.; Zabel, T.; Sigg, H; Faist, J.


    Germanium is a strong candidate as a laser source for silicon photonics. It is widely accepted that the band structure of germanium can be altered by tensile strain so as to reduce the energy difference between its direct and indirect band gaps. However, the conventional deformation potential model most widely adopted to describe this transformation happens to have been investigated only up to 1 % uniaxially loaded strains. In this work, we use a micro-bridge geometry to uniaxially stress ger...

  19. Tensile Residual Stress Mitigation Using Low Temperature Phase Transformation Filler Wire in Welded Armor Plates

    Feng, Zhili [ORNL; Bunn, Jeffrey R [ORNL; Tzelepis, Demetrios A [ORNL; Payzant, E Andrew [ORNL; Yu, Xinghua [ORNL


    Hydrogen induced cracking (HIC) has been a persistent issue in welding of high-strength steels. Mitigating residual stresses is one of the most efficient ways to control HIC. The current study develops a proactive in-process weld residual stress mitigation technique, which manipulates the thermal expansion and contraction sequence in the weldments during welding process. When the steel weld is cooled after welding, martensitic transformation will occur at a temperature below 400 C. Volume expansion in the weld due to the martensitic transformation will reduce tensile stresses in the weld and heat affected zone and in some cases produce compressive residual stresses in the weld. Based on this concept, a customized filler wire which undergoes a martensitic phase transformation during cooling was developed. The new filler wire shows significant improvement in terms of reducing the tendency of HIC in high strength steels. Bulk residual stress mapping using neutron diffraction revealed reduced tensile and compressive residual stresses in the welds made by the new filler wire.

  20. 3-D distribution of tensile stress in rock specimens for the Brazilian test

    Yong Yu; Chunyan Meng


    It is claimed that the formula used for calculating the tensile strength of a disk-shaped rock specimen in the Brazilian test is not accurate, because the formula is based on the 2-dimensional elastic theory and only suitable for very long or very short cylinders. The Matlab software was used to obtain the 2-dimensional distribution of stress in the rock specimen for Brazilian test. Then the 2-dimensional stress distribution in Brazilian disk was analyzed by the Marc FEM software. It can be found that the results obtained by the two software packages can verify each other. Finally, the 3-dimensional elastic stress in the specimen was calculated. The results demonstrate that the distribution of stress on the cross section of the specimen is similar to that in 2-dimension. However, the value of the stress on the cross section varies along the thickness of the specimen and the stress is bigger when getting closer to the end of the specimen. For the specimen with a height-to-diameter ratio of 1 and a Poisson's ratio of 0.25, the tensile strength calculated with the classical 2-D formula is 23.3% smaller than the real strength. Therefore, the classical 2-D formula is too conservative.

  1. Mitigation of Tensile Weld Stresses in Alloy 22 Using Laser Peening

    Chen, H L; Evans, K J; Hackel, L A; Rankin, J E; Yamamoto, R M; Demma, A G; Dewald, A T; Lee, M J; Hill, M R


    The goal of the Yucca Mountain Project (YMP) is safe permanent disposal of high-level nuclear waste. One of the many technical challenges to this plan is the design of the Engineered Barrier System (EBS) including the waste package that will contain the radioactive waste. One potential failure mode of the waste package is stress corrosion cracking (SCC), which occurs when three criteria simultaneously exist. These criteria are a potentially corrosive environment, a material susceptible to SCC, and the presence of tensile residual stresses at the surface of the material. While many design decisions have been made to attempt to minimize the occurrence of the first two conditions, it is necessary to control the third condition, the presence of tensile residual stresses. These stresses occur as a result of a variety of manufacturing techniques, including welding. While most of the residual stresses due to the welding of the waste package can be mitigated through solution heat-treating, the final closure weld, which occurs after the radioactive waste has been placed in the waste package, must be treated to eliminate the presence of tensile residual stress near the surface. Laser peening is a commercially proven technology that has been shown to create compressive residual stress in both unstressed materials, as well as materials containing tensile surface residual stresses generated by welding. Lawrence Livermore National Laboratory (LLNL) has developed the laser peening process and the associated hardware for use by the YMP. Upon completion of the testing and engineering phases, LLNL will transfer the laser peening technology to U.S. industry and assist DOE in developing vendors to supply production units to be installed at the YMP facilities. The overall testing effort is divided into-two phases. Phase I of this project consisted of a study into the effectiveness of laser peening in generating compressive stress in small Alloy 22 base metal coupons and converting

  2. Direct Shear Tests of Sandstone Under Constant Normal Tensile Stress Condition Using a Simple Auxiliary Device

    Cen, Duofeng; Huang, Da


    Tension-shear failure is a typical failure mode in the rock masses in unloading zones induced by excavation or river incision, etc., such as in excavation-disturbed zone of deep underground caverns and superficial rocks of high steep slopes. However, almost all the current shear failure criteria for rock are usually derived on the basis of compression-shear failure. This paper proposes a simple device for use with a servo-controlled compression-shear testing machine to conduct the tension-shear tests of cuboid rock specimens, to test the direct shear behavior of sandstone under different constant normal tensile stress conditions ( σ = -1, -1.5, -2, -2.5 and -3 MPa) as well as the uniaxial tension behavior. Generally, the fracture surface roughness decreases and the proportion of comminution areas in fracture surface increases as the change of stress state from tension to tension-shear and to compression-shear. Stepped fracture is a primary fracture pattern in the tension-shear tests. The shear stiffness, shear deformation and normal deformation (except the normal deformation for σ = -1 MPa) decrease during shearing, while the total normal deformation containing the pre-shearing portion increases as the normal tensile stress level (| σ|) goes up. Shear strength is more sensitive to the normal tensile stress than to the normal compressive stress, and the power function failure criterion (or Mohr envelope form of Hoek-Brown criterion) is examined to be the optimal criterion for the tested sandstone in the full region of tested normal stress in this study.

  3. Cell division plane orientation based on tensile stress in Arabidopsis thaliana

    Louveaux, Marion; Julien, Jean-Daniel; Mirabet, Vincent; Boudaoud, Arezki; Hamant, Olivier


    Cell geometry has long been proposed to play a key role in the orientation of symmetric cell division planes. In particular, the recently proposed Besson–Dumais rule generalizes Errera’s rule and predicts that cells divide along one of the local minima of plane area. However, this rule has been tested only on tissues with rather local spherical shape and homogeneous growth. Here, we tested the application of the Besson–Dumais rule to the divisions occurring in the Arabidopsis shoot apex, which contains domains with anisotropic curvature and differential growth. We found that the Besson–Dumais rule works well in the central part of the apex, but fails to account for cell division planes in the saddle-shaped boundary region. Because curvature anisotropy and differential growth prescribe directional tensile stress in that region, we tested the putative contribution of anisotropic stress fields to cell division plane orientation at the shoot apex. To do so, we compared two division rules: geometrical (new plane along the shortest path) and mechanical (new plane along maximal tension). The mechanical division rule reproduced the enrichment of long planes observed in the boundary region. Experimental perturbation of mechanical stress pattern further supported a contribution of anisotropic tensile stress in division plane orientation. Importantly, simulations of tissues growing in an isotropic stress field, and dividing along maximal tension, provided division plane distributions comparable to those obtained with the geometrical rule. We thus propose that division plane orientation by tensile stress offers a general rule for symmetric cell division in plants. PMID:27436908

  4. The two-dimensional magnetic change process of grain-oriented silicon steel under tensile stress

    Saito, Akihiko; Nakata, Kumi; Murashige, Shinichi


    The effect of tensile stress on the magnetization properties of silicon steel samples declined from the rolling direction has been investigated. The locus for the two-dimensional magnetization change was measured. The locus of magnetization due to magnetic field without stress was different from that under tension. The locus of magnetization with tension has two knees which correspond to the two knees of the hysteresis curve with tension. These results indicate the essential importance of investigations of the two-dimensional magnetization process.

  5. The effect of tensile stress on the conformational free energy landscape of disulfide bonds.

    Padmesh Anjukandi

    Full Text Available Disulfide bridges are no longer considered to merely stabilize protein structure, but are increasingly recognized to play a functional role in many regulatory biomolecular processes. Recent studies have uncovered that the redox activity of native disulfides depends on their C-C-S-S dihedrals, χ2 and χ'2. Moreover, the interplay of chemical reactivity and mechanical stress of disulfide switches has been recently elucidated using force-clamp spectroscopy and computer simulation. The χ2 and χ'2 angles have been found to change from conformations that are open to nucleophilic attack to sterically hindered, so-called closed states upon exerting tensile stress. In view of the growing evidence of the importance of C-C-S-S dihedrals in tuning the reactivity of disulfides, here we present a systematic study of the conformational diversity of disulfides as a function of tensile stress. With the help of force-clamp metadynamics simulations, we show that tensile stress brings about a large stabilization of the closed conformers, thereby giving rise to drastic changes in the conformational free energy landscape of disulfides. Statistical analysis shows that native TDi, DO and interchain Ig protein disulfides prefer open conformations, whereas the intrachain disulfide bridges in Ig proteins favor closed conformations. Correlating mechanical stress with the distance between the two a-carbons of the disulfide moiety reveals that the strain of intrachain Ig protein disulfides corresponds to a mechanical activation of about 100 pN. Such mechanical activation leads to a severalfold increase of the rate of the elementary redox S(N2 reaction step. All these findings constitute a step forward towards achieving a full understanding of functional disulfides.

  6. Reduction of tensile residual stresses during the drawing process of tungsten wires

    Rodriguez Ripoll, Manel, E-mail: [Fraunhofer Institute for Mechanics of Materials IWM, Woehlerstrasse 11, 79108 Freiburg (Germany); Weygand, Sabine M. [University of Applied Sciences Karlsruhe, Department of Mechanical Engineering and Mechatronics, Moltkestrasse 30, 76133 Karlsruhe (Germany); Riedel, Hermann [Fraunhofer Institute for Mechanics of Materials IWM, Woehlerstrasse 11, 79108 Freiburg (Germany)


    Tungsten wires are commonly used in the lighting industry as filaments for lamps. During the drawing process, the inhomogeneous deformation imparted by the drawing die causes tensile residual stresses at the wire surface in circumferential direction. These stresses have a detrimental effect for the wire because they are responsible for driving longitudinal cracks, known as splits. This work proposes two methods for reducing the residual stresses during wire drawing, namely applying an advanced die geometry and performing an inexpensive post-drawing treatment based on targeted bending operations. These two methods are analyzed with finite element simulations using material parameters obtained by mechanical tests on tungsten wires at different temperatures as input data. The computed results predict a substantial reduction of the circumferential residual stresses, thus reducing the risk of splitting.

  7. Constitutive modeling of void-growth-based tensile ductile failures with stress triaxiality effects

    Mora Cordova, Angel


    In most metals and alloys, the evolution of voids has been generally recognized as the basic failure mechanism. Furthermore, stress triaxiality has been found to influence void growth dramatically. Besides strain intensity, it is understood to be the most important factor that controls the initiation of ductile fracture. We include sensitivity of stress triaxiality in a variational porous plasticity model, which was originally derived from hydrostatic expansion. Under loading conditions rather than hydrostatic deformation, we allow the critical pressure for voids to be exceeded so that the growth due to plasticity becomes dependent on the stress triaxiality. The limitations of the spherical void growth assumption are investigated. Our improved constitutive model is validated through good agreements with experimental data. Its capacity for reproducing realistic failure patterns is also indicated by a numerical simulation of a compact tensile (CT) test. © 2013 Elsevier Inc.

  8. Effects on stress rupture life and tensile strength of tin additions to Inconel 718

    Dreshfield, R. L.; Johnson, W.


    Because Inconel 718 represents a major use of columbium and a large potential source of columbium for aerospace alloys could be that of columbium derived from tin slags, the effects of tin additions to Inconel 718 at levels which might be typical of or exceed those anticipated if tin slag derived columbium were used as a melting stock were investigated. Tin was added to 15 pound Inconel 718 heats at levels varying from none added to approximately 10,000 ppm (1 wt%). Limited 1200 F stress rupture testing was performed at stresses from 68,000 to 115,000 psi and a few tensile tests were performed at room temperature, 800 and 1200 F. Additions of tin in excess of 800 ppm were detrimental to ductility and stress rupture life.

  9. Neutron diffraction measurements for the determination of residual stresses in MMC tensile and fatigue specimens

    Fiori, F.; Girardin, E.; Giuliani, A.;


    , residual stresses are present in both the matrix and the particles microstructure, prior to any macroscopic loading. They vary with the temperature and with the type and level of loading imposed to the material, having a strong influence on the mechanical behaviour of MMCs. Neutron diffraction measurements...... have been performed at RISO (Roskilde, DK) and HMI-BENSC (Berlin, D), for the determination of residual stress in AA2124 + 17% SiCp and AA359 + 20% SiCp specimens, submitted to tensile and fatigue tests. For each of the investigated samples, the macrostress has been separated from the elastic...... and thermal mismatch microstresses. The results show that, in general, the main contribution to the stress state of both matrix and reinforcement is given by the thermal microstresses, already existing due to heat treatment prior to mechanical tests. (C) 2000 Elsevier Science B.V. All rights reserved....

  10. Dynamic behavior of nano-voids in magnesium under hydrostatic tensile stress

    Ponga, Mauricio; Ramabathiran, Amuthan A.; Bhattacharya, Kaushik; Ortiz, Michael


    We investigate the mechanisms responsible for nano-void growth in single crystal magnesium under dynamic hydrostatic tensile stress. A key conclusion derived from our study is that there is no secondary strain hardening near the nano-void. This behavior, which is in remarkable contrast to face-centered cubic and body-centered cubic materials, greatly limits the peak stress and explains the relatively lower spall strength of magnesium. The lack of secondary strain hardening is due to the fact that pyramidal dislocations do not interact with basal or prismatic dislocations. Our analysis also shows that for loads applied at moderate strain rates (\\overset{\\centerdot}{ɛ} ≤slant {{10}6} s-1) the peak stress, dislocation velocity and temperature distribution converge asymptotically. However at very high strain rates (\\overset{\\centerdot}{ɛ} ≥slant {{10}8} s-1), there is a sharp transition in these quantities.

  11. Investigation of the dynamic mechanical behavior of polyetheretherketone (PEEK) in the high stress tensile regime

    Berer, M.; Major, Z.; Pinter, G.; Constantinescu, D. M.; Marsavina, L.


    Due to its outstanding mechanical performance both in static and dynamic loading and its resistance up to very high temperatures, Polyetheretherketone (PEEK) has attracted many practical applications. The loaded contact state for the application of PEEK rolls as bearing elements was recently analyzed by the corresponding author. High irreversible deformations on the mantle side were caused by the rolling contact and thus the rolling performance is supposed to be strongly affected by the dynamic mechanical properties of this irreversibly deformed material. Tensile fatigue tests at various stress levels up to the thermally dominated fatigue regime were conducted in order to get information regarding the dynamic mechanical material behavior at high stress regimes. Two types of PEEK (annealed and untreated) were investigated and two load ratios, R, were used (0.1 and 0.5). During the fatigue tests extensometer strain, load and surface temperature were recorded and a quantitative hysteresis loop analysis with calculated secant modulus and dynamic modulus was performed. Furthermore, the concept of isocyclic stress-strain diagrams was applied to enlarge and confirm the results obtained from the hysteresis loop analysis. A sharp transition between thermally dominated and mechanically dominated fatigue regimes was found for both PEEK types (annealed and untreated) and for both load ratios. Moreover, the annealed PEEK was stiffer in the tensile fatigue tests than the untreated material. Both examined PEEK types showed distinct hardening throughout the fatigue tests which made them "more elastic" (higher stiffness and less damping).


    Zhongjun Ren; Xianghe Peng; Chunhe Yang


    Based on the analysis of the deformation in an infinite isotropic elastic matrix with an embedded elliptic crack under far field coupled tensile and shear stresses,the energy release rate and a mixed fracture criterion are obtained using an energy balance approach.The additional compliance tensor induced by a single opening elliptic microcrack in a representative volume element is derived,and the effect of microcracks with random orientations is analyzed with the Taylor's scheme by introducing an appropriate probability density function.A micromechanical damage model for rocks and concretes is obtained and is verified with experimental results.

  13. Effects of residual stress and dislocation on tensile deformation behavior of SiCw/Al composites


    By means of XRD, Instron electronic tensile machine and TEM, the dislocation states and strengthening mechanisms of SiC whisker reinforced pure aluminum matrix composites were studied with different annealing treatment processes and matrixes. The results showed that the strengthening mechanisms of SiCw/p-Al composite and SiCw/6061Al composites are different. For the SiCw/p-Al composite, the thermal residual stress plays more important role in strengthening than the high density dislocations in matrix; for the SiCw/6061Al composite, the dislocation strengthening and precipitation are main strengthening factors.

  14. Ab initio local-energy and local-stress analysis of tensile behaviours of tilt grain boundaries in Al and Cu

    Wang, Hao; Kohyama, Masanori; Tanaka, Shingo; Shiihara, Yoshinori


    Tensile deformation and failure of Σ9 tilt grain boundaries (GBs) in Al and Cu have been examined by first-principles tensile tests (FPTTs). Local-energy and local-stress schemes were applied to clarify the variations of local energies and local hydrostatic stresses for all atoms during the deformation process. The GBs in Al and Cu exhibited quite different tensile behaviours in the FPTTs, despite their similar initial configurations. For the Al GB, there are two stages of deformation before failure. In the first stage, the back bonds of the interfacial bonds are mainly stretched, due to special high strength of the interfacial reconstructed bonds. In the second stage, the interfacial bonds begin to be significantly stretched due to high concentrated stresses, while stretching of the back bonds is suppressed. The atoms at the interfacial, back and bulk bonds have very different variations of local energies and local stresses during each stage, because the behaviour of each atom is significantly dependent on each local structural change due to the high sensitivity of sp electrons to the local environment in Al. The Cu GB has much higher tensile strength, and a natural introduction of stacking faults (SFs) occurs via the {111} shear slip in the bulk regions between the interfaces before the maximum stress is reached. This is caused by the smaller SF energy and lower ideal shear strength of Cu than Al, and is triggered by highly accumulated local energies and stress at the interface atoms. The local-energy distribution around the SF is consistent with the previous theoretical estimation. After the introduction of the SF, the local energies and stresses of all the atoms in the Cu GB supercell tend to become similar to each other during the tensile process, in contrast to the inhomogeneity in the Al GB. The origins of the different tensile behaviours observed for Al and Cu GBs are discussed with respect to the different bonding natures of Al and Cu, which are dominated

  15. Stress-deformed state of cylindrical specimens during indirect tensile strength testing

    Levan Japaridze


    In this study, the interaction between cylindrical specimen made of homogeneous, isotropic, and linearly elastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed that the specimen is diametrically compressed by elliptic normal contact stresses. The frictional contact stresses between the specimen and platens are neglected. The analytical solution starts from the contact problem of the loading jaws of any curvature and cylindrical specimen. The contact width, corresponding loading angle (2q0), and elliptical stresses obtained through solution of the contact problems are used as boundary conditions for a cylindrical specimen. The problem of the theory of elasticity for a cylinder is solved using Muskhelishvili’s method. In this method, the displacements and stresses are represented in terms of two analytical functions of a complex variable. In the main approaches, the nonlinear inter-action between the loading bearing blocks and the specimen as well as the curvature of their surfaces and the elastic parameters of their materials are taken into account. Numerical examples are solved using MATLAB to demonstrate the influence of deformability, curvature of the specimen and platens on the distribution of the normal contact stresses as well as on the tensile and compressive stresses acting across the loaded diameter. Derived equations also allow calculating the modulus of elasticity, total deformation modulus and creep parameters of the specimen material based on the experimental data of radial contraction of the specimen.

  16. Stress-deformed state of cylindrical specimens during indirect tensile strength testing

    Levan Japaridze


    Full Text Available In this study, the interaction between cylindrical specimen made of homogeneous, isotropic, and linearly elastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed that the specimen is diametrically compressed by elliptic normal contact stresses. The frictional contact stresses between the specimen and platens are neglected. The analytical solution starts from the contact problem of the loading jaws of any curvature and cylindrical specimen. The contact width, corresponding loading angle (2θ0, and elliptical stresses obtained through solution of the contact problems are used as boundary conditions for a cylindrical specimen. The problem of the theory of elasticity for a cylinder is solved using Muskhelishvili's method. In this method, the displacements and stresses are represented in terms of two analytical functions of a complex variable. In the main approaches, the nonlinear interaction between the loading bearing blocks and the specimen as well as the curvature of their surfaces and the elastic parameters of their materials are taken into account. Numerical examples are solved using MATLAB to demonstrate the influence of deformability, curvature of the specimen and platens on the distribution of the normal contact stresses as well as on the tensile and compressive stresses acting across the loaded diameter. Derived equations also allow calculating the modulus of elasticity, total deformation modulus and creep parameters of the specimen material based on the experimental data of radial contraction of the specimen.

  17. Tensile behavior and flow stress anisotropy of accumulative roll bonded Cu-Nb nanolaminates

    Nizolek, Thomas, E-mail:; Avallone, Jaclyn T.; Pollock, Tresa M. [Materials Department, University of California Santa Barbara, Santa Barbara, California 93106 (United States); Beyerlein, Irene J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Mara, Nathan A. [Institute for Materials Science and the Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)


    The flow stress, ductility, and in-plane anisotropy are evaluated for bulk accumulative roll bonded copper-niobium nanolaminates with layer thicknesses ranging from 1.8 μm to 15 nm. Uniaxial tensile tests conducted parallel to the rolling direction and transverse direction demonstrate that ductility generally decreases with decreasing layer thickness; however, at 30 nm, both high strengths (1200 MPa) and significant ductility (8%) are achieved. The yield strength increases monotonically with decreasing layer thickness, consistent with the Hall-Petch relationship, and significant in-plane flow stress anisotropy is observed. Taylor polycrystal modeling is used to demonstrate that crystallographic texture is responsible for the in-plane anisotropy and that the effects of texture dominate even at nanoscale layer thicknesses.

  18. Performance enhancement in uniaxially tensile stressed GeSn n-channel fin tunneling field-effect transistor: Impact of stress direction

    Wang, Hongjuan; Han, Genquan; Jiang, Xiangwei; Liu, Yan; Zhang, Chunfu; Zhang, Jincheng; Hao, Yue


    In this work, the boosting effect on the performance of GeSn n-channel fin tunneling FET (nFinTFET) enabled by uniaxial tensile stress is investigated theoretically. As the fin rotates within the (001) plane, the uniaxial tensile stress is always along its direction. The electrical characteristics of tensile-stressed GeSn nFinTFETs with point and line tunneling modes are computed utilizing the technology computer aided design (TCAD) simulator in which the dynamic nonlocal band-to-band tunneling (BTBT) algorithm is employed. In comparison with the relaxed devices, tensile-stressed GeSn nFinTFETs achieve a substantial enhancement in band-to-band tunneling generation rate (G BTBT) and on-state current I ON owing to the reduced bandgap E G induced by the tensile stress. Performance improvement of GeSn nFinTFETs induced by tensile stress demonstrates a strong dependence on channel direction and tunneling modes. Under the same magnitude of stress, line-nFinTFETs obtain a more pronounced I ON enhancement over the transistors with point tunneling mode.

  19. Tensile properties of single stress fibers isolated from cultured vascular smooth muscle cells.

    Deguchi, Shinji; Ohashi, Toshiro; Sato, Masaaki


    Stress fibers (SFs), a contractile bundle of actin filaments, play a critical role in mechanotransduction in adherent cells; yet, the mechanical properties of SFs are poorly understood. Here, we measured tensile properties of single SFs by in vitro manipulation with cantilevers. SFs were isolated from cultured vascular smooth muscle cells with a combination of low ionic-strength extraction and detergent extraction and were stretched until breaking. The breaking force and the Young's modulus (assuming that SFs were isotropic) were, on average, 377 nN and 1.45 MPa, which were approximately 600-fold greater and three orders of magnitude lower, respectively, than those of actin filaments reported previously. Strain-induced stiffening was observed in the force-strain curve. We also found that the extracted SFs shortened to approximately 80% of the original length in an ATP-independent manner after they were dislodged from the substrate, suggesting that SFs had preexisting strain in the cytoplasm. The force required for stretching the single SFs from the zero-stress length back to the original length was approximately 10 nN, which was comparable with the traction force level applied by adherent cells at single adhesion sites to maintain cell integrity. These results suggest that SFs can bear intracellular stresses that may affect overall cell mechanical properties and will impact interpretation of intracellular stress distribution and force-transmission mechanism in adherent cells.

  20. Influence of residual stresses on the tensile strength of composite-metal sandwich laminates

    Herakovich, C. T.; Wong, D. M.


    The tensile strength of boron-epoxy/aluminum sandwich laminates is discussed relative to the residual thermal stresses generated by curing and bonding at elevated temperatures. It is shown that the sandwich laminates investigated exhibit three dinstinct modes of failure, depending upon the fiber orientation of the composite. Sandwich laminates with moderate to high percentage of 0-deg fibers exhibit early failures initiated by edge effect; laminates with moderate to high percentage of 90-deg fibers fail according to a first-ply failure criterion; laminates with moderate to high percentages of plus or minus 45 deg plies fail at strains equal to or greater than the failure strain of the corresponding all-composite laminate.

  1. Local protrusions formed on Si(111) surface by surface melting and solidification under applied tensile stress

    Nishimura, T.; Tomitori, M.


    The surface structure and composition of Si(111) was modified, by heating it to 1300 °C in ultrahigh vacuum under an external tensile stress. A stress of approximately 1 GPa was applied, by pressing on the center of the rear side of the sample. This process produced two protrusions of approximately 100 μm in height, to the left and right of the center. Scanning Auger electron spectroscopy revealed Fe, Cr, Ni, and C impurities at the top of one protrusion, and C at the top of the other. These impurities likely diffused into the tops of the protrusions during heating, and segregated to the local surface during cooling when the protrusions formed. The protrusion formation mechanism is discussed. Their formation was related to non-uniform surface temperature, electromigration, piezoresistivity, freezing-point depression due to surface alloying with the impurities, and volume expansion during solidification from surface melting. These findings provide a perspective on controlling surface structures and compositions using heat and stress to induce self-assembly.

  2. Influence of Tensile Stresses on α+β – Titanium Alloy VT22 Corrosion Resistance in Marine Environment

    Yu. A. Puchkov


    Full Text Available Tensile stresses and hydrogen render strong influence on the titanic alloys propensity for delayed fracture. The protective film serves аs a barrier for penetration in hydrogen alloy. Therefore to study the stress effect on its structure and protective properties is of significant interest.The aim of this work is to research the tensile stress influence on the passivation, indexes of corrosion, protective film structure and reveal reasons for promoting hydrogenation and emerging propensity for delayed fracture of titanium alloy VТ22 in the marine air atmosphere.The fulfillеd research has shown that:- there is а tendency to reduce the passivation abilities of the alloy VТ22 in synthetic marine water (3 % solution of NaCl with increasing tensile stresses up to 1170 МPа, namely to reduce the potential of free corrosion and the rate of its сhange, thus the alloy remains absolutely (rather resistant;- the protective film consists of a titanium hydroxide layer under which there is the titanium oxide layer adjoining to the alloy, basically providing the corrosion protection.- the factors providing hydrogenation of titanium alloys and formation in their surface zone fragile hydrides, causing the appearing propensity for delayed fracture, alongside with tensile stresses are:- substances promoting chemisorbtion of hydrogen available in the alloy and on its surface;- the cathodic polarization caused by the coupling;- the presence of the structural defects promoting the formation of pitting and local аcidifying of the environment surrounding the alloy.

  3. Experimental and numerical determination of critical stress intensity factor of aluminum curved thin sheets under tensile stress

    Heidarvand, Majid; Soltani, Naser; Hajializadeh, Farshid [University of Tehran, Tehran (Iran, Islamic Republic of)


    We determined the fracture toughness of aluminum curved thin sheets using tensile stress tests and finite element method. We applied Linear elastic fracture mechanics (LEFM) and Feddersen procedure to evaluate stress intensity factor of the samples with central wire-cut cracks and fatigue cracks with different lengths to investigate the notch radius effect. Special fixture design was utilized to establish uniform stress distribution at the crack zone. Less than 9 % difference was found between the wire-cut and the fatigue cracked samples. Since generating central fatigue crack with different lengths required so much effort, wire-cut cracked samples were used to determine critical stress intensity factor. Finite element analysis was also performed on one-quarter of the specimen using both the singular Borsum elements and the regular isoparametric elements to further investigate fracture toughness of the samples. It was observed that the singular elements presented better results than the isoparametric ones. A slight difference was also found between the results obtained from finite element method using singular elements and the experimental results.

  4. Stress-induced crack path in Aji granite under tensile stress

    Kudo, Yozo; Sano, Osam; Murashige, Naokuni; Mizuta, Yoshiaki; Nakagawa, Koji


    The double-torsion test using Aji granite was carried out to investigate the interaction between stress-induced crack path and mineral grains. Crack velocities were controlled at range 10-7 m/s to 10-1 m/s. After the stressed specimens were dyed, we checked the crack path by thin section analysis, using an optical microscope. The stress-induced crack path was divided into two types, transgranular and intergranular cracks, and each path was subdivided with respect to mineral grains. In spite of the extensive range of crack velocities, the ratios between the transgranular and intergranular crack lengths did not change. The crack paths were all jagged, and often showed detour around the grain boundary when faced with obstacles like hard grains or preexisting cracks. That is to say, quartz grain played an important role as an obstacle. Feldspar grain could change the crack path because of its cleavage plane. Biolite grain had a serious effect on the path even if its constitution ratio is very small. Fractal dimensions of the crack paths were calculated by three methods, as indicators of surface roughness. The fractal dimensions were shown in a slight trend with the change of crack velocity. This trend can be explained from the point of limited cracking rate in stress corrosion.

  5. Experimental scale model study of cracking in brick masonry under tensile and shear stress

    Gálvez Ruiz, J. C.


    Full Text Available This article discusses the results of research conducted on the failure behaviour of brick masonry under tensile and shear stress. The study was designed to develop test models and generate experimental results able to provide greater insight into tensile and shear stresses cracking in brick masonry. The results of a campaign conducted with two types of specimens are discussed: 1 double-edge notched specimens under non-symmetrical compression stress, and 2 three point bending specimens under nonsymmetrical loading. Tests were run on specimens of similar size (similarity rate 2 and different bed joint orientation to determine how bed joint orientation affects crack propagation. The tests were conducted on scale models (1/4 of a single wythe, stretcher bond brickwork masonry wall one half foot thick.Este artículo presenta los resultados de la investigación realizada sobre el comportamiento en rotura de la fábrica de ladrillo bajo solicitaciones de tracción y cortante. La investigación está encaminada a proporcionar modelos de ensayo y resultados experimentales que permitan conocer mejor los procesos de agrietamiento de la fábrica de ladrillo bajo tensiones normales de tracción y tangenciales. Se presentan los resultados de una campaña experimental desarrollada con dos tipos de probeta: 1 la probeta compacta con doble entalla solicitada a compresión asimétrica, y 2 la probeta de flexión con entalla solicitada bajo carga asimétrica aplicada en tres puntos. Se han ensayado probetas de dos tamaños semejantes (razón de semejanza 2 y varias orientaciones de los tendeles, con el fin de ver cómo afecta la orientación de los tendeles en la propagación de las grietas. Los ensayos se han realizado con probetas a escala 1/4 de un muro de fábrica de ladrillo de una hoja a soga de medio pie de espesor.

  6. The effects of cyclic tensile and stress-relaxation tests on porcine skin.

    Remache, D; Caliez, M; Gratton, M; Dos Santos, S


    When a living tissue is subjected to cyclic stretching, the stress-strain curves show a shift down with the increase in the number of cycles until stabilization. This phenomenon is referred to in the literature as a preconditioning and is performed to obtain repeatable and predictable measurements. Preconditioning has been routinely performed in skin tissue tests; however, its effects on the mechanical properties of the material such as viscoelastic response, tangent modulus, sensitivity to strain rate, the stress relaxation rate, etc….remain unclear. In addition, various physical interpretations of this phenomenon have been proposed and there is no general agreement on its origin at the microscopic or mesoscopic scales. The purpose of this study was to investigate the effect of the cyclical stretching and the stress-relaxation tests on the mechanical properties of the porcine skin. Cyclic uniaxial tensile tests at large and constant strain were performed on different skin samples. The change in the reaction force, and skin's tangent modulus as a function of the number of cycles, as well as the strain rate effect on the mechanical behavior of skin samples after cycling were investigated. Stress-relaxation tests were also performed on skin samples. The change in the reaction force as a function of relaxation time and the strain rate effect on the mechanical behavior of skin samples after the stress-relaxation were investigated. The mechanical behavior of a skin sample under stress-relaxation test was modeled using a combination of hyperelasticity and viscoelasticity. Overall, the results showed that the mechanical behavior of the skin was strongly influenced by cycling and stress relaxation tests. Indeed, it was observed that the skin's resistance decreased by about half for two hours of cycling; the tangent modulus degraded by nearly 30% and skin samples became insensitive to the strain rates and accumulated progressively an inelastic deformation over time during

  7. The Effect of Grain Size and Strain on the Tensile Flow Stress of Aluminium at Room Temperature

    Hansen, Niels


    Tensile-stress-strain data over a strain range from 0.2 to 30% were obtained at room temperature for 99.999 and 99.5% aluminium as a function of grain size. The yield stress-grain size relationship can be expressed by a Petch-Hall relation with approximately the same slope for the two materials. ...... stress-grain size relationship was analyzed in terms of matrix strengthening and grain boundary strengthening according to the dislocation concept of Ashby. At intermediate strains this approach gives a good description of the effect of strain, grain size and purity on the flow stress....

  8. Tensile stress corrosion cracking of type 304 stainless steel irradiated to very high dose

    Chung, H. M.; Ruther, W. E.; Strain, R. V.; Shack, W. J.


    Certain safety-related core internal structural components of light water reactors, usually fabricated from Type 304 or 316 austenitic stainless steels (SSs), accumulate very high levels of irradiation damage (20--100 displacement per atom or dpa) by the end of life. The data bases and mechanistic understanding of, the degradation of such highly irradiated components, however, are not well established. A key question is the nature of irradiation-assisted intergranular cracking at very high dose, i.e., is it purely mechanical failure or is it stress-commotion cracking? In this work, hot-cell tests and microstructural characterization were performed on Type 304 SS from the hexagonal fuel can of the decommissioned EBR-11 reactor after irradiation to {approximately}50 dpa at {approximately}370 C. Slow-strain-rate tensile tests were conducted at 289 C in air and in water at several levels of electrochemical potential (ECP), and microstructural characteristics were analyzed by scanning and transmission electron microcopies. The material deformed significantly by twinning and exhibited surprisingly high ductility in air, but was susceptible to severe intergranular stress corrosion cracking (IGSCC) at high ECP. Low levels of dissolved O and ECP were effective in suppressing the susceptibility of the heavily irradiated material to IGSCC, indicating that the stress corrosion process associated with irradiation-induced grain-boundary Cr depletion, rather than purely mechanical separation of grain boundaries, plays the dominant role. However, although IGSCC was suppressed, the material was susceptible to dislocation channeling at low ECP, and this susceptibility led to poor work-hardening capability and low ductility.



    In order to explore the quantitative method of metal magnetic memory testing(MMMT) and clarify the relationship between Hp(y), the normal component of spontaneous stray field, and applied stress or residual stress, the static tensile tests of 0.45%C steel sheet specimens are carried out on a servo hydraulic MTS810 machine. Hp(y) values are measured during the test process by an EMS-2003 metal magnetic memory diagnostic apparatus and a non-magnetic electric control displacement instrument. Residual stresses of some points on the surface of a specimen are measured by a Stress Tech X-Stress 3000 X-ray diffraction instrument. The results show that the same variation rules of Hp(y) value versus applied tensile stress are presented under the different conditions of load-on and load-off. However, the same rule does not exist between the Hp(y) value and residual stress. The variation of Hp(y) value reflects the history of applied tensile stress.

  10. Fused deposition modeling (FDM) fabricated part behavior under tensile stress, thermal cycling, and fluid pressure

    Hossain, Mohammad Shojib

    Material extrusion based additive manufacturing (AM) technology, such as fused deposition modeling (FDM), is gaining popularity with the numerous 3D printers available worldwide. FDM technology is advancing from exclusively prototype construction to achieving production-grade quality. Today, FDM-fabricated parts are widely used in the aerospace industries, biomedical applications, and other industries that may require custom fabricated, low volume parts. These applications are and were possible because of the different production grade material options (e.g., acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polyphenylsulfone (PPSF), etc.) available to use in FDM systems. Recent researchers are exploring other material options including polycaprolactone (PCL), polymethylmethacrylate (PMMA), composites containing ceramic, glass and metal fillers, and even metals which depict the diversified materials and possibility of new material options using FDM technology. The understanding of the behavior and mechanical properties of the finished FDM-fabricated parts is of utmost importance in the advancement of this technology. The processing parameters, e.g., build orientation, raster width (RW), contour width (CW), raster angle (RA), and raster to raster air gap (RRAG) are important factors in determining the mechanical properties of FDM fabricated parts. The work presented here focused on the mechanical properties improvement by modifying those build parameters. The main concentration is on how modifying those parameters can improve ultimate tensile stress (UTS), Young's modulus, and tensile strain of the final product. In this research, PC parts were fabricated using three build methods: 1) default method, 2) Insight revision method, and 3) visual feedback method. By modifying build parameters, the highest average UTS obtained for PC was 63.96 MPa which was 7% higher than that of 59.73 MPa obtained using the default build parameters. The parameter modification

  11. Effect of thermal residual stresses on yielding behavior under tensile or compressive loading of short fiber reinforced metal matrix composite

    丁向东; 连建设; 江中浩; 孙军


    Using large strain two-dimension axisymmetric elasto-plastic finite element method and the modified law of mixture, the effects of thermal residual stresses on the yielding behavior of short fiber reinforced metal matrix composite and their dependencies on the material structure parameters (fiber volume fraction, fiber aspect ratio and fiber end distance) were studied. It is demonstrated that the stress-strain partition parameter can be used to describe the stress transfer from the matrix to the fiber. The variation of the second derivation of the stress-strain partition parameter can be used to determine the elastic modulus, the proportion limit, the initial and final yield strengths. In the presence of thermal residual stress, these yielding properties are asymmetric and are influenced differently by the material structure parameters under tensile and compressive loadings.

  12. Evaluation of impacts of stress triaxiality on plastic deformability of RAFM steel using various types of tensile specimen

    Kato, Taichiro, E-mail: [Japan Atomic Energy Agency, 2-166, Obuchi-omotedate, Rokkasho, Aomori 039-3212 (Japan); Ohata, Mitsuru [Osaka University, 2-1, Yamada-Oka, Suita, Osaka 565-0871 (Japan); Nogami, Shuhei [Tohoku University, 6-6-01-2, Aramaki-aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Tanigawa, Hiroyasu [Japan Atomic Energy Agency, 2-166, Obuchi-omotedate, Rokkasho, Aomori 039-3212 (Japan)


    Highlights: • The fracture ductility is lower as the stress triaxiality is higher. • Voids of the interrupted RB1 specimen were observed along grain boundaries and expanded parallel to the tensile axis. • Voids of interrupted R0.2 specimen were rounded shape than those of RB1. • The fracture surface of specimens were observed the elongated and the equiaxed dimples. • The decrease of plastic deformability of the notched specimen was caused by the process of voids formation and crack growth due to the effect of plastic constraint of the notch. - Abstract: A case study on a fusion blanket design such as DEMO indicated that there could be some sections with high stress triaxiality, a parameter to evaluate the magnitude of plastic constraint, in the case of plasma disruption or coolant loss accident. Therefore, it is necessary to accurately understand the ductility loss limit of structural material in order to conduct the structural design assessment of the irradiated and embrittled fusion reactor blanket. Tensile tests were conducted by using three kinds of tensile specimen shapes to investigate of the plastic deformability of F82H. From the results, the fracture ductility is lower as the stress triaxiality is higher. Voids of the interrupted RB1 specimen were observed along grain boundaries and expanded parallel to the tensile axis. That of interrupted R0.2 specimen was rounded shape compared with those of RB1. The fracture surface of RB1 and R0.2 specimens were observed the elongated dimples and the equiaxed dimples without so much elongation, respectively. It is considered that the decrease of plastic deformability for the notched specimen was caused by the process of voids formation and crack growth due to the effect of plastic constraint of the notch.

  13. Influence of the microstructural changes and induced residual stresses on tensile properties of wrought magnesium alloy friction stir welds

    Commin, Loreleie, E-mail: [LMPF, Arts et Metiers ParisTech, rue St Dominique, 51000 Chalons en Champagne (France); Dumont, Myriam [Aix-Marseille Universite, CNRS, IM2NP (UMR 6242), Faculte St-Jerome, Case 261, Av. Escadrille Normandie-Niemen, 13 397 Marseille Cedex 20 (France); Rotinat, Rene; Pierron, Fabrice [LMPF, Arts et Metiers ParisTech, rue St Dominique, 51000 Chalons en Champagne (France); Masse, Jean-Eric; Barrallier, Laurent [MecaSurf, Arts et Metiers ParisTech, 2 cours des Arts et Metiers, 13100 Aix en Provence (France)


    Highlights: Black-Right-Pointing-Pointer Study of AZ31 FSW mechanical behaviour. Black-Right-Pointing-Pointer Early yielding occurs in the TMAZ, the nugget and base metal zones undergo almost no plastic strains. Black-Right-Pointing-Pointer Texture gradient in the TMAZ localises the deformations in this area. Black-Right-Pointing-Pointer Residual stresses have a major influence in FSW mechanical behaviour. - Abstract: Friction stir welding induces a microstructural evolution and residual stresses that will influence the resulting mechanical properties. Friction stir welds produced from magnesium alloy hot rolled plates were studied. Electron back scattered diffraction was used to determine the texture evolution, residual stresses were analysed using X ray diffraction and tensile tests coupled with speckle interferometry were performed. The residual stresses induced during friction stir welding present a major influence on the final mechanical properties.

  14. Cracking and Deformation Modelling of Tensile RC Members Using Stress Transfer Approach

    Ronaldas Jakubovskis


    Full Text Available The paper presents a modeling technique for bond, cracking and deformation analysis of RC members. The proposed mod-eling technique is not restricted by the geometrical dimensions of the analyzed member and may be applied for various load-ing conditions. Tensile as well as bending RC members may be analyzed using the proposed technique. Adequacy of the modeling strategy was evaluated by the developed numerical discrete crack algorithm, which allows modeling deformation and cracking behavior of tensile RC members. Comparison of experimental and numerical results proved the applicability of the proposed modeling strategy.

  15. Effect of Prior Exposure at Elevated Temperatures on Tensile Properties and Stress-Strain Behavior of Four Non-Oxide Ceramic Matrix Composites



  16. Analysis of Tensile Stress-Strain and Work-Hardening Behavior in 9Cr-1Mo Ferritic Steel

    Choudhary, B. K.; Palaparti, D. P. Rao; Samuel, E. Isaac


    Detailed analysis on tensile true stress ( σ)-true plastic strain ( ɛ) and work-hardening behavior of 9Cr-1Mo steel have been performed in the framework of the Voce relationship and Kocks-Mecking approach for wide range of temperatures, 300 K to 873 K (27 °C to 600 °C) and strain rates (6.33 × 10-5 to 6.33 × 10-3 s-1). At all test conditions, σ- ɛ data were adequately described by the Voce equation. 9Cr-1Mo steel exhibited two-stage work-hardening behavior characterized by a rapid decrease in instantaneous work-hardening rate ( θ = dσ/ dɛ) with stress at low stresses (transient stage) followed by a gradual decrease in θ at high stresses (stage III). The variations of work-hardening parameters and θ- σ as a function of temperature and strain rate exhibited three distinct temperature regimes. Both work-hardening parameters and θ- σ displayed signatures of dynamic strain aging at intermediate temperatures and dominance of dynamic recovery at high temperatures. Excellent correlations have been obtained between work-hardening parameters evaluated using the Voce relationship and the respective tensile properties. A comparison of work-hardening parameters obtained using the Voce equation and Kocks-Mecking approach suggested an analogy between the two for the steel.

  17. Stone Matrix Asphalt (SMA is a gap-graded mix that is gaining popularity worldwide. Generally, gap graded mixes are thought to be weak in fatigue resistance. In this study, cellulose fibers were pre-blended in PG64-22 binder with fiber proportions of 0.2%, 0.4%, 0.6%, 0.8% and 1.0% by weight of aggregates. The fiber-modified binder showed improved rheological properties and showed that the PG64-22 binder can be modified and raised to PG70-22 grade. The cellulose oil palm fiber (COPF was found to improve the diameteral fatigue performance of SMA design mix. The fatigue life increased to a maximum at a fiber content of about 0.6%, whilst the tensile stress and stiffness also showed a similar trend in performance. The initial strains of the mix were lowest at a fiber content of 0.6%.

    Ratnasamy Muniandy


    Full Text Available Stone Matrix Asphalt (SMA is a gap-graded mix that is gaining popularity worldwide. Generally, gap graded mixes are thought to be weak in fatigue resistance. In this study, cellulose fibers were pre-blended in PG64-22 binder with fiber proportions of 0.2%, 0.4%, 0.6%, 0.8% and 1.0% by weight of aggregates. The fiber-modified binder showed improved rheological properties and showed that the PG64-22 binder can be modified and raised to PG70-22 grade. The cellulose oil palm fiber (COPF was found to improve the diameteral fatigue performance of SMA design mix. The fatigue life increased to a maximum at a fiber content of about 0.6%, whilst the tensile stress and stiffness also showed a similar trend in performance. The initial strains of the mix were lowest at a fiber content of 0.6%.

  18. Effect of compressive and tensile stresses on swelling and creep strain of Fe-18Cr-10Ni-Ti austenitic steel

    Neustroev, V.S.; Makarov, E.I.; Belozerov, S.V.; Ostrovsky, Z.E. [JSC ' SSC RIAR' (Russian Federation)


    At present, work in justification of the lifetime prolongation of the operated VVER-440 and VVER-1000 internals as well as of the operation of new VVER reactor internals up to 60 years is the most urgent. Fe-0.08C-18Cr-10Ni-Ti austenitic steel, being the material of operated and new VVER internals, was selected for the experiment. As the design of internals is very complicated and there are many holes for cooling, areas with compressive and tensile stresses may appear, so it is important to investigate the effect of stresses on the properties and structure of the material. Experiments to investigate the effect of tensile stress on the properties and structure of the material have been carried out both at 'SSC RIAR', Russia and abroad, but the effect of compressive stress has not been practically studied. Besides, we had to check if the known mechanisms and dependence of creep strain on stress type would remain. This paper presents the effect of compressive and tensile stresses on swelling, microstructure and creep strain of Fe-0.08C-18Cr-10Ni-Ti steel. It appears that: -) creep strain of the specimens is in the proportion to damage dose and tensile stress, and -) hardening induced by irradiation is the same for both stressed and non-stressed specimens

  19. Effect of stress-induced grain growth during room temperature tensile deformation on ductility in nanocrystalline metals

    Weichang Xu; Pinqiang Dai; Xiaolei Wu


    In the present study defect-free nanocrystalline (nc) Ni–Co alloys with the Co content ranging from 2.4–59.3% (wt.%) were prepared by pulse electrodeposition. X-ray diffraction analysis shows that only a single face-centred cubic solid solution is formed for each alloy and that the grain size reduces monotonically with increasing Co content, which is consistent with transmission electron microscopy (TEM) observations. In the nc Ni–Co alloys, both the ultimate tensile strength and the elongation to failure increase as the Co content increases. The TEM observations reveal that stress-induced grain growth during tensile deformation is significantly suppressed for the nc Ni–Co alloys rich in Co in sharp contrast to those poor in Co. We believe that sufficient solutes could effectively pin grain boundaries making grain boundary motions (e.g. grain boundary migration and/or grain rotation) during deformation more difficult. Thus, stress-induced grain growth is greatly suppressed. At the same time, shear banding plasticity instability is correspondingly delayed leading to the enhanced ductility.

  20. Residual Stresses and Tensile Properties of Friction Stir Welded AZ31B-H24 Magnesium Alloy in Lap Configuration

    Naik, Bhukya Srinivasa; Cao, Xinjin; Wanjara, Priti; Friedman, Jacob; Chen, Daolun


    AZ31B-H24 Mg alloy sheets with a thickness of 2 mm were friction stir welded in lap configuration using two tool rotational rates of 1000 and 1500 rpm and two welding speeds of 10 and 20 mm/s. The residual stresses in the longitudinal and transverse directions of the weldments were determined using X-ray diffraction. The shear tensile behavior of the lap joints was evaluated at low [233 K (-40 °C)], room [298 K (25 °C)], and elevated [453 K (180 °C)] temperatures. The failure load was highest for the lower heat input condition that was obtained at a tool rotational rate of 1000 rpm and a welding speed of 20 mm/s for all the test temperatures, due to the smaller hooking height, larger effective sheet thickness, and lower tensile residual stresses, as compared to the other two welding conditions that were conducted at a higher tool rotational rate or lower welding speed. The lap joints usually fractured on the advancing side of the top sheet near the interface between the thermo-mechanically affected zone and the stir zone. Elevated temperature testing of the weld assembled at a tool rotational rate of 1000 rpm and a welding speed of 20 mm/s led to the failure along the sheet interface in shear fracture mode due to the high integrity of the joint that exhibited large plastic deformation and higher total energy absorption.

  1. Tensile stress-strain and work hardening behaviour of P9 steel for wrapper application in sodium cooled fast reactors

    Christopher, J.; Choudhary, B. K.; Isaac Samuel, E.; Mathew, M. D.; Jayakumar, T.


    Tensile flow behaviour of P9 steel with different silicon content has been examined in the framework of Hollomon, Ludwik, Swift, Ludwigson and Voce relationships for a wide temperature range (300-873 K) at a strain rate of 1.3 × 10 -3 s -1. Ludwigson equation described true stress ( σ)-true plastic strain ( ɛ) data most accurately in the range 300-723 K. At high temperatures (773-873 K), Ludwigson equation reduces to Hollomon equation. The variations of instantaneous work hardening rate ( θ = dσ/ dɛ) and θσ with stress indicated two-stage work hardening behaviour. True stress-true plastic strain, flow parameters, θ vs. σ and θσ vs. σ with respect to temperature exhibited three distinct temperature regimes and displayed anomalous behaviour due to dynamic strain ageing at intermediate temperatures. Rapid decrease in flow stress and flow parameters, and rapid shift in θ- σ and θσ- σ towards lower stresses with increase in temperature indicated dominance of dynamic recovery at high temperatures.

  2. Determination of the hot rolling stress by means of tensile tests; Determinacion de la tension de laminacion en caliente a partir de ensayos de traccion

    Monsalve, A.; Artigas, A.; Celentano, D.; Guzman, A.; Colas, R.; Houbaert, Y.


    Prediction of mechanical behavior of hot rolled steels is an important aspect during industrial processing. The rolling stress needed to the process were estimated using three methods, the first of which is related to the Sellars's model that takes into account the friction coefficient and the yield stress. The second method estimates the rolling stress as the average stress obtained during the tensile tests. The third method, estimates the rolling stress from the data of power consumed by the rolling equipment. This methodology was applied in this study to a carbon steel. The conclusion of the work is that results obtained by Sellars's and consumed power, are coincident. The method based on the average tensile stress predicts stresses lower than those obtained with other two methods. (Author) 26 refs.

  3. Is crack branching under shear loading caused by shear fracture? ——A critical review on maximum circumferential stress theory



    When a crack is subjected to shear force, crack branching usually occurs. Theoretical study shows that the crack branching under shear loading is caused by tensile stress, but not caused by shear fracture. The co-plane shear fracture could be obtained if compressive stress with given direction is applied to the specimen, subsequently, calculated shear fracture toughness, KⅡ C, is larger than KⅠ C. A prerequisite of possible occurrence of mode Ⅱ fracture was proposed. The study of shear fracture shows that the maximum circumferential stress theory considered its criterion as a parametric equation of a curve in KⅠ, KⅡ plane is incorrect; the predicted ratio KⅡ C/KⅠ C=0.866 is incorrect too.

  4. Tensile properties and microstructure of 2024 aluminum alloy subjected to the high magnetic field and external stress

    Li, Gui-Rong; Xue, Fei; Wang, Hong-Ming; Zheng, Rui; Zhu, Yi; Chu, Qiang-Ze; Cheng, Jiang-Feng


    In order to explore the dependence of plasticity of metallic material on a high magnetic field, the effects of the different magnetic induction intensities ( H = 0 T, 0.5 T, 1 T, 3 T, and 5 T) and pulses number (N = 0, 10, 20, 30, 40, and 50) on tensile strength (σ b) and elongation (δ) of 2024 aluminum alloy are investigated in the synchronous presences of a high magnetic field and external stress. The results show that the magnetic field exerts apparent and positive effects on the tensile properties of the alloy. Especially under the optimized condition of H * = 1 T and N* = 30, the σ b and δ are 410 MPa and 17% that are enhanced by 9.3% and 30.8% respectively in comparison to those of the untreated sample. The synchronous increases of tensile properties are attributed to the magneto-plasticity effect on a quantum scale. That is, the magnetic field will accelerate the state conversion of radical pair generated between the dislocation and obstacles from singlet to the triplet state. The bonding energy between them is meanwhile lowered and the moving flexibility of dislocations will be enhanced. At H * = 1 T and N* = 30, the dislocation density is enhanced by 1.28 times. The relevant minimum grain size is 266.1 nm, which is reduced by 35.2%. The grain refining is attributed to the dislocation accumulation and subsequent dynamic recrystallization. The (211) and (220) peak intensities are weakened. It is deduced that together with the recrystallization, the fine grains will transfer towards the slip plane and contribute to the slipping deformation. Project supported by the National Natural Science Foundation of China (Grant Nos. 51371091, 51174099, and 51001054) and the Industrial Center of Jiangsu University, China (Grant No. ZXJG201586).

  5. Effect of tensile stress on the formation of S-phase during low-temperature plasma carburizing of 316L foil

    Li Wei [School of Metallurgy and Materials, University of Birmingham, B15 2TT (United Kingdom); Li Xiaoying, E-mail: [School of Metallurgy and Materials, University of Birmingham, B15 2TT (United Kingdom); Dong Hanshan [School of Metallurgy and Materials, University of Birmingham, B15 2TT (United Kingdom)


    Low-temperature plasma carburizing of austenitic stainless steel can produce a carbon-supersaturated austenite layer, the 'S-phase', on the surface, which has high hardness, excellent wear and fatigue properties, and good corrosion resistance. Although the S-phase was discovered some years ago, the basic understanding of S-phase formation remains incomplete. In this paper, the effect of tensile stresses (0-80 MPa) on the formation and stability of S-phase during carburizing of 316L stainless steel foils at 400, 425 and 450 deg. C for 10 h has been investigated for the first time. The microstructures were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy and the mechanical properties were evaluated by microhardness and tensile tests. The results showed that the in situ applied tensile stress effectively thickened S-phase layers. The calculated activation energy for carbon diffusion in 316L was reduced from 142.76 to 133.91 kJ mol{sup -1} when a tensile stress of 40 MPa was applied. However, chromium carbides were formed in the outmost surface when the tensile stress exceeded 40 MPa. The results are discussed and explained through appropriate thermodynamic calculations.

  6. Incorporation of Mean/Maximum Stress Effects in the Multiaxial Racetrack Filter

    Marco Antonio Meggiolaro


    Full Text Available This work extends the Multiaxial Racetrack Filter (MRF to incorporate mean or maximum stress effects, adopting a filter amplitude that depends on the current stress level along the stress or strain path. In this way, a small stress or strain amplitude event can be filtered out if associated with a non-damaging low mean or peak stress level, while another event with the very same amplitude can be preserved if happening under a more damaging high mean or peak stress level. The variable value of the filter amplitude must be calculated in real time, thus it cannot depend on the peak or mean stresses along a load event, because it would require cycle identification and as so information about future events. Instead, mean/maximum stress effects are modeled in the filter as a function of the current (instantaneous hydrostatic or normal stress along the multiaxial load path, respectively for invariantbased and critical-plane models. The MRF efficiency is evaluated from tension-torsion experiments in 316L stainless steel tubular specimens under non-proportional (NP load paths, showing it can robustly filter out nondamaging events even under multiaxial NP variable amplitude loading histories

  7. In-shoe plantar tri-axial stress profiles during maximum-effort cutting maneuvers.

    Cong, Yan; Lam, Wing Kai; Cheung, Jason Tak-Man; Zhang, Ming


    Soft tissue injuries, such as anterior cruciate ligament rupture, ankle sprain and foot skin problems, frequently occur during cutting maneuvers. These injuries are often regarded as associated with abnormal joint torque and interfacial friction caused by excessive external and in-shoe shear forces. This study simultaneously investigated the dynamic in-shoe localized plantar pressure and shear stress during lateral shuffling and 45° sidestep cutting maneuvers. Tri-axial force transducers were affixed at the first and second metatarsal heads, lateral forefoot, and heel regions in the midsole of a basketball shoe. Seventeen basketball players executed both cutting maneuvers with maximum efforts. Lateral shuffling cutting had a larger mediolateral braking force than 45° sidestep cutting. This large braking force was concentrated at the first metatarsal head, as indicated by its maximum medial shear stress (312.2 ± 157.0 kPa). During propulsion phase, peak shear stress occurred at the second metatarsal head (271.3 ± 124.3 kPa). Compared with lateral shuffling cutting, 45° sidestep cutting produced larger peak propulsion shear stress (463.0 ± 272.6 kPa) but smaller peak braking shear stress (184.8 ± 181.7 kPa), of which both were found at the first metatarsal head. During both cutting maneuvers, maximum medial and posterior shear stress occurred at the first metatarsal head, whereas maximum pressure occurred at the second metatarsal head. The first and second metatarsal heads sustained relatively high pressure and shear stress and were expected to be susceptible to plantar tissue discomfort or injury. Due to different stress distribution, distinct pressure and shear cushioning mechanisms in basketball footwear might be considered over different foot regions.

  8. Maximum length of large diameter Czochralski silicon single crystals at fracture stress limit of seed

    Kim, K. M.; Smetana, P.


    Growth of large diameter Czochralski (CZ) silicon crystals require complete elimination of dislocations by means of Dash technique, where the seed diameter is reduced to a small size typically 3 mm in conjunction with increase in the pull rate. The maximum length of the large CZ silicon is estimated at the fracture stress limit of the seed neck diameter ( d). The maximum lengths for 200 and 300 mm CZ crystals amount to 197 and 87 cm, respectively, with d = 0.3 cm; the estimated maximum weight is 144 kg.

  9. Effect of external tensile stress on blue InGaN/GaN multi-quantum-well light-emitting diodes

    Tawfik, Wael Z. [Interdisciplinary Program of Photonic Engineering, Chonnam National University, Yongbong 300, Gwangju 500-757 (Korea, Republic of); Department of Physics, Faculty of Science, Beni-Suef University, Beni-Suef 62511 (Egypt); Song, Juhui; Lee, Jung Ju; Ha, Jun Seok; Ryu, Sang-Wan [Interdisciplinary Program of Photonic Engineering, Chonnam National University, Yongbong 300, Gwangju 500-757 (Korea, Republic of); Choi, Hee Seok [Interdisciplinary Program of Photonic Engineering, Chonnam National University, Yongbong 300, Gwangju 500-757 (Korea, Republic of); LG Innotek Co., Ltd., 413-901 Paju (Korea, Republic of); Ryu, Bengso [Interdisciplinary Program of Photonic Engineering, Chonnam National University, Yongbong 300, Gwangju 500-757 (Korea, Republic of); Lee, June Key, E-mail: [Interdisciplinary Program of Photonic Engineering, Chonnam National University, Yongbong 300, Gwangju 500-757 (Korea, Republic of)


    The influence of external tensile stress on blue InGaN/GaN multi-quantum-well (MQW) light-emitting diodes (LEDs) is demonstrated. It was found that applying external tensile stress effectively compensates for the compressive strain developed in the InGaN active layer, thus reducing the quantum-confined Stark effect by attenuating the piezoelectric polarization from the InGaN layer. With 35 A/cm{sup 2} of current density (∼50 mA), the light output power could be improved by ∼40% when the LEDs were subjected to an external tensile stress. The blueshift in electroluminescence (EL) spectra was reduced by applying the external tensile stress. In contrast, when the LEDs were exposed to external compressive stress, the light output power intensity was decreased by ∼12% at a current density of 35 A/cm{sup 2}. The simulation results confirm that the relaxation of compressive strain in the InGaN/GaN MQW structure results in the reduction of the piezoelectric field and improves the overlap of electron and hole wave functions.

  10. Tensile stress patterns predicted in the articular disc of the human temporomandibular joint

    Koolstra, J.H.; Tanaka, E.


    The direction of the first principal stress in the articular disc of the temporomandibular joint was predicted with a biomechanical model of the human masticatory system. The results were compared with the orientation of its collagen fibers. Furthermore, the effect of an active pull of the superior

  11. Tensile testing


    A complete guide to the uniaxial tensile test, the cornerstone test for determining the mechanical properties of materials: Learn ways to predict material behavior through tensile testing. Learn how to test metals, alloys, composites, ceramics, and plastics to determine strength, ductility and elastic/plastic deformation. A must for laboratory managers, technicians, materials and design engineers, and students involved with uniaxial tensile testing. Tensile Testing , Second Edition begins with an introduction and overview of the test, with clear explanations of how materials properties are determined from test results. Subsequent sections illustrate how knowledge gained through tensile tests, such as tension properties to predict the behavior (including strength, ductility, elastic or plastic deformation, tensile and yield strengths) have resulted in improvements in materals applications. The Second Edition is completely revised and updated. It includes expanded coverage throughout the volume on a variety of ...

  12. Hypersonic Velocities and Submicrocrack Formation in Ductile Polymers under Uniaxial Tensile Stress

    Shichijyo, Shiro; Nishimura, Kazuhiro; Shirouzu, Shigenori; Matsushige, Kazumi; Takemura, Tetuo


    Longitudinal hypersonic sound velocities in two kinds of ductile polymer, polycarbonate (PC) and polyethylene terephthalate (PET), were examined by Brillouin scattering. These two materials exhibited a decrease in hypersonic sound velocity (the softening phenomenon) when stress was applied, but the amount of softening as well as its angular dependence with respect to the stress direction were much smaller than those for a typical brittle polymer, poly (methyl methacrylate) (PMMA). Furthermore, a correlation between these acoustic properties and the formation of submicrocracks was demonstrated by small-angle X-ray scattering (SAXS) measurements. The difference in the anisotropies in the softening of sound velocity between ductile and brittle polymers is discussed from the viewpoint of the shape and density of the submicrocracks

  13. The Behavior of Ceramic Matrix, Fiber Composites under Combined Impact and Tensile Stresses


    driven, testing machine and the Hounsfield Tensometer was located across the bed of the Instron so that the specimen could be pre-stressed by the...45 7. Specimen configuration in the tensometer grips. 46 8. Cut-away drawing of the furnace and dual purpose specimen 47 jig used in the various...Optimization was carried out using a small die assembly to produce specimens 50 mm x 15 mm x 1 mm, from which were machined flexural test specimens 50

  14. Impact of residual stress on the adhesion and tensile fracture of TiN/CrN multi-layered coatings from first principles

    Yin, Deqiang; Peng, Xianghe; Qin, Yi; Wang, Zhongchang


    Multilayered TiN/CrN coatings find a wide range of technological applications where their internal hetero-interfaces and corresponding residual stress have been long suspected as capable of influencing their intriguing mechanical and chemical performances such as the thermal stability, hardness, and corrosion, tribological and wear resistance. Here, we investigate, by first-principles calculations, atomic and electronic structures of the TiN/CrN interface and how the residual stress influences the adhesion and ideal tensile strength of the multilayered coatings. We find that calculated adhesion energies of the interfaces with (1 1 1) and (0 0 1) orientations are small under no residual stress, yet increase almost linearly when the residual stress is imposed, suggesting that the residual stress plays a dominant role in affecting adhesion. The strengthened adhesion affected by the residual stress is found to be attributable to the stress-induced shrinkage of bonds, which results in enhanced interactions between the bonds in the TiN/CrN coatings. Using several analytic techniques, we have characterized the electronic structure of the interface carefully and determined the interfacial bonding to be primarily ionic with a small degree of covalency. The tensile simulations reveal that the interface with the (1 1 1) texture is more brittle than that with the (0 0 1), although the former presents greater ideal tensile strength. The findings presented here shed light on the impact of residual stress on the adhesion and ideal tensile strength of the TiN/CrN multi-layers, which information could be hard to obtain by means of experiments alone but which is of practical importance for further understanding and improvement of the multi-layered coatings at atomic scale.

  15. Fabrication of Fe-based ribbon with controlled permeability by Joule heating under tensile stress

    Yanai, T. [Department of Electrical and Electronic Engineering, Faculty of Engineering of the University of Nagasaki, Nagasaki 852-8521 (Japan)], E-mail:; Takagi, K.; Takahashi, K.; Nakano, M. [Department of Electrical and Electronic Engineering, Faculty of Engineering of the University of Nagasaki, Nagasaki 852-8521 (Japan); Yoshizawa, Y. [Advanced Electronics Research Laboratory, Hitachi Metals Ltd., Kumagaya 360-0843 (Japan); Fukunaga, H. [Department of Electrical and Electronic Engineering, Faculty of Engineering of the University of Nagasaki, Nagasaki 852-8521 (Japan)


    We prepared an Fe-based ribbon with controlled permeability and low magnetic loss by continuous stress-annealing by joule heating (CSA-JH) method. The shortest annealing time necessary for the obtaining of the ribbons with completely developed anisotropy was 1 s, but in order to obtain the sufficiently crystallized ribbons with small saturation magnetostriction it is required to perform annealing longer than 2 s. A toroidal core was prepared from a long ribbon with controlled permeability and small saturation magnetostriction, and the magnetic loss and relative permeability of the core were evaluated in the frequency range of 0.1-3 MHz. The permeability was kept constant up to 2 MHz, and the magnetic loss is lower than that for other types of core with a similar permeability value. These results suggest that the CSA-JH method is a promising method for realizing an Fe-based core with excellent magnetic properties.

  16. Creep measurements confirm steady flow after stress maximum in extension of branched polymer melts

    Javier Alvarez, Nicolas; Román Marín, José Manuel; Huang, Qian;


    We provide conclusive evidence of nonmonotonic mechanical behavior in the extension of long-chain branched polymer melts. While nonmonotonic behavior is known to occur for solids, for the case of polymeric melts, this phenomenon is in direct contrast with current theoretical models. We rule out...... the possibility of the overshoot being an experimental artifact by confirming the existence of steady flow after a maximum in the ratio of stress to strain rate versus strain under both constant stress and constant strain-rate kinematics. This observation indicates the omission of important physics from current...

  17. Design of reinforced concrete walls casted in place for the maximum normal stress of compression

    T. C. Braguim

    Full Text Available It is important to evaluate which designing models are safe and appropriate to structural analysis of buildings constructed in Concrete Wall system. In this work it is evaluated, through comparison of maximum normal stress of compression, a simple numerical model, which represents the walls with frame elements, with another much more robust and refined, which represents the walls with shells elements. The designing of the normal stress of compression it is done for both cases, based on NBR 16055, to conclude if the wall thickness initially adopted, it is enough or not.

  18. Effect of strain rate and stress triaxiality on tensile behavior of Titanium alloy Ti-10-2-3 at elevated temperatures

    Bobbili, Ravindranadh, E-mail:; Madhu, Vemuri


    In this study, Split hopkinson tension bar (SHTB) has been employed to investigate the dynamic tensile flow behavior of Ti-10-2-3 alloy at high strain rates and elevated temperatures. The combined effect of stress triaxiality, strain rate and temperature and on the tensile behavior of the alloy was evaluated. Johnson-Cook (J-C) constitutive and fracture models were developed based on high strain rate tensile data. A modified Johnson–Cook model was established and proved to have high accuracy. A comparative assessment has been done to confirm the accuracy of modified J–C model based on finite element method (FEM). The improved model provides better description on the influence of equivalent plastic strain rate and temperature on the plastic flow. The simulation results proved to be in good agreement with the experimental data. The fracture surfaces of specimens tested under various strain rates and temperatures were studied under scanning electron microscopy (SEM).

  19. Characterization of spontaneous magnetic signals induced by cyclic tensile stress in crack propagation stage

    Huang, Haihong, E-mail:; Jiang, Shilin; Wang, Yan; Zhang, Lei; Liu, Zhifeng


    Influenced by the geomagnetic field, crack can induce spontaneous magnetic signals in ferromagnetic steels. The normal component of surface spontaneous magnetic signals of the center-cracked sheet specimens, H{sub p}(y), was measured throughout the tension–tension fatigue tests. The variation of H{sub p}(y) and its maximum gradient K{sub max} in the crack propagation stage were studied. It shows that H{sub p}(y) began to change its polarity, just right on the crack position, in the intermediate stage of crack propagation. The cause for this phenomenon was also discussed. The peak-to-peak value, ΔH{sub p}(y), of the magnetic signal when H{sub p}(y) changing its polarity was collected, and discrete wavelet transform (DWT) was further used to acquire high frequency components of the H{sub p}(y) signal. The results show that the K{sub max} increased exponentially with the increase of loading cycles; an approximate linear relationship was found between K{sub max} and crack length 2a in the intermediate stage of crack propagation; and the high-frequency component of H{sub p}(y) can be used to identify the late stage of crack propagation. - Highlights: • We investigated how H{sub p}(y) varied in different fatigue crack propagation stages. • The H{sub p}(y) began to change its polarity in the intermediate stage of crack propagation. • An approximate linear relationship was found between the K{sub max} and crack length. • The high-frequency component of H{sub p}(y) can be used to identify the late stage.

  20. Optimal design of the gerotor (2-ellipses) for reducing maximum contact stress

    Kwak, Hyo Seo; Li, Sheng Huan [Dept. of Mechanical Convergence Technology, Pusan National University, Busan (Korea, Republic of); Kim, Chul [School of Mechanical Design and Manufacturing, Busan Institute of Science and Technology, Busan (Korea, Republic of)


    The oil pump, which is used as lubricator of engines and auto transmission, supplies working oil to the rotating elements to prevent wear. The gerotor pump is used widely in the automobile industry. When wear occurs due to contact between an inner rotor and an outer rotor, the efficiency of the gerotor pump decreases rapidly, and elastic deformation from the contacts also causes vibration and noise. This paper reports the optimal design of a gerotor with a 2-ellipses combined lobe shape that reduces the maximum contact stress. An automatic program was developed to calculate Hertzian contact stress of the gerotor using the Matlab and the effect of the design parameter on the maximum contact stress was analyzed. In addition, the method of theoretical analysis for obtaining the contact stress was verified by performing the fluid-structural coupled analysis using the commercial software, Ansys, considering both the driving force of the inner rotor and the fluid pressure, which is generated by working oil.


    Ji Changjiang; Li Zhonghua; Sun Jun


    A closed-form solution for predicting the tangential stress of an inclusion located in mixed mode Ⅰ and Ⅱ crack tip field was developed based on the Eshelby equivalent inclusion theory. Then a mixed mode fracture criterion, including the fracture direction and the critical load, was established based on the maximum tangential stress in the inclusion for brittle inclusioninduced fracture materials. The proposed fracture criterion is a function of the inclusion fracture stress, its size and volume fraction, as well as the elastic constants of the inclusion and the matrix material. The present criterion will reduce to the conventional one as the inclusion having the same elastic behavior as the matrix material. The proposed solutions are in good agreement with detailed finite element analysis and measurement.

  2. Finite Element Analysis of the Maximum Stress at the Joints of the Transmission Tower

    Itam, Zarina; Beddu, Salmia; Liyana Mohd Kamal, Nur; Bamashmos, Khaled H.


    Transmission towers are tall structures, usually a steel lattice tower, used to support an overhead power line. Usually, transmission towers are analyzed as frame-truss systems and the members are assumed to be pin-connected without explicitly considering the effects of joints on the tower behavior. In this research, an engineering example of joint will be analyzed with the consideration of the joint detailing to investigate how it will affect the tower analysis. A static analysis using STAAD Pro was conducted to indicate the joint with the maximum stress. This joint will then be explicitly analyzed in ANSYS using the Finite Element Method. Three approaches were used in the software which are the simple plate model, bonded contact with no bolts, and beam element bolts. Results from the joint analysis show that stress values increased with joint details consideration. This proves that joints and connections play an important role in the distribution of stress within the transmission tower.

  3. Measuring the stress field around an evolving crack in tensile deformed Mg AZ31 using three-dimensional X-ray diffraction

    Oddershede, Jette; Camin, Bettina; Schmidt, Søren;


    The stress field around a notch in a coarse grained Mg AZ31 sample has been measured under tensile load using the individual grains as probes in an in situ high energy synchrotron diffraction experiment. The experimental set-up, a variant of three-dimensional X-ray diffraction microscopy, allows...... element simulation. It was found that a full three-dimensional simulation was required to account for the measured transition from the overall plane stress case away from the notch to the essentially plane strain case observed near the notch tip. The measured and simulated stress contours were shown...

  4. The influence of applied tensile stress on power loss in Co-rich amorphous Co-Fe-Si-B ribbons with induced magnetic anisotropy

    Nielsen, H; Nielsen, K; Nielsen, Otto V


    The influence on power loss PTof applied tensile stress σ in amorphous (Co0.89Fe0.11)72Mo3Si15B10(lambda_{s} > 0) and Co73Mo2Si15B10(lambda_{s} <0) ribbons with different induced magnetic anisotropy Kuis reported. The losses are measured under sinusoidal flux conditions atf = 50Hz,J_{max} = 0.57T...


    This report discusses the design, operation, and purpose of a new biaxial tensile test instrument to measure the stress-strain behavior of fabrics...comparison is made between these data and previous work performed with other tensile test equipment.

  6. Corrosion behavior of 2195 and 1420 Al-Li alloys in neutral 3.5% NaCl solution under tensile stress

    LI Jin-feng; CHEN Wen-jing; ZHAO Xu-shan; REN Wen-da; ZHENG Zi-qiao


    The corrosion behaviors of 1420 and 2195 Al-Li alloys under 308 and 490 MPa tensile stress respectively in neutral 3.5% NaCl solution were investigated using electrochemical impedance spectroscopy(EIS) and scanning electron microscope(SEM). It is found that the unstressed 1420 alloy is featured with large and discrete pits, while general corrosion and localized corrosion including intergranular corrosion and pitting corrosion occur on the unstressed 2195 alloy. As stress is applied to 1420 alloy, the pit becomes denser and its size is decreased. While, for the stressed 2195 alloy, intergranular corrosion is greatly aggravated and severe general corrosion is developed from connected pits. The EIS analysis shows that more severe general corrosion and localized corrosion occur on the stressed 2195 Al-Li alloy than on 1420 Al-Li alloy. It is suggested that tensile stress has greater effect on the corrosion of 2195 Al-Li alloy than on 1420 Al-Li alloy.

  7. Effect of applied tensile stress on the transformation behavior of medium carbon low alloy steels. Chutanso tei gokinko no hentai kyodo ni oyobosu hippari oryoku fuka no koka

    Kanetsuki, Y.; Katsumata, M.; Kaida, O.; Kaiso, M. (Kobe Steel, Ltd., Tokyo (Japan))


    Techniques of controlled rolling and cooling are actively being used as the manufacturing process of high strength and high tenacity steel plates. The reason behind this is that the ferrite-pearlite texture can be made very finely. However, with regard to low alloy carbon steel bars with enhanced hardenability, its texture becomes hard bainite texture in the cooling process after rolling, hence its workability is not good. In this research, in lieu of controlled rolling, the possibility of the process that the tensile stress, whose effect of facilitating transformation is known, is applied before the transformation and its texture is controlled to the ferrite-pearlite texture at the cooling rate of air cooling. In other words, with regard to medium carbon low alloy steels, its transformation behavior was studied by a tensile test in which additional stress was controlled during its continuous cooling. The results are as follows: It was found that by adding stress, the ferrite transformation was expedited. This was because the nuclei formation of ferrite, which was enhanced by inner stress, was facilitated. Furthermore, when the above transformation took place at the same time of deformation, an uniform elongation about 60% was obtained. 13 refs., 13 figs., 1 tab.

  8. Effects of tensile and compressive in-plane stress fields on adhesion in laser induced delamination experiments

    Fedorov, A.; Vellinga, W. P.; De Hosson, J. Th. M.


    In this work, the adhesion of a polymer coating on steel substrate subjected to uniaxial tensile plastic deformations was studied with the laser induced delamination technique. A decrease in the practical work of adhesion has been measured as the deformation of the substrate progressed. Moreover, it

  9. Fatigue life prediction method for contact wire using maximum local stress

    Kim, Yong Seok; Haochuang, Li; Seok, Chang Sung; Koo, Jae Mean [Sungkyunkwan University, Suwon (Korea, Republic of); Lee, Ki Won; Kwon, Sam Young; Cho, Yong Hyeon [Korea Railroad Research Institute, Uiwang (Korea, Republic of)


    Railway contact wires supplying electricity to trains are exposed to repeated mechanical strain and stress caused by their own weight and discontinuous contact with a pantograph during train operation. Since the speed of railway transportation has increased continuously, railway industries have recently reported a number of contact wire failures caused by mechanical fatigue fractures instead of normal wear, which has been a more common failure mechanism. To secure the safety and durability of contact wires in environments with increased train speeds, a bending fatigue test on contact wire has been performed. The test equipment is too complicated to evaluate the fatigue characteristics of contact wire. Thus, the axial tension fatigue test was performed for a standard specimen, and the bending fatigue life for the contact wire structure was then predicted using the maximum local stress occurring at the top of the contact wire. Lastly, the tested bending fatigue life of the structure was compared with the fatigue life predicted by the axial tension fatigue test for verification.

  10. Maximum-power-point tracking with reduced mechanical stress applied to wind-energy-conversion-systems

    Gonzalez, L.G. [Departamento de Electronica y Comunicaciones, Universidad de los Andes, nucleo la Hechicera, 5101 Merida (Venezuela); Figueres, E.; Garcera, G. [Grupo de Sistemas Electronicos Industriales, Universidad Politecnica de Valencia, Camino de vera s/n, 46022 Valencia (Spain); Carranza, O. [Escuela Superior de Computo, Instituto Politecnico Nacional, Av. Juan de Dios Batiz s/n, 07738 DF (Mexico)


    This paper presents an improved maximum-power-point tracking algorithm for wind-energy-conversion-systems. The proposed method significantly reduces the turbine mechanical stress with regard to conventional techniques, so that both the maintenance needs and the medium time between failures are expected to be improved. To achieve these objectives, a sensorless speed control loop receives its reference signal from a modified Perturb and Observe algorithm, in which the typical steps on the reference speed have been substituted by a fixed and well-defined slope ramp signal. As a result, it is achieved a soft dynamic response of both the torque and the speed of the wind turbine, so that the whole system suffers from a lower mechanical stress than with conventional P and O techniques. The proposed method has been applied to a wind turbine based on a permanent magnet synchronous generator operating at variable speed, which is connected to the distribution grid by means of a back to back converter. (author)

  11. Impact of the Weld Geometry on the Stress Intensity Factor of the Welded T-Joint Exposed to the Tensile Force and the Bending Moment

    Djoković Jelena M.


    Full Text Available In this paper it is analyzed the welded T-joint exposed to the axial tensile force and the bending moment, for determining the impact of the weld geometry on the fracture mechanics parameters. The stress intensity factor was calculated analytically, based on the concept of the linear elastic fracture mechanics (LEFM, by application of the Mathematica® programming routine. The presence of the weld was taken into account through the corresponding correction factors. The results show that increase of the size of the triangular welds leads to decrease of the stress intensity factor, while the SIF increases with increase of the welds’ width. The ratio of the two welded plates’ thicknesses shows that plate thicknesses do not exhibit significant influence on the stress intensity factor behavior.

  12. Impact of the Weld Geometry on the Stress Intensity Factor of the Welded T-Joint Exposed to the Tensile Force and the Bending Moment

    Djoković, Jelena M.; Nikolić, Ružica R.; Bujňák, Ján


    In this paper it is analyzed the welded T-joint exposed to the axial tensile force and the bending moment, for determining the impact of the weld geometry on the fracture mechanics parameters. The stress intensity factor was calculated analytically, based on the concept of the linear elastic fracture mechanics (LEFM), by application of the Mathematica® programming routine. The presence of the weld was taken into account through the corresponding correction factors. The results show that increase of the size of the triangular welds leads to decrease of the stress intensity factor, while the SIF increases with increase of the welds' width. The ratio of the two welded plates' thicknesses shows that plate thicknesses do not exhibit significant influence on the stress intensity factor behavior.

  13. The Influence of the Supporting Wheel Deflection of Large-scale Rotary Kiln on Maximum Contact Stress

    Li Xuejun; Qiu Weiliang; Yuan Yincai; Li Ping


    The relation between the maximum contact stress ratio and deflection angle is derived from Hertz contact theory when the deflection of rotary kiln supporting wheel happens. According to the analysis of practical example, the maximum contact stress ratio within the deflection range of rotary kiln supporting wheel is listed. The contact stress will increase largely when rotary kiln supporting wheel deflects with little angle,which probably will result in accidents correlating to safety. This will provide theory conference for the design,the operating condition analysis and adjusting of the rotary kiln.

  14. 全数字电枢电流控制卷取机恒张力系统%All-Digital Armature Current Controller for Constant Tensile-stress

    孟文博; 孟文涛


    Using 8031 to control armature current for constant tensil-stress reel control system has been studied. The control method for diameter filter and dynamic current filteris is discussed%利用8031实现电枢电流控制的卷取机恒张力控 制,同时研究了卷径滤波、动态电流滤波的必要性和实现方法.该模型已成功地 在工厂使用

  15. Microarray analysis of expression of cell death-associated genes in rat spinal cord cells exposed to cyclic tensile stresses in vitro

    Roberts Sally


    Full Text Available Abstract Background The application of mechanical insults to the spinal cord results in profound cellular and molecular changes, including the induction of neuronal cell death and altered gene expression profiles. Previous studies have described alterations in gene expression following spinal cord injury, but the specificity of this response to mechanical stimuli is difficult to investigate in vivo. Therefore, we have investigated the effect of cyclic tensile stresses on cultured spinal cord cells from E15 Sprague-Dawley rats, using the FX3000® Flexercell Strain Unit. We examined cell morphology and viability over a 72 hour time course. Microarray analysis of gene expression was performed using the Affymetrix GeneChip System®, where categorization of identified genes was performed using the Gene Ontology (GO and Kyoto Encyclopedia of Genes and Genomes (KEGG systems. Changes in expression of 12 genes were validated with quantitative real-time reverse transcription polymerase chain reaction (RT-PCR. Results The application of cyclic tensile stress reduced the viability of cultured spinal cord cells significantly in a dose- and time-dependent manner. Increasing either the strain or the strain rate independently was associated with significant decreases in spinal cord cell survival. There was no clear evidence of additive effects of strain level with strain rate. GO analysis identified 44 candidate genes which were significantly related to "apoptosis" and 17 genes related to "response to stimulus". KEGG analysis identified changes in the expression levels of 12 genes of the mitogen-activated protein kinase (MAPK signaling pathway, which were confirmed to be upregulated by RT-PCR analysis. Conclusions We have demonstrated that spinal cord cells undergo cell death in response to cyclic tensile stresses, which were dose- and time-dependent. In addition, we have identified the up regulation of various genes, in particular of the MAPK pathway, which

  16. Maximum Stress Estimation Model for Multi-Span Waler Beams with Deflections at the Supports Using Average Strains

    Sung Woo Park


    Full Text Available The safety of a multi-span waler beam subjected simultaneously to a distributed load and deflections at its supports can be secured by limiting the maximum stress of the beam to a specific value to prevent the beam from reaching a limit state for failure or collapse. Despite the fact that the vast majority of accidents on construction sites occur at waler beams in retaining wall systems, no safety monitoring model that can consider deflections at the supports of the beam is available. In this paper, a maximum stress estimation model for a waler beam based on average strains measured from vibrating wire strain gauges (VWSGs, the most frequently used sensors in construction field, is presented. The model is derived by defining the relationship between the maximum stress and the average strains measured from VWSGs. In addition to the maximum stress, support reactions, deflections at supports, and the magnitudes of distributed loads for the beam structure can be identified by the estimation model using the average strains. Using simulation tests on two multi-span beams, the performance of the model is evaluated by estimating maximum stress, deflections at supports, support reactions, and the magnitudes of distributed loads.

  17. Tensile stress-dependent fracture behavior and its influences on photovoltaic characteristics in flexible PbS/CdS thin-film solar cells.

    Lee, Seung Min; Yeon, Deuk Ho; Mohanty, Bhaskar Chandra; Cho, Yong Soo


    Tensile stress-dependent fracture behavior of flexible PbS/CdS heterojunction thin-film solar cells on indium tin oxide-coated polyethylene terephthalate (PET) substrates is investigated in terms of the variations of fracture parameters with applied strains and their influences on photovoltaic properties. The PbS absorber layer that exhibits only mechanical cracks within the applied strain range from ∼0.67 to 1.33% is prepared by chemical bath deposition at different temperatures of 50, 70, and 90 °C. The PbS thin films prepared at 50 °C demonstrate better mechanical resistance against the applied bending strain with the highest crack initiating bending strain of ∼1.14% and the lowest saturated crack density of 0.036 μm(-1). Photovoltaic properties of the cells depend on the deposition temperature and the level of applied tensile stress. The values of short-circuit current density and fill factor are dramatically reduced above a certain level of applied strain, while open-circuit voltage is nearly maintained. The dependency of photovoltaic properties on the progress of fractures is understood as related to the reduced fracture energy and toughness, which is limitedly controllable by microstructural features of the absorber layer.

  18. Simultaneous imaging and measurement of tensile stress on cornea by using a common-path optical coherence tomography system with an external contact reference

    Utkarsh Sharma; Jin U. Kang


    The objective of this study is to demonstrate that tensile stress resulting due to applied force on cornea can be accurately measured by using a time-domain common-path optical coherence tomography (OCT) system with an external contact reference. The unique design of the common-path OCT is utilized to set up an imaging system in which a chicken eye is placed adjacent to a glass plate serving as the external reference plane for the imaging system. As the force is applied to the chicken eye, it presses against the reference glass plate. The modified OCT image obtained is used to calculate the size of contact area, which is then used to derive the tensile stress on the cornea. The drop in signal levels upon contact of reference glass plate with the tissue are extremely sharp because of the sharp decline in reference power levels itself, thus providing us with an accurate measurement of contact area. The experimental results were in good agreement with the numerical predictions. The results of this study might be useful in providing new insights and ideas to improve the precision and safety of currently used ophthalmic surgical techniques. This research outlines a method which could be used to provide high resolution OCT images and a precise feedback of the forces applied to the cornea simultaneously.


    周小平; 王建华; 张永兴; 哈秋聆


    The mechanical behavior of rock under uniaxial tensile loading is different from that of rock under compressive loads. A micromechanics-based model was proposed for mesoscopic heterogeneous brittle rock undergoing irreversible changes of their microscopic structures due to microcrack growth. The complete stress-strain relation including linear elasticity, nonlinear hardening,rapid stress drop and strain softening was obtained. The influence of all microcracks with different sizes and orientations were introduced into the constitutive relation by using the probability density function describing the distribution of orientations and the probability density function describing the distribution of sizes. The influence of Weibull distribution describing the distribution of orientations and Rayleigh function describing the distribution of sizes on the constitutive relation were researched. Theoretical predictions have shown to be consistent with the experimental results.

  20. Analysis of the tensile stress-strain behavior of elastomers at constant strain rates. I - Criteria for separability of the time and strain effects

    Hong, S. D.; Fedors, R. F.; Schwarzl, F.; Moacanin, J.; Landel, R. F.


    A theoretical analysis of the tensile stress-strain relation of elastomers at constant strain rate is presented which shows that the time and the stress effect are separable if the experimental time scale coincides with a segment of the relaxation modulus that can be described by a single power law. It is also shown that time-strain separability is valid if the strain function is linearly proportional to the Cauchy strain, and that when time-strain separability holds, two strain-dependent quantities can be obtained experimentally. In the case where time and strain effect are not separable, superposition can be achieved only by using temperature and strain-dependent shift factors.

  1. The development of a tensile-shear punch correlation for yield properties of model austenitic alloys

    Hankin, G.L.; Faulkner, R.G. [Loughborough Univ. (United Kingdom); Hamilton, M.L.; Garner, F.A. [Pacific Northwest National Lab., Richland, WA (United States)


    The effective shear yield and maximum strengths of a set of neutron-irradiated, isotopically tailored austentic alloys were evaluated using the shear punch test. The dependence on composition and neutron dose showed the same trends as were observed in the corresponding miniature tensile specimen study conducted earlier. A single tensile-shear punch correlation was developed for the three alloys in which the maximum shear stress or Tresca criterion was successfully applied to predict the slope. The correlation will predict the tensile yield strength of the three different austenitic alloys tested to within {+-}53 MPa. The accuracy of the correlation improves with increasing material strength, to within {+-} MPa for predicting tensile yield strengths in the range of 400-800 MPa.

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

    Paglietti, A.


    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.

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

    Paglietti, A.


    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.

  4. The Influence of Pressure Distribution on the Maximum Values of Stress in FEM Analysis of Plain Bearings

    Vasile Cojocaru


    Full Text Available Several methods can be used in the FEM studies to apply the loads on a plain bearing. The paper presents a comparative analysis of maximum stress obtained for three loading scenarios: resultant force applied on the shaft – bearing assembly, variable pressure with sinusoidal distribution applied on the bearing surface, variable pressure with parabolic distribution applied on the bearing surface.

  5. Comparison of Maximum Gear-Tooth Operating Bending Stresses Derived from Niemann's Analytical Procedure and the Finite Element Method

    Ándonios D. Tsolakis


    Full Text Available Problem statement: Main purpose of this study was to investigation toothed gear loading problems using the Finite Element Method. Approach: We used Niemann's equations to compare maximum bending stress which was developed at critical gear-tooth flank point during gear meshing, applied for three distinct spur-gear sizes, each having different teeth number, module and power rating. Results: The results emerging after the application of Niemann's equations were compared to the results derived by application of the Finite Element Method (FEM for the same gear-loading input data. Results are quite satisfactory, since von Mises' equivalent stresses calculated with FEM are of the same order with the results of classical analytical method. Conclusion: Judging from the emerging results, deviation of the two methods, analytical (Niemann's equations and computational (FEM, referring to maximum bending stress is fairly slight, independently of the applied geometrical and loading data of each gear.

  6. Effect of tensile stress on the in-plane resistivity anisotropy in BaFe[subscript 2]As[subscript 2

    Blomberg, E.C.; Kreyssig, A.; Tanatar, M.A.; Fernandes, R.M.; Kim, M.G.; Thaler, A.; Schmalian, J.; Bud; ko, S.L.; Canfield, P.C.; Goldman, A.I.; Prozorov, R. (Ames); (Iowa State)


    The effect of uniaxial tensile stress and the resultant strain on the structural/magnetic transition in the parent compound of the iron arsenide superconductor BaFe{sub 2}As{sub 2} is characterized by temperature-dependent electrical resistivity, x-ray diffraction, and quantitative polarized light imaging. We show that strain induces a measurable uniaxial structural distortion above the first-order magnetic transition and significantly smears the structural transition. This response is different from that found in another parent compound, SrFe{sub 2}As{sub 2}, where the coupled structural and magnetic transitions are strongly first order. This difference in the structural responses explains the in-plane resistivity anisotropy above the transition in BaFe{sub 2}As{sub 2}. This conclusion is supported by the Ginzburg-Landau-type phenomenological model for the effect of the uniaxial strain on the resistivity anisotropy.

  7. Effects of Nitrogen and Tensile Direction on Stress Corrosion Cracking Susceptibility of Ni-Free FeCrMnC-Based Duplex Stainless Steels

    Ha, Heon-Young; Lee, Chang-Hoon; Lee, Tae-Ho; Kim, Sangshik


    Stress corrosion cracking (SCC) behavior of Ni-free duplex stainless steels containing N and C (Febalance-19Cr-8Mn-0.25C-(0.03, 0.21)N, in wt %) was investigated by using a slow strain rate test (SSRT) in air and aqueous NaCl solution with different tensile directions, including parallel (longitudinal) and perpendicular (transverse) to the rolling direction. It was found that alloying N was effective in increasing the resistance to SCC, while it was higher along the longitudinal direction than the transverse direction. The SCC susceptibility of the two alloys was assessed based on the electrochemical resistance to pitting corrosion, the corrosion morphology, and the fractographic analysis. PMID:28772651

  8. The influence of cobalt on the tensile and stress-rupture properties of the nickel-base superalloy mar-m247

    Nathal, M. V.; Maier, R. D.; Ebert, L. J.


    The influence of cobalt on the mechanical properties of MAR-M247, a cast nickel-base superalloy, was investigated. Nickel was substituted for cobalt to produce 0, 5, and the standard 10 pct cobalt versions of MAR-M247. Tensile tests were performed between 649 and 982 dgC; stress-rupture tests were conducted at temperatures ranging from 760 to 982 dgC. The tensile properties were not significantly affected by cobalt level, but a slight peak in strength at 5 pct Co was apparent. A -80 °C shift in the peak yield strength temperature as Co level was reduced from 10 to 0 pct was also evident. This behavior was related to a reduction in the γ' volume fraction, an increase in γ' particle size, an increase in W and Ti concentrations in the γ', and a decrease in Cr and Al concentrations in the γ as Co level in MAR-M247 was reduced. Stress-rupture properties, however, were more significantly affected by Co level. The 10 pct Co alloy exhibited rupture lives typically 1.2 times greater than that of the 5 pct Co alloy and 3 times greater than that of the 0 pct Co alloy. The steady state creep rate of the 10 pct Co alloy was generally equal to that of the 5 pct Co alloy, but was only one third as large as the creep rate of the 0 pct Co alloy. This behavior was associated with a decrease in γ' volume fraction and the formation of a grain boundary carbide film as cobalt level was reduced.

  9. Towards the prediction of pre-mining stresses in the European continent. [Estimates of vertical and probable maximum lateral stress in Europe

    Blackwood, R.L.


    There are now available sufficient data from in-situ, pre-mining stress measurements to allow a first attempt at predicting the maximum stress magnitudes likely to occur in a given mining context. The sub-horizontal (lateral) stress generally dominates the stress field, becoming critical to stope stability in many cases. For cut-and-fill mining in particular, where developed fill pressures are influenced by lateral displacement of pillars or stope backs, extraction maximization planning by mathematical modelling techniques demands the best available estimate of pre-mining stresses. While field measurements are still essential for this purpose, in the present paper it is suggested that the worst stress case can be predicted for preliminary design or feasibility study purposes. In the Eurpoean continent the vertical component of pre-mining stress may be estimated by adding 2 MPa to the pressure due to overburden weight. The maximum lateral stress likely to be encountered is about 57 MPa at depths of some 800m to 1000m below the surface.

  10. Effect of temperature-dependent surface heat transfer coefficient on the maximum surface stress in ceramics during quenching

    Shao, Y. F.; Song, F.; Jiang, C. P.; Xu, X. H.; Wei, J. C.; Zhou, Z. L.


    We study the difference in the maximum stress on a cylinder surface σmax using the measured surface heat transfer coefficient hm instead of its average value ha during quenching. In the quenching temperatures of 200, 300, 400, 500, 600 and 800°C, the maximum surface stress σmmax calculated by hm is always smaller than σamax calculated by ha, except in the case of 800°C; while the time to reach σmax calculated by hm (fmmax) is always earlier than that by ha (famax). It is inconsistent with the traditional view that σmax increases with increasing Biot number and the time to reach σmax decreases with increasing Biot number. Other temperature-dependent properties also have a small effect on the trend of their mutual ratios with quenching temperatures. Such a difference between the two maximum surface stresses is caused by the dramatic variation of hm with temperature, which needs to be considered in engineering analysis.

  11. Estimation of a stress field in the earth`s crust using drilling-induced tensile fractures observed at well WD-1 in the Kakkonda geothermal field; Kakkonda WD-1 sei de kansokusareta drilling induced tensile fracture ni yoru chikaku oryokuba no suitei

    Okabe, T. [GERD Geothermal Energy Research and Development Co. Ltd., Tokyo (Japan); Hayashi, K. [Tohoku Univ., Sendai (Japan). Inst. of Fluid Science; Kato, O.; Doi, N.; Miyazaki, S. [Japan Metals and Chemicals Co. Ltd., Tokyo (Japan); Uchida, T. [New Energy and Industrial Technology Development Organization, Tokyo, (Japan)


    This paper describes estimation of a stress field in the earth`s crust in the Kakkonda geothermal field. Formation micro imager (FMI) logging known as a crack detecting logging was performed in the well WD-1. This FMI logging has made observation possible on cracks along well axis thought to indicate size and direction of the crust stress, and drilling-induced tensile fractures (DTF). It was verified that these DTFs are generated initially in an azimuth determined by in-situ stress (an angle up to the DTF as measured counterclockwise with due north as a starting point, expressed in {theta}) in the well`s circumferential direction. It was also confirmed that a large number of cracks incline at a certain angle to the well axis (an angle made by the well axis and the DTF, expressed in {gamma}). The DTF is a crack initially generated on well walls as a result of such tensile stresses as mud pressure and thermal stress acting on the well walls during well excavation, caused by the in-situ stress field. Measurement was made on the {theta} and {gamma} from the FMI logging result, and estimation was given on a three-dimensional stress field. Elucidating the three-dimensional crust stress field in a geothermal reservoir is important in making clear the formation mechanism thereof and the growth of water-permeable cracks. This method can be regarded as an effective method. 9 refs., 8 figs., 1 tab.

  12. Analysis of Maximum Shear Stress of Asphalt Pavement%沥青路面最大剪应力分析

    陈光伟; 费国新; 陈荣生


    Factors and variation of the maximum shear stress of the typical semi-rigid asphalt pavement and bridge deck pavement in Jiangsu were calculated and analyzed using ABAQUS software. The maximum shear stress distribution was consistent with the semi-rigid asphalt pavement and bridge deck pavement and the maximum shear stress level was close under the level. The maximum shear stress showed a positive correlation with the verticaland horizontal vehicle loads and was significantly affected by the loads. The maximum shear stress decreased as the pavement thickness and modulus increase, and increased as the semi-rigid base thickness and modulus increase, but the increase value was small. Thereby these analysis above would provides an academic basis for solving the rutting problem.%采用ABAQUS软件对典型半刚性基层沥青路面及桥面铺装层中最大剪应力影响因素及变化规律进行了计算与分析。分析表明:半刚性基层沥青路面与水泥混凝土桥面铺装层最大剪应力分布与变化规律基本一致,在相同荷载条件作用下,最大剪应力水平亦接近;最大剪应力与车辆垂直荷载和水平荷载作用呈正比关系,最大剪应力受其影响显著;最大剪应力随着面层或铺装层厚度、模量的增加而相应地变小,随着半刚性基层厚度与模量的增加而变大。以上抗剪影响因素及变化规律的研究为解决车辙问题提供了一定的理论基础。

  13. Stress distribution and lattice distortions in Nb3Sn multifilament wires under uniaxial tensile loading at 4.2 K

    Scheuerlein, C; Buta, F; Seeber, B; Senatore, C; Flükiger, R; Siegrist, T; Besara, T; Kadar, J; Bordini, B; Ballarino, A; Bottura, L


    The lattice parameter changes in three types of Nb3Sn superconducting wires during uniaxial stress-strain measurements at 4.2 K have been measured by high-energy synchrotron x-ray diffraction. The nearly-stress-free Nb3Sn lattice parameter has been determined using extracted filaments, and the elastic strain in the axial and transverse wire directions in the different wire phases has been calculated. The mechanical properties of the PIT and RRP wire are mainly determined by the properties of Nb3Sn and unreacted Nb. This is in contrast to the bronze route wire, where the matrix can carry substantial loads. In straight wires the axial Nb3Sn pre-strain is strongest in the bronze route wire, its value being smaller in the PIT and RRP wires. A strong reduction of the non-Cu elastic modulus of about 30\\% is observed during cool-down from ambient temperature to 4.2 K. The Nb3Sn Poisson ratio at 4.2 K measured in the untwisted bronze route wire is 0.35. The present study also shows that the process route has a strong...

  14. Elongation Transducer For Tensile Tests

    Roberts, Paul W.; Stokes, Thomas R.


    Extensometer transducer measures elongation of tensile-test specimen with negligible distortion of test results. Used in stress-versus-strain tests of small specimens of composite materials. Clamping stress distributed more evenly. Specimen clamped gently between jaw and facing surface of housing. Friction force of load points on conical tips onto specimen depends on compression of spring, adjusted by turning cover on housing. Limp, light nylon-insulated electrical leads impose minimal extraneous loads on measuring elements.

  15. Dynamic Tensile Test Results for Several Metals


    8217• AFWAL-TR-82-4026 SDYNAMIC TENSILE TEST RESULTS FOR SEVERAL METALS SUNIVERSITY OF DAYTON RESEA CH INSTITUTE ’ 300 COLLEGE PARK DR. DAYTON, OHIO... Tensile Test Results for March - September 1981 Several Metals 6. PERFORMING oDG. REPORT NUMBER UDR-TR-82-05 7. AUTHOR(s) S. CONTRACT OfR GRANT NUMBER(&) S...tensile stresses above 10 s The split Hopkinson bar tensile test (see next section) can extend this range another decade. Resolution of rapidly


    Korinko, P.; Chapman, G.


    A task was undertaken to compare various properties of different glovebox gloves, having various compositions, for use in gloveboxes at the Savannah River Site (SRS). One aspect of this project was to determine the tensile strength (TS) of the gloves. Longitudinal tensile samples were cut from 15 different gloves and tensile tested. The stress, load, and elongation at failure were determined. All of the gloves that are approved for glovebox use and listed in the glovebox procurement specification met the tensile and elongation requirements. The Viton{reg_sign} compound gloves are not listed in the specification, but exhibited lower tensile strengths than permissible based on the Butyl rubber requirements. Piercan Polyurethane gloves were the thinnest samples and exhibited the highest tensile strength of the materials tested.

  17. Performance and stress analysis of oxide thermoelectric module architecture designed for maximum power output

    Wijesekara, Waruna; Rosendahl, Lasse; Wu, NingYu;

    Oxide thermoelectric materials are promising candidates for energy harvesting from mid to high temperature heat sources. In this work, the oxide thermoelectric materials and the final design of the high temperature thermoelectric module were developed. Also, prototypes of oxide thermoelectric...... generator were built for high temperature applications. This paper specifically discusses the thermoelectric module design and the prototype validations of the design. Here p type calcium cobalt oxide and n type aluminum doped ZnO were developed as the oxide thermoelectric materials. Hot side and cold side...... temperatures were used as 1100 K and 400 K respectively. Using analytical methods, the optimum thermoelement length and the thermoelements area ratio were explored in order to provide the maximum power output by the uni-couple and it is compared to methods reported in literature. Based on operating conditions...

  18. Maximum Stress Estimation Model for Multi-Span Waler Beams with Deflections at the Supports Using Average Strains

    Sung Woo Park; Byung Kwan Oh; Hyo Seon Park


    The safety of a multi-span waler beam subjected simultaneously to a distributed load and deflections at its supports can be secured by limiting the maximum stress of the beam to a specific value to prevent the beam from reaching a limit state for failure or collapse. Despite the fact that the vast majority of accidents on construction sites occur at waler beams in retaining wall systems, no safety monitoring model that can consider deflections at the supports of the beam is available. In this...

  19. Effect of the Volume Fraction of Jute Fiber on the Interlaminar Shear Stress and Tensile Behavior Characteristics of Hybrid Glass/Jute Fiber Reinforced Polymer Composite Bar for Concrete Structures

    Chan-Gi Park


    Full Text Available Hybrid glass/jute fiber reinforced polymer (HGJFRP composite bars were manufactured for concrete structures, and their interlaminar shear stress and tensile performance were evaluated. HGJFRP composite bars were manufactured using a combination of pultrusion and braiding processes. Jute fiber was surface-treated with a silane coupling agent. The mixing ratio of the fiber to the vinyl ester used in the HGJFRP composite bars was 7 : 3. Jute fiber was used to replace glass fiber in proportions of 0, 30, 50, 70, and 100%. The interlaminar shear stress decreased as the proportion of jute fiber increased. Fractures appeared due to delamination between the surface-treated component and the main part of the HGJFRP composite bar. Tensile load-strain curves with 50% jute fiber exhibited linear behavior. With a jute fiber volume fraction of 70%, some plastic deformation occurred. A jute fiber mixing ratio of 100% resulted in a display of linear elastic brittle behavior from the fiber; however, when the surface of the fiber was coated with poly(vinyl acetate, following failure, the jute fiber exhibited partial load resistance. The tensile strength decreased as the jute fiber content increased; however, the tensile strength did not vary linearly with jute fiber content.

  20. Elastic stress transmission and transformation (ESTT) by confined liquid: A new mechanics for fracture in elastic lithosphere of the earth

    Xu, Xing-Wang; Peters, Stephen; Liang, Guang-He; Zhang, Bao-Lin


    We report on a new mechanical principle, which suggests that a confined liquid in the elastic lithosphere has the potential to transmit a maximum applied compressive stress. This stress can be transmitted to the internal contacts between rock and liquid and would then be transformed into a normal compressive stress with tangential tensile stress components. During this process, both effective compressive normal stress and tensile tangential stresses arise along the liquid–rock contact. The minimum effective tensile tangential stress causes the surrounding rock to rupture. Liquid-driven fracture initiates at the point along the rock–liquid boundary where the maximum compressive stress is applied and propagates along a plane that is perpendicular to the minimum effective tensile tangential stress and also is perpendicular to the minimum principal stress.

  1. 拉应力对玻璃纤维增强聚合物基复合材料介电强度的影响%Effect of tensile stress on dielectric strength of glass fiber reinforced composites

    于涛; 刘钧; 肖加余


    Under the condition of tensile stress, dielectric strengths of resin and unique directional glass fiber reinforced resin composites were tested, and a relationship between dielectric strength and tensile stress of the resin and glass fiber/resin composites was studied. A negative exponential equation for expressing the relationship between dielectric strength and tensile stress for the resin was proposed and then was experimental proved. It has been found that the interface of the fiber and the resin plays a dominant role on the dielectric strength of composites.%在拉应力条件下,测试了聚合物基体和单向玻璃纤维增强聚合物基复合材料的介电强度,探索了聚合物基体和玻璃纤维/聚合物复合材料的介电强度与拉应力的关系,提出并证明了聚合物基体的介电强度与拉应力呈负指数关系,复合材料中纤维与基体的界面是影响材料介电强度的主要因素。

  2. Effect of tensile and torsion on GMI in amorphous wire

    Blanco, J. M.; Zhukov, A.; Gonzalez, J.


    GMI effect, Δ Z/Z = [ Z( H) - Z( Hmax)]/ Z( Hmax) has been measured in (Fe 0.94Co 0.06) 72.5B 15Si 12.5 wire under tensile, σ ten, and torsional, σ tor, stresses. Generally Δ Z/Z( H) dependence has a non-monotonic shape with a maximum at certain axial magnetic field, Hm. Both tension and torsion modify Δ Z/Z( H) dependence. Application of tension results in an increase of Hm with σ ten. Torsional stress dependence of GMI effect has asymmetry with a maximum at torsion angle, φ, around + 12π/m in as-cast wire, when Δ Z/Z is around 250%. An increase of Δ Z/Zm up to 350% and change of Δ Z/Z(φ) dependence towards a nearly symmetric shape have been observed after Joule heating.

  3. Influence of oxidative stress, diaphragm fatigue, and inspiratory muscle training on the plasma cytokine response to maximum sustainable voluntary ventilation.

    Mills, Dean E; Johnson, Michael A; McPhilimey, Martin J; Williams, Neil C; Gonzalez, Javier T; Barnett, Yvonne A; Sharpe, Graham R


    The influence of oxidative stress, diaphragm fatigue, and inspiratory muscle training (IMT) on the cytokine response to maximum sustainable voluntary ventilation (MSVV) is unknown. Twelve healthy males were divided equally into an IMT or placebo (PLA) group, and before and after a 6-wk intervention they undertook, on separate days, 1 h of (1) passive rest and (2) MSVV, whereby participants undertook volitional hyperpnea at rest that mimicked the breathing and respiratory muscle recruitment patterns commensurate with heavy cycling exercise. Plasma cytokines remained unchanged during passive rest. There was a main effect of time (P ventilation and increases in plasma IL-6 concentration. In conclusion, increases in plasma IL-1β and IL-6 concentrations during MSVV were not due to diaphragm fatigue or DNA damage in PBMC. Increases in plasma IL-6 concentration during MSVV are attenuated following IMT, and the plasma IL-6 response is dependent upon the level of respiratory muscle work and minute ventilation.

  4. Approximate Calculation of Flexural Stresses and Tensile Strains in Asphalt Pavements%沥青路面结构层弯拉应力与应变的近似计算

    吁新华; 谈至明


    The flexural stresses and tensile strains in asphalt pavement layers were studied. The hood face coefficient was proposed to characterize the influences of vertical compression stresses and shear stresses on the flexural stresses and tensile strains; the neutral axis moving coefficient was introduced to describe the differences between smooth contact and full friction contact in layers; the flexure torque distribution coefficient was put forward to show the influences of different bend curvature on asphalt layer and base. As to asphalt pavement with nonuniform modulus, the surface equivalent modulus was deduced by bending rigidity equivalent principle, and then the errors of the approximate calculation methods for the tensile strains at the bottom of surface and the flexural stresses at the bottom of base in asphalt pavement whit nonuniform modulus were discussed. Usually, the approximate calculation errors are less than 5%.%研究了各种条件下沥青路面结构弯拉应力和应变规律,引入曲面系数修正竖向压应力和剪应力的影响,引入面层弯曲中性轴下移量参数修正层间光滑与连续之间的差异,引入面层与基层弯矩分配系数反映面层、基层弯曲曲率不同的影响;对于模量不均匀面层,提出了弯曲刚度等效原则换算式;最后,讨论了各种条件下的沥青面层层底弯拉应变、半刚性或刚性基层层底弯拉应力的计算精度,其误差均不超过5%.

  5. Measurement of internal tensile stress in Co{sub 68.2}Fe{sub 4.3}Cr{sub 3.5}Si{sub 13}B{sub 11} glass-coated amorphous microwires using the stress sensitivity of saturation magnetostriction

    Liu, Kaihuang, E-mail:; Lu, Zhichao; Liu, Tiancheng; Li, Deren


    The internal tensile stresses in Co{sub 68.2}Fe{sub 4.3}Cr{sub 3.5}Si{sub 13}B{sub 11} glass-coated amorphous microwires are measured experimentally by using the stress sensitivity of saturation magnetostriction. The obtained results show that the internal tensile stress is 1420 MPa for microwire with metallic core diameter of 20.7 µm and glass cover thickness of 14.5 µm, while it decreases to 640 MPa after glass removal. The measured results agree well with the theoretical results calculated by Chiriac et al. - Highlights: • Internal stresses in amorphous microwires have been measured experimentally. • The stress sensitivity of saturation magnetostriction was adopted. • The results agree with the theoretical results calculated by Chiriac et al.

  6. Dynamic-tensile-extrusion response of fluoropolymers

    Brown, Eric N [Los Alamos National Laboratory; Trujillo, Carl P [Los Alamos National Laboratory; Gray, George T [Los Alamos National Laboratory


    The current work applies the recently developed Dynamic-Tensile-Extrusion (Dyn-Ten-Ext) technique to polytetrafluoroethylene (PTFE) and polychlorotrifluoroethylene (PCTFE). Similar to the Taylor Impact Rod, Dynamic-Tensile-Extrusion is a strongly integrated test, probing a wide range of strain rates and stress states. However, the stress state is primarily tensile enabling investigation of dynamic tensile failure modes. Here we investigate the influence of this propensity to neck or not between PCTFE and PTFE on their response under dynamic tensile extrusion loading. The results of the Dyn-Ten-Ext technique are compared with two classic techniques. Both polymers have been investigated using Tensile Split Hopkinson Pressure Bar. The quasistatic and dynamic responses of both fluoro-polymers have been extensively characterized. The two polymers exhibit significantly different failure behavior under tensile loading at moderate strain rates. Polytetrafluoroethylene resists formation of a neck and exhibits significant strain hardening. Independent of temperature or strain rate, PTFE sustains true strains to failure of approximately 1.5. Polychlorotrifluoroethylene, on the other hand, consistently necks at true strains of approximately 0.05.

  7. Material Properties and Tensile Behaviors of Polypropylene Geogrid and Geonet for Reinforcement of Soil Structures


    The properties and tensile behaviors of polypropylene (PP) geogrids and geonets for reinforcement of soil structures are investigated.Mass per unit area of the geogrids and geonets was weighed using an electronic balance and aperture sizes of the geonets were exactly measured using a computer.Laboratory tests were performed using a small tensile machine capable of monitoring tensile force and displacement.Tensile failure behaviors were described,and tensile index properties such as tensile strength,maximum tensile strain,tensile forces corresponding to different strains in the geogrids and gronets were obtained.The characterization of these indexes is discussed.

  8. Use of Maximum Likelihood-Mixed Models to select stable reference genes: a case of heat stress response in sheep

    Salces Judit


    Full Text Available Abstract Background Reference genes with stable expression are required to normalize expression differences of target genes in qPCR experiments. Several procedures and companion software have been proposed to find the most stable genes. Model based procedures are attractive because they provide a solid statistical framework. NormFinder, a widely used software, uses a model based method. The pairwise comparison procedure implemented in GeNorm is a simpler procedure but one of the most extensively used. In the present work a statistical approach based in Maximum Likelihood estimation under mixed models was tested and compared with NormFinder and geNorm softwares. Sixteen candidate genes were tested in whole blood samples from control and heat stressed sheep. Results A model including gene and treatment as fixed effects, sample (animal, gene by treatment, gene by sample and treatment by sample interactions as random effects with heteroskedastic residual variance in gene by treatment levels was selected using goodness of fit and predictive ability criteria among a variety of models. Mean Square Error obtained under the selected model was used as indicator of gene expression stability. Genes top and bottom ranked by the three approaches were similar; however, notable differences for the best pair of genes selected for each method and the remaining genes of the rankings were shown. Differences among the expression values of normalized targets for each statistical approach were also found. Conclusions Optimal statistical properties of Maximum Likelihood estimation joined to mixed model flexibility allow for more accurate estimation of expression stability of genes under many different situations. Accurate selection of reference genes has a direct impact over the normalized expression values of a given target gene. This may be critical when the aim of the study is to compare expression rate differences among samples under different environmental

  9. Giant stress-impedance effect in amorphous and current annealed Fe 73.5Cu 1Nb 3Si 13.5B 9 wires

    Han, Wei; Li, Deren; Lu, Zhichao; Zhou, Shaoxiong; Zhang, Honghao


    The giant stress-impedance (GSI) effect in Fe 73.5Cu 1Nb 3Si 13.5B 9 wires is measured to investigate the influence of Joule heating and pulse current annealing as well as tensile stress applied during the annealing process on it. The results show that the GSI effect changes drastically with annealing techniques and the maximum stress-impedance ratio of 80% is obtained at 5.5 MHz under applied tensile stress of 20 MPa.

  10. Strain Rate Sensitivity of Epoxy Resin in Tensile and Shear Loading

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


    The mechanical response of E-862 and PR-520 resins is investigated in tensile and shear loadings. At both types of loading the resins are tested at strain rates of about 5x10(exp 5), 2, and 450 to 700 /s. In addition, dynamic shear modulus tests are carried out at various frequencies and temperatures, and tensile stress relaxation tests are conducted at room temperature. The results show that the toughened PR-520 resin can carry higher stresses than the untoughened E-862 resin. Strain rate has a significant effect on the response of both resins. In shear both resins show a ductile response with maximum stress that is increasing with strain rate. In tension a ductile response is observed at low strain rate (approx. 5x10(exp 5) /s), and brittle response is observed at the medium and high strain rates (2, and 700 /s). The hydrostatic component of the stress in the tensile tests causes premature failure in the E-862 resin. Localized deformation develops in the PR-520 resin when loaded in shear. An internal state variable constitutive model is proposed for modeling the response of the resins. The model includes a state variable that accounts for the effect of the hydrostatic component of the stress on the deformation.

  11. Multi-scale investigation of tensile creep of ultra-high performance concrete for bridge applications

    Garas Yanni, Victor Youssef

    achieving satisfactory microstructural refinement at the same temperature input despite the maximum temperature applied. For the first time, the presence of a 10 microm (394 micro inch) wide porous fiber-cementitious matrix interface was demonstrated by nanoindentation and SEM for non-thermally treated UHPC only. Tensile creep at 90 days increased by 64% and 46% upon eliminating fibers for thermally and non-thermally treated UHPC, respectively. Increases in creep upon reducing the fiber content suggested that fibers carry part of the sustained load and thus reduce creep. Tensile creep strain was proportional to the stress applied up to 60% of the ultimate strength. No tensile creep failure occurred for a period of 1 year for pre-cracked UHPC under stress level of 40%. Also, no tensile creep failure occurred for a period of 90 days under stress level of 60%. Tensile creep failure occurred at stress levels of 70% and 80%. This study showed that fibers cannot be accounted for as shear reinforcement in lieu of stirrups unless micro-defect-free fiber-matrix interface is achieved.

  12. Experimental Analysis of Tensile Mechanical Properties of Sprayed FRP

    Zhao Yang


    Full Text Available To study the tensile mechanical properties of sprayed FRP, 13 groups of specimens were tested through uniaxial tensile experiments, being analyzed about stress-strain curve, tensile strength, elastic modulus, breaking elongation, and other mechanical properties. Influencing factors on tensile mechanical properties of sprayed FRP such as fiber type, resin type, fiber volume ratio, fiber length, and composite thickness were studied in the paper too. The results show that both fiber type and resin type have an obvious influence on tensile mechanical properties of sprayed FRP. There will be a specific fiber volume ratio for sprayed FRP to obtain the best tensile mechanical property. The increase of fiber length can lead to better tensile performance, while that of composite thickness results in property degradation. The study can provide reference to popularization and application of sprayed FRP material used in structure reinforcement.

  13. Molecular dynamics simulation of the test of single-walled carbon nanotubes under tensile loading

    FU ChenXin; CHEN YunFei; JIAO JiWei


    Molecular dynamics (MD) simulations were performed to do the test of single-walled carbon nanotubes (SWCNT) under tensile loading with the use of Brenner potential to describe the interactions of atoms in SWCNTs. The Young's modulus and tensile strength for SWCNTs were calculated and the values found are 4.2 TPa and 1.40―1.77 TPa, respectively. During the simulation, it was found that if the SWCNTs are unloaded prior to the maximum stress, the stress-strain curve for unloading process overlaps with the loading one, showing that the SWCNT's deformation up to its fracture point is completely elastic. The MD simulation also demonstrates the fracture process for several types of SWCNT and the breaking mechanisms for SWCNTs were analyzed based on the energy and structure behavior.

  14. Modeling of tensile testing on perfect and defective graphenylene nanotubes using molecular dynamics simulations

    Rouhi, Saeed


    Molecular dynamics simulations are employed here to study the mechanical properties of graphenylene nanotubes (NTs). The effects of different geometrical parameters, such as NT length and diameter, on the behavior of graphenylene NTs under tensile testing are investigated. Moreover, the tensile test is simulated at several temperatures, to obtain the stress-strain curves of both armchair and zigzag graphenylene NTs. It is shown that graphenylene NTs with larger diameter possess larger elastic moduli. The elastic modulus of graphenylene NTs is about one half that of carbon NTs. However, the maximum tolerable stress and strain of the graphenylene NTs decreases with increasing NT diameter. Investigating the effect of vacancy defects on the elastic properties of the graphenylene NTs, it is shown that Young’s modulus of armchair and zigzag graphenylene NTs decreases nonlinearly with increasing defect percentages.

  15. Molecular dynamics simulation of the test of single-walled carbon nanotubes under tensile loading


    Molecular dynamics (MD) simulations were performed to do the test of sin-gle-walled carbon nanotubes (SWCNT) under tensile loading with the use of Bren-ner potential to describe the interactions of atoms in SWCNTs. The Young’s modulus and tensile strength for SWCNTs were calculated and the values found are 4.2 TPa and 1.40―1.77 TPa, respectively. During the simulation, it was found that if the SWCNTs are unloaded prior to the maximum stress, the stress-strain curve for unloading process overlaps with the loading one, showing that the SWCNT’s de-formation up to its fracture point is completely elastic. The MD simulation also demonstrates the fracture process for several types of SWCNT and the breaking mechanisms for SWCNTs were analyzed based on the energy and structure be-havior.

  16. Mechanical properties of gold twinned nanocubes under different triaxial tensile rates

    Yang, Zailin; Zhang, Guowei; Luo, Gang; Sun, Xiaoqing; Zhao, Jianwei


    The gold twinned nanocubes under different triaxial tensile rates are explored by molecular dynamics simulation. Hydrostatic stress and Mises stress are defined in order to understand triaxial stresses. Twin boundaries prevent dislocations between twin boundaries from developing and dislocation angles are inconspicuous, which causes little difference between triaxial stresses. The mechanical properties of the nanocubes under low and high tensile rates are different. The curves of nanocubes under high tensile rates are more abrupt than those under low tensile rates. When the tensile rate is extremely big, the loadings are out of the nanocubes and there are not deformation and fracture in the internal nanocubes.

  17. 超声振动单向拉伸20号钢内部应力及断口形貌分析%Analysis of Internal Stress and Fracture Morphology for 20 Steel Under Ultrasonic Vibration Uniaxial Tensile

    程雪利; 赵明利; 秦军; 刘传绍


    对20号钢进行了超声振动单向拉伸试验,对其内部应力进行了有限元分析,得出了工件在直径最小处两端的应力最大,中间次之,这和断口断裂的位置是一致的.研究了工件中心点处塑性应变及应力随时间变化的曲线,证明了在超声振动单向拉伸下工件内部受到的是一个交变的应力载荷.通过对超声与常态拉伸断口的比较,发现了所有断口都是杯锥型断口,而超声拉伸的断口杯状边缘更明显,断口内部更平整,断口更明亮;还发现了随着频率的降低,断口变得粗糙且不均匀,功率越大,典型疲劳条纹也越明显.%In this paper,the ultrasonic vibration uniaxial tensile test of the #20 steel was conducted and the internal stress was analyzed by finite element method.It is concluded that the stress of workpiece on both ends of the minimum diameter place is the biggest and that of the middle is bigger,which is consistent with the position of the fracture.Since the plastic strain and stress curve are changed with time,it is proved that the intemal workpiece is subject to an altemative stress load under ultrasonic vibration uniaxial tensile.Based on the comparison between the tensile fracture of the ultrasonic and that of the common condition,it is found that all the fracture is a cup of cone fracture type and the fracture has more apparent cup edges,more smooth and bright at ultrasound stretch.Furthermore,it is found that the fracture becomes coarse and uneven with the decrease of frequency.Therefore,the greater the power is,the more obvious the typical fatigue stripe is.

  18. Flow Stress Behavior of 7B04-T6 Aluminum Alloy Sheet During Warm Tensile%7B04-T6铝合金板材温拉伸流变应力行为研究

    韩伟; 吕彩琴; 张翼


    在温度为473~623 K、应变速率为0.1 s-1~0.001 s-1的条件下对7B04-T6铝合金板材进行温拉伸实验,研究该材料在所选定温度和应变速率下的流变应力变化数据.分别对Fields and Backofen方程和加入软化因子"s"的流变应力数学方程进行修正,建立该材料的两个流变应力数学模型.两模型中,Fields and Backofen模型在峰值应力之前能更好地反映流变应力的变化;加入软化因子的流变应力模型在峰值应力之后软化阶段能更好地反映流变应力的变化.%The flow stress of 7B04-T6 aluminum alloy sheet in the selected temperature and strain rate is learned based on warm tensile tests which were carried out in the temperature ranging from 473 K to 623 K and the strain rate ranging from 0. 1 s-1 to 0. 001 s-1. Two flow stress mathematical models of this material were established by modifying the Fields- Backofen equation and the flow stress mathematical equation containing a softening factor “s”. By comparing the two models, the Fields-Backofen model fit the flow stress better before the peak stress , the flow stress model containing a softening factor fit the flow stress better in the softening stage after the peak stress.

  19. Residual tensile stresses and piezoelectric properties in BiFeO3-Bi(Zn1/2Ti1/2O3-PbTiO3 ternary solid solution perovskite ceramics

    Weilin Zheng


    Full Text Available For low dielectric loss perovskite-structured (1-x-yBiFeO3-xBi(Zn1/2Ti1/2O3-yPbTiO3 (BF-BZT-PT (x = 0.04-0.15 and y = 0.15-0.26 ceramics in rhombohedral/tetragonal coexistent phase, structural phase transitions were studied using differential thermal analyzer combined with temperature-dependent dielectric measurement. Two lattice structural phase transitions are disclosed in various BF-BZT-PT perovskites, which is different from its membership of BiFeO3 exhibiting just one lattice structural phase transition at Curie temperature TC= 830oC. Consequently, residual internal tensile stresses were revealed experimentally through XRD measurements on ceramic pellets and counterpart powders, which are reasonably attributed to special structural phase transition sequence of BF-BZT-PT solid solution perovskites. Low piezoresponse was observed and argued extrinsically resulting from residual tensile stresses pinning ferroelectric polarization switching. Post-annealing and subsequent quenching was found effective for eliminating residual internal stresses in those BZT-less ceramics, and good piezoelectric property of d33 ≥ 28 pC/N obtained for 0.70BF-0.08BZT-0.22PT and 0.05 wt% MnO2-doped 0.70BF-0.04BZT-0.26PT ceramics with TC ≥ 640oC, while it seemed no effective for those BZT-rich BF-BZT-PT ceramics with x = 0.14 and 0.15 studied here.

  20. The de-correlation of westerly winds and westerly-wind stress over the Southern Ocean during the Last Glacial Maximum

    Liu, Wei; Lu, Jian; Leung, Lai-Yung R.; Xie, Shang-Ping; Liu, Zhengyu; Zhu, Jiang


    This paper investigates the changes of the Southern Westerly Winds (SWW) and Southern Ocean (SO) upwelling between the Last Glacial Maximum (LGM) and preindustrial (PI) in the PMIP3/CMIP5 simulations, highlighting the role of the Antarctic sea ice in modulating the wind stress effect on the ocean. Particularly, a discrepancy may occur between the changes in SWW and westerly wind stress, caused primarily by an equatorward expansion of winter Antarctic sea ice that undermines the wind stress in driving the liquid ocean. Such discrepancy may reflect the LGM condition in reality, in view of that the model simulates this condition has most credible simulation of modern SWW and Antarctic sea ice. The effect of wind stress on the SO upwelling is further explored via the wind-induced Ekman pumping, which is reduced under the LGM condition in all models, in part by the sea-ice “capping” effect present in the models.

  1. 张应力对TbDy-Fe RGMF磁性能的影响%Effect of Tensile Stress on Magnetic Properties of TbDy-Fe Giant Magnetostrictive Thin Films

    郑运相; 张鲁钟; 刘全洲; 周白杨


    The effect of the tensile stress on the magnetostriction and soft magnetic properties of the TbDy-Fe rare-earth giant magnetostrictive thin film (RGMF),synthesized by ion beam sputtering deposition (IBSD),was ex-perimentally investigated by measurement of cantilever deflection and hysteresis loop with LK-G150 laser micro-dis-placement sensor and alternating gradient magnetometer;mathematically modeled,theoretically analyzed and numer-ically simulated with software OOMMF.The simulated results show that the tensile stress significantly improves the magnetstrictive sensitivity of the TbDy-Fe RGMF at a low magnetic field,but slightly reduces the saturated magne-tostrictive sensitivity.To be specific,as the tensile stress increases,the coercive force of the TbDy-Fe RGMF decrea-ses,accompanied by an improvement of the magnetostrictive sensitivity at a low magnetic field.The simulated and measured results were found to be in fairly good agreement.%通过离子束溅射沉积法制备了受不同张应力作用的TbDy-Fe稀土超磁致伸缩薄膜样品.借助LK-G150激光微位移传感器和交变梯度磁强计分别测试薄膜的悬臂梁自由端偏转量与磁滞回线,通过微磁学模拟软件OOMMF模拟计算不同张应力作用下薄膜的磁性能;研究张应力对薄膜磁致伸缩性能及软磁性能的影响.结果表明:张应力能显著提高薄膜的低场磁敏性,但其饱和磁致伸缩性能有所降低;模拟计算结果与实验结果均表明:随着薄膜所受张应力的增加,薄膜的矫顽力逐渐减小,软磁性能得到了改善.

  2. Residual Tensile Strength of Plain Concrete Under Tensile Fatigue Loading


    The functional relation between the residual tensile strength of plain concrete and number of cycles was determined. 99 tappered prism specimens of plain concrete were tested under uniaxial tensile fatigue loading. Based on the probability distribution of the residual tensile strength, the empirical expressions of the residual tensile strength corresponding to the number of cycles were obtained. The residual tensile strength attenuating curves can be used to predict the residual fatigue life of the specimen under variable-amplitude fatigue loading. There is a good correlation between residual tensile strength and residual secant elastic modulus.The relationship between the residual secant elastic modulus and number of cycles was also established.

  3. Tensile properties of bacterial cellulose nanofibers - polyester composites

    Abral, H.; Mahardika, M.


    The paper shows tensile properties of bacterial cellulose (BC) nanofibers and polyester (PO) matrix composites. Tensile properties including tensile strength (TS), modulus elasticity (ME), and elongation (EL) were observed respectively. BC nanofibers exist in the form of a sheet that was then varied in matrix PO. The BC sheet was mounted by one, three, five and seven pieces respectively in the matrix PO. The tensile strength of the composites was conducted by using the tensile equipment. The results showed that the tensile strength of the composite with a single sheet of BC was lower than that of pure PO. The ST value achieved maximum level in the number of layers of BC three pieces, but then it decreased for the composites reinforced five and seven pieces of BC nanofiber, respectively. Scanning Electron Microscope (SEM) observation exhibits bad interface bonding between BC nanofibers and PO matrix.

  4. 拉伸速率对CMDB力学性能的影响%Effect of Tensile Rate on Menchanical Properties of CMDB Propellant

    陈竚; 任黎; 齐晓飞; 马亚南; 曹磊


    The effect of tensile rate(2~200 mm·min-1) on stress vs strain curve, maximum tensile strength and elongation rate of CMDB propellant at different temperature(-50~50℃) was investigated, by means of unilateral tensile method. It was found that the stress vs strain curve could be divided into three stages, maximum tensile strength decreased and maximum elongation rate increased with test temperature increasing at simple tensile rate, while maximum tensile strength increased and maximum elongation rate decreased with tensile rate increasing at simple test temperature. In addition, maximum tensile strength and elongation rate of CMDB propellant present power-law function relation with tensile rate.%  采用单向拉伸实验研究了不同拉伸速率(2~200 mm·min-1)条件下CMDB推进剂的应力--应变曲线变化规律,并得到了不同温度条件下(-50~50℃)拉伸速率对CMDB 推进剂最大拉伸强度和最大伸长率的影响。结果表明:CMDB推进剂的应力--应变曲线大体可分为3个阶段;同样拉伸速率条件下,CMDB推进剂的最大拉伸强度和最大伸长率随温度升高分别减小和增大;同样温度条件下,最大拉伸强度和最大伸长率随拉伸速率增加分别增大和减小;CMDB推进剂的最大拉伸强度、最大伸长率与拉伸速率存在较好的幂函数关系。

  5. The GMI effect of FeCo-based ribbon annealed with Joule heat under tensile stress in flowing atmosphere%流动气体中应力焦耳热退火FeCo基薄带的GMI效应

    方允樟; 许启明; 叶慧群; 郑金菊; 范晓珍; 潘乐敏; 马云; 李文忠


    采用单辊快淬法制备Fe36Co36Nb4Si4.8B19.2(FeCo基合金)薄带,在流动的气体中,施加不同的张应力并通以直流电进行退火,采用HP4294A型阻抗分析仪测量纵向驱动巨磁阴抗效应(LDGMI)曲线.对系列LDGMI曲线特征与外加张应力关系的分析结果表明,在流动气体中进行电流退火的FeCo基合金薄带,外加张应力的作用是感生横向易磁化结构,通过这种横向易磁化结构的控制,可以有效地改变LDGMI曲线的形状.该研究结果对于开发能满足各种实际需求的新型GMI传感器具有现实的指导意义.%The Fe36 Co36 Nb4Si4.8B19.2 (FeCo-based) amorphous ribbon was prepared by single roller quench and annealed with Joule-heat in flowing atmosphere under tesile stress. The longitudinally driven giant magneto-impedance (LGMI) effect of the stress-joule-heated FeCo-based ribbons were measured with HP4294A impedance analyzer. The results from analyzing the relation between the tensile stress and the character of the stress-Joule-heated FeCo-based ribbon LDGMI effect curves shows that, the transverse magnetic easy axial will be induced after the tensile stress applied during the proccess of the FeCo-based ribbon being Joule-heated in flowing atmosphere. The shape of the LDGMI curves can be effectively changed by controlling the transverse magnetic easy axial. This result is very important for develop the new GMI magnetic sensor which will be appropriate for various applications in future.

  6. Tensile properties of polymethyl methacrylate coated natural fabric Sterculia urens

    Jayaramudu, J


    Full Text Available stress, Young's modulus and % elongation at break were determined using a Universal Testing Machine. The effect of alkali treatment and the polymethyl methacrylate coating on tensile properties of the fabric was studied. The morphology of the fabric...

  7. Multiphasic stress relaxation response of freshly isolated and cultured vascular smooth muscle cells measured by quasi-in situ tensile test.

    Nagayama, Kazuaki; Saito, Shunsuke; Matsumoto, Takeo


    Vascular smooth muscle cells (SMCs) undergo a phenotypic change from a contractile to a synthetic state under pathological conditions, such as atherogenesis and restenosis. Although the viscoelastic properties of SMCs are of particular interest because of their role in the development of these vascular diseases, the effects of phenotypic changes on their viscoelastic properties are unclear at this stage. We performed the stress relaxation test at constant strain (ε=30%) for the freshly isolated contractile SMCs (FSMCs) and the cultured synthetic SMCs (CSMCs) maintaining in situ cell shape and cytoskeletal integrity. We also investigated the effect of extracellular Ca2+ on their viscoelastic behaviors. FSMCs and CSMCs exhibited multiphasic stress relaxation, which consisted of rapid relaxation, occurring on a time scale of several seconds and several 10 seconds, and slow relaxation occurring on a time scale of 1000 seconds. The estimated elastic modulus of CSMCs was less than one-half that of FSMCs, that was associated with a decreased of amount of actin stress fibers (SFs) during the transition from contractile to synthetic phenotypes. FSMCs showed a conservation of tension with extracellular Ca2+ following rapid stress relaxation. In contrast, CSMCs showed a consecutive decrease in tension independent of Ca2+. This suggests that the decrease in tension in a long time scale may be involved in mechanical remodeling of SFs induced through a Rho-dependent pathway, which is Ca2+-independent and become predominant in the transition from contractile to synthetic phenotypes.

  8. All-Atom Molecular-Level Computational Analyses of Polyurea/Fused-Silica Interfacial Decohesion Caused by Impinging Tensile Stress-Waves


    Interfacial decohesion, Reactive forcefields Paper type Research paper International Journal of Structural Integrity Vol. 5 No. 4, 2014 pp. 339-367 © Emerald ...interaction was conducted to provide additional insight into the outcome of the stress-wave/interface interactions. 4. Results and discussion The main emphasis

  9. Tensile properties of V-Cr-Ti alloys after exposure in hydrogen-containing environments

    Natesan, K.; Soppett, W.K. [Argonne National Lab., IL (United States)


    A systematic study has been initiated to evaluate the performance of several V-Cr-Ti alloys after exposure to environments containing hydrogen at various partial pressures. The goal is to correlate the chemistry of the exposure environment with the hydrogen uptake in the samples and its influence on the microstructure and tensile properties of the alloys. At present, four heats of alloys (BL-63, BL-71, and T87, plus 44 from General Atomics) are being evaluated. Other variables of interest are the effect of initial grain size on hydrogen uptake and tensile properties, and the synergistic effects of oxygen and hydrogen on the tensile behavior of the alloys. Experiments conducted thus far on specimens of various V-Cr-Ti alloys exposed to pH{sub 2} levels of 0.01 and 3 {times} 10{sup {minus}6} torr showed negligible effect of H{sub 2} on either maximum engineering stress of uniform/total elongation. Further, preliminary tests on specimens annealed at different temperatures showed that grain size variation by a factor of {approx}2 had a negligible effect on tensile properties.

  10. Tensile behavior of irradiated manganese-stabilized stainless steel

    Klueh, R.L. [Oak Ridge National Lab., TN (United States)


    Tensile tests were conducted on seven experimental, high-manganese austenitic stainless steels after irradiation up to 44 dpa in the FFTF. An Fe-20Mn-12Cr-0.25C base composition was used, to which various combinations of Ti, W, V, B, and P were added to improve strength. Nominal amounts added were 0.1% Ti, 1% W, 0.1% V, 0.005% B, and 0.03% P. Irradiation was carried out at 420, 520, and 600{degrees}C on the steels in the solution-annealed and 20% cold-worked conditions. Tensile tests were conducted at the irradiation temperature. Results were compared with type 316 SS. Neutron irradiation hardened all of the solution-annealed steels at 420, 520, and 600{degrees}C, as measured by the increase in yield stress and ultimate tensile strength. The steel to which all five elements were added to the base composition showed the least amount of hardening. It also showed a smaller loss of ductility (uniform and total elongation) than the other steels. The total and uniform elongations of this steel after irradiation at 420{degrees}C was over four times that of the other manganese-stabilized steels and 316 SS. There was much less difference in strength and ductility at the two higher irradiation temperatures, where there was considerably less hardening, and thus, less loss of ductility. In the cold-worked condition, hardening occured only after irradiation at 420{degrees}C, and there was much less difference in the properties of the steels after irradiation. At the 420{degrees}C irradiation temperature, most of the manganese-stabilized steels maintained more ductility than the 316 SS. After irradiation at 420{degrees}C, the temperature of maximum hardening, the steel to which all five of the elements were added had the best uniform elongation.

  11. Fan-head shear rupture mechanism as a source of off-fault tensile cracking

    Tarasov, Boris


    This presentation discusses the role of a recently identified fan-head shear rupture mechanism [1] in the creation of off-fault tensile cracks observed in earthquake laboratory experiments conducted on brittle photoelastic specimens [2,3]. According to the fan-mechanism the shear rupture propagation is associated with consecutive creation of small slabs in the fracture tip which, due to rotation caused by shear displacement of the fracture interfaces, form a fan-structure representing the fracture head. The fan-head combines such unique features as: extremely low shear resistance (below the frictional strength) and self-sustaining tensile stress intensification along one side of the interface. The variation of tensile stress within the fan-head zone is like this: it increases with distance from the fracture tip up to a maximum value and then decreases. For the initial formation of the fan-head high local stresses corresponding to the fracture strength should be applied in a small area, however after completions of the fan-head it can propagate dynamically through the material at low shear stresses (even below the frictional strength). The fan-mechanism allows explaining all unique features associated with the off-fault cracking process observed in photoelastic experiments [2,3]. In these experiments spontaneous shear ruptures were nucleated in a bonded, precut, inclined and pre-stressed interface by producing a local pressure pulse in a small area. Isochromatic fringe patterns around a shear rupture propagating along bonded interface indicate the following features of the off-fault tensile crack development: tensile cracks nucleate and grow periodically along one side of the interface at a roughly constant angle (about 80 degrees) relative to the shear rupture interface; the tensile crack nucleation takes place some distance behind the rupture tip; with distance from the point of nucleation tensile cracks grow up to a certain length within the rupture head zone

  12. Analysis of forces acting on bottom outlet structure and measures for tensile stress on upstream dam surface%导流底孔结构受力分析与坝上游面拉应力控制措施

    程宵; 苏凯; 伍鹤皋


    Based on a bottom outlet project, with regard to the characteristics of forces acting on the structure during the blocking period, the stress distributions of the structure and upstream dam surface were studied by means of the 3D finite element method. The results show that a wide range of tensile stress along the dam axis will appear at the upstream dam surface when the position of the seam which links the orifice of the bottom outlet and the dam is arranged in front of the upstream dam surface. In order to reduce the tensile stress along the dam axis efficiently, measures of filling materials in the seams at both sides of the dam or moving the position of the seam which links the orifice and the dam to the parallel position of the upstream dam surface should be taken. In this way, the possibility of concrete crack on the upstream dam surface during the construction, operation and blocking periods may be reduced.%结合某导流底孔工程,针对封堵期结构的受力特征,采用三维有限单元法对导流底孔坝段结构和坝上游面的应力分布情况进行计算分析.结果表明:导流底孔进水口段和坝内孔身段的分缝布置于坝面上游时,坝上游面将出现较大范围的横河向拉应力,当考虑大坝两侧分缝内填充材料作用或将导流底孔进水口段与坝内孔身段的分缝位置下移至与大坝上游面平齐时,能够有效地减小坝上游面拉应力的数值与范围,降低坝上游面混凝土受拉开裂的可能性.

  13. An Average Failure Index Method for the Tensile Strength Prediction of Composite Adhesive-bondedJoints

    ZHANG Jianyu; SHAN Meijuan; ZHAO Libin; FEI Binjun


    An average failure index method based on accurate FEA was proposed for the tensile strength prediction of composite out-of-plane adhesive-bondedπjoints. Based on the simple and independent maximum stress failure criterion, the failure index was introduced to characterize the degree of stress components close to their corresponding material strength. With a brief load transfer analysis, the weak fillers were prominent and further detailed discussion was performed. The maximum value among the average failure indices which were related with different stress components was filtrated to represent the failure strength of the critical surface, which is either the two curved upside surfaces or the bottom plane of the fillers for compositeπjoints. The tensile strength of three kinds ofπjoints with different material systems, configurations and lay-ups was predicted by the proposed method and corresponding experiments were conducted. Good agreements between the numerical and experimental results give evidence of the effectiveness of the proposed method. In contrast to the existed time-consuming strength prediction methods, the proposed method provides a capability of quickly assessing the failure of complex out-of-plane joints and is easy and convenient to be widely utilized in engineering.


    Guoming Hu; Yanmin Wang; Pingbo Xie; Zhidong Pan


    The core mechanism of comminution could be reduced to the breakage of individual particles that occurs through contact with other particles or with the grinding media, or with the solid walls of the mill. When brittle particles are loaded in compression or by impact, substantial tensile stresses are induced within the particles. These tensile stresses are responsible for splitting failure of brittle particles. Since many engineering materials have Poisson's ratios very close to 0.3, the influence of Poisson's ratio on the tensile strength is neglected in many studies. In this paper, the state of stress in a spherical particle due to two diametrically opposed forces is analyzed theoretically. A simple equation for the tensile stress at the centre of the particle is obtained. It is found reasonable to propose this tensile stress at the instant of failure as the tensile strength of the particle. Moreover, this tensile strength is a function of the Poisson's ratio of the material. As the state of stress along the z-axis in an irregular specimen tends to be similar to that in a spherical particle compressed diametrically with the same force, this tensile strength has some validity for irregular particles as well.Therefore, it could be used as the tensile strength for brittle particles in general. The effect of Poisson's ratio on the tensile strength is discussed.

  15. EUROFER 97. Tensile, charpy, creep and structural tests

    Rieth, M.; Schirra, M.; Falkenstein, A.; Graf, P.; Heger, S.; Kempe, H.; Lindau, R.; Zimmermann, H.


    EUROFER 97 - the European reference material for the first wall of a DEMO fusion reactor - was produced as 3.5 t batch of rods and plates. Following the history of the development activities from conventional martensitic 12% Cr steel, MANET and OPTIFER up to the low or reduced activation (RAFM) EUROFER steel, results obtained from experiments on specimens from rods (diameter 100 mm) and plates (14 mm) are presented for a basic characterization. Physical and mechanical properties are compared with those of OPTIFER-1W and the F82H-mod 2% W steel. The transition behaviour was determined by plotting a continuous TTT (time temperature transition) diagram. In addition, extension coefficients were determined from room temperature up to 1000 C. Hardening tests at temperatures from 850 C to 1120 C illustrated the range of maximum hardness as well as grain size development. Tempering tests and additional annealing experiments from 300 C to 875 C allowed characterizing tempering behaviour and stability. Charpy properties were examined for various heat treatments and specimen types between 60 C and -100 C. Further, ductility criteria like FATT, DBTT and 68 J were determined. Particular attention was paid to the influence of grain size and O{sub 2} content. Tensile strength was measured for several heat treatments between room temperature and 700 C. Long-term ageing was investigated by means of stabilization annealing experiments. These were carried out with various temperature/time combinations including tensile tests. In EUROFER tensile strength was hardly affected by the different heat treatments while the ductility criteria showed only a moderate increase in temperature. Therefore, it can be concluded that EUROFER is not susceptible to ageing. Creep and creep rupture properties were investigated in the temperature range of 450 C to 650 C. So far, creep times of up to 15000 h have been covered by the experiments. The status of the test program allows for an extrapolation of

  16. High temperature tensile properties of V-4Cr-4Ti

    Zinkle, S.J.; Rowcliffe, A.F.; Stevens, C.O. [Oak Ridge National Lab., TN (United States)


    Tensile tests have been performed on V-4Cr-4Ti at 750 and 800 C in order to extend the data base beyond the current limit of 700 C. From comparison with previous measurements, the yield strength is nearly constant and tensile elongations decrease slightly with increasing temperature between 300 and 800 C. The ultimate strength exhibits an apparent maximum near 600 C (attributable to dynamic strain aging) but adequate strength is maintained up to 800 C. The reduction in area measured on tensile specimens remained high ({approximately}80%) for test temperatures up to 800 C, in contrast to previous reported results.

  17. The transient behavior of electrorheological fluid in tensile flow

    Tian, Yu; Zhang, Minliang; Zhu, Xuli; Jiang, Jile; Meng, Yonggang; Wen, Shizhu


    Transient behaviors of (ER) fluids in tensile flow and applied stepwise voltages were experimentally studied. The transient tensile stress rises exponentially with time. The characteristic rising time of tensile stress is independent of the amplitude of the applied voltage and the tensile velocity, while the amplitude of tensile yield stress is significantly affected by the two factors. The transient tension applied as a stepwise voltage is different from a stable tension pre-applied at constant voltage in different particle chain structure forming processes. Because of the chain aggregation during an intermittent voltage on-off test, the achieved tensile yield stress showed an exponent of 2.75 to the applied electric field at low separation velocities (0.2 mm s-1), higher than the square relationship predicted by traditional polarization models, and the exponent of 1.5 predicted by the conduction model. The results achieved in this study show that the mechanical properties of ER fluids are greatly affected by the method of applying the electric field, the strain rate, and the gap geometry between electrodes. These factors should be properly considered in the design and control of ER actuators.

  18. Improved Tensile Adhesion Specimens for High Strength Epoxy Systems in Aerospace Applications

    Haddock, M. Reed; McLennan, Michael L.


    An improved tensile adhesion button has been designed and tested that results in higher measured tensile adhesion strength while providing increased capability for testing high strength epoxy adhesive systems. The best attributes of two well-established tensile button designs were combined and refined into an optimized tensile button. The most significant design change to the tensile button was to improve alignment of the bonded tensile button specimens during tensile testing by changing the interface between the tensile button and the tensile test machine. The established or old button design uses a test fixture that pulls from a grooved annulus or anvil head while the new button design pulls from a threaded hole in the centerline of the button. Finite element (FE) analysis showed that asymmetric loading of the established anvil head tensile button significantly increases the stress concentration in the adhesive, causing failure at lower tensile test loads. The new tensile button was designed to eliminate asymmetric loading and eliminate misalignment sensitivity. Enhanced alignment resulted in improved tensile adhesion strength measurement up to 13.8 MPa (2000psi) over the established button design. Another design change increased the capability of the button by increasing the threaded hole diameter allowing it to test high strength epoxy systems up to 85 MPa(less than 12,000 psi). The improved tensile button can be used in button- to-button or button-to-panel configurations.

  19. Modeling the Tensile Properties of Soybean Protein Yarns

    石风俊; 崔世忠


    The tensile properties of a series of soybean protein yarns are tested in USTER THINKPAID Ⅲ.A nonlinear viscoelastic model has been proposed to describe the tensile behavior of soybean protein yarns.The model is composed of a Maxwell element,a linear spring and a nonlinear spring.The tensile properties of soybean protein yarn are analyzed.The stress-strain curves of the yarns are fitted.The average breaking tenacity and specific work of rupture are calculated using the average breaking strain.Comparisons indicate that theoretical predictions conform the experimental results very well.

  20. Tensile Properties of Weft Knitted Fabric Reinforced Composites



    Seven kinds of weft knitted fabrics from glass fiber yarns were used as reinforcement to make fabric/epoxy composite laminates. Tensile tests were carried out to examine and compare the mechanical properties in course and wale direction of these composites. On the basis of experimental results, attempts have been made to analyze some main factors influencing stress-strain curve, ultimate tensile strength and initial elastic modulus of specimens.

  1. Concrete under Impact Loading, Tensile Strength and Bond

    Reinhardt, H.W.


    Uniaxial impact tensile tests on plain concrete were carried out with the aid of Split Hopkinson Bar equipment with stress rates of up to 60000 N/mm2. s. Various concrete mixes were investigated under. dry and wet conditions. All the concretes showed an increase in strength with increasing stress

  2. Concrete under Impact Loading, Tensile Strength and Bond

    Reinhardt, H.W.


    Uniaxial impact tensile tests on plain concrete were carried out with the aid of Split Hopkinson Bar equipment with stress rates of up to 60000 N/mm2. s. Various concrete mixes were investigated under. dry and wet conditions. All the concretes showed an increase in strength with increasing stress ra

  3. True Triaxial Strength and Brittle Fracture of the Granodiorite at the SAFOD Drillhole Wall, and the Potential for Estimating the Maximum Horizontal Principal Stress

    Lee, H.; Haimson, B.


    drillhole wall conditions is drastically different from that conventionally expected, but is compatible with breakout formation mechanism in granite (Haimson, Int. J. Rock Mech., 2007). All the 'unjacketed' true triaxial strength data can be fitted by a simple function in the octahedral shear stress versus octahedral normal stress domain, yielding a Nadai-type true triaxial strength criterion. The criterion can be used in conjunction with breakouts that have been located within the cored zone to yield the maximum horizontal in situ stress σH when the other two principal stress are known. Assuming that the state of stress at breakout-drillhole intersections (located for example by BHTV logging) is sufficient to bring about brittle failure (Vernik and Zoback, 1992), one can substitute the known principal stresses there (obtained from the Kirsch solution) for the corresponding values in the criterion. The in situ σv is given by the overburden density, σh is typically obtained from hydrofrac shut-in pressures, breakout width is extracted from BHTV logs, borehole fluid pressure is a function of its density, and the Poisson's ratio is obtained from mechanical lab testing. The only unknown, σH, is thus readily computed. An actual computation was not carried out because data on hydrofrac pressures and breakout dimensions were not available at the time of this submission.

  4. Improved Tensile Test for Ceramics

    Osiecki, R. A.


    For almost-nondestructive tensile testing of ceramics, steel rod is bonded to sample of ceramic. Assembly is then pulled apart in conventional tensile-test machine. Test destroys only shallow surface layer which can be machined away making specimen ready for other uses. Method should be useful as manufacturing inspection procedure for low-strength brittle materials.

  5. Finite element analysis on stresses field of normalized layer thickness within ceramic coating on aluminized steel


    Multilayer ceramic coatings were fabricated on steel substrate using a combined technique of hot dipping aluminum(HDA)and plasma electrolytic oxidation(PEO). A triangle of normalized layer thickness was created for describing thickness ratios of HDA/PEO coatings. Then, the effect of thickness ratio on stresses field of HDA/PEO coatings subjected to uniform normal contact load was investigated by finite element method. Results show that the surface tensile stress is mainly affected by the thickness ratio of Al layer when the total thickness of coating is unchanged. With the increase of Al layer thickness, the surface tensile stress rises quickly. When Al2O3 layer thickness increases, surface tensile stress is diminished. Meanwhile, the maximum shear stress moves rapidly towards internal part of HDA/PEO coatings. Shear stress at the Al2O3/Al interface is minimal when Al2O3 layer and Al layer have the same thickness.

  6. Tensile Strength of Natural Fiber Reinforced Polyester Composite

    Ismail, Al Emran; Awang, Muhd. Khairudin; Sa'at, Mohd Hisham


    Nowadays, increasing awareness of replacing synthetic fiber such as glass fiber has emerged due to environmental problems and pollutions. Automotive manufacturers also seek new material especially biodegradable material to be non-load bearing application parts. This present work discussed on the effect of silane treatment on coir fiber reinforced composites. From the results of tensile tests, fibers treated with silane have attained maximum material stiffness. However, to achieve maximum ultimate tensile strength and strain at failure performances, untreated fibers work very well through fiber bridging and internal friction between fiber and polymeric matrix. Scanning electron microscope (SEM) observations have coincided with these results.

  7. finite element model for predicting residual stresses in shielded ...


    The generated residual stresses were measured using an X. E066 electrodes were used ... direction (σx) had a maximum value of 375MPa (tensile) and minimum value of ... method are in fair agreement with the experimental results. Based on ...

  8. Maximum Fidelity

    Kinkhabwala, Ali


    The most fundamental problem in statistics is the inference of an unknown probability distribution from a finite number of samples. For a specific observed data set, answers to the following questions would be desirable: (1) Estimation: Which candidate distribution provides the best fit to the observed data?, (2) Goodness-of-fit: How concordant is this distribution with the observed data?, and (3) Uncertainty: How concordant are other candidate distributions with the observed data? A simple unified approach for univariate data that addresses these traditionally distinct statistical notions is presented called "maximum fidelity". Maximum fidelity is a strict frequentist approach that is fundamentally based on model concordance with the observed data. The fidelity statistic is a general information measure based on the coordinate-independent cumulative distribution and critical yet previously neglected symmetry considerations. An approximation for the null distribution of the fidelity allows its direct conversi...

  9. Deformation of two welded elastic half-spaces due to a long inclined tensile fault

    Anil Kumar; Sarva Jit Singh; Jagdish Singh


    The calculation of the deformation caused by shear and tensile faults is necessary for the investigation of seismic and volcanic sources. The solution of the two-dimensional problem of a long inclined shear fault in two welded half-spaces is well known. The purpose of this note is to present the corresponding solution for a tensile fault. Closed-form analytical expressions for the Airy stress function for a tensile line source in two welded half-spaces are first obtained. These expressions are then integrated analytically to derive the Airy stress function for a long tensile fault of arbitrary dip and finite width. Closed-form analytical expressions for the displacements and stresses follow immediately from the Airy stress function. These expressions are suitable for computing the displacement and stress fields around a long inclined tensile fault near an internal boundary.

  10. Effect of specimen geometry on tensile strength of cortical bone.

    Feng, Liang; Jasiuk, Iwona


    We investigate the effect of specimen geometry on the ultimate tensile strength of cortical bone measured by a tensile test. This article is motivated by the fact that there is no clear consensus in the literature on a suitable specimen shape for cortical bone testing. We consider three commonly used tensile test specimen shapes: strip, dumbbell with sharp junctions, and dumbbell with rounded junctions. We conduct this study computationally, using a finite element method, and experimentally by testing porcine femurs. Our results show that local stress concentration factors in the specimen lead to reduced values in the measured tensile strength. The higher the stress concentrations are, the lower is the measured strength. We find that the strip specimens are not a good choice due to high stress concentrations. For the same reason, dumbbell specimens with sharp junctions between the grip and gage sections should also be avoided. The dumbbell shaped tensile test specimens with an arc transition and a maximized radius of fillet are a better choice because such geometry lowers stress concentrations.

  11. Evaluation of Tensile Strength of Unresin Continuous Carbon Fiber Cables as Tensile Reinforcement for Concrete Structures

    Ohta, Toshiaki; Djamaluddin, rudy; Seo, SungTag; Sajima, Takao; Harada, Koji


    As a tensile reinforcement of a concrete structure member, tensile strength of Unresin Continuous Carbon Fiber (UCCF) cables should be stated clearly. It has been reported that, through direct tensile test, tensile capacity of UCCF cables ranged from 30%

  12. Tensile properties of V-Cr-Ti alloys after exposure in hydrogen-containing environments

    Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)


    A systematic study has been initiated at Argonne National Laboratory to evaluate the performance of several V-Cr-Ti alloys after exposure to environments containing hydrogen at various partial pressures. The goal is to correlate the chemistry of the exposure environment with hydrogen uptake in the samples and its influence on the microstructure and tensile properties of the alloys. At present, the principal effort has focused on the V-4Cr-4Ti alloy of heat identified as BL-71; however other alloys (V-5Cr-5Ti alloy of heats BL-63, and T87, plus V-4Cr-4Ti alloy from General Atomics [GA]) are also being evaluated. Other variables of interest are the effect of initial grain size on the tensile behavior of the alloys. Experiments conducted on specimens of various V-Cr-Ti alloys exposed to pH{sub 2} levels of 0.01 and 3 {times} 10{sup {minus}6} torr showed negligible effect of H{sub 2} on either maximum engineering stress or uniform and total elongation. However, uniform and total elongation decreased substantially when the alloys were exposed to 1.0 torr H{sub 2} pressure. Preliminary data from sequential exposures of the materials to low-pO{sub 2} and several low-pH{sub 2} environments did not reveal an adverse effect on the maximum engineering stress or on uniform and total elongation. Further, tests in H{sub 2} environments on specimens annealed at different temperatures showed that grain-size variation by a factor of {approx}2 had little or no effect on tensile properties.

  13. Effects of Iron-Rich Intermetallics and Grain Structure on Semisolid Tensile Properties of Al-Cu 206 Cast Alloys near Solidus Temperature

    Bolouri, Amir; Liu, Kun; Chen, X.-Grant


    The effects of iron-rich intermetallics and grain size on the semisolid tensile properties of Al-Cu 206 cast alloys near the solidus were evaluated in relation to the mush microstructure. Analyses of the stress-displacement curves showed that the damage expanded faster in the mush structure dominated by plate-like β-Fe compared to the mush structure dominated by Chinese script-like α-Fe. While there was no evidence of void formation on the β-Fe intermetallics, they blocked the interdendritic liquid channels and thus hindered liquid flow and feeding during semisolid deformation. In contrast, the interdendritic liquid flows more freely within the mush structure containing α-Fe. The tensile properties of the alloy containing α-Fe are generally higher than those containing β-Fe over the crucial liquid fraction range of 0.6 to 2.8 pct, indicating that the latter alloy may be more susceptible to stress-related casting defects such as hot tearing. A comparison of the semisolid tensile properties of the alloy containing α-Fe with different grain sizes showed that the maximum stress and elongation of the alloy with finer grains were moderately higher for the liquid fractions of 2.2 to 3.6 pct. The application of semisolid tensile properties for the evaluation of the hot tearing susceptibility of experimental alloys is discussed.

  14. Uniaxial Tensile Test for Soil.


    1370 UNIAXIAL TENSILE TEST FOR SOIL(U) ARMY’ ENGINEER 1/2 LD D A LEAVELL ET AL. APR 67 I4ES/TR/GL-67-14 UNCLSED F/ 9/10NL Eammhhmhhhml mommomhhhhmhl...mmohhhmmhmhhl mmohhmhhhomhl mhhhhhhhhhhhomu 3Wo HhII~ "’OM U1.2 1111 . 111.6 U- TECHNICAL REPORT GL-87-10 UNIAXIAL TENSILE TEST FOR SOIL by Daniel A...Classification) Uniaxial Tensile Test for Soil 12 PERSONAL AUTHOR(S) Leavell, Daniel A.; Peters, John F. 13a. TYPE OF REPORT 1 3b TIME COVERED 14. DATE OF

  15. Tensile properties of V-Cr-Ti alloys after exposure in helium and low-partial-pressure oxygen environments

    Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)


    A test program is in progress to evaluate the effect of oxygen at low pO{sub 2} on the tensile properties of V-(4-5)wt% Cr-(4-5)wt% Ti alloys. Some of the tensile specimens were precharged with oxygen at low pO{sub 2} at 500{degrees}C and reannealed in vacuum at 500{degrees}C in environments with various pO{sub 2} levels and subsequently tensile tested at room temperature. The preliminary results indicate that both approaches are appropriate for evaluating the effect of oxygen uptake on the tensile properties of the alloys. The data showed that in the relatively short-time tests conducted thus far, the maximum engineering stress slightly increased after oxygen exposure but the uniform and total elongation values exhibited significant decrease after exposure in oxygen-containing environments. The data for a specimen exposed to a helium environment were similar to those obtained in low pO{sub 2} environments.

  16. Estimation of Single-fibre Tensile Properties from the Bundle Tensile Curve of Polyester Fibres



    Fibre bundle tensile curves can be used to characterise fibre processing properties and end-use performance directly and to predict single-fibre properties in theory. In this paper, the tensile behaviour of polyester fibre-bundles has been analysed in characteristic values and diagramming. The characteristic distributions which include the symmetry distribution on right part, SRBS′ (e), on left part, SLBS′(e) and the curve on base-line modification, MBS′ (e),based on the modulus distribution, BS′ (e), as well as the frequency density function of broken fibres, B′ (e), have been derived from the tail of bundle tensile curves. The theoretical and measured results show that the most important curves are MBS′ ( e ) and B′ ( e ) and can be used to estimate the breaking-extension distribution of single fibres. Especially for MBS′(e), the modulus distribution can accurately characterize single-fibre tensile properties and is no limitation as the calculation of B′(e) because the bundle specific stress Y(e) of no fibre breaking at extension e should be found at first.

  17. Manufacturing of Plutonium Tensile Specimens

    Knapp, Cameron M [Los Alamos National Laboratory


    Details workflow conducted to manufacture high density alpha Plutonium tensile specimens to support Los Alamos National Laboratory's science campaigns. Introduces topics including the metallurgical challenge of Plutonium and the use of high performance super-computing to drive design. Addresses the utilization of Abaqus finite element analysis, programmable computer numerical controlled (CNC) machining, as well as glove box ergonomics and safety in order to design a process that will yield high quality Plutonium tensile specimens.

  18. Heat treatment effects on tensile properties of V-(4-5) wt.% Cr-(4-5) wt.% Ti alloys

    Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)


    Effects of thermomechanical treatments on microstructures and mechanical properties are of interest for long term application of V-Cr-Ti alloys in fusion reactor systems. Influence of thermal annealing at 1050{degrees}C on stress/strain behavior, maximum engineering strength, and uniform and total elongation were evaluated. The results show that multiple annealing has minimal effect on the tensile properties of V-(4-5)Cr-(4-5)Ti alloys tested at room temperature and at 500{degrees}C.

  19. Induced martensitic transformation during tensile test in nanostructured bainitic steels

    Morales-Rivas, L. [Department of Physical Metallurgy, National Center for Metallurgical Research (CENIM-CSIC), Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); University of Kaiserslautern, Materials Testing, Gottlieb - Daimler - Str., 67663 Kaiserslautern (Germany); Garcia-Mateo, C., E-mail: [Department of Physical Metallurgy, National Center for Metallurgical Research (CENIM-CSIC), Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Kuntz, Matthias [Robert Bosch GmbH, Materials and Processing Dept, P.O. Box 300240, Stuttgart (Germany); Sourmail, Thomas [Asco Industries CREAS (Research Centre) Metallurgy, BP 70045, Hagondange Cedex 57301 (France); Caballero, F.G. [Department of Physical Metallurgy, National Center for Metallurgical Research (CENIM-CSIC), Avda. Gregorio del Amo, 8, 28040 Madrid (Spain)


    Retained austenite in nanostructured bainite is able to undergo mechanically induced martensitic transformation. However, the link between transformation and deformation mechanisms involved makes difficult the understanding of the process. In this work, a model has been developed to assess the effect of the external stress itself on the martensite phase transformation. In addition, after a detailed initial microstructural characterization, the martensite fraction evolution during tensile deformation has been obtained by means of X-ray diffraction analyses after interrupted tensile tests in several nanostructured bainitic steels. Experimental results have been compared to the outputs of the model, as a reference. They suggests that stress partitioning between phases upon tensile deformation is promoted by isothermal transformation at lower temperatures.

  20. Tensile fracture and shear localization under high loading rate in tungsten alloys

    Couque, H.; Lankford, J.; Bose, A


    The influence of loading rate and microstructure on the tensile and compressive failure properties of three microstructurally dissimilar tungsten alloys has been investigated. Dynamic tensile fracture properties were characterized through fracture toughness tests performed at a stress intensity loading rate of 106 MPa $\\sqrt{{\\rm m}}$ s-1, and by tensile testing at a strain rate of 103 s-1. Shear banding phenomena were investigated by means of compression tests performed at strain rates of 5 ...

  1. Demonstration of concurrent tensile testing and magnetic resonance elastography.

    Brinker, Spencer; Klatt, Dieter


    Magnetic Resonance Elastography (MRE) is a technique used to measure the mechanical properties of soft tissues and has already shown its diagnostic potential for pathologies involving fibrogenesis and neurodegeneration. Experimental investigation of loading during MRE is fairly unexplored and may help to better understand changing mechanical properties in relation to organ function. Tensile testing is a common technique for examining mechanical properties of materials and is used as the simultaneous comparison method with MRE in this study. 3D MRE data was acquired during quasistatic uniaxial tensile loading of an Ecoflex 0010 cylindrical specimen. Individual MRE scans at 1.5, 2.0, and 2.5kHz where performed on engineering strain increments of 20% from 0% to 140% while tensile reaction force was recorded using a load cell attached to an adjustable elongation slide. Tensile stress-strain relation resembled the Fung hyperelastic strain energy model. We observe that the MRE shear storage modulus is related to the state of tensile deformation. This study demonstrates the feasibility of simultaneous tensile testing during MRE and the new design can potentially be used for MRE calibration using pre-tension. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Device Design and Test of Fatigue Behaviour of Expansion Anchor Subjected to Tensile Loads

    Zhang Jinfeng


    Full Text Available In order to study on the fatigue behaviour of expansion anchor (M16, grade 8.8 for overhead contact system in electrification railways, a set of safe, practical loading device is designed and a fatigue test campaign was carried out at structural laboratory of China Academy of Building Research on expansion anchor embedded in concrete block. The mobile frame of the loading device was designed well by finite-element simulation. According to some fatigue performance test of expansion anchor with different size and form, the device have been assessed experimentally its dependability. The results were found that no fatigue damage phenomenon occurred in all specimens after 2×106 cycles tensile fatigue test in this specific series. It shows that in the condition of medium level or slightly lower maximum stress limit and nominal stress range, expansion bolt has good fatigue resistance. The biggest relative displacement and the residual relative displacement after test (Δδ = δ2-δ1 was also strongly lower than the symbol of the fatigue test failure index of this specific series (0.5mm in the high cycle fatigue regime. The ultimate tension failures mode after fatigue tests in all tested samples take place in the concrete anchorage zone. The reduction range of the ultimate tensile strength properties of the anchorage system was not obvious, and the concrete was seen to be the weakest link of the system.

  3. Tensile failure of two-dimensional quasi-brittle foams

    Mangipudi, K. R.; Onck, P. R.


    Stress redistribution caused by damage onset and the subsequent local softening plays an important role in determining the ultimate tensile strength of a cellular structure. The formation of damage process zones with struts dissipating a finite amount of fracture energy will require the macroscopic

  4. Tensile Test For Arboform Samples

    Plavanescu (Mazurchevici), Simona; Quadrini, Fabrizio; Nedelcu, Dumitru


    Petroleum-based plastic materials constitute a major environmental problem due to their low biodegradability and accumulation in various environments. Therefore, searching for novel biodegradable plastics is received particular attention. Our studied material, "Liquid wood" produced from lignin, natural fibres and natural additives, is completely biodegradable in natural environment, in normal conditions. This paper presents the behaviour of Arboform and Arboform reinforced with Aramidic Fibers tensile test analysis. Experimental data show that the tensile strength reached an average value of 15.8 MPa, the modulus of elasticity after tests is 3513.3MPA for Arboform and for the reinforcement the tensile strength is 23.625MPa, the modulus of elasticity after tests is 3411.5MPA, the materials present a brittle behaviour. The high mechanical properties of newly developed material, better than of other ordinary plastics, recommend it as a potential environment-friendly substituent for synthetic plastics, which are present in all fields of activity.

  5. Tensile strength on friction stir processed AMg5 (5083) aluminum alloy

    Chumaevsky, A. V.; Eliseev, A. A.; Filippov, A. V.; Rubtsov, V. E.; Tarasov, S. Yu.


    The results of the tensile tests carried out both on AMg5 (5083) aluminum alloy samples base and those obtained using friction stir processing technique are reported. The tensile test samples have been prepared from the friction stir processed plates so that their tensile axis was parallel to the processing direction. The maximum tensile strength of the processed samples was 9% higher than of the base metal. The fractographic examination shows the presence of flat areas inherent of the brittle fracture in all three friction processed samples. The load-extension curves show that friction stir processing may suppress the serrated yielding.

  6. Thermographic studies on IMI-834 titanium alloy during tensile loading

    Kumar, Jalaj [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India)], E-mail:; Baby, Sony; Kumar, Vikas [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India)


    To study the material deformation kinetics under monotonic loading conditions, infrared radiation thermography (IRT) has been used in the present investigation. Studies were performed on IMI-834 titanium alloy, which is used in the compressor module of an aeroengine. The compressor has variable states of stress triaxialities at different locations. The effect of stress triaxiality on material deformation was investigated with the use of smooth and axisymmetrically notched round tensile specimens of the alloy. Instantaneous surface temperatures were measured on specimens during tensile deformation through IRT technique. The notched specimen exhibited localized and higher rate of temperature evolution during loading. Using surface temperature evolution curves, thermoelastic and inelastic regions were identified for smooth and notched specimens. With the help of Lord Kelvin's equation, stresses were predicted for thermoelastic region. A good correlation was found between the predicted and experimental stresses for this region.

  7. Relativity between corrosion-induced stress and stress corrosion cracking of brass in an ammonia solution


    The susceptibility to stress corrosion cracking (SCC) of brass in an ammonia solution with various pH values or under various applied potentials was measured at slow strain rate tests. The additive stress in the same solution was measured using two methods. The results indicate that the variation of the susceptibility to SCC with pH value or with potential is in an excellent agreement with the corrosion (passive film or dezincification layer)-induced stress. When pH ? 7, the corrosion-induced tensile stress and the susceptibility to SCC have maximum values and hardly change with increasing the pH value. However, when pH < 7, both the corrosion-induced tensile stress and the susceptibility to SCC reduce rapidly with decreasing the pH value. Both the corrosion-induced tensile stress and the susceptibility to SCC have maximum values at the open-circuit potential, decrease slightly under the anodic polarization, and reduce gradually to zero under the cathodic polarization.

  8. Different stimulation strategies to enhance the performance of subsurface heat exchangers based on tensile fractures

    Pluymaekers, M.P.D.; Wees, J.D.A.M. van; Hoedeman, G.C.; Fokker, P.A.


    Tensile fraccing in non-critically stressed tectonic environments, such as occur in large parts of the Netherlands, allows stimulation with a negligible level of seismicity. In this paper we analyse the performance of two tensile hydraulic stimulation strategies, for geothermal systems at large dept

  9. Analysis of residual stress in the resin of metal-resin adhesion structures by scanning acoustic microscopy.

    Ohno, Hiroki; Endo, Kazuhiko; Nagano-Takebe, Futami; Ida, Yusuke; Kakino, Ken; Narita, Toshio


    The residual stress caused by polymerization shrinkage and thermal contraction of a heat-curing resin containing 4-META on a metal-resin structure was measured by a scanning acoustic microscope. The tensile residual stress in the resin occurred within 70 µm of the adhesion interface with a flat plate specimen. The maximum tensile stress was about 58 MPa at the interface. On a metal plate specimen with retention holes, ring-like cracks in the resin occurred around the retention holes with the adhesive specimen and many linear cracks occurred in the resin vertical to the longitudinal direction of the metal frame with the non-adhesive specimens. There was tensile residual stress on the resin surface at the center of the retention holes of the adhesion specimen, indicating that the stress in the specimen with surface treatment for adhesion was higher than in that without surface treatment.

  10. Tensile properties of V-Cr-Ti alloys after exposure in oxygen-containing environments

    Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)


    A systematic study was conducted to evaluate the oxidation kinetics of V-4Cr-4Ti (44 alloy) and V-5Cr-5Ti alloys (55 alloy) and to establish the role of oxygen ingress on the tensile behavior of the alloys at room temperature and at 500 C. The oxidation rate of the 44 alloy is slightly higher than that of the 55 alloy. The oxidation process followed parabolic kinetics. Maximum engineering stress for 55 alloy increased with an increase in oxidation time at 500 C. The maximum stress values for 55 alloy were higher at room temperature than ta 500 C for the same oxidation treatment. Maximum engineering stresses for 44 alloy were substantially lower than those for 55 alloy in the same oxidation {approx}500 h exposure in air at 500 C; the same values were 4.8 and 6.1%, respectively, at 500 C after {approx}2060 h oxidation in air at 500 C. Maximum engineering stress for 44 alloy at room temperature was 421.6--440.6 MPa after {approx}250 h exposure at 500 C in environments with a pO{sub 2} range of 1 {times} 10{sup {minus}6} to 760 torr. The corresponding uniform and total elongation values were 11--14.4% and 14.5--21.7%, respectively. Measurements of crack depths in various specimens showed that depth is independent of pO{sub 2} in the preexposure environment and was of 70--95 {micro}m after 250--275 h exposure at 500 C.

  11. Development of Tensile Softening Model for Plain Concrete

    Lee, S.K.; Song, Y.C. [Korea Electric Power Research Institute, Taejon (Korea)


    Large-scale direct tensile softenng tests using plate concrete specimens(4000, 5000psi) with notch were performed under uniaxial stress. There were presented the basic physical properties and the complete load-CMOD(Crack Mouth Opening Displacement) curves for them And them the fracture energy was evaluated using the complete load-CMOD curves respectively, and there was presents optimal tensile softening model which is modified by a little revision of an existing one. Therefore, here provided the real verification data through the tests for developing other nonlinear concrete finite element models. (author). 32 refs., 38 figs., 4 tabs.

  12. Surface, structural and tensile properties of proton beam irradiated zirconium

    Rafique, Mohsin; Chae, San; Kim, Yong-Soo


    This paper reports the surface, structural and tensile properties of proton beam irradiated pure zirconium (99.8%). The Zr samples were irradiated by 3.5 MeV protons using MC-50 cyclotron accelerator at different doses ranging from 1 × 1013 to 1 × 1016 protons/cm2. Both un-irradiated and irradiated samples were characterized using Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD) and Universal Testing Machine (UTM). The average surface roughness of the specimens was determined by using Nanotech WSxM 5.0 develop 7.0 software. The FESEM results revealed the formation of bubbles, cracks and black spots on the samples' surface at different doses whereas the XRD results indicated the presence of residual stresses in the irradiated specimens. Williamson-Hall analysis of the diffraction peaks was carried out to investigate changes in crystallite size and lattice strain in the irradiated specimens. The tensile properties such as the yield stress, ultimate tensile stress and percentage elongation exhibited a decreasing trend after irradiation in general, however, an inconsistent behavior was observed in their dependence on proton dose. The changes in tensile properties of Zr were associated with the production of radiation-induced defects including bubbles, cracks, precipitates and simultaneous recovery by the thermal energy generated with the increase of irradiation dose.

  13. High-speed tensile test instrument.

    Mott, P H; Twigg, J N; Roland, D F; Schrader, H S; Pathak, J A; Roland, C M


    A novel high-speed tensile test instrument is described, capable of measuring the mechanical response of elastomers at strain rates ranging from 10 to 1600 s(-1) for strains through failure. The device employs a drop weight that engages levers to stretch a sample on a horizontal track. To improve dynamic equilibrium, a common problem in high speed testing, equal and opposite loading was applied to each end of the sample. Demonstrative results are reported for two elastomers at strain rates to 588 s(-1) with maximum strains of 4.3. At the higher strain rates, there is a substantial inertial contribution to the measured force, an effect unaccounted for in prior works using the drop weight technique. The strain rates were essentially constant over most of the strain range and fill a three-decade gap in the data from existing methods.

  14. [The direct tensile test of composite resins using the small specimen--effect of the preparation of specimen, the size of specimen and the testing condition on the tensile properties].

    Fujishima, A; Miyazaki, T; Kuneshita, H; Suzuki, E; Miyaji, T


    The direct tensile test of composite resins using the specimen with the gauge length 10 mm has been developed by authors. In this study smaller specimens with the gauge length 5 mm and 2 mm were also investigated. As the gauge length became smaller, tensile properties such as the proportional limit, the proof stress, and the tensile strength showed the tendency to become higher. The effect of strain rate on the tensile properties appeared clearly when using the specimen with the gauge length 2 mm. The small specimen was found to have many advantages for the preparation, the cost of material and the handling during the tensile test.

  15. Tensile Fracture Mechanism of Claviform Hybrid Composite Rebar

    CAI Lurong; ZENG Qingdun; WANG Ronghui


    Based on the shear-lag theory,a hexagonal model of fiber bundles was established to study the tensile fracture mechanism of a claviform hybrid composite rebar.Firstly,the stress redistributions are investigated on two conditions:one condition is that interfacial damage is taken into accotmt and the other is not.Then,a micro-statistical analysis of the multiple tensile failures of the rebar was performed by using the random critical-core theory.The results indicate that the predictions of the tensile failure strains of the rebar,in which the interracial damage is taken into account,are in better agreement with the existing experimental results than those when only elastic case is considered.Through the comparison between the theoretical and experimental results,the shear-lag theory and the model are verified feasibly in studying the claviform hybrid composite rebar.

  16. Tensile test of dumbbell-shaped specimen in thickness direction

    Iizuka, Takashi


    Sheet metal forming is widely used in manufacturing shops, and evaluation of forming limit for sheet metal is important. However, specimen shape influences on the fracture of the sheet metal. As one of methods to decrease these effects, an uniaxial tensile test using specimen dumbbell-shaped in thickness direction had been examined using FEM analysis. In this study, actually specimen dumbbell-shaped in thickness direction was fabricated using a new incremental sheet forging method, and uniaxial tensile test was conducted. Load-stroke diagram, fracture morphologies, stress-strain curves and shape after fracture were investigated, and effects of specimen shape were considered. Elongation was larger as using specimen dumbbell-shaped in the width direction. Stress-strain curves until necking occurred were less influenced by specimen shape. However, yield stress decreased and local elongation increased as using specimen dumbbell-shaped in the width direction. The reasons why these tendencies showed were considered in the view of specimen shapes.

  17. Osmotic pressure induced tensile forces in tendon collagen

    Masic, Admir; Bertinetti, Luca; Schuetz, Roman; Chang, Shu-Wei; Metzger, Till Hartmut; Buehler, Markus J.; Fratzl, Peter


    Water is an important component of collagen in tendons, but its role for the function of this load-carrying protein structure is poorly understood. Here we use a combination of multi-scale experimentation and computation to show that water is an integral part of the collagen molecule, which changes conformation upon water removal. The consequence is a shortening of the molecule that translates into tensile stresses in the range of several to almost 100 MPa, largely surpassing those of about 0.3 MPa generated by contractile muscles. Although a complete drying of collagen would be relevant for technical applications, such as the fabrication of leather or parchment, stresses comparable to muscle contraction already occur at small osmotic pressures common in biological environments. We suggest, therefore, that water-generated tensile stresses may play a role in living collagen-based materials such as tendon or bone.

  18. Uniaxial tension and tensile creep behaviors of EPS

    康颖安; 李显方; 谭加才


    The mechanical behavior of EPS(Expanded polystyrene) with three densities at room temperature and under tension loading was studied.The results show that EPS material is characterized by brittle behavior in the tension tests,and tensile properties of EPS increase with the increase of density.Volume fraction has no a significant effect on the modulus of these foams.The tensile creep strain increases with stress for EPS with same density,indicating that the creep behavior is of the stress dependency.And the creep behavior of EPS exhibits density dependency,which the creep strain decreases with densities for a fixed stress value.Moreover the creep behavior under the constant tension load is well in coincidence with the three-parameter solid model.

  19. Investigation of anistropic behavior of Montney Shale under indirect tensile strength test

    Keneti, S.A.R.; Wong, R.C.K. [Calgary Univ., Calgary, AB (Canada)


    The Montney Shale Formation is located near the British Columbia and Alberta borders and is one of the largest economically feasible resource plays in North America. Hydraulic fracturing is used to enhance the gas production. Initiation and propagation of hydraulically induced fracture is controlled by in-situ stresses magnitude and orientation and the reservoir tensile strength. The tensile strength becomes one of the most important parameters in governing hydraulic fracturing of the reservoir if the in-situ stresses composing one vertical and two horizontal stresses are comparable or lie within a narrow range. Different point and line load tests were used in this study to determine the tensile strength of Montney shale cores in two perpendicular directions. The paper discussed image analysis of Montney shale cores and tensile strength tests, including Brazilian tests for measuring tensile strength in the horizontal direction and point load tests for measuring tensile strength in the vertical direction. The effect of anisotropic tensile strength on hydraulic fracturing of Montney shale was also presented. It was concluded from the test results that the Montney shale exhibits a high anisotropy in tensile strength. 11 refs., 3 tabs., 11 figs.

  20. Gage for Measuring Decrease in Dimension of Test Specimen in Tensile Test.

    respect to the frame member and provides an output signal proportional to displacement. Elastic bands are used to support the test gage on a tensile test machine which is used to apply a stress to the test specimen. (Author)

  1. Stress in hard metal films

    Janssen, G.C.A.M.; Kamminga, J.D.


    In the absence of thermal stress, tensile stress in hard metal films is caused by grain boundary shrinkage and compressive stress is caused by ion peening. It is shown that the two contributions are additive. Moreover tensile stress generated at the grain boundaries does not relax by ion bombardment


    BRAD Raluca


    Full Text Available An objective approach to select the best fabric for technical and home textiles consists in mechanical properties evaluation. The goal of this study is to analyze the behavior of knitted fabrics undergoing stretch stress. In this respect, three types of 2 colors Rib structure (backstripes jacquard, twillback jacquard and double-layered 3x3 rib fabric have been presented and tested for tensile strength and elongation on three directions. First, the elasticity and the behavior of knitted Rib fabrics were described The fabrics were knitted using 100% PAN yarns with Nm 1/15x2 on a E5 CMS 330 Stoll V-bed knitting machine, and have been tested using INSTROM 5587 Tensile Testing Machine in respect of standards conditions. After a relaxation period, 15 specimens were prepared, being disposed at 0°, 45 and 90 angles to the wale direction on the flat knitted panel. The tensile strength and the elongation values were recorded and mean values were computed. After strength and tensile elongation testing for 3 types of rib based knitted fabrics, one can see that the double layer knit presents the best mechanical behavior, followed by birds-eyebacking 2 colors Jacquard and then back striped Jacquard. For tensile stress in bias direction, the twillbacking Jacquard has a good breakage resistance value due to the higher number of rib sinker loops in structure that are positioned on the same direction with the tensile force. The twillbacking Jacquard structure could be considered as an alternative for the base material for decorative and home textile products.


    S. M. Dhengle


    Full Text Available There are many causes of flywheel failure. Among them, maximum tensile and bending stresses induced in the rim and tensile stresses induced in the arm under the action of centrifugal forces are the main causes of flywheel failure. Hence in this work evaluation of stresses in the rim and arm are studied using finite element method and results are validated by analytical calculations .The models of flywheel having four, six and eight no. arms are developed for FE analysis. The FE analysis is carried out for different cases of loading applied on the flywheel and the maximum Von mises stresses and deflection in the rim are determined. From this analysis it is found that Maximum stresses induced are in the rim and arm junction. Due to tangential forces, maximum bending stresses occurs near the hub end of the arm. It is also observed that for low angular velocity the effect gravity on stresses and deflection of rim and arm is predominant.

  4. Changes to Tensile Strength and Electromagnetic Shielding Effectiveness in Neutron Irradiated Carbon Nanocomposites


    for brittle materials (left) and ductile materials (right). Note that on the brittle curve, the ultimate tensile strength (2) is the point of...fracture. On the ductile curve, the highest stress is at (1) and the fracture stress is at (4), which is less than ultimate tensile strength [25...individual constituent materials. An example of a composite is concrete – cement (matrix) and aggregate, or gravel, (reinforcement), and sometimes rebar


    Konstandinos G. Raptis


    Full Text Available Purpose of this study is the consideration of loading and contact problems encountered at rotating machine elements and especially at toothed gears. The later are some of the most commonly used mechanical components for rotary motion and power transmission. This fact proves the necessity for improved reliability and enhanced service life, which require precise and clear knowledge of the stress field at gear tooth. This study investigates the maximum allowable stresses occurring during spur gear tooth meshing computed using Niemann’s formulas at Highest Point of Single Tooth Contact (HPSTC. Gear material, module, power rating and number of teeth are considered as variable parameters. Furthermore, the maximum allowable stresses for maximum power transmission conditions are considered keeping the other parameters constant. After the application of Niemann’s formulas to both loading cases, the derived results are compared to the respective estimations of Finite Element Method (FEM using ANSYS software. Comparison of the results derived from Niemann’s formulas and FEM show that deviations between the two methods are kept at low level for both loading cases independently of the applied power (either random or maximum and the respective tangential load.

  6. Axial residual stresses in boron fibers

    Behrendt, D. R.


    A method of measuring axial residual stresses in boron fibers is presented. With this method, the axial residual stress distribution as a function of radius is determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diam fibers are similar, being compressive at the surface and changing monotonically to a region of tensile stress within the boron. At approximately 25% of the original radius, the stress reaches a maximum tensile stress of about 860 MN sq m and then decreases to a compressive stress near the tungsten boride core. Data are presented for 203-micron diam B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102-micron diam B/W and boron on carbon (B/C) show that the residual stresses are similar in the outer regions of the fibers, but that large differences near and in the core are observed. Fracture of boron fibers is discussed.

  7. 用于应力应变和疲劳显微分析的原位拉伸系统的研制%In-situ Tensile Testing System for Microscopic Analysis on Stress-strain and Fatigue

    杨洁; 韩立; 陈代谢; 初明璋; 林云生; 刘俊标


    Synchronizing detection has to be introduced into materials' testing systems in order to meet the need in industrial applications and fatigue theory. An in-situ tensile stage, which is integrated with fatigue testing components, is investigated by our laboratory. It is integrated in scanning electron microscope and can be applied in in-situ observations on the whole testing process on micro scale. In this system-, a DC servo motor actuates the mechanical components to apply tensile load to the specimen. Dedicated PID close loop controller chip for the motor was used in the micro tensile module control system based on PC 104 embedded system. To realize its high precision and stability, optimized algorithm to the key technologies such as data collection and original position holding were added. In this paper, the design of the tensile stage and the composition of hardware and software program are introduced. Results from the tensile testing using the in-situ tensile system are also exhibited, which provides sufficient information on materials' tensile properties on both macro and micro scale.%工业上的应用和材料学的发展客观上要求对材料的力学性能测试进行实时动态观测。本研究部自主研发出了配合扫描电子显微镜的原位拉伸试验系统,成功地实现了对拉伸试验全过程的原位观测和微区分析,并初步具备了原位疲劳试验的功能。该系统使用直流伺服电机驱动机械部分对样品施加拉伸载荷,在基于PCl04的嵌入式控制系统中,使用专用PID控制芯片实现电机的闭环控制,并在软件设计中对数据采集、原位保持等关键技术进行了算法优化,以实现较高的精度和稳定性。本文介绍了该系统的机械结构、软硬件组成,并展示了使用该系统对金属材料进行原位拉伸实验得到的数据和结果。该结果为材料的拉伸性能提供了很好的宏观和微观证据。

  8. An Experimental Study of the Influence of in-Plane Fiber Waviness on Unidirectional Laminates Tensile Properties

    Zhao, Cong; Xiao, Jun; Li, Yong; Chu, Qiyi; Xu, Ting; Wang, Bendong


    As one of the most common process induced defects of automated fiber placement, in-plane fiber waviness and its influences on mechanical properties of fiber reinforced composite lack experimental studies. In this paper, a new approach to prepare the test specimen with in-plane fiber waviness is proposed in consideration of the mismatch between the current test standard and actual fiber trajectory. Based on the generation mechanism of in-plane fiber waviness during automated fiber placement, the magnitude of in-plane fiber waviness is characterized by axial compressive strain of prepreg tow. The elastic constants and tensile strength of unidirectional laminates with in-plane fiber waviness are calculated by off-axis and maximum stress theory. Experimental results show that the tensile properties infade dramatically with increasing magnitude of the waviness, in good agreement with theoretical analyses. When prepreg tow compressive strain reaches 1.2%, the longitudinal tensile modulus and strength of unidirectional laminate decreased by 25.5% and 57.7%, respectively.

  9. Deformation mechanisms of carbon nanotube fibres under tensile loading by in situ Raman spectroscopy analysis.

    Li, Qiu; Kang, Yi-Lan; Qiu, Wei; Li, Ya-Li; Huang, Gan-Yun; Guo, Jian-Gang; Deng, Wei-Lin; Zhong, Xiao-Hua


    Deformation mechanisms of carbon nanotube (CNT) fibres under tensile loading are studied by means of in situ Raman spectroscopy to detect the CNT deformation and stress distributions in the fibres. The G' band in the Raman spectrum responds distinctly to the tensile stress in Raman shift, width and intensity. The G' band changes with the tensile deformation of the fibre at different stages, namely elastic deformation, strengthening and damage-fracture. It is deduced that the individual CNTs only deform elastically without obvious damage or bond breaking. The yield and fracture of fibres can be due to the slippage among the CNTs.

  10. Porosity Defect Remodeling and Tensile Analysis of Cast Steel

    Linfeng Sun


    Full Text Available Tensile properties on ASTM A216 WCB cast steel with centerline porosity defect were studied with radiographic mapping and finite element remodeling technique. Non-linear elastic and plastic behaviors dependent on porosity were mathematically described by relevant equation sets. According to the ASTM E8 tensile test standard, matrix and defect specimens were machined into two categories by two types of height. After applying radiographic inspection, defect morphologies were mapped to the mid-sections of the finite element models and the porosity fraction fields had been generated with interpolation method. ABAQUS input parameters were confirmed by trial simulations to the matrix specimen and comparison with experimental outcomes. Fine agreements of the result curves between simulations and experiments could be observed, and predicted positions of the tensile fracture were found to be in accordance with the tests. Chord modulus was used to obtain the equivalent elastic stiffness because of the non-linear features. The results showed that elongation was the most influenced term to the defect cast steel, compared with elastic stiffness and yield stress. Additional visual explanations on the tensile fracture caused by void propagation were also given by the result contours at different mechanical stages, including distributions of Mises stress and plastic strain.

  11. Analytical Algorithms for the Blend Ratios by Fibre-bundle Tensile Curves Part I:Typical Tensile Curve and the Strength and Work Methods

    YU Wei-dong(于伟东); POSTLE Ron; YAN Hao-jing(严灏景)


    The blend ratio and tensile properties are vital important characteristics of blended fibre bundles. Fibre-bundle tensile behaviour has been measured by means of the Sirolan-Tensor in order to derive a typical specific stress - extension curve. According to the typical tensile curve, the relationships between the blend ratio and the tensile parameters are discussed and established. Two new algorithms, so-called the strength method and the work method, have been developed for the blend-ratio estimation of blended fibre bundles. The relevant blend-ratios and calculations of the two methods are defined in detail. Also, the characteristics have been explained for every calculation and compared to each others. The experimental results show that the blend ratios estimated from the theoretical methods are high coincidence with the measured results. Meanwhile, the specific stress - extension curve of blended fibre bundles depends directly on the blend ratios of the fibre bundles.

  12. Deformation behavior of reduced activation ferritic steel during tensile test

    Shiba, Kiyoyuki [Department of Material Science and Engineering, Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibakaki 319-1195 (Japan)]. E-mail:; Hirose, Takanori [Department of Fusion Engineering Research, Japan Atomic Energy Research Institute, 801-1 Mukouyama, Naka, Ibaraki 311-0193 (Japan)


    Deformation behavior of reduced activation martensitic steel F82H during tensile tests were studied. True stress-true strain diagrams were calculated with minimum diameter determined from the specimen profile obtained by laser micro-gauge scanning the diameter along the longitudinal direction during tensile test. Cylindrical specimens of F82H were used for the measurement and test temperatures were room temperature (RT), 300, 400, 500 and 600 deg. C. Tensile tests were carried out with 1 x 10{sup -4} s{sup -1} of strain rate. Other strain rates (1 x 10{sup -3} and 1 x 10{sup -5} s{sup -1}) were applied for the tests at RT. Although uniform elongation of F82H is relatively small at elevated temperature, true stress increases to fracture after necking starts. True stress decreases temporarily after yielding at 600 deg. C, but it increases again to fracture like the specimens tested at lower temperatures. Influence of strain rate to true stress-true strain relationship at room temperature was small, but unstable deformation occurred in narrower area at higher strain rate.

  13. Source mechanism of small-moderate earthquakes and tectonic stress field in Yunnan Province

    吴建平; 明跃红; 王椿镛


    In the paper, source mechanisms of 33 small-moderate earthquakes occurred in Yunnan are determined by modeling of regional waveforms from Yunnan digital seismic network. The result shows that most earthquakes occurred within or near the Chuandian rhombic block have strike-slip mechanism. The orientations of maximum compressive stresses obtained from source mechanism are changed from NNW-SSN to NS in the areas from north to south of the block, and tensile stresses are mainly in ENE-WSW or NE-SE. In the eastern Tibetan Plateau, the orientations of maximum compressive stress radiate toward outside from the plateau, and the tensile stress orientations mostly parallel to arc structures. Near 28°N the orientations of both maximum compressive stress and tensile stress changed greatly, and the boundary seems to correspond to the southwestern extended line of Longmenshan fault. Outside of the Chuandian rhombic block, the orientations of P and T axes are some different from those within the block. The comparison shows that the source mechanism of small-moderate events presented in the paper is consistence with that of moderate-strong earthquakes determined by Harvard University, which means the source mechanism of small-moderate events can be used to study the tectonic stress field in this region.


    Arif GÜRAY


    Full Text Available In this work, the diagonal tensile strength of furniture edge joints such as wooden dowel, minifix, and alyan screw was investigated in panel-constructed boards for Suntalam and MDF Lam. For this purpose, a diagonal tensile strength test was applied to the 72 samples. According to the results, the maximum diagonal tensile strength was found to be in MDF Lam boards that jointed with alyan screw.

  15. Temperature and stress fields of multi-track laser cladding

    ZHAO Hong-yun; ZHANG nong-tao; XU Chun-hua; YANG Xian-qun


    Based on genetic algorithm and neural network algorithm, the finite element analyses on the temperature fields and stress fields of multi-track laser cladding were carried out by using the ANSYS software. The results show that, in the multi-track cladding process, the temperature field ellipse leans to the cladding formed, and the front cladding has preheating function on the following cladding. During cladding, the longitudinal stress is the largest, the lateral stress is the second, and the thickness direction stress is the smallest. The center of the cladding is in the tensile stress condition. The longitudinal tensile stress is higher than the lateral or thickness direction stress by several times, and the tensile stress achieves the maximum at the area of joint between the cladding and substrate. Therefore, it is inferred that transversal crack is the most main crack form in multi-track laser cladding. Moreover, the joint between cladding and substrate is the crack sensitive area, and this is consistent with the actual experiments.

  16. Finite element analysis of notch tensile behavior of alloy 718

    Sridhar, A.; Srivathsa, B.


    Notch tensile behavior of alloy 718 is characterized in conventionally heat treated condition as a function of U and V notches at 25, 200 & 400 °C. The experimental results were then compared with the values obtained from simulation of notched geometries in ANSYS software using smooth specimen data. An excellent agreement is noticed between simulated and experimental true stress-true strain curves.

  17. Elastic-plastic analysis of the SS-3 tensile specimen

    Majumdar, S. [Argonne National Lab., IL (United States)


    Tensile tests of most irradiated specimens of vanadium alloys are conducted using the miniature SS-3 specimen which is not ASTM approved. Detailed elastic-plastic finite element analysis of the specimen was conducted to show that, as long as the ultimate to yield strength ratio is less than or equal to 1.25 (which is satisfied by many irradiated materials), the stress-plastic strain curve obtained by using such a specimen is representative of the true material behavior.

  18. Determination of Tensile Properties of Polymers at High Strain Rates

    Major Z.


    Full Text Available In the field of high rate testing of polymers the measured properties are highly dependent on the applied methodology. Hence, the test setup as whole but in particular also the geometrical type of specimen plays a decisive role. The widely used standard for the determination of tensile properties of polymers (ISO527-2 was extended by a novel standard (ISO18872:2007, which is targeted on the determination of tensile properties at high strain rates. In this standard also a novel specimen shape is proposed. Hand in hand with the introduction of new specimen geometry the question of comparability arises. To point out the differences in stress-strain response of the ISO18872 specimen and the ISO527-2 multipurpose specimen tensile tests over a wide loading rate range were conducted in this paper. A digital image correlation system in combination with a high speed camera was used to characterize the local material behaviour. Different parameters like nominal stress, true stress, nominal strain, true strain as well as volumetric strain were determined and used to compare the two specimen geometries.

  19. Seismological Studies for Tensile Faults

    Gwo-Bin Ou


    Full Text Available A shear slip fault, an equivalence of a double couple source, has often been assumed to be a kinematic source model in ground motion simulation. Estimation of seismic moment based on the shear slip model indicates the size of an earthquake. However, if the dislocation of the hanging wall relative to the footwall includes not only a shear slip tangent to the fault plane but also expansion and compression normal to the fault plane, the radiating seismic waves will feature differences from those out of the shear slip fault. Taking account of the effects resulting from expansion and compression to a fault plane, we can resolve the tension and pressure axes as well as the fault plane solution more exactly from ground motions than previously, and can evaluate how far a fault zone opens or contracts during a developing rupture. In addition to a tensile angle and Poisson¡¦s ratio for the medium, a tensile fault with five degrees of freedom has been extended from the shear slip fault with only three degrees of freedom, strike, dip, and slip.

  20. Tensile Properties of GRCop-84

    Ellis, David L.; Loewenthal, William S.; Yun, Hee-Man


    This is a chapter in the final report on GRCop-84 for the Reusable Launch Vehicle (RLV) Second Generation/Project Constellation Program. It contains information on the tensile properties of GRCop-84. GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) was produced by extrusion and Hot Isostatic Pressing (HIPing). Some of the extrusions were rolled to plate and sheet while other extrusions were drawn into tubing. The material was further subjected to various heat treatments corresponding to annealing, anticipated typical brazing conditions, an end-of-life condition and various elevated temperature exposures to attempt to improve creep resistance. As anticipated, cold work increased strength while decreasing ductility. Annealing at 600 C (1112 F) and higher temperatures was effective. An exposure for 100 h at 500 C (932 F) resulted in an increase in strength rather than the anticipated decrease. High temperature simulated-braze cycles and thermal exposures lowered the strength of GRCop-84, but the deceases were small compared to precipitation strengthened copper alloys. It was observed that the excess Cr could form large precipitates that lower the reduction in area though it appears a minimum amount is required. Overall, GRCop-84 exhibits good stability of its tensile properties, which makes it an excellent candidate for rocket engine liners and many other high temperature applications.

  1. Tensile properties of the hip joint ligaments are largely variable and age-dependent - An in-vitro analysis in an age range of 14-93 years.

    Schleifenbaum, Stefan; Prietzel, Torsten; Hädrich, Carsten; Möbius, Robert; Sichting, Freddy; Hammer, Niels


    Hip joint stability is maintained by the surrounding ligaments, muscles, and the atmospheric pressure exerted via these structures. It is unclear whether the ligaments are capable of preventing dislocation solely due to their tensile properties, and to what extent they undergo age-related changes. This study aimed to obtain stress-strain data of the hip ligaments over a large age range. Stress-strain data of the iliofemoral (IL), ischiofemoral (IS) and pubofemoral ligament (PF) were obtained from cadavers ranging between 14 and 93 years using a highly standardized setting. Maximum strains were compared to the distances required for dislocation. Elastic modulus was 24.4 (IL), 22.4 (IS) and 24.9N/mm(2) (PF) respectively. Maximum strain was 84.5%, 86.1%, 72.4% and ultimate stress 10.0, 7.7 and 6.5N/mm(2) for the IL, IS and PF respectively. None of these values varied significantly between ligaments or sides. The IS' elastic modulus was higher and maximum strain lower in males. Lower elastic moduli of the PF and higher maximum strains for the IS and PF were revealed in the ≥55 compared to the <55 population. Maximum strain exceeded the dislocation distance of the IS without external hip joint rotation in females, and of the IS and cranial IL under external rotation in both genders. Tensile and failure load properties of the hip joint ligaments are largely variable. The IS and PF change age-dependently. Though the hip ligaments contribute to hip stability, the IS and cranial IL may not prevent dislocation due to their elasticity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Indigenous Design for Automatic Testing of Tensile Strength Using Graphical User Interface

    Ali Rafay


    Full Text Available Tensile Testing is a fundamental material test to measure the tenacity and tensile strength. Tensile strength means ability to take tensile stress. This Universal Testing Machine is designed using Dual Cylinder Technique in order to comply with the maximun load (tensile force with the reduction of minimum physical effort and minimized losses.It is to provide material testing opportunity to the students of different institutions, locally and globally, at lowest price; so that they can have a comprehensive understanding of the testing procedures and examining material properties on practical grounds with a minimum expenditure. The testing mechanism is automated along with the inclusion of all necessary parameters and the movement of the members. Specimens of different engineering materials were used to carry out the test and their mechanical strength was tested and compared with the actual values

  3. Stress analysis and ferroelectric properties of Pb(Zr0.52Ti0.48)0.96Nb0.04O3 thin film grown on different thickness of BaPbO3 electrodes

    Wen, Xin-Yi; Yu, Jun; Wang, Yun-Bo; Zhou, Wen-Li; Gao, Jun-Xiong


    Pb(Zr0.52Ti0.48)0.96Nb0.04O3 (PZTN) thin films were deposited on BaPbO3 (BPO) electrodes by rf-magnetron sputtering. 34, 68, 135, and 270 nm thick BPOs were adopted in this study. The preferred orientation changes from slightly (100)/(001) to slightly (101)/(110) as the BPO thickness increased. The mean grain sizes obtained by Williamson-Hall plots are 81 nm, 120 nm, 146 nm, and 90 nm, respectively. The same tendency was observed by atomic force microscopy method. In residual stress analysis, tensile stress was observed in every film. The stress magnitude is the maximum in the film with 135 nm thick BPO. Through a simple calculation, we suggest that the tensile stress in our films mainly originates from the phase transformation stresses. We also note that the ferroelectric and dielectrics properties are improved with the raise of tensile stresses. A possible reason is that the tensile stress benefits the tetragonal-monoclinic phase transition in the PZTN films with composition near morphotropic phase boundary. The other possible reason is that the raise of the tensile stress is consistent with the increasing of grain size, which decreases the grain boundary density and facilitate domain mobility.

  4. Tensile behavior of nanocrystalline copper

    Sanders, P.G.; Weertman, J.R. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Eastman, J.A. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering]|[Argonne National Lab., IL (United States). Materials Science Div.


    High density nanocrystalline copper produced by inert gas condensation was tested in tension. Displacements were measured using foil strain gauges, which greatly improved the accuracy of the strain data. The Young`s modulus of nanocrystalline copper was found to be consistent with that of coarse-grained copper. Total elongations of {approx} 1% were observed in samples with grain sizes less than 50 nm, while a sample with a grain size of 110 nm exhibited more than 10% elongation, perhaps signifying a change to a dislocation-based deformation mechanism in the larger-grained material. In addition, tensile tests were performed as a function of strain rate, with a possible trend of decreased strength and increased elongation as the strain rate was decreased.

  5. Numerical Parametric Analysis of Bond Coat Thickness Effect on Residual Stresses in Zirconia-Based Thermal Barrier Coatings

    Abbas, Musharaf; Hasham, Hasan Junaid; Baig, Yasir


    Numerical-based finite element investigation has been conducted to explain the effect of bond coat thickness on stress distribution in traditional and nanostructured yttria-stabilized zirconia (YSZ)-based thermal barrier coatings (TBC). Stress components have been determined to quantitatively analyze the mechanical response of both kinds of coatings under the thermal shock effect. It has been found that maximum radial tensile and compressive stresses that exist at thermally grown oxide (TGO)/bond coat interface and within TGO respectively decrease with an increase in bond coat thickness. Effect of bond coat thickness on axial tensile stresses is not significant. However, axial compressive stresses that exist at the edge of the specimen near bond coat/substrate interface decrease appreciably with the increase in bond coat thickness. Residual stress profile as a function of bond coat thickness is further explained for comparative analysis of both coatings to draw some useful conclusions helpful in failure studies of TBCs.

  6. Analysis and simulation for tensile behavior of anisotropic open-cell elastic foams

    卢子兴; 刘强; 陈鑫


    Based on the elongated Kelvin model, a simplified periodic structural cell is obtained to investigate the tensile behavior of anisotropic open-cell elastic foams due to Kelvin model’s periodicity and symmetry in the whole space. The half-strut element and elastic deflection theory are used to analyze the tensile response as done in the previous studies. This study produces theoretical expressions for the tensile stress-strain curve in the rise and transverse directions. In addition, the theoretical results are examined with finite element simulation using an existing formula. The results indicate that the theoretical analysis agrees with the finite element simulation when the strain is not too high, and the present model is better. At the same time, the anisotropy ratio has a significant effect on the mechanical properties of foams. As the anisotropy ratio increases, the tensile stress is improved in the rising direction but drops in the transverse direction under the same strain.

  7. Two new tensile devices for X-ray diffraction experiments

    Freri, N.; Tintori, A.; Depero, L.E.; Sangaletti, L. [Brescia Univ. (Italy); Cernuschi, F.; Ghia, S. [Ente Nazionale per l`Energia Elettrica, Milan (Italy)


    Two tensile devices were designed to be used with parallel beam and parafocusing-geometry diffractometers. In thefirst case the device was designed to be attached to a strainflex diffractometer by Rigaku Inc., dedicated to stress analysis and commonly used in metallurgical industry. Since the sample does not move during the measurement, the tensile device can be kept fixed on the experimental table. The device design takes into account the steric hindrance by moving parts of diffractometer. The maximun load that can be applied to the sample is 60.000 N. An attachement to a Siemens D5000 diffractometer with Eulerian cradle has also benn designed for applying a load up tp 6000 N to a sample in the parafocusing-geometry. The installation does not require a re-alignment of the diffractometer. In both cases strain gages were applied to both sides of the specimen for the simultaneous determination of the macroscopic strains. Experiments based on the use of these devices are planned to determine the crystallographic elastic constants and study the influence of the microstructure on the mechanical behaviour of residual stresses in the zone of almost static stresses as well as the influence of residual stresses on uniaxially loaded samples. In addition, by using these devices, it is possible to measure the unstressed d-0 spacings providing useful information in the neutron diffraction study fo stress fields in steel samples.

  8. Stress gradients in CrN coatings

    Janssen, G.C.A.M.; Tichelaar, F.D.; Visser, C.C.G.


    Stress in hard films is the net sum of tensile stress generated at the grain boundaries, compressive stress due to ion peening, and thermal stress due to the difference in thermal expansion of the coating and substrate. The tensile part due to grain boundaries is thickness dependent. The other two c

  9. Understanding the tensile properties of concrete

    Weerheijm, J.


    The response of concrete under tensile loading is crucial for most applications because concrete is much weaker in tension than in compression. Understanding the response mechanisms of concrete under tensile conditions is therefore key to understanding and using concrete in structural applications.

  10. Surfactant effects on soil aggregate tensile strength

    Little is known regarding a soil aggregate's tensile strength response to surfactants that may be applied to alleviate soil water repellency. Two laboratory investigations were performed to determine surfactant effects on the tensile strength of 1) Ap horizons of nine wettable, agricultural soils co...

  11. In-Situ Neutron Diffraction Under Tensile Loading of Powder-in-Tube Cu/Nb3Sn Composite Wires Effect of Reaction Heat Treatment on Texture, Internal Stress State and Load Transfer

    Scheuerlein, C; Thilly, L


    The strain induced degradation of Nb3Sn superconductors can hamper the performance of high field magnets. We report elastic strain measurements in the different phases of entire non-heat treated and fully reacted Nb3Sn composite strands as a function of uniaxial stress during in-situ deformation under neutron beam. After the reaction heat treatment the Cu matrix loses entirely its load carrying capability and the applied stress is transferred to the remaining Nb-Ta alloy and to the brittle (Nb-Ta)3Sn phase, which exhibits a preferential grain orientation parallel to the strand axis.

  12. In vivo mechanical properties of thoracic aortic aneurysmal wall estimated from in vitro biaxial tensile test.

    Fukui, Tomohiro; Matsumoto, Takeo; Tanaka, Toshihiro; Ohashi, Toshiro; Kumagai, Kiichiro; Akimoto, Hiroji; Tabayashi, Koichi; Sato, Masaaki


    To investigate the mechanism of aneurysm rupture, it is necessary to examine the mechanical properties of aneurysm tissues in vivo. A new approach to evaluate in vivo mechanical properties of aortic aneurysmal tissues has been proposed in this study. The shape of the aneurysm was modeled as a sphere, and equi-biaxial stress in the in vivo state was estimated from the diameter and the wall thickness of each aneurysm and mean blood pressure of each patient. The mechanical properties of the aneurysm at the in vivo stress were estimated from its in vitro biaxial tensile properties. There were no significant correlations among maximum diameter D, wall thickness t, and mean infinitesimal strain in the in vivo state epsilon(m). This indicates the wall deformation during aneurysm development was not elastic but plastic. The mean incremental elastic modulus H(m), an index of tissue stiffness, had a significant positive correlation with elastic modulus anisotropy index K(H). This indicates the aneurysmal wall got more anisotropic in vivo as it becomes stiffer.

  13. Measurement of pressure and displacement of the membranous labyrinth in endolymphatic hydrops by the tensile test.

    Tanaka, M; Ishii, T; Takayama, M


    We measured the mechanical characteristics, particularly the strength of various regions of the membranous labyrinth by the penetration test with a specially designed machine. A load-displacement curve was drawn by the tensile test for the Reissner's and basement membranes. Additionally, a stress-strain curve was drawn. The modulus of elasticity was measured showing a straight line in the stress-strain curve: 1.5 x 10(2) mN/mm2 for Reissner's membrane and 9.3 x 10(2)-1.3 x 10(3) mN/mm2 for the basement membrane. Furthermore, the endolymphatic pressure was calculated at the point in time when the maximum strain as the limit of elasticity was 0.2. It was 81 Pa. The displacement of Reissner's membrane was 0.2 mm when the initial tension was taken as 0 in the formula, and that of the basement membrane was 3 to 37 microns when the initial tension was 0, 0.1, 0.2 and 0.3.

  14. Modeling elastic tensile fractures in snow using nonlocal damage mechanics

    Borstad, C. P.; McClung, D. M.


    The initiation and propagation of tensile fractures in snow and ice are fundamental to numerous important physical processes in the cryosphere, from iceberg calving to ice shelf rift propagation to slab avalanche release. The heterogeneous nature of snow and ice, their proximity to the melting temperature, and the varied governing timescales typically lead to nonlinear fracture behavior which does not follow the predictions of Linear Elastic Fracture Mechanics (LEFM). Furthermore, traditional fracture mechanics is formally inapplicable for predicting crack initiation in the absence of a pre-existing flaw or stress concentration. An alternative to fracture mechanics is continuum damage mechanics, which accounts for the material degradation associated with cracking in a numerically efficient framework. However, damage models which are formulated locally (e.g. stress and strain are defined as point properties) suffer from mesh-sensitive crack trajectories, spurious localization of damage and improper fracture energy dissipation with mesh refinement. Nonlocal formulations of damage, which smear the effects of the material heterogeneity over an intrinsic length scale related to the material microstructure, overcome these difficulties and lead to numerically efficient and mesh-objective simulations of the tensile failure of heterogeneous materials. We present the results of numerical simulations of tensile fracture initiation and propagation in cohesive snow using a nonlocal damage model. Seventeen beam bending experiments, both notched and unnotched, were conducted using blocks of cohesive dry snow extracted from an alpine snowpack. Material properties and fracture parameters were calculated from the experimental data using beam theory and quasi-brittle fracture mechanics. Using these parameters, a nonlocal isotropic damage model was applied to two-dimensional finite element meshes of the same scale as the experiments. The model was capable of simulating the propagation

  15. Tensile and fracture behavior of DZ951 Ni-base superalloy

    CHU Zhao-kuang; YU Jin-jiang; SUN Xiao-feng; ZHAO Nai-ren; GUAN Heng-rong; HU Zhuang-qi


    The tensile and fracture behavior of DZ951 directionally solidified Ni-base superalloy was studied in the temperature range of 20-1 100 ℃. The fracture mode was examined by scanning electron microscopy. The results show the experimental temperature has no significant effect on the tensile strengths, which are greater than 1 000 MPa from room temperature to 800 ℃. The yield strength reaches its maximum (970 MPa) at 800 ℃. When the experimental temperature is higher than 800 ℃, the tensile and yield strengths decrease evidently and the ductility increases remarkably. The fractograph of fracture surface for the tensile specimen at room temperature shows a dimple-ductile fracture mode. The fractograph from 600 to 800 ℃ shows a slide fracture mode. The fractograph from 900 to 1 100 ℃ exhibits a creep rupture mode with uneven deformation.

  16. The role of shear and tensile failure in dynamically triggered landslides

    Gipprich, T.L.; Snieder, R.K.; Jibson, R.W.; Kimman, W.


    Dynamic stresses generated by earthquakes can trigger landslides. Current methods of landslide analysis such as pseudo-static analysis and Newmark's method focus on the effects of earthquake accelerations on the landslide mass to characterize dynamic landslide behaviour. One limitation of these methods is their use Mohr-Coulomb failure criteria, which only accounts for shear failure, but the role of tensile failure is not accounted for. We develop a limit-equilibrium model to investigate the dynamic stresses generated by a given ground motion due to a plane wave and use this model to assess the role of shear and tensile failure in the initiation of slope instability. We do so by incorporating a modified Griffith failure envelope, which combines shear and tensile failure into a single criterion. Tests of dynamic stresses in both homogeneous and layered slopes demonstrate that two modes of failure exist, tensile failure in the uppermost meters of a slope and shear failure at greater depth. Further, we derive equations that express the dynamic stress in the near-surface in the acceleration measured at the surface. These equations are used to approximately define the depth range for each mechanism of failure. The depths at which these failure mechanisms occur suggest that shear and tensile failure might collaborate in generating slope failure. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

  17. A Study of Tensile Strength Tests of Arborous Species Root System in Forest Engineering Technique of Shallow Landslide

    YANG Yonghong; LIU Shuzhen; WANG Chenghua; TANG Chuan


    One experiment was conducted, through tensile tests of Albazzia and Eucalypt roots culled from the fields. The other experiment was conducted, by testing anti-drawing strength of these root systems in the Albazzia and Eucalypt lands. These two experiments had an aim to give insights into the maximum tensile strength and anti-drawing strength of the root systems. Results indicated that the maximum tensile strength of root system is in an exponential relation with the diameter of root system while the maximum tensile strength is positively correlative with the diameter of root system. Anti-drawing force of root system together with root diameter, length, and soil bulk density are folded into a regression equation in an attempt to figure out the static friction coefficient between root system and its ambient soil.

  18. Residual stress around the cortical surface in bovine femoral diaphysis.

    Yamada, Satoshi; Tadano, Shigeru


    Residual stress in living tissue plays an important role in mechanical strength. We have reported that residual stress exists in the bone tissue of a rabbit's tibiofibula. The purpose of this study is to measure the residual stress around the outer cortical region of bovine femoral diaphysis and to discuss the distribution of the stress. This work proposed the sin(2) psi method of X-ray diffraction to the measurement of residual stresses in bone tissue. In this method, residual stress can be estimated from the variation in the interplanar spacings orientated to a number of directions without the lattice strain in the stress direction. Four-point bending tests of strip specimens taken from bovine femoral diaphysis were carried out during X-ray irradiation in advance. In the proximal, middle, and distal sections of bovine femoral diaphyses, the residual stresses at the cortical surface were measured using characteristic Mo-Kalpha X-rays. The bending tests of strip specimens with X-ray irradiation showed that the method could reliably estimate residual stresses in the bone tissue. The residual stress of the bone axial direction was larger than that of the circumferential direction. The stresses in the middle part of five diaphyses along the bone axial direction were tensile. The maximum stress was 162 MPa at the lateral position and the minimum was 78 MPa at the posterior position. The residual stress in the bone axial direction varies around the circumferential region. In addition, the bone axial distributions of residual stresses were different in the proximal, middle, and distal sections of the individual femur. Furthermore, it was confirmed that residual stress in the bone tissue was released by the cutting out of the specimen. The residual stresses in bone tissue could be measured by this method. The results show that residual stress in the bone axial direction at the cortical surface in bovine femoral diaphysis is tensile and varies around the circumferential

  19. Effects of zonal heat treatment on residual stresses and mechanical properties of electron beam welded TC4 alloy plates

    HU Mei-juan; LIU Jin-he


    Zonal heat treatment(ZHT) was conducted in situ to 14.5 mm-thick TC4 alloy plates by means of defocused electron beam after welding. The effects of ZHT on residual stresses, microstructures and mechanical properties of electron beam welded joints were investigated. Experimental results show residual stresses after welding are mostly relieved through ZHT, and the maximum values of longitudinal tensile stress and transverse compressive stress reduce by 76% and 65%, respectively. The tensile strength and ductility of welded joint after ZHT at slow scanning velocity are improved because of the reduction of residual stress and the microstructural changes of the base and weld metal. ZHT at fast scanning velocity is detrimental to the ductility of welded joint, which is resulted from insufficiently coarsened alpha phase in the fusion zone and the appearance of martensite in the base metal.

  20. Autologous nerve graft repair of different degrees of sciatic nerve defect: stress and displacement at the anastomosis in a three-dimensional fnite element simulation model

    Cheng-dong Piao


    Full Text Available In the repair of peripheral nerve injury using autologous or synthetic nerve grafting, the magnitude of tensile forces at the anastomosis affects its response to physiological stress and the ultimate success of the treatment. One-dimensional stretching is commonly used to measure changes in tensile stress and strain however, the accuracy of this simple method is limited. Therefore, in the present study, we established three-dimensional finite element models of sciatic nerve defects repaired by autologous nerve grafts. Using PRO E 5.0 finite element simulation software, we calculated the maximum stress and displacement of an anastomosis under a 5 N load in 10-, 20-, 30-, 40-mm long autologous nerve grafts. We found that maximum displacement increased with graft length, consistent with specimen force. These findings indicate that three-dimensional finite element simulation is a feasible method for analyzing stress and displacement at the anastomosis after autologous nerve grafting.

  1. Autologous nerve graft repair of different degrees of sciatic nerve defect:stress and displacement at the anastomosis in a three-dimensional finite element simulation model

    Cheng-dong Piao; Kun Yang; Peng Li; Min Luo


    In the repair of peripheral nerve injury using autologous or synthetic nerve grafting, the mag-nitude of tensile forces at the anastomosis affects its response to physiological stress and the ultimate success of the treatment. One-dimensional stretching is commonly used to measure changes in tensile stress and strain; however, the accuracy of this simple method is limited. There-fore, in the present study, we established three-dimensional ifnite element models of sciatic nerve defects repaired by autologous nerve grafts. Using PRO E 5.0 ifnite element simulation software, we calculated the maximum stress and displacement of an anastomosis under a 5 N load in 10-, 20-, 30-, 40-mm long autologous nerve grafts. We found that maximum displacement increased with graft length, consistent with specimen force. These ifndings indicate that three-dimensional ifnite element simulation is a feasible method for analyzing stress and displacement at the anas-tomosis after autologous nerve grafting.

  2. Viscoelastic finite element stress analysis of the thermal compatibility of dental bilayer ceramic systems.

    DeHoff, Paul H; Anusavice, Kenneth J


    The aim of this study was to test the hypothesis that viscoelastic finite element analyses can reliably predict the effect of geometry on maximum tensile stresses in bilayer screening tests that are used to determine thermal compatibility. Three-dimensional viscoelastic finite element models of a beam, cylinder, disk, sphere, central incisor crown, molar crown, and posterior three-unit fixed partial denture (FPD) were used to calculate residual stresses after simulated bench cooling. Four compatible and four incompatible systems were evaluated. The highest residual tensile stresses for all material combinations were associated with the three-unit FPD. Residual tensile stresses ranged from 5.4 MPa in the disk for a compatible combination to 262 MPa in the three-unit FPD for an incompatible system. Residual tensile stresses in the three-unit FPD ranged from 16.8 MPa to 44.0 MPa for the compatible systems and from 175 MPa to 262 MPa for the incompatible systems. Based on finite element calculations, it is predicted that all-ceramic dental prostheses with an average thermal contraction mismatch (500 degrees C to 25 degrees C) greater than +/- 1.0 ppm/K will likely exhibit a relatively high percentage of failures in clinical use compared with systems having smaller thermal contraction mismatch between core and veneering ceramics.

  3. Acellularization-Induced Changes in Tensile Properties Are Organ Specific - An In-Vitro Mechanical and Structural Analysis of Porcine Soft Tissues.

    Stefan Schleifenbaum

    Full Text Available Though xenogeneic acellular scaffolds are frequently used for surgical reconstruction, knowledge of their mechanical properties is lacking. This study compared the mechanical, histological and ultrastructural properties of various native and acellular specimens.Porcine esophagi, ureters and skin were tested mechanically in a native or acellular condition, focusing on the elastic modulus, ultimate tensile stress and maximum strain. The testing protocol for soft tissues was standardized, including the adaption of the tissue's water content and partial plastination to minimize material slippage as well as templates for normed sample dimensions and precise cross-section measurements. The native and acellular tissues were compared at the microscopic and ultrastructural level with a focus on type I collagens.Increased elastic modulus and ultimate tensile stress values were quantified in acellular esophagi and ureters compared to the native condition. In contrast, these values were strongly decreased in the skin after acellularization. Acellularization-related decreases in maximum strain were found in all tissues. Type I collagens were well-preserved in these samples; however, clotting and a loss of cross-linking type I collagens was observed ultrastructurally. Elastins and fibronectins were preserved in the esophagi and ureters. A loss of the epidermal layer and decreased fibronectin content was present in the skin.Acellularization induces changes in the tensile properties of soft tissues. Some of these changes appear to be organ specific. Loss of cross-linking type I collagen may indicate increased mechanical strength due to decreasing transverse forces acting upon the scaffolds, whereas fibronectin loss may be related to decreased load-bearing capacity. Potentially, the alterations in tissue mechanics are linked to organ function and to the interplay of cells and the extracellular matrix, which is different in hollow organs when compared to skin.

  4. An Experimental Study of Dynamic Tensile Failure of Rocks Subjected to Hydrostatic Confinement

    Wu, Bangbiao; Yao, Wei; Xia, Kaiwen


    It is critical to understand the dynamic tensile failure of confined rocks in many rock engineering applications, such as underground blasting in mining projects. To simulate the in situ stress state of underground rocks, a modified split Hopkinson pressure bar system is utilized to load Brazilian disc (BD) samples hydrostatically, and then exert dynamic load to the sample by impacting the striker on the incident bar. The pulse shaper technique is used to generate a slowly rising stress wave to facilitate the dynamic force balance in the tests. Five groups of Laurentian granite BD samples (with static BD tensile strength of 12.8 MPa) under the hydrostatic confinement of 0, 5, 10, 15, and 20 MPa were tested with different loading rates. The result shows that the dynamic tensile strength increases with the hydrostatic confining pressure. It is also observed that under the same hydrostatic pressure, the dynamic tensile strength increases with the loading rate, revealing the so-called rate dependency for engineering materials. Furthermore, the increment of the tensile strength decreases with the hydrostatic confinement, which resembles the static tensile behavior of rock under confining pressure, as reported in the literature. The recovered samples are examined using X-ray micro-computed tomography method and the observed crack pattern is consistent with the experimental result.

  5. Tensile strength and fracture of cemented granular aggregates.

    Affes, R; Delenne, J-Y; Monerie, Y; Radjaï, F; Topin, V


    Cemented granular aggregates include a broad class of geomaterials such as sedimentary rocks and some biomaterials such as the wheat endosperm. We present a 3D lattice element method for the simulation of such materials, modeled as a jammed assembly of particles bound together by a matrix partially filling the interstitial space. From extensive simulation data, we analyze the mechanical properties of aggregates subjected to tensile loading as a function of matrix volume fraction and particle-matrix adhesion. We observe a linear elastic behavior followed by a brutal failure along a fracture surface. The effective stiffness before failure increases almost linearly with the matrix volume fraction. We show that the tensile strength of the aggregates increases with both the increasing tensile strength at the particle-matrix interface and decreasing stress concentration as a function of matrix volume fraction. The proportion of broken bonds in the particle phase reveals a range of values of the particle-matrix adhesion and matrix volume fraction for which the cracks bypass the particles and hence no particle damage occurs. This limit is shown to depend on the relative toughness of the particle-matrix interface with respect to the particles.

  6. Stress Domains in Si\\(111\\)/a-Si3N4 Nanopixel: Ten-Million-Atom Molecular Dynamics Simulations on Parallel Computers

    Omeltchenko, Andrey; Bachlechner, Martina E.; Nakano, Aiichiro; Kalia, Rajiv K.; Vashishta, Priya; Ebbsjö, Ingvar; Madhukar, Anupam; Messina, Paul


    Parallel molecular dynamics simulations are performed to determine atomic-level stresses in Si\\(111\\)/Si3N4\\(0001\\) and Si\\(111\\)/a-Si3N4 nanopixels. Compared to the crystalline case, the stresses in amorphous Si3N4 are highly inhomogeneous in the plane of the interface. In silicon below the interface, for a 25 nm square mesa stress domains with triangular symmetry are observed, whereas for a rectangular, 54 nm×33 nm, mesa tensile stress domains \\(~300 Å\\) are separated by Y-shaped compressive domain wall. Maximum stresses in the domains and domain walls are -2 GPa and +2 GPa, respectively.

  7. Stress domains in Si(111)/a-Si3N4 nanopixel: ten-million-atom molecular dynamics simulations on parallel computers

    Omeltchenko; Bachlechner; Nakano; Kalia; Vashishta; Ebbsjo; Madhukar; Messina


    Parallel molecular dynamics simulations are performed to determine atomic-level stresses in Si(111)/Si(3)N4(0001) and Si(111)/a-Si3N4 nanopixels. Compared to the crystalline case, the stresses in amorphous Si3N4 are highly inhomogeneous in the plane of the interface. In silicon below the interface, for a 25 nm square mesa stress domains with triangular symmetry are observed, whereas for a rectangular, 54 nmx33 nm, mesa tensile stress domains ( approximately 300 A) are separated by Y-shaped compressive domain wall. Maximum stresses in the domains and domain walls are -2 GPa and +2 GPa, respectively.

  8. Stress

    ... diabetes. Your Stress-Free System for Family Dinners! - 2017-03-book-oclock-scramble.html Your Stress-Free System for Family Dinners! A year of delicious meals to help prevent ...

  9. Stress

    ... sudden negative change, such as losing a job, divorce, or illness Traumatic stress, which happens when you ... stress, so you can avoid more serious health effects. NIH: National Institute of Mental Health

  10. The Dynamic Tensile Behavior of Railway Wheel Steel at High Strain Rates

    Jing, Lin; Han, Liangliang; Zhao, Longmao; Zhang, Ying


    The dynamic tensile tests on D1 railway wheel steel at high strain rates were conducted using a split Hopkinson tensile bar (SHTB) apparatus, compared to quasi-static tests. Three different types of specimens, which were machined from three different positions (i.e., the rim, web and hub) of a railway wheel, were prepared and examined. The rim specimens were checked to have a higher yield stress and ultimate tensile strength than those web and hub specimens under both quasi-static and dynamic loadings, and the railway wheel steel was demonstrated to be strain rate dependent in dynamic tension. The dynamic tensile fracture surfaces of all the wheel steel specimens are cup-cone-shaped morphology on a macroscopic scale and with the quasi-ductile fracture features on the microscopic scale.


    徐永福; 董平; 孙德安


    The tensile strength of a single soil particle is usually measured indirectly by compressing the grain between flat platens until failure occurs,and is defined as the tensile stress at whole-particle fracture. The tensile strength appears to decrease monotonically with the diameter of particles,and is usually characterized by the Weibull statistics. For granular materials,it is impossible to measure constant tensile strength,unless the flaw effect is taken into account in the framework of fractal. The fractal dimension of flaw distribution equals to that of the fragmentation of granular materials. The Weibull statistics is modified using the fractal model of flaw distribution. Goodness-of-fit statistics shows that the modified model fits the experimental data much better than the conventional model. The modified model has only one parameter,the fractal dimension of fragmentation D,which can be determined using the mass-size distribution.


    Gussev, Maxim N [ORNL; Busby, Jeremy T [ORNL; Field, Kevin G [ORNL; Sokolov, Mikhail A [ORNL; Gray, Mr. Sean [University of Michigan


    The influence of scale factor (tensile specimen geometry and dimensions) on mechanical test results was investigated for different widely used types of small specimens (SS-1, SS-2, SS-3, and SS-J3) and a set of materials. It was found that the effect of scale factor on the accurate determination of yield stress, ultimate tensile stress, and uniform elongation values was weak; however, clear systematic differences were observed and should be accounted for during interpretation of results. In contrast, total elongation values were strongly sensitive to variations in specimen geometry. Modern experimental methods like digital image correlation allow the impact of scale factor to be reduced. Using these techniques, it was shown that true stress true strain curves describing strain-hardening behavior were very close for different specimen types. The limits of miniaturization are discussed, and an ultra-miniature specimen concept was suggested and evaluated. This type of specimen, as expected, may be suitable for SEM and TEM in situ testing.

  13. Nanoscale Morphology in Tensile Fracture of a Brittle Amorphous Ribbon

    Xifeng LI; Kaifeng ZHANG; Guofeng WANG


    The paper reports on the observation of nanoscale morphology on the tensile fracture surface of a brittle amorphous Fe-based ribbon. The formation of nanoscale damage cavity structure is a main characteristic morphology on the fracture surfaces. Approaching the ribbon boundary, these damage cavities assemble and form the nanoscale periodic corrugations, which are neither Wallner lines nor crack front waves. The periodic corrugations result from the interactions between the reflected elastic waves by the boundaries of amorphous ribbon and the stress fields of the crack tip.

  14. Tensile Properties of Poly (N-vinyl caprolactam) Gels

    Morgret, Leslie D.; Hinkley, Jeffrey A.


    N-vinyl caprolactam was copolymerized with ethylene glycol dimethacrylate using a free-radical initiator in alcohol/water solution. The resulting gels were thermally-responsive in water, undergoing an approximate fivefold reversible volume shrinkage between room temperature and ca. 50 C. Tensile testing showed that the stress-strain behavior was qualitatively different in the collapsed state above the temperature-induced transition. At the higher temperature, gels were stiffer, more ductile, and showed greater time dependence. Implications for the design of gel actuators are briefly discussed.

  15. Strain rate effects on tensile strength of iron green bodies

    Nishida Masahiro


    Full Text Available Impact tensile strength of iron green bodies with densities of 7.2 and 7.4 g/cm3 was examined by Brazilian test using the split-Hopkinson pressure bar (Kolsky bar method. The powder material used for the experiments was a press-ready premix containing Distaloy AE, graphite, and lubricant. During dynamic compression, the failure behavior of specimens was observed using a high-speed video camera. The failure stress and failure behavior of dynamic compressive tests were compared with those of static compressive tests.

  16. Strain rate effects on tensile strength of iron green bodies

    Nishida, Masahiro; Kuroyanagi, Yuki; Häggblad, Hans-Åke; Jonsén, Pär; Gustafsson, Gustaf


    Impact tensile strength of iron green bodies with densities of 7.2 and 7.4 g/cm3 was examined by Brazilian test using the split-Hopkinson pressure bar (Kolsky bar) method. The powder material used for the experiments was a press-ready premix containing Distaloy AE, graphite, and lubricant. During dynamic compression, the failure behavior of specimens was observed using a high-speed video camera. The failure stress and failure behavior of dynamic compressive tests were compared with those of static compressive tests.

  17. 氟中毒对动物前交叉韧带拉伸力学特性影响%Effect on tensile properties of animals'anterior cruciate ligament of fluorosis

    李亚军; 罗民; 李鹏; 彭传刚


    目的 对比分析正常与氟中毒家兔前交叉韧带拉伸力学性能指标,确定氟中毒对动物前交叉韧带拉伸力学特性是否有影响.方法 复制氟中毒家兔动物模型,取正常和氟中毒家兔前交叉韧带进行拉伸力学性能实验.结果 正常家兔前交叉韧带的最大载荷为(18.4.±1.1)N,最大应力为(7.1±0.43) MPa,最大位移为(1.1 ±0.08)mm,最大应变为(13.4±0.93)%;氟中毒模型组前交叉韧带最大载荷为(10.3±1.0)N,最大位移为(0.6±0.07) mm,最大应力为(3.9±0.4) MPa,最大应变为(9.5±0.8)%,氟中毒模型组动物前交叉韧带拉伸最大载荷、最大应力、最大位移、最大应变小于正常对照组,差异显著(P<0.05).结论 氟中毒模型组动物前交叉韧带拉伸力学性能发生了改变.%Abstract:Objective Contrastive analysis on tensile properties and index of anterior cruciate ligament between normal and fluorine poisoned rabbit was conducted to study the effect on tensile properties of animals' anterior cruciate ligament of fluorosis.Methods We duplicated the animal model of fluorine poisoned rabbit,and then took the anterior cruciate ligament of normal and poisoned rabbit and conducted the experiment on tensile mechanical properties.Results In normal rabbits,we found the anterior cruciate ligament with maximum load of 18.4.± 1.1N,maximum stress of 7.1 ± 0.43 MPa,maximum displacement of 1.1 ± 0.08mm and maximum strain of 13.4 ± 0.93% ; In poisoned rabbits,we found the anterior cruciate ligament with maximum load of 10.3 ± 1.0N,maximum displacement of 0.6 ± 0.07mm,maximum stress of 3.9 ± 0.4 MPa and maximum strain of 9.5 ± 0.8%.The results showed the tensile maximum load,maximum stress,maximum displacement,and maximum strain of animals'anterior cruciate ligament in fluoride poisoned model group were less than the normal control group,they were significantly different (P < 0.05).Conclusion The tensile mechanical properties of anterior

  18. Weibull Effective Area for Hertzian Ring Crack Initiation Stress

    Jadaan, Osama M. [University of Wisconsin, Platteville; Wereszczak, Andrew A [ORNL; Johanns, Kurt E [ORNL


    Spherical or Hertzian indentation is used to characterize and guide the development of engineered ceramics under consideration for diverse applications involving contact, wear, rolling fatigue, and impact. Ring crack initiation can be one important damage mechanism of Hertzian indentation. It is caused by sufficiently-high, surface-located, radial tensile stresses in an annular ring located adjacent to and outside of the Hertzian contact circle. While the maximum radial tensile stress is known to be dependent on the elastic properties of the sphere and target, the diameter of the sphere, the applied compressive force, and the coefficient of friction, the Weibull effective area too will be affected by those parameters. However, the estimations of a maximum radial tensile stress and Weibull effective area are difficult to obtain because the coefficient of friction during Hertzian indentation is complex, likely intractable, and not known a priori. Circumventing this, the Weibull effective area expressions are derived here for the two extremes that bracket all coefficients of friction; namely, (1) the classical, frictionless, Hertzian case where only complete slip occurs, and (2) the case where no slip occurs or where the coefficient of friction is infinite.

  19. some tensile properties of unsaturated polyester resin reinforced wi

    Dr Obe

    This study investigated the tensile response of polyester composites ... SOME TENSILE PROPERTIES OF UNSATURATED POLYESTER RESIN REINFORCED WITH VARYING VOLUME ... the characterization of the particles and their.

  20. Maximum Autocorrelation Factorial Kriging

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Pedersen, John L.


    This paper describes maximum autocorrelation factor (MAF) analysis, maximum autocorrelation factorial kriging, and its application to irregularly sampled stream sediment geochemical data from South Greenland. Kriged MAF images are compared with kriged images of varimax rotated factors from...

  1. Insensitivity on tensile properties of forged Mg-13Li-X alloy to hot-rolling deformation

    LI Li; LI Huan-xi; ZHOU Tie-tao; CHEN Chang-qi; WU Qiu-lin; ZHANG Qing-quan; FU Zu-ming


    In order to examine the dependences of tensile properties of a forged Mg-13Li-X alloy on hot-rolling deformation and the underlying mechanisms tensile tests, residual stress measurements and texture analyses were conducted in the present study. It is found that after a hot-rolling deformation of 50% at 200 ℃, no much changes in tensile properties, nature and magnitude of residual stresses, and texture type and intensity can be identified for the alloy investigated. The insensitivity of tensile properties of the Mg-Li-X alloy to hot-rolling deformation is attributed at least partially to the insensitivity of residual stress and texture to hot-rolling.

  2. Tensile properties and fracture characteristics of spray cast alloy IC6 (Ni-7.8Al-14Mo-0.05B)

    MI Guo-fa; WANG Hong-wei; TIAN Shi-fan; LI Zhou; ZENG Song-yan


    Tensile testing results of spray cast Ni3Al-based superalloy indicated that the yield strength and tensile strength increase with the increasing of temperature and reached maximum at around 760℃, then decrease with the increasing of temperature. After high temperature isostatic pressing (HIP), yield strength decreased and ductility and tensile strength increased. Stereographic projection showed that no matter at room temperature, medium temperature or high temperature, cracks extend along (111).

  3. A predictive model of the tensile strength of twisted carbon nanotube yarns

    Jeon, Seung-Yeol; Jang, Jinhyeok; Koo, Bon-Woong; Kim, Young-Woon; Yu, Woong-Ryeol


    Due to the outstanding mechanical properties of individual carbon nanotubes (CNTs) at the nanoscale, CNT yarns are expected to demonstrate high strength at the macroscale. In this study, a predictable model was developed to predict the tensile strength of twisted CNT yarns. First, the failure mechanism of twisted CNT yarns was investigated using in situ tensile tests and ex situ observations. It was revealed that CNT bundles, which are groups of CNTs that are tightly bound together, formed during tensile loading, leaving some voids around the bundles. Failure of the CNT yarns occurred as the CNT bundles were pulled out of the yarns. Two stresses that determined the tensile strength of the CNT yarns were identified: interfacial shear and frictional stresses originating from van der Waals interactions, and the lateral pressure generated by the twisted yarn structure. Molecular dynamics and yarn mechanics were used to calculate these two stresses. Finally, the tensile strength of CNT yarns was predicted and compared with experimental data, showing reasonable agreement.

  4. 弯曲应力作用下喷射混凝土受拉区碳化试验研究%Influence of accelerated carbonation on shotcrete at tensile area under bending stress

    王家滨; 牛荻涛; 张永利


    In order to research the carbonation of shotcrete single-layer lining in tunnel,the accelerator carbona-tion of shotcrete with and without steel fiber under bending stress which the ratios of flexural strength were 0, 0.25,0.5 and 0.75,respectively were studied.The carbonation depth of shotcrete obeys Fick's first law and in-creased with the carbonation age and bending stress improved.In the similar experiment conditions,the carbon-ation depth of shotcrete was small than ordinary concrete.Meanwhile,the carbonation depth of steel fiber rein-forced shotcrete was much less than ordinary shotcrete at the same age.Based on the influence coefficients of bending stress,steel fiber and construction mode,the carbonation depth prediction model of ordinary concrete was modified.%为了研究隧道喷射混凝土单层衬砌碳化规律,采用快速碳化实验方法,研究了不同弯曲应力(0,0.25,0.5及0.75)作用下喷射混凝土及钢纤维喷射混凝土受拉区碳化深度变化规律.结果表明,喷射混凝土碳化深度经时变化规律服从Fick第一定律,碳化深度随着碳化龄期和弯曲应力的增加而增大.同实验条件下,喷射混凝土碳化深度小于普通混凝土,而钢纤维的加入进一步减小喷射混凝土同龄期碳化深度.在考虑弯曲应力影响系数、钢纤维影响系数及施工方式影响系数基础上对普通混凝土碳化深度预测模型进行修正,使其能够较好预测喷射混凝土碳化深度.

  5. Effects of Cyclic Tensile Stress on Human Periodontal Ligament Fibroblasts Apoptosis%周期性张应力对牙周膜成纤维细胞凋亡的影响

    尹崇英; 姚如永; 张广耘; 袁晓; 张月; 于江波; 郑如松; 陈正岗; 曹海萌; 仇静


    Objective:To investigate the effect of cyclic stretch on Human periodontal ligament fibroblasts apoptosis and PI3k/Akt signaling pathway involved.Methods:In vitro culture -tensile stimulate models of HPDLFs were established by using a multi-passage load adding system.Cyclic stretch was applied on the fibroblasts in different groups for 1,6,12,and 24 h,respectively.The loading was set for 15% surface elongation,with frequency 1/6 Hz.Meanwhile,the blank normal control group and negative control group,0h+LY294002 was established by static group.The cell apoptosis was determined by Hoechst 33258 staining.The expression of Bcl-2 and Bax mRNA was detected by RT-PCR.Results:Hoechst 33258 staining showed that after treatment with loading,the cell took the typical appearance of apoptosis with chromatin condensation and apoptotic bodies.RT-PCR displayed that the rate of Bcl-2 / Bax mRNA expression decreased in loaded HPDLFs group compared with that in unloaded HPDLFs(P < 0.01).The rate decreased to the lowest level at 12h following loading,and then enhanced gradually.Compared with that in the loading group,the HPDLFs apoptosis increased at corresponding time points in the LY294002 group (P <0.05).Conclusion:The cyclic stretch can promote the apoptosis of HPDLFs in a time-dependent manner,then the HPDLFs apoptosis was inhibited PI3K/AKT signaling pathway may participate in the regulation of apoptosis of HPDLFs induced by cyclic stretch.%目的:在体外条件下,探讨周期张应力作用对人牙周膜成纤维细胞凋亡的影响及PI3k/AKt信号通路在细胞凋亡中的作用.方法:应用多通道细胞牵张应力加载系统,以HPDLFs(人牙周膜成纤维细胞)为对象构建细胞体外培养-力学刺激模型,对照组为0h,0h+LY294002,加力组1h,6h,12 h,12 h+LY294002,24 h,力值定为15%,频率为1/6HZ,即10循环/分钟.采用Hoechst33258染色检测细胞形态和凋亡情况,应用RT-PCR技术检测Bcl-2、Bax的表达情况.结果:Hoechst33258细

  6. 3D Finite Element Numerical Simulation of Residual Stresses on Electron Beam Welded BT20 Plates

    Lixing HUO; Furong CHEN; Yufeng ZHANG; Li ZHANG; Fangjun LIU; Gang CHEN


    A three-dimensional finite-element model (FEM) used for calculating electron beam (EB) welding temperature and stresses fields of thin plates of BT20 titanium has been developed in which the nonlinear thermophysical and thermo-mechanical properties of the material has been considered. The welding temperature field, the distributions of residual stresses in aswelded (AW) and electron beam local post-weld heat treatment (EBLPWHT) conditions have been successfully simulated.The results show that: (1) In the weld center, the maximum magnitude of residual tensile stresses of BT20 thin plates of Ti alloy is equal to 60%~ 70% of its yield strength σs. (2) The residual tensile stresses in weld center can be even decreased after EBLPWHT and the longitudinal tensile stresses are decreased about 50% compared to joints in AW conditions. (3)The numerical calculating results of residual stresses by using FEM are basically in agreement with the experimental results.Combined with numerical calculating results, the effects of electron beam welding and EBLPWHT on the distribution of welding residual stresses in thin plates of BT20 have been analyzed in detail.

  7. A novel tensile test method to assess texture and gaping in salmon fillets.

    Ashton, Thomas J; Michie, Ian; Johnston, Ian A


    A new tensile strength method was developed to quantify the force required to tear a standardized block of Atlantic salmon muscle with the aim of identifying those samples more prone to factory downgrading as a result of softness and fillet gaping. The new method effectively overcomes problems of sample attachment encountered with previous tensile strength tests. The repeatability and sensitivity and predictability of the new technique were evaluated against other common instrumental texture measurement methods. The relationship between sensory assessments of firmness and parameters from the instrumental texture methods was also determined. Data from the new method were shown to have the strongest correlations with gaping severity (r =-0.514, P tensile test in the top cluster, alongside the Warner Bratzler method, demonstrating that it also yields adequate data with respect to these tests. None of the tested sensory analysis attributes showed significant relationships to mechanical tests except fillet firmness, with correlations (r) of 0.42 for cylinder probe maximum force (P = 0.005) and 0.31 for tensile work (P = 0.04). It was concluded that the tensile test method developed provides an important addition to the available tools for mechanical analysis of salmon quality, particularly with respect to the prediction of gaping during factory processing, which is a serious commercial problem. A novel, reliable method of measuring flesh tensile strength in salmon, provides data of relevance to gaping.

  8. High Velocity Tensile Test for Thin Plate Specimen with One Bar Method

    Itabashi, Masaaki

    In order to design thin-walled impact-resistant structure, for example, an automotive body, dynamic behavior of thin plate is essential. So far, except for laminated composite materials, high velocity tensile test of thin plate specimen did not attract impact researchers' and engineers' attention very much. In this paper, the previous thin plate specimen assembly for the one bar method was improved. The one bar method has been utilized for cylindrical specimens of various solid materials and is known as an effective high velocity tensile testing technique. Unfortunately, the previous assembly introduced a tremendous initial peak on stress-strain curves, even for aluminum alloys. With a new specimen assembly, stress-strain curves for IF (Interstitial-atom Free) steel and 7075-T6 aluminum alloy obtained by the one bar method were almost equivalent to those obtained by the tensile version of the split Hopkinson pressure bar method.

  9. Statistical Tensile Strength for High Strain Rate of Aramid and UHMWPE Fibers

    YANG Bin; XIONG Tao; XIONG Jie


    Dynamic tensile impact properties of aramid (Technora(R)) and UHMWPE (DC851) fiber bundles were studied at two high strain rates by means of reflecting type Split Hopkinson Bar, and stress-strain curves of fiber yarns at different strain rates were obtained. Experimental results show that the initial elastic modulus, failure strength and unstable strain of aramid fiber yarns are strain rate insensitive, whereas the initial elastic modulus and unstable strain of UHMWPE fiber yarns are strain rate sensitive. A fiber-bundle statistical constitutive equation was used to describe the tensile behavior of aramid and UHMWPE fiber bundles at high strain rates. The good consistency between the simulated results and experimental data indicates that the modified double Weibull function can represent the tensile strength distribution of aramid and UHMWPE fibers and the method of extracting Weibull parameters from fiber bundles stress-strain data is valid.

  10. Tensile properties of a nickel-base alloy subjected to surface severe plastic deformation

    Tian, J.W. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States); Dai, K. [Quality Engineering and Software Technology, East Hartford, CT 06108 (United States); Villegas, J.C. [Intel Corporation, Chandler, AZ (United States); Shaw, L. [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, CT (United States)], E-mail:; Liaw, P.K. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States); Klarstrom, D.L. [Haynes International, Inc., Kokomo, IN (United States); Ortiz, A.L. [Departamento de Ingenieria Mecanica, Energetica y de los Materiales, Universidad de Extremadura, 06071 Badajoz (Spain)


    A surface severe plastic deformation (S{sup 2}PD) method has been applied to bulk specimens of HASTELLOY C-2000 alloy, a nickel-base alloy. The mechanical properties of the processed C-2000 alloy were determined via tensile tests and Vickers hardness measurements, whereas the microstructure was characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The improved tensile strength was related to the nanostructure at the surface region, the residual compressive stresses, and the work-hardened surface layer, all of which resulted from the S{sup 2}PD process. To understand the contributions of these three factors, finite element modeling was performed. It was found that the improved tensile strength could be interpreted based on the contributions of nano-grains, residual stresses, and work hardening.

  11. Making High-Tensile-Strength Amalgam Components

    Grugel, Richard


    Structural components made of amalgams can be made to have tensile strengths much greater than previously known to be possible. Amalgams, perhaps best known for their use in dental fillings, have several useful attributes, including room-temperature fabrication, corrosion resistance, dimensional stability, and high compressive strength. However, the range of applications of amalgams has been limited by their very small tensile strengths. Now, it has been discovered that the tensile strength of an amalgam depends critically on the sizes and shapes of the particles from which it is made and, consequently, the tensile strength can be greatly increased through suitable choice of the particles. Heretofore, the powder particles used to make amalgams have been, variously, in the form of micron-sized spheroids or flakes. The tensile reinforcement contributed by the spheroids and flakes is minimal because fracture paths simply go around these particles. However, if spheroids or flakes are replaced by strands having greater lengths, then tensile reinforcement can be increased significantly. The feasibility of this concept was shown in an experiment in which electrical copper wires, serving as demonstration substitutes for copper powder particles, were triturated with gallium by use of a mortar and pestle and the resulting amalgam was compressed into a mold. The tensile strength of the amalgam specimen was then measured and found to be greater than 10(exp 4) psi (greater than about 69 MPa). Much remains to be done to optimize the properties of amalgams for various applications through suitable choice of starting constituents and modification of the trituration and molding processes. The choice of wire size and composition are expected to be especially important. Perusal of phase diagrams of metal mixtures could give insight that would enable choices of solid and liquid metal constituents. Finally, whereas heretofore, only binary alloys have been considered for amalgams

  12. Surface orientation effects on bending properties of surgical mesh are independent of tensile properties.

    Simon, David D; Andrews, Sharon M; Robinson-Zeigler, Rebecca; Valdes, Thelma; Woods, Terry O


    Current mechanical testing of surgical mesh focuses primarily on tensile properties even though implanted devices are not subjected to pure tensile loads. Our objective was to determine the flexural (bending) properties of surgical mesh and determine if they correlate with mesh tensile properties. The flexural rigidity values of 11 different surgical mesh designs were determined along three textile directions (machine, cross-machine, and 45° to machine; n = 5 for each) using ASTM D1388-14 while tracking surface orientation. Tensile testing was also performed on the same specimens using ASTM D882-12. Linear regressions were performed to compare mesh flexural rigidity to mesh thickness, areal mass density, filament diameter, ultimate tensile strength, and maximum extension. Of 33 mesh specimen groups, 30 had significant differences in flexural rigidity values when comparing surface orientations (top and bottom). Flexural rigidity and mesh tensile properties also varied with textile direction (machine and cross-machine). There was no strong correlation between the flexural and tensile properties, with mesh thickness having the best overall correlation with flexural rigidity. Currently, surface orientation is not indicated on marketed surgical mesh, and a single mesh may behave differently depending on the direction of loading. The lack of correlation between flexural stiffness and tensile properties indicates the need to examine mesh bending stiffness to provide a more comprehensive understanding of surgical mesh mechanical behaviors. Further investigation is needed to determine if these flexural properties result in the surgical mesh behaving mechanically different depending on implantation direction. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.


    Qin Zhang; Ke Wang; Y. Men; Qiang Fu


    Most of the articles on polymer nanocomposites focus on the importance of chemistry used to modify the surface of the clay, usually montmorillonite (MMT), and characterization of the nano-scale structure obtained. The role and importance of processing were also discussed recently. However, few papers concerning the correlation between morphology of MMT and mechanical properties were published. In order to understand the tensile behavior of PP/Montmorillonite(MMT) nanocomposites better, and to further improve the reinforcement efficiency, we first prepared the PP nanocomposites via direct melt intercalation using conventional twin-screw extrusion. The dispersion and tensile property of the composites were then investigated by SEM, XRD, TEM and a video-controlled tensile set-up. The macroscopic and microscopic dispersion of MMT in PP matrix was verified by XRD and TEM, combined with SEM. The tensile properties were obtained by video-controlled tensile set-up, which gives true stress-strain curve. It was found that a partly intercalated and partly exfoliated structure (also called incomplete exfoliation) existed in the system. Though the tensile strength of PPnanocomposites is not much improved in engineering stress-strain curves, more than 20% increase of true stress was found ina true stress-strain experiment at high true strain, which indicates that only oriented silicate layers can have a big effect ontensile properties. Not only orientation of silicate platelets but also the degree of exfoliation is a key factor to determine thereinforcement efficiency. The reinforcement efficiency of MMT has been discussed based on the "continuum" Halpin-Tsaiequations. A good agreement was found between experimental data and theoretical prediction by changing N value (numberofplatelets per stack) which corresponding to different state of the dispersion of MMT in PP matrix.

  14. Flat medial-lateral conformity in total knee replacements does not minimize contact stresses.

    Rawlinson, Jeremy J; Bartel, Donald L


    The potential for wear in UHMWPE components for total knee replacements can be reduced by decreasing the stresses and strains arising from tibial-femoral contact. The conformity of the articular surfaces has a large effect on the resultant stresses, and components that achieve flat medial-lateral contact have been assumed to produce the lowest stresses due to their perfect conformity. We computed the stresses arising from curved and flat contact on a half-space using two-dimensional, plane strain elasticity solutions and finite element analyses to compare the performance of curved and flat indenters. These indenters were represented by a polynomial so the profiles could be continuously varied from curved to flat. Curved contact resulted in maximum stresses at the center of contact, while flat contact produced maximum stresses at the edge of contact. In addition, three contemporary tibial configurations (flat-on-flat, curved-on-flat, and curved-on-curved geometries) were analyzed using the finite element method with nonlinear material properties. The maximum contact stress, von Mises stress, and von Mises strain were lowest for the curved-on-curved model. The other configurations resulted in higher contact stresses, von Mises stresses, and von Mises strains. The perfect conformity arising from flat contact did not reduce the contact stresses in the UHMWPE component. The tensile stresses, however, were lowest for the flat-on-flat geometry compared with the other two configurations. Relating these distinct differences could prove useful in interpretation of data from simulator and retrieval studies.

  15. Study on the Forming Limit Nomogram of Tensile Stamping Operations

    Dachang KANG; Haobin TIAN; Shihong ZHANG


    Based on plasticity theory and physical experiments, the quantitative relationships between elongation δ obtained by uniaxial tensile test and forming limits of tensile stamping operations are given, which mainly resolves the problem that forming limits can be derived from simple tensile test. The forming limit nomogram of tensile stamping operations is also established to apply to engineering.

  16. Characteristics of the tensile mechanical properties of fresh and dry forewings of beetles.

    Tuo, Wanyong; Chen, Jinxiang; Wu, Zhishen; Xie, Juan; Wang, Yong


    Based on a tensile experiment and observations by scanning electron microscopy (SEM), this study demonstrated the characteristics of the tensile mechanical properties of the fresh and dry forewings of two types of beetles. The results revealed obvious differences in the tensile fracture morphologies and characteristics of the tensile mechanical properties of fresh and dry forewings of Cybister tripunctatus Olivier and Allomyrina dichotoma. For fresh forewings of these two types of beetles, a viscous, flow-like, polymer matrix plastic deformation was observed on the fracture surfaces, with soft morphologies and many fibers being pulled out, whereas on the dry forewings, the tensile fracture surfaces were straightforward, and there were no features resembling those found on the fresh forewings. The fresh forewings exhibited a greater fracture strain than the dry forewings, which was caused by the relative slippage of hydroxyl inter-chain bonds due to the presence of water in the fibers and proteins in the fresh forewings. Our study is the first to demonstrate the phenomenon of sudden stress drops caused by the fracturing of the lower skin because the lower skin fractured before the forewings of A. dichotoma reached their ultimate tensile strength. We also investigated the reasons underlying this phenomenon. This research provides a much better understanding of the mechanical properties of beetle forewings and facilitates the correct selection of study objects for biomimetic materials and development of the corresponding applications.

  17. Effects of Aluminum Addition on Tensile and Cup Forming Properties of Three Twinning Induced Plasticity Steels

    Hong, Seokmin; Shin, Sang Yong; Kim, Hyoung Seop; Lee, Sunghak; Kim, Sung-Kyu; Chin, Kwang-Geun; Kim, Nack J.


    In the present study, a high Mn twinning induced plasticity (TWIP) steel and two Al-added TWIP steels were fabricated, and their microstructures, tensile properties, and cup formability were analyzed to investigate the effects of Al addition on deformation mechanisms in tensile and cup forming tests. In the high Mn steel, the twin formation was activated to increase the strain hardening rate and ultimate tensile strength, which needed the high punch load during the cup forming test. In the Al-added TWIP steels, the twin formation was reduced, while the slip activation increased, thereby leading to the decrease in strain hardening rate and ultimate tensile strength. As twins and slips were homogeneously formed during the tensile or cup forming test, the punch load required for the cup forming and residual stresses were relatively low, and the tensile ductility was sufficiently high even after the cup forming test. This indicated that making use of twins and slips simultaneously in TWIP steels by the Al addition was an effective way to improve overall properties including cup formability.

  18. Mechanical characterization of stomach tissue under uniaxial tensile action.

    Jia, Z G; Li, W; Zhou, Z R


    In this article, the tensile properties of gastric wall were investigated by using biomechanical test and theoretical analysis. The samples of porcine stomach strips from smaller and greater curvature of the stomach were cut in longitudinal and circumferential direction, respectively. The loading-unloading, stress relaxation, strain creep, tensile fracture tests were performed at mucosa-submucosa, serosa-muscle and intact layer, respectively. Results showed that the biomechanical properties of the porcine stomach depended on the layers, orientations and locations of the gastric wall and presented typical viscoelastic, nonlinear and anisotropic mechanical properties. During loading-unloading test, the stress of serosa-muscle layer in the longitudinal direction was 15-20% more than that in the circumferential direction at 12% stretch ratio, while it could reach about 40% for the intact layer and 50% for the mucosa-submucosa layer. The results of stress relaxation and strain creep showed that the variation degree was obviously faster in the circumferential direction than that in the longitudinal direction, and the ultimate residual values were also different for the different layers, orientations and locations. In the process of fracture test, the serosa-muscle layer fractured firstly followed by the mucosa-submucosa layer when the intact layer was tested, the longitudinal strips firstly began to fracture and the required stress value was about twice as much as that in the circumferential strips. The anisotropy and heterogeneity of mechanical characterization of the porcine stomach were related to its complicated geometry, structure and functions. The results would help us to understand the biomechanics of soft organ tissue. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Texture evolution during tensile necking of copper processed by equal channel angular extrusion

    Pantleon, Wolfgang; Richter, S.; Martin, S.


    profiles are obtained with the scattering vector parallel to the in situ tensile axis. In this case the profiles initially show an opposite asymmetry, but during the in situ deformation the asymmetry reverses sign as the deformation under new loading conditions leads to changes in the intra-grain stresses....

  20. High-strain-rate tensile mechanical response of a polyurethane elastomeric material

    Fan, J.T.; Weerheijm, J.; Sluys, L.J.


    The dynamic tensile mechanical response of a soft polymer material (Clear Flex 75) is investigated using a split Hopkinson tension bar (SHTB). Stress-strain relations are derived to reveal the mechanical properties at moderate and high strain rates. These relations appear to be rate dependent. Under

  1. Plain bearing stresses due to forming and oil film pressure

    Burke-Veliz, A.; Wang, D.; Wahdy, N.; Reed, P. A. S.; Merritt, D.; Syngellakis, S.


    This paper describes a methodology for assessing critical stress ranges arising in automotive plain bearings during engine operations. An industry-produced and run simulation program provides information on oil film pressure and overall bearing deformation during accelerated performance tests. This code performs an elasto-hydrodynamic lubrication analysis accounting for the compliance of the housing and journal. Finite element analyses of a multilayer bearing are performed to assess the conditions responsible for possible fatigue damage over the bearing lining. The residual stresses arising from the forming and fitting process are first assessed. The stress analyses over the engine cycle show the intensity and distribution of cyclic tensile and compressive stresses in the bearing. The location of maximum stress range is found to be consistent with the damage observed in accelerated fatigue tests. Critical zones are identified in the lining for possible fatigue crack initiation and growth studies.

  2. Plain bearing stresses due to forming and oil film pressure

    Burke-Veliz, A; Reed, P A S; Syngellakis, S [University of Southampton, School of Engineering Sciences, Southampton SO17 1BJ (United Kingdom); Wang, D; Wahdy, N; Merritt, D, E-mail: allan.burke@itesm.m [MAHLE Engine Systems UK Ltd, 2 Central park Drive, Rugby CV23 0WE (United Kingdom)


    This paper describes a methodology for assessing critical stress ranges arising in automotive plain bearings during engine operations. An industry-produced and run simulation program provides information on oil film pressure and overall bearing deformation during accelerated performance tests. This code performs an elasto-hydrodynamic lubrication analysis accounting for the compliance of the housing and journal. Finite element analyses of a multilayer bearing are performed to assess the conditions responsible for possible fatigue damage over the bearing lining. The residual stresses arising from the forming and fitting process are first assessed. The stress analyses over the engine cycle show the intensity and distribution of cyclic tensile and compressive stresses in the bearing. The location of maximum stress range is found to be consistent with the damage observed in accelerated fatigue tests. Critical zones are identified in the lining for possible fatigue crack initiation and growth studies.

  3. Effects of vacuum annealing treatment on microstructures and residual stress of AlSi10Mg parts produced by selective laser melting process

    Chen, Tian; Wang, Linzhi; Tan, Sheng


    Selective laser melting (SLM)-fabricated AlSi10Mg parts were heat-treated under vacuum to eliminate the residual stress. Microstructure evolutions and tensile properties of the SLM-fabricated parts before and after vacuum annealing treatment were studied. The results show that the crystalline structure of SLM-fabricated AlSi10Mg part was not modified after the vacuum annealing treatment. Additionally, the grain refinement had occurred after the vacuum annealing treatment. Moreover, with increasing of the vacuum annealing time, the second phase increased and transformed to spheroidization and coarsening. The SLM-produced parts after vacuum annealing at 300∘C for 2 h had the maximum ultimate tensile strength (UTS), yield strength (YS) and elongation, while the elastic modulus decreased significantly. In addition, the tensile residual stress was found in the as-fabricated AlSi10Mg samples by the microindentation method.

  4. Effect of adhesive geometry on the tensile properties of AISI 1350 steel

    A. Yasar


    Full Text Available It is utilized increasingly to use adhesive bonding in automotive industry to join structural components of metallic materials. The aim of this experimental study is to extend the information available to the automotive design engineer and contribute the better understanding of how the various geometrical shaped of steel parts affect the adhesive bonding. In this study, different types of lap joints, such as butt, step butt, scarf, tubular lap, were used to determine the mechanical strength of SAE/AISI 1350 steel. It has been observed that the cylindrical geometries can be subject to more stress compared to square specimens generally and the geometries with both tensile and shear stress can stand more stress per unit compared with the specimens with only tensile stress.

  5. Mechanical failure of zigzag graphene nanoribbons under tensile strain induced by edge reconstruction

    Cheng, Yingchun


    The structural and mechanical properties of graphene nanoribbons (GNRs) under uniaxial tensile strain are studied by density functional theory. The ideal strength of a zigzag GNR (120 GPa) is close to that of pristine graphene. However, for a GNR with both edges reconstructed to pentagon–heptagon pairs (from hexagon–hexagon pairs) it decreases to 94 GPa and the maximum tensile strain is reduced to 15%. Our results constitute a comprehensive picture of the edge structure effect on the mechanical properties of GNRs.

  6. Stress

    Keller, Hanne Dauer


    Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....

  7. Stress

    Keller, Hanne Dauer


    Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....

  8. Characterization of surface damage of a solid plate under tensile loading using nonlinear Rayleigh waves


    This letter reports experimental observation of a direct correlation between the acoustic nonlinearity parameter (NP) measured with nonlinear Rayleigh waves and the accumulation of plasticity damage in an AZ31 magnesium alloy plate specimen.Rayleigh waves are generated and detected with wedge transducers,and the NPs are measured at different stress levels.The results show that there is a significant increase in the NPs with monotonic tensile loads surpassing the material's yielding stress.The research sugge...

  9. Effect of Workwear Fabric Characteristics on the Changes in Tensile Properties of Sewing Threads after Sewing

    Vinay Kumar Midha, Ph.D.; A. Mukhopadhyay, Ph.D.; V. K. Kothari, Ph.D.; R. Chattopadhyay, Ph.D.


    During sewing at high speed, the needle thread issubjected to repeated tensile stresses, heat, bending,pressure, torsion and wearing. These stresses act onthe thread repeatedly and the thread passes 50-80times through the fabric, the needle eye and thebobbin case mechanism, before getting incorporatedinto the seam. As a result both the sewing thread andthe yarns in the fabric get abraded/ severed during theseaming process. A number of researchers observedthat there could be 30% to 40% strengt...

  10. Numerical Analysis of Dynamic Splitting-Tensile and Direct Tension Tests


    tensile tests. The concrete material model employed in the nonlinear analysis was a hypoelastic model based on a uniaxial stress-strain relation (Figure... hypoelastic model based upon the uniaxial stress-strain relation depicted in Figure 48. The tension failure envelope illustrated in Figure 49 w~s...strain rates associated with high intensity loadings from conventional explosives. Both an elastic and an inelastic concrete model were employed in all

  11. Stress Induced in the Periodontal Ligament under Orthodontic Loading (Part I): A Finite Element Method Study Using Linear Analysis.

    Hemanth, M; Deoli, Shilpi; Raghuveer, H P; Rani, M S; Hegde, Chatura; Vedavathi, B


    Orthodontic tooth movement is a complex procedure that occurs due to various biomechanical changes in the periodontium. Optimal orthodontic forces yield maximum tooth movement whereas if the forces fall beyond the optimal threshold it can cause deleterious effects. Among various types of tooth movements intrusion and lingual root torque are associated with causing root resoprtion, especially with the incisors. Therefore in this study, the stress patterns in the periodontal ligament (PDL) were evaluated with intrusion and lingual root torque using finite element method (FEM). A three-dimensional (3D) FEM model of the maxillary incisors was generated using SOLIDWORKS modeling software. Stresses in the PDL were evaluated with intrusive and lingual root torque movements by a 3D FEM using ANSYS software using linear stress analysis. It was observed that with the application of intrusive load compressive stresses were distributed at the apex whereas tensile stress was seen at the cervical margin. With the application of lingual root torque maximum compressive stress was distributed at the apex and tensile stress was distributed throughout the PDL. For intrusive and lingual root torque movements stress values over the PDL was within the range of optimal stress value as proposed by Lee, with a given force system by Proffit as optimum forces for orthodontic tooth movement using linear properties.

  12. Mechanical state assessment using lamb wave technique in static tensile tests

    Burkov, M. V.; Shah, R. T.; Eremin, A. V.; Byakov, A. V.; Panin, S. V.


    The paper deals with the investigation of Lamb wave ultrasonic technique for damage (or mechanical state) evaluation of AA7068T3 specimens in the course of tensile testing. Two piezoelectric transducers (PZT), one of which is used as an actuator and the other as sensor, were adhesively bonded on the specimen surface using epoxy. Two frequencies of testing signals (60 kHz and 350 kHz) were used. The set of static tensile tests were performed. The recorded signals were processed to calculate the informative parameters in order to evaluate the changes in stress-strain state of the specimens and their microstructure.

  13. Tensile behavior of F82H with and without spectral tailoring

    Shiba, K. E-mail:; Klueh, R.L.; Miwa, Y.; Robertson, J.P.; Hishinuma, A


    The effects of neutron spectrum on tensile properties of the low-activation martensitic steel F82H (8Cr-2WVTa) was examined using a thermal neutron shield to tailor the neutron spectrum for steels irradiated in the high flux isotope reactor (HFIR). The yield stresses of spectrally tailored specimens irradiated in HFIR to 5 dpa at 300 deg. C and 500 deg. C are on trend lines obtained from unshielded irradiation in HFIR. No significant effect of the neutron spectrum on tensile properties could be detected.

  14. Tensile strain measurements of ceramic fibers using scanning laser acoustic microscopy

    Kent, Renee M.; Vary, Alex


    A noncontacting technique using scanning laser acoustic microscopy for making in situ tensile strain measurements of small diameter fibers was implemented for the tensile strain analysis of individual Nicalon SiC fibers (nominal diameter 15 microns). Stress vs strain curves for the fibers were plotted from the experimental data. The mean elastic modulus of the fibers was determined to be 185.3 GPa. Similar measurements were made for Carborundum SiC fibers (nominal diameter 28 microns) and Saphikon sapphire fibers (nominal diameter 140 microns).


    万华培; 汪洋; 夏源明


    A complete three-dimensional FEM model of the Bar-Bar Tensile Impact Apparatus (BTIA) is constructed, in which the slots in the bars and the glue layers between the bars and the flat-shaped specimen are included. For elastic-plastic specimen material, Ly12cz aluminum alloy, the process of tensile impact experiments is simulated and the matching relation between the specimen geometry and the bars is investigated. Based on the FEM analysis, an iterative method is proposed to design a reasonable specimen geometry for obtaining the true dynamic stress-strain relation for a certain specimen material.

  16. Suspended germanium cross-shaped microstructures for enhancing biaxial tensile strain

    Ishida, Satomi; Kako, Satoshi; Oda, Katsuya; Ido, Tatemi; Iwamoto, Satoshi; Arakawa, Yasuhiko


    We fabricate a suspended germanium cross-shaped microstructure to biaxially enhance residual tensile strain using a germanium epilayer directly grown on a silicon-on-insulator substrate. Such a suspended germanium system with enhanced biaxial tensile strain will be a promising platform for incorporating optical cavities toward the realization of germanium lasers. We demonstrate systematic control over biaxial tensile strain and photoluminescence peaks by changing structural geometry. The photoluminescence peaks corresponding to the direct recombination between the conduction Γ valley and two strain-induced separated valence bands have been clearly assigned. A maximum biaxial strain of 0.8% has been achieved, which is almost half of that required to transform germanium into a direct band-gap semiconductor.

  17. Static tensile and tensile creep testing of four boron nitride coated ceramic fibers at elevated temperatures

    Coguill, Scott L.; Adams, Donald F.; Zimmerman, Richard S.


    Six types of uncoated ceramic fibers were static tensile and tensile creep tested at various elevated temperatures. Three types of boron nitride coated fibers were also tested. Room temperature static tensile tests were initially performed on all fibers, at gage lengths of 1, 2, and 4 inches, to determine the magnitude of end effects from the gripping system used. Tests at one elevated temperature, at gage lengths of 8 and 10 inches, were also conducted, to determine end effects at elevated temperatures. Fiber cross sectional shapes and areas were determined using scanning electron microscopy. Creep testing was typically performed for 4 hours, in an air atmosphere.

  18. Effect of discrete fibre reinforcement on soil tensile strength

    Jian Li


    Full Text Available The tensile behaviour of soil plays a significantly important role in various engineering applications. Compacted soils used in geotechnical constructions such as dams and clayey liners in waste containment facilities can suffer from cracking due to tensile failure. In order to increase soil tensile strength, discrete fibre reinforcement technique was proposed. An innovative tensile apparatus was developed to determine the tensile strength characteristics of fibre reinforced soil. The effects of fibre content, dry density and water content on the tensile strength were studied. The results indicate that the developed test apparatus was applicable in determining tensile strength of soils. Fibre inclusion can significantly increase soil tensile strength and soil tensile failure ductility. The tensile strength basically increases with increasing fibre content. As the fibre content increases from 0% to 0.2%, the tensile strength increases by 65.7%. The tensile strength of fibre reinforced soil increases with increasing dry density and decreases with decreasing water content. For instance, the tensile strength at a dry density of 1.7 Mg/m3 is 2.8 times higher than that at 1.4 Mg/m3. It decreases by 30% as the water content increases from 14.5% to 20.5%. Furthermore, it is observed that the tensile strength of fibre reinforced soil is dominated by fibre pull-out resistance, depending on the interfacial mechanical interaction between fibre surface and soil matrix.

  19. Effect of discrete fibre reinforcement on soil tensile strength

    Jian Li; Chaosheng Tang; Deying Wang; Xiangjun Pei; Bin Shi


    The tensile behaviour of soil plays a significantly important role in various engineering applications. Compacted soils used in geotechnical constructions such as dams and clayey liners in waste containment facilities can suffer from cracking due to tensile failure. In order to increase soil tensile strength, discrete fibre reinforcement technique was proposed. An innovative tensile apparatus was developed to deter-mine the tensile strength characteristics of fibre reinforced soil. The effects of fibre content, dry density and water content on the tensile strength were studied. The results indicate that the developed test apparatus was applicable in determining tensile strength of soils. Fibre inclusion can significantly in-crease soil tensile strength and soil tensile failure ductility. The tensile strength basically increases with increasing fibre content. As the fibre content increases from 0%to 0.2%, the tensile strength increases by 65.7%. The tensile strength of fibre reinforced soil increases with increasing dry density and decreases with decreasing water content. For instance, the tensile strength at a dry density of 1.7 Mg/m3 is 2.8 times higher than that at 1.4 Mg/m3. It decreases by 30% as the water content increases from 14.5% to 20.5%. Furthermore, it is observed that the tensile strength of fibre reinforced soil is dominated by fibre pull-out resistance, depending on the interfacial mechanical interaction between fibre surface and soil matrix.

  20. Influence of temperature on threshold stress for reorientation of hydrides and residual stress variation across thickness of Zr-2.5Nb alloy pressure tube

    Singh, R.N. [Materials Science, Technology and Society, Malmo University, SE20506 (Sweden) and Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)]. E-mail:; Lala Mikin, R. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Roorkee 247 667, Uttaranchal (India); Dey, G.K. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Sah, D.N. [Post Irradiation Examination Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Batra, I.S. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Stahle, P. [Materials Science, Technology and Society, Malmo University, SE20506 (Sweden)


    Threshold stress, {sigma} {sub th}, for reorientation of hydrides in cold worked and stress-relieved (CWSR) Zr-2.5Nb pressure tube material was determined in the temperature range of 523-673 K. Using tapered gage tensile specimen, mean value of {sigma} {sub th} was experimentally determined by two methods, half thickness method and area compensation method. The difference between local values of {sigma} {sub th} measured across the thickness of the tube and the mean {sigma} {sub th} values yielded the residual stress variation across the tube thickness. It was observed that both the mean threshold stress and residual stress decrease with increase in reorientation temperature. Also, the maximum value of residual stresses was observed near the midsection of the tube.

  1. In vitro comparison of the tensile bond strength of denture adhesives on denture bases.

    Kore, Doris R; Kattadiyil, Mathew T; Hall, Dan B; Bahjri, Khaled


    With several denture adhesives available, it is important for dentists to make appropriate patient recommendations. The purpose of this study was to evaluate the tensile bond strength of denture adhesives on denture base materials at time intervals of up to 24 hours. Fixodent, Super Poligrip, Effergrip, and SeaBond denture adhesives were tested with 3 denture base materials: 2 heat-polymerized (Lucitone 199 and SR Ivocap) and 1 visible-light-polymerized (shade-stable Eclipse). Artificial saliva with mucin was used as a control. Tensile bond strength was tested in accordance with American Dental Association specifications at 5 minutes, 3 hours, 6 hours, 12 hours, and 24 hours after applying the adhesive. Maximum forces before failure were recorded in megapascals (MPa), and the data were subjected to a 2-way analysis of variance (α=.05). All 4 adhesives had greater tensile bond strength than the control. Fixodent, Super Poligrip, and SeaBond had higher tensile bond strength values than Effergrip. All adhesives had the greatest tensile bond strength at 5 minutes and the least at 24 hours. The 3 denture bases produced significantly different results with each adhesive (Padhesives had the greatest tensile bond strength, followed by Ivocap and Eclipse. All 4 adhesives had greater tensile bond strength than the control, and all 4 adhesives were strongest at the 5-minute interval. On all 3 types of denture bases, Effergrip produced significantly lower tensile bond strength, and Fixodent, Super Poligrip, and SeaBond produced significantly higher tensile bond strength. At 24 hours, the adhesive-base combinations with the highest tensile bond strength were Fixodent on Lucitone 199, Fixodent on Eclipse, Fixodent on Ivocap, and Super Poligrip on Ivocap. Copyright © 2013 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  2. Maximum Autocorrelation Factorial Kriging

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Pedersen, John L.; Steenfelt, Agnete


    This paper describes maximum autocorrelation factor (MAF) analysis, maximum autocorrelation factorial kriging, and its application to irregularly sampled stream sediment geochemical data from South Greenland. Kriged MAF images are compared with kriged images of varimax rotated factors from an ordinary non-spatial factor analysis, and they are interpreted in a geological context. It is demonstrated that MAF analysis contrary to ordinary non-spatial factor analysis gives an objective discrimina...

  3. Stress

    Jensen, Line Skov; Lova, Lotte; Hansen, Zandra Kulikovsky; Schønemann, Emilie; Larsen, Line Lyngby; Colberg Olsen, Maria Sophia; Juhl, Nadja; Magnussen, Bogi Roin


    Stress er en tilstand som er meget omdiskuteret i samfundet, og dette besværliggør i en vis grad konkretiseringen af mulige løsningsforslag i bestræbelsen på at forebygge den såkaldte folkesygdom. Hovedkonklusionen er, at selv om der bliver gjort meget for at forebygge, er der ikke meget der aktivt kan sættes i værk for at reducere antallet af stressramte, før en fælles forståelse af stressårsager og effektiv stresshåndtering er fremlagt. Problemformuleringen er besvaret gennem en undersø...

  4. Tensile rock mass strength estimated using InSAR

    Jonsson, Sigurjon


    The large-scale strength of rock is known to be lower than the strength determined from small-scale samples in the laboratory. However, it is not well known how strength scales with sample size. I estimate kilometer-scale tensional rock mass strength by measuring offsets across new tensional fractures (joints), formed above a shallow magmatic dike intrusion in western Arabia in 2009. I use satellite radar observations to derive 3D ground displacements and by quantifying the extension accommodated by the joints and the maximum extension that did not result in a fracture, I put bounds on the joint initiation threshold of the surface rocks. The results indicate that the kilometer-scale tensile strength of the granitic rock mass is 1–3 MPa, almost an order of magnitude lower than typical laboratory values.

  5. Effects of Voids on Concrete Tensile Fracturing: A Mesoscale Study

    Lei Xu


    Full Text Available A two-dimensional mesoscale modeling framework, which considers concrete as a four-phase material including voids, is developed for studying the effects of voids on concrete tensile fracturing under the plane stress condition. Aggregate is assumed to behave elastically, while a continuum damaged plasticity model is employed to describe the mechanical behaviors of mortar and ITZ. The effects of voids on the fracture mechanism of concrete under uniaxial tension are first detailed, followed by an extensive investigation of the effects of void volume fraction on concrete tensile fracturing. It is found that both the prepeak and postpeak mesoscale cracking in concrete are highly affected by voids, and there is not a straightforward relation between void volume fraction and the postpeak behavior due to the randomness of void distribution. The fracture pattern of concrete specimen with voids is controlled by both the aggregate arrangement and the distribution of voids, and two types of failure modes are identified for concrete specimens under uniaxial tension. It is suggested that voids should be explicitly modeled for the accurate fracturing simulation of concrete on the mesoscale.

  6. Dynamic compressive and tensile strengths of spark plasma sintered alumina

    Girlitsky, I.; Zaretsky, E.; Kalabukhov, S.; Dariel, M. P.; Frage, N.


    Fully dense submicron grain size alumina samples were manufactured from alumina nano-powder using Spark Plasma Sintering and tested in two kinds of VISAR-instrumented planar impact tests. In the first kind, samples were loaded by 1-mm tungsten impactors, accelerated to a velocity of about 1 km/s. These tests were aimed at studying the Hugoniot elastic limit (HEL) of Spark Plasma Sintering (SPS)-processed alumina and the decay, with propagation distance, of the elastic precursor wave. In the tests of the second kind, alumina samples of 3-mm thickness were loaded by 1-mm copper impactors accelerated to 100-1000 m/s. These tests were aimed at studying the dynamic tensile (spall) strength of the alumina specimens. The tensile fracture of the un-alloyed alumina shows a monotonic decline of the spall strength with the amplitude of the loading stress pulse. Analysis of the decay of the elastic precursor wave allowed determining the rate of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of the shock-induced inelastic deformation and to clarify the mechanisms responsible for the deformation. The 1-% addition of Cr2O3 decreases the HEL of the SPS-processed alumina by 5-% and its spall strength by 50% but barely affects its static properties.

  7. Dynamic yield and tensile strengths of spark plasma sintered alumina

    Girlitsky, I.; Zaretsky, E.; Kalabukhov, S.; Dariel, M.; Frage, N.


    Fully dense alumina samples with 0.6 μm grain size were produced from alumina powder using Spark Plasma Sintering and tested in two types of VISAR-instrumented planar impact tests. In the tests of the first type the samples of 0.28 to 6-mm thickness were loaded by 1-mm tungsten impactors accelerated up to a velocity of about 1 km/s. These tests were aimed to study the Hugoniot elastic limit (HEL) of the SPS-processed alumina and the decay of the elastic precursor wave with propagation distance. In the second type of test the samples of ~3-mm thickness were loaded by 1-mm copper impactors accelerated up to velocities 100-1000 m/s. These tests were aimed to study the dynamic tensile (spall) strength of the alumina. The data on tensile fracture of the alumina demonstrate a monotonic decline of the spall strength with the amplitude of the loading stress pulse. The data on the decay of the elastic precursor wave allows for determining the rates of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of shock-induced inelastic deformation and, thus, to derive some conclusions concerning the mechanisms responsible of the deformation.

  8. Quantifying the tensile strength of microbial mats grown over noncohesive sediments.

    Vignaga, E; Haynes, H; Sloan, W T


    Biofilms in marine and fluvial environments can comprise strong bacterial and diatom mats covering large areas of the bed and act to bind sediments. In this case the bed material becomes highly resistant to shear stresses applied by the overlying fluid motion and detachment, when it does occur, is manifest in patches of biofilm of the order cm(2) being entrained into the flow. This article is the first to report tensile test data specific to the centimeter scale using moist biofilm/sediment composite materials; the strain (ε)-stress (σ) relationships permit quantification of the elasticity (Young's modulus, E) and cohesive strength of each specimen. Specifically, we compare the mechanical strength of cyanobacterial biofilm-only samples to that of biofilm cultured over sediment samples (glass beads or natural sands of d ~ 1 mm) for up to 8 weeks. The range of tensile strength (1,288-3,283 Pa) for composite materials was up to three times higher than previous tensile tests conducted at smaller scale on mixed culture biofilm [Ohashi et al. (1999) Water Sci Technol 39:261-268], yet of similar range to cohesive strength values recorded on return activated sludge flocs [RAS; Poppele and Hozalski (2003) J Microbiol Methods 55:607-615]. Composite materials were 3-6 times weaker than biofilm-only samples, indicating that adhesion to sediment grains is weaker than cohesion within the biofilm. Furthermore, in order to relate the tensile test results to the more common in-situ failure of bio-mats due to shear flow, controlled erosion experiments were conducted in a hydraulic flume with live fluid flow. Here, the fluid shear stress causing erosion was 3 orders of magnitude lower than tensile stress; this highlights both the problem of interpreting material properties measured ex-situ and the need for a better mechanistic model of bio-mat detachment.

  9. Evaluation of damage models by finite element prediction of fracture in cylindrical tensile test.

    Eom, Jaegun; Kim, Mincheol; Lee, Seongwon; Ryu, Hoyeun; Joun, Mansoo


    In this research, tensile tests of cylindrical specimens of a mild steel are predicted via the finite element method, with emphasis on the fracture predictions of various damage models. An analytical model is introduced for this purpose. An iterative material identification procedure is used to obtain the flow stress, making it possible to exactly predict a tensile test up to the fracture point, in the engineering sense. A node-splitting technique is used to generate the cracks on the damaged elements. The damage models of McClintock, Rice-Tracey, Cockcroft-Latham, Freudenthal, Brozzo et al. and Oyane et al. are evaluated by comparing their predictions from the tensile test perspective.

  10. Characterization of macroscopic tensile strength of polycrystalline metals with two-scale finite element analysis

    Watanabe, Ikumu; Terada, Kenjiro; Neto, Eduardo Alberto de Souza; Perić, Djordje

    The objective of this contribution is to develop an elastic-plastic-damage constitutive model for crystal grain and to incorporate it with two-scale finite element analyses based on mathematical homogenization method, in order to characterize the macroscopic tensile strength of polycrystalline metals. More specifically, the constitutive model for single crystal is obtained by combining hyperelasticity, a rate-independent single crystal plasticity and a continuum damage model. The evolution equations, stress update algorithm and consistent tangent are derived within the framework of standard elastoplasticity at finite strain. By employing two-scale finite element analysis, the ductile behaviour of polycrystalline metals and corresponding tensile strength are evaluated. The importance of finite element formulation is examined by comparing performance of several finite elements and their convergence behaviour is assessed with mesh refinement. Finally, the grain size effect on yield and tensile strength is analysed in order to illustrate the versatility of the proposed two-scale model.

  11. Effect of depth and tubule direction on ultimate tensile strength of human coronal dentin.

    Inoue, Satoshi; Pereira, Patricia N R; Kawamoto, Chiharu; Nakajima, Masatoshi; Koshiro, Kenichi; Tagami, Junji; Carvalho, Ricardo M; Pashley, David H; Sano, Hidehiko


    The purpose of this study was to evaluate the effect of dentin depth and tubule direction on the ultimate tensile strength (UTS) of human dentin. Dentin slabs of 0.5-mm thickness were trimmed either from the mesial and distal (for specimens with the tubules parallel to the tensile force; parallel group) or from the occlusal and pulpal surfaces (perpendicular group) to reduce the cross-sectional area of the superficial, middle, and deep regions to 0.25 mm2, and subjected to microtensile testing. From SEM photomicrographs of the fractured specimens of the parallel group, the tubule density was investigated. For both parallel and perpendicular groups, superficial dentin showed a significantly higher UTS than deep dentin. The tubule density of superficial dentin was significantly lower than that of middle and deep dentin. When performing the microtensile bond test to deep dentin, it is possible that cohesive failure of dentin can occur at relatively low tensile stresses.

  12. Tensile properties of copper alloyed austempered ductile iron: Effect of austempering parameters

    Batra, U.; Ray, S.; Prabhakar, S. R.


    A ductile iron containing 0.6% copper as the main alloying element was austenitized at 850 °C for 120 min and was subsequently austempered for 60 min at austempering temperatures of 270, 330, and 380 °C. The samples were also austempered at 330 °C for austempering times of 30 150 min. The structural parameters for the austempered alloy austenite (X γ ), average carbon content (C γ ), the product X γ C γ , and the size of the bainitic ferrite needle (d α ) were determined using x-ray diffraction. The effect of austempering temperature and time has been studied with respect to tensile properties such as 0.2% proof stress, ultimate tensile strength (UTS), percentage of elongation, and quality index. These properties have been correlated with the structural parameters of the austempered ductile iron microstructure. Fracture studies have been carried out on the tensile fracture surfaces of the austempered ductile iron (ADI).

  13. Thermal and Tensile Properties of Treated and Untreated Red Balau (Shorea Dipterocarpaceae Filled LDPE Composites

    Ruth Anayimi Lafia-Araga


    Full Text Available Red balau saw dust was heat-treated at 180°C and 200°C for one hour, extrusion compounded with Low Density Polyethylene (LDPE at 20%, 40% and 60% volume fraction loadings and injection moulded. Thermal and tensile properties of the resultant composites were investigated as a function of filler loadings and treatment temperature. Increase in tensile moduli and decrease in tensile stress and strain were observed as filler loading and treatment temperature increased. Thermogravimetric analysis revealed an increase in degradation peak temperature of the composites from heat treated compared to the untreated wood composites. Differential scanning calorimetry revealed a decreasing trend in the degree of crystallinity (Xc of the matrix when heat treated wood was used as filler. However, untreated wood showed an increase in Xc with increasing wood content.

  14. Stress corrosion cracking of brass in ammonia solution


    Brass foil with a protective layer formed on one side was deflected during corrosion in an ammonia solution under various applied potentials, and then corrosion-induced stress generated at brass/dezincification layer under different potentials could be measured. At the same time, susceptibility to stress corrosion cracking(SCC) of brass in the ammonia solution under various applied potentials was measured using a single-edge notched specimen. At open-circuit potential, both corrosion-induced tensile stress and susceptibility to SCC(Iσ) had a maximum value. Both tensile stress σp and susceptibility Iσ decreased slightly under anodic polarization, but reduced steeply with the decrease in potential of cathodic polarization. At the cathodic potential of -500  mV(vs SCE), corrosion-induced stress became compressive because of copper-plating layer, correspondingly, susceptibility to SCC was zero. Therefore, the variation of SCC susceptibility with potential is consistent with that of the corrosion-induced additive stress.

  15. Ten deg off-axis tensile test for intralaminar shear characterization of fiber composites

    Chamis, C. C.; Sinclair, J. H.


    A combined theoretical and experimental investigation was conducted to assess the suitability of the 10 deg off-axis tensile test specimen for the intralaminar shear characterization of unidirectional composites. Composite mechanics, a combined-stress failure criterion, and a finite element analysis were used to determine theoretically the stress-strain variation across the specimen width and the relative stress and strain magnitudes at the 10 deg plane. Strain gages were used to measure the strain variation across the specimen width at specimen midlength and near the end tabs. Specimens from Mod-I/epoxy, T-300/epoxy, and S-glass/epoxy were used in the experimental program. It was found that the 10 deg off-axis tensile test specimen is suitable for intralaminar shear characterization and it is recommended that it should be considered as a possible standard test specimen for such a characterization.

  16. Effect of alkaline solutions on the tensile properties of glass-polyester pipes

    Putić Slaviša S.


    Full Text Available Construction materials, traditionally used in process equipment, are today successfully replaced by composite materials. Hence, many pipes are made of these materials. The subject of this study was the influence of liquids on the state of stresses and tensile strengths in the longitudinal and circumferential direction of glass-polyester pipes of a definite structure and known fabrication process. These analyses are of great importance for the use of glass-polyester pipes in the chemical industry. The tensile properties (the ultimate tensile strength and the modulus of elasticity were tested and determined for specimens cut out of the pipes; flat specimens for the tensile properties in the longitudinal direction and ring specimens for the tensile properties in the circumferential direction. First, the tension test was performed on virgin samples (without the influence of any liquid, to obtain knowledge about the original tensile properties of the material composite studied. Subsequently, the specimens were soaked in alkaline solutions: sodium hydroxide (strong alkali and ammonium hydroxide (weak alkali. These solutions were selected because of their considerable difference in pH values. The specimens and rings were left for 3, 10, 30 and 60 days in each liquid at room temperature. Then, the samples were tested on tension by the standard testing procedure. A comparison of the obtained results was made based on the pH values of the aggressive media in which the examined material had been soaked, as well as based on the original tensile properties and the number of days of treatment. Micromechanical analyses of sample breakage helped in the elucidation of the influence of the liquids on the structure of the composite pipe and enabled models and mechanisms that produced the change of strength to be proposed.

  17. Size-scaling of tensile failure stress in boron carbide

    Wereszczak, Andrew A [ORNL; Kirkland, Timothy Philip [ORNL; Strong, Kevin T [ORNL; Jadaan, Osama M. [University of Wisconsin, Platteville; Thompson, G. A. [U.S. Army Dental and Trauma Research Detachment, Greak Lakes


    Weibull strength-size-scaling in a rotary-ground, hot-pressed boron carbide is described when strength test coupons sampled effective areas from the very small (~ 0.001 square millimeters) to the very large (~ 40,000 square millimeters). Equibiaxial flexure and Hertzian testing were used for the strength testing. Characteristic strengths for several different specimen geometries are analyzed as a function of effective area. Characteristic strength was found to substantially increase with decreased effective area, and exhibited a bilinear relationship. Machining damage limited strength as measured with equibiaxial flexure testing for effective areas greater than ~ 1 mm2 and microstructural-scale flaws limited strength for effective areas less than 0.1 mm2 for the Hertzian testing. The selections of a ceramic strength to account for ballistically-induced tile deflection and to account for expanding cavity modeling are considered in context with the measured strength-size-scaling.

  18. Evaluation of the stress corrosion cracking resistance of several high strength low alloy steels

    Humphries, T. S.; Nelson, E. E.


    The stress corrosion cracking resistance was studied for high strength alloy steels 4130, 4340, for H-11 at selected strength levels, and for D6AC and HY140 at a single strength. Round tensile and C-ring type specimens were stressed up to 100 percent of their yield strengths and exposed to alternate immersion in salt water, salt spray, the atmosphere at Marshall Space Flight Center, and the seacoast at Kennedy Space Center. Under the test conditions, 4130 and 4340 steels heat treated to a tensile strength of 1240 MPa (180 ksi), H-11 and D6AC heat treated to a tensile strength of 1450 MPa (210 ksi), and HY140 (1020 MPa, 148 ksi) are resistant to stress corrosion cracking because failures were not encountered at stress levels up to 75 percent of their yield strengths. A maximum exposure period of one month for alternate immersion in salt water or salt spray and three months for seacoast is indicated for alloy steel to avoid false indications of stress corrosion cracking because of failure resulting from severe pitting.

  19. Investigation of the applicability of a tensile testing machine for measuring mucoadhesive strength.

    Dyvik, K; Graffner, C


    The applicability of a tensile testing machine (M30K, JJ Lloyd Instruments Ltd, GB) is investigated for measuring mucoadhesive strengths. A sample of an aqueous dispersion of a polymer with expected mucoadhesive properties is placed between two homemade discs of polyoxymethylene. The upper disc is mounted on a movable part of the machine while the lower disc is fixed on the stationary frame. A tensile force is submitted and the maximum detachment force at fracture and the adhesion work are estimated from the force displacement curve recorded. In some experiments, native mucous tissue of the large intestine of pigs was glued to the upper disc. Four polymers polycarbophil (Carbopol EX-55), carboxypolymethylene (Carbopol 934P), hydroxypropylmethylcellulose (Methocel K4M), and sodium alginate, are used in five different concentrations. At least three measurements are made of each polymer and concentration. Viscosity and osmolality are determined. By standardizing the time of sample equilibration and the run rate before measurement, it is possible to get good reproducibility of the tensile values. Based on the maximum nominal breaking force and the work consumed, it is concluded that the tensile strength is dependent both on the concentration and the type of polymer. The conclusions are the same independent of whether mucous pig tissue is used, or not. The same rank order in adhesive properties of the polymers is achieved as from using modified surface tensiometers.

  20. In situ geomechanics of crystalline and sedimentary rocks; Part IV, continued field testing of the modified U.S. Geological Survey 3-D borehole stress probe

    Nichols, Thomas C.


    Two modified and calibrated U.S. Geological Survey 3-D borehole probes were successfully tested in the field at a site on South Table Mountain, near Golden, Colo. The probes were installed in separate core holes at depths of 84 and 99 cm in the latite cap rock and subsequently stress relieved with overcoring techniques. The determined stresses from both probes are very low and contain both tensile and compressive components. Magnitudes range from 1196 KPa in tension to 832 KPa in compression. The principal stress orientations are in fair agreement whereas the horizontal secondary principal stress directions are in good agreement; the maximum horizontal compressive stress is oriented N. 76? W.-S. 76? E. for one probe and N. 63? W.-S. 63? E. for the second probe. The greatest determined Young's modulus of the rock is in the N. 89? E. direction, only 15? from the maximum horizontal compressive stress direction.

  1. Influence of Simulated Acid Rain Corrosion on the Uniaxial Tensile Mechanical Properties of Concrete

    Ying-zi Zhang


    Full Text Available An experimental study on the uniaxial tensile property of concrete exposed to the acid rain environment was carried out. Acid rain with pH level of 1.0 was deposed by the mixture of sulfate and nitric acid solution in the laboratory. Dumbbell-shaped concrete specimens were immersed in the simulated acid rain completely. After being exposed to the deposed mixture for a certain period, uniaxial tensile test was performed on the concrete specimens. The results indicate that elastic modulus, tensile strength, and peak strain have a slight increase at the initial corrosion stage, and with the extension of corrosion process, elastic modulus and tensile strength decrease gradually, while the peak strain still increases. It is found that the compressive strength is more sensitive than the tensile strength in aggressive environment. Based on the experimental results, an equation was proposed to describe the ascending branch of the stress-strain curve of the concrete corroded by acid rain.

  2. Tensile Fracture Behavior of Progressively-Drawn Pearlitic Steels

    Jesús Toribio


    Full Text Available In this paper a study is presented of the tensile fracture behavior of progressively-drawn pearlitic steels obtained from five different cold-drawing chains, including each drawing step from the initial hot-rolled bar (not cold-drawn at all to the final commercial product (pre-stressing steel wire. To this end, samples of the different wires were tested up to fracture by means of standard tension tests, and later, all of the fracture surfaces were analyzed by scanning electron microscopy (SEM. Micro-fracture maps (MFMs were assembled to characterize the different fractographic modes and to study their evolution with the level of cumulative plastic strain during cold drawing.

  3. Tensile Strain Hardening Behavior and Fractography of Superalloy GH39

    WANG Hui


    Full Text Available The strain hardening behaviour and fractography of superalloy GH39 was investigated by tensile test at different strain rates. Results indicate that strain hardening behaviours are different during the deformation process. True stress-strain curve obeys the Hollomon relationship partly. The strain hardening exponentn in this stage is constant in the initial plastic stage. However, the value of n increased with true strain ε increasing when true strain is between 0.014 and 0.13. A lot of deformation twinning can be found, the twins and dislocations worked together to increase the value of n. The strain hardening exponent is increased lightly with the strain rate increasing, SEM observations show that in the case of low strain rate, the fracture mode is typical ductile, but there is a tendency from ductile to brittle fracture with increasing the strain rate.

  4. Tensile mechanical response of polyethylene – clay nanocomposites.


    Full Text Available In this work we report on the microstructural and the mechanical characteristics of high density polyethylene (HDPE-clay nanocomposites, with particular attention to the creep behaviour. The samples were prepared through melt compounding, using two high-density polyethylenes with different melt flow rate (MFR, two different organo-modified clays, and changing the relative amount of a polyethylene grafted with maleic anhydride (PEgMA compatibilizer. The intercalation process is more effective as the matrix melt viscosity decreases (higher MFR, while the clay interlamellar spacing increases as the compatibilizer amount increases. The relative stiffness of the nanocomposites increases with the addition of clay, with a limited enhancement of the relative yield stress. The better intercalation obtained by the addition of the compatibilizer is not accompanied by a concurrent improvement of the tensile mechanical properties. The creep resistance is enhanced by the introduction of clay, with an appreciable dependence on both the polyethylene and the clay type.

  5. Effect of elastic and plastic tensile mechanical loading on the magnetic properties of NGO electrical steel

    Leuning, N.; Steentjes, S.; Schulte, M.; Bleck, W.; Hameyer, K.


    The magnetic properties of non-grain-oriented (NGO) electrical steels are highly susceptible to mechanical stresses, i.e., residual, external or thermal ones. For rotating electrical machines, mechanical stresses are inevitable and originate from different sources, e.g., material processing, machine manufacturing and operating conditions. The efficiency and specific losses are largely altered by different mechanical stress states. In this paper the effect of tensile stresses and plastic deformations on the magnetic properties of a 2.9 wt% Si electrical steel are studied. Particular attention is paid to the effect of magnetic anisotropy, i.e., the influence of the direction of applied mechanical stress with respect to the rolling direction. Due to mechanical stress, the induced anisotropy has to be evaluated as it is related to the stress-dependent magnetostriction constant and the grain alignment.




    Full Text Available Multilayer pressure vessel is designed to work under high-pressure condition. This paper introduces the stress analysis and the burst pressure calculation of a two-layer shrink fitted pressure vessel. In the shrink-fitting problems, considering long hollow cylinders, the plane strain hypothesis can be regarded as more natural. Generally hoops stress distribution is non-linear and sharply reduced toward the outer surface. By shrink fitting concentric shells towards the inner shells are placed in residual compression so that the initial compressive hoop stress must be relieved by internal pressure before hoop tensile stress are developed. Therefore the maximum hoop stress will be reduced, resulting more burst pressure. The analytical results of stress distribution and burst pressure is calculated and validated by ANSYS Workbench results.

  7. Monotonic tensile behavior analysis of three-dimensional needle-punched woven C/SiC composites by acoustic emission

    Peng Fang; Laifei Cheng; Litong Zhang; Jingjiang Nie


    High toughness and reliable three-dimensional needled C/SiC composites were fabricated by chemical vapor infiltration (CVI). An approach to analyze the tensile behaviors at room temperature and the damage accumulation of the composites by means of acoustic emission was researched. Also the fracture morphology was examined by S-4700 SEM after tensile tests to prove the damage mechanism. The results indicate that the cumulative energy of acoustic emission (AE) signals can be used to monitor and evaluate the damage evolution in ceramic-matrix composites. The initiation of room-temperature tensile damage in C/SiC composites occurred with the growth of micro-cracks in the matrix at the stress level about 40% of the ultimate fracture stress. The level 70% of the fracture stress could be defined as the critical damage strength.

  8. Experimental Study of Anchor Tensile Plate Cable Anchorage System in Concrete Girder of Actual Bridge%锚拉板式混凝土索梁锚固体系实桥试验研究

    石雪飞; 周军勇; 胡可; 阮欣


    tensile plate with the concrete main girder ,the stress distribution in the stay ca‐ble anchorage zone is basically identical ,but the differences of the stress distribution and the an‐chor tensile plate displacement in the connecting zone are obvious .The measured stress and dis‐placement of the anchor tensile plate exhibit good linear correlation with the applied load of the stay cable tension .The maximum stress of the measurement points is 269 MPa and the structure is still in the working state of elasticity .The measured values and the values calculated by the fi‐nite element for the stress distribution of the anchor tensile plate are agreeable .The effect of the stress dispersing and transmitting of the plate components is sound .T he measured stress distri‐bution and displacement of the anchor tensile plate in the connecting zone are agreeable with the stress distribution and displacement calculated by the finite element for the connecting way of the sliding ,but the frictional coefficients do not govern the sliding results .

  9. Relation between incremental lines and tensile strength of coronal dentin.

    Inoue, Toshiko; Saito, Makoto; Yamamoto, Masato; Nishimura, Fumio; Miyazaki, Takashi


    In one aspect, this study examined the tensile strength of coronal dentin, as a function of the location of incremental lines, in two types of teeth: human molar versus bovine incisor. In another aspect, tensile strength in coronal dentin was examined with tensile loading in two different orientations to the incremental lines: parallel versus perpendicular. There were four experimental groups in this study: HPa, human molar dentin with tensile orientation parallel to the incremental lines; HPe, human molar dentin with tensile orientation perpendicular to the incremental lines; BPa, bovine incisor dentin with tensile orientation parallel to the incremental lines; BPe, bovine incisor dentin with tensile orientation perpendicular to the incremental lines. Tensile strengths of the parallel group (HPa and BPa) were significantly higher (pincremental lines, was thus confirmed in coronal dentin. However, there were no differences in anisotropy effect between the two tooth types.

  10. Tensile Instability in a Thick Elastic Body

    Overvelde, Johannes T. B.; Dykstra, David M. J.; de Rooij, Rijk; Weaver, James; Bertoldi, Katia


    A range of instabilities can occur in soft bodies that undergo large deformation. While most of them arise under compressive forces, it has previously been shown analytically that a tensile instability can occur in an elastic block subjected to equitriaxial tension. Guided by this result, we conducted centimeter-scale experiments on thick elastomeric samples under generalized plane strain conditions and observed for the first time this elastic tensile instability. We found that equibiaxial stretching leads to the formation of a wavy pattern, as regions of the sample alternatively flatten and extend in the out-of-plane direction. Our work uncovers a new type of instability that can be triggered in elastic bodies, enlarging the design space for smart structures that harness instabilities to enhance their functionality.

  11. Maximum likely scale estimation

    Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo


    A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and/or ...

  12. 冬季覆盖地膜的拉伸试验及有限元仿真分析%Study on the Tensile Test and Analysis of Winter Mulching

    杨业龙; 叶云霞; 谢建华; 曹晓冉; 孙超伟


    Through the testing of the mechanical properties of the longitudinal , transverse and orthogonal tear tensile load and tensile elongation for the polyethylene mulching film covered in winter which thickness is 0.006mm, the mechanical constitutive properties of the mulching film were obtained .The finite element software ANSYS was used to emulating and discussing the deformation and stress strain for the mulching film when was picked up by the mulching film pole tooth , the results show that: for the mulching film in winter , the tensile strength of longitudinal is greater to the transverse and the rectangular tear;the maximum variant of the mulching film was that it was picked up on the top of the mulching film pole tooth , the maximum of the deformation and stress strain was that it was picked up at the junction of the film and the central of pole tooth .%通过对冬季覆盖厚度为0 .006 mm 的聚乙烯残地膜纵向、横向和直角撕裂拉伸负荷,以及断裂伸长率等力学性能的测试,获得了残地膜力学本构特性. 利用有限元软件 ANSYS对拾膜杆齿捡膜时地膜的变形和应力应变情况进行仿真和分析. 结果表明:冬季覆盖地膜纵向的拉伸强度大于横向的拉伸强度和直角撕裂的拉伸强度;拾膜时,杆齿端部的地膜变形最大,应力应变最大值都发生在与杆齿中部接触的地膜处.

  13. 49 CFR 230.26 - Tensile strength of shell plates.


    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tensile strength of shell plates. 230.26 Section... Appurtenances Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of steel or wrought-iron shell plates is not known, it shall be taken at 50,000 psi for steel and...

  14. In-situ tensile testing of propellant samples within SEM

    Benedetto, G.L. di; Ramshorst, M.C.J. van; Duvalois, W.; Hooijmeijer, P.A.; Heijden, A.E.D.M. van der; Klerk, W.P.C. de


    A tensile module system placed within a FEI NovaNanoSEM 650 Scanning Electron Microscope (SEM) was utilized in this work to conduct in-situ tensile testing of propellant material samples. This tensile module system allows for real-time in-situ SEM analysis of the samples to determine the failure mec

  15. Tensile and characterization properties of regenerated cellulose empty fruit bunch biocomposite films using ionic liquid

    Husseinsyah, Salmah; Zailuddin, Nur Liyana Izyan; Li, Chew Li; Mostapha @ Zakaria, Marliza


    The regenerated cellulose (RC) empty fruit bunch (EFB) biocomposite films were prepared using ionic liquid. The tensile strength and modulus of elasticity of regenerated cellulose biocomposite films achieved maximum value at 2 wt% of EFB contents while at 3 and 4 wt% of EFB the tensile strength and modulus of elasticity tend to decreased. The elongation at break tends to decreased at 2 wt% of EFB content but increased at 3 and 4 wt% of EFB contents. The crystallinity index reaches maximum at 2 wt% EFB content, followed by declination with further addition of EFB content. The morphology study illustrated that regenerated cellulose biocomposite films at 2 wt% of EFB contents exhibit a smooth surface that suggested the reinforcement was surrounded by the regenerated cellulose matrix, while at 4 wt% EFB content shows a rough morphology.

  16. Specimen type and size effects on lithium hydride tensile strength distributions

    Oakes, Jr, R E


    Weibull's two-parameter statistical-distribution function is used to account for the effects of specimen size and loading differences on strength distributions of lithium hydride. Three distinctly differing uniaxial specimen types (i.e., an elliptical-transition pure tensile specimen, an internally pressurized ring tensile, and two sizes of four-point-flexure specimens) are shown to provide different strength distributions as expected, because of their differing sizes and modes of loading. After separation of strengths into volumetric- and surface-initiated failure distributions, the Weibull characteristic strength parameters for the higher-strength tests associated with internal fracture initiations are shown to vary as predicted by the effective specimen volume Weibull relationship. Lower-strength results correlate with the effective area to much lesser degree, probably because of the limited number of surface-related failures and the different machining methods used to prepare the specimen. The strength distribution from the fourth specimen type, the predominantly equibiaxially stressed disk-flexure specimen, is well below that predicted by the two-parameter Weibull-derived effective volume or surface area relations. The two-parameter Weibull model cannot account for the increased failure probability associated with multiaxial stress fields. Derivations of effective volume and area relationships for those specimens for which none were found in the literature, the elliptical-transition tensile, the ring tensile, and the disk flexure (including the outer region), are also included.

  17. On the tensile strength of a fiberreinforced ceramic composite containing a crack-like flaw

    Budiansky, Bernard; Cui, Yingqing Lawrence


    T HE TENSILE STRENGTH of a fiber-reinforced ceramic composite containing a through-the-fiber flaw in the form of a sharp crack is studied. The strength of a brittle unreinforced ceramic containing a sharp crack of length 2 a0, subjected to uniaxial load in the direction normal to the crack plane, is given by linear elastic fracture mechanics as σ s = Km/√π a0, where km is the fracture toughness of the material. However, for a fiber-reinforced ceramic, the strength can only be determined on the basis of a full analysis of crack growth in the matrix and the failure of crack-bridging fibers. The tensile strength of a flawed ceramic material that is reinforced by fibers aligned in the direction perpendicular to the flaw surfaces is studied in this paper. Crack-bridging fibers are assumed to slip relative to the matrix when a critical interface shear stress is reached. The orthotropy of the composite produced by the presence of aligned fibers is rigorously accounted for in the analysis. The dependence of the composite tensile strength on fiber tensile strength, matrix toughness, flaw-size and frictional shear stress at the fiber-matrix interface is determined and described in terms of a universal set of non-dimensional parameters.

  18. Tensile strength of thin resin composite layers as a function of layer thickness.

    Alster, D; Feilzer, A J; De Gee, A J; Davidson, C L


    As a rule, cast restorations do not allow for free curing contraction of the resin composite luting cement. In a rigid situation, the resulting contraction stress is inversely proportional to the resin layer thickness. Adhesive technology has demonstrated, however, that thin joints may be considerably stronger than thicker ones. To investigate the effects of layer thickness and contraction stress on the tensile strength of resin composite joints, we cured cylindrical samples of a chemically initiated resin composite (Clearfil F2) in restrained conditions and subsequently loaded them in tension. The samples had a diameter of 5.35 mm and thicknesses of 50, 100, 200, 300, 400, 500, 600, and 700 microns, 1.4 mm, or 2.7 mm. None of the samples fractured due to contraction stress prior to tensile loading. Tensile strength decreased gradually from 62 +/- 2 MPa for the 50-microns layer to 31 +/- 4 MPa for the 2.7-mm layer. The failures were exclusively cohesive in resin for layers between 50 and 400 microns thick. Between 500 and 700 microns, the failures were cohesive or mixed adhesive/cohesive, while the 1.4- and 2.7-mm layers always failed in a mixed adhesive/cohesive mode. For the resin composite tested, the contraction stress did not endanger the cohesive strength. It was concluded that if adhesion to tooth structure were improved, thinner adhesive joints might enhance the clinical success of luted restorations.

  19. Assessement of tensile strength of graphites by the Iosipescu coupon test

    Luis Guilherme Borzani Manhani


    Full Text Available Polycrystalline graphites are widely used in the metallurgical, nuclear and aerospace industries. Graphites are particulated composites manufactured with a mixture of coke with pitch, and changes in relative proportions of these materials cause modifications in their mechanical properties. Uniaxial tension tests must be avoided for mechanical characterization in this kind of brittle material, due to difficulties in making the relatively long specimens and premature damages caused during testing set-up. On other types of tests, e.g. bending tests, the specimens are submitted to combined stress states (normal and transverse shear stresses. The Iosipescu shear test, is performed in a beam with two 90° opposite notches machined at the mid-length of the specimens, by applying two forces couples, so that a pure and uniform shear stress state is generated at the cross section between the two notches. When a material is isotropic and brittle, a failure at 45° in relation to the beam long axis can take place, i.e., the tensile normal stress acts parallel to the lateral surface of the notches, controls the failure and the result of the shear test is numerically equivalent to the tensile strength. This work has evaluated a graphite of the type used in rocket nozzles by the Iosipescu test and the resulted stress, ~11 MPa, was found to be equal to the tensile strength. Thus, the tensile strength can be evaluated just by a single and simple experiment, thus avoiding complicated machining of specimen and testing set-up.

  20. Maximum information photoelectron metrology

    Hockett, P; Wollenhaupt, M; Baumert, T


    Photoelectron interferograms, manifested in photoelectron angular distributions (PADs), are a high-information, coherent observable. In order to obtain the maximum information from angle-resolved photoionization experiments it is desirable to record the full, 3D, photoelectron momentum distribution. Here we apply tomographic reconstruction techniques to obtain such 3D distributions from multiphoton ionization of potassium atoms, and fully analyse the energy and angular content of the 3D data. The PADs obtained as a function of energy indicate good agreement with previous 2D data and detailed analysis [Hockett et. al., Phys. Rev. Lett. 112, 223001 (2014)] over the main spectral features, but also indicate unexpected symmetry-breaking in certain regions of momentum space, thus revealing additional continuum interferences which cannot otherwise be observed. These observations reflect the presence of additional ionization pathways and, most generally, illustrate the power of maximum information measurements of th...

  1. Low Cycle Tensile-Tensile Fatigue Life Prediction of Ceramic Matrix Composites%陶瓷基复合材料低循环拉-拉疲劳寿命预测

    孙志刚; 许仁红; 宋迎东


    采用细观力学方法建立预测纤维增强陶瓷基复合材料低循环拉一拉疲劳寿命的模型.该模型考虑初始加载到疲劳峰值应力时,基体出现裂纹,纤维/基体界面发生脱粘,部分纤维将发生断裂,并采用统计方法得到初始加载到峰值应力时的纤维失效体积分数;在后续循环过程中,考虑纤维相对基体在界面脱粘区滑移造成界面切应力下降,纤维失效模型与Evans界面磨损模型相结合,得到循环过程中纤维失效体积分数与界面切应力、循环数之间的关系;当纤维失效导致剩余强度下降,并小于疲劳峰值应力时,判断材料失效.采用剩余强度方法对陶瓷基复合材料的S-N曲线进行预测,并将预测的S-N曲线与试验数据进行对比,结果吻合较好.%A micro mechanics approach to predict low cycle tensile-tensile fatigue life of fiber reinforced ceramic matrix composites is presented. When first loading to fatigue maximum stress, matrix cracking, fiber/matrix interface de-bonding occur, and partial fibers fracture. The statistical approach is used to determine the percentage of fracture fibers. Upon cycling, fiber slips relative to matrix in the interface de-bonding region, which makes interface shear stress decreased. By combing fiber failure model and interface wear model, the relationship between the percentage of fiber failure and interface, or cycles, is determined. Residual strength of ceramic matrix composites decreases as fiber failure. When residual strength is lower than fatigue mavimnm stress, the material fails. The residual strength approach is used to predict the S-N curve of ceramic matrix composites, the S-N curve agrees well with experiment data.

  2. Impact-induced tensile waves in a kind of phase-transforming materials

    Huang, Shou-Jun


    This paper concerns the global propagation of impact-induced tensile waves in a kind of phase-transforming materials. It is well-known that the governing system of partial differential equations is hyperbolic-elliptic and the initial-boundary value problem is not well-posed at all levels of loading. By making use of fully nonlinear stress-strain curve to model this material, Dai and Kong succeeded in constructing a physical solution of the above initial-boundary value problem. For the impact of intermediate range, they assumed that $\\beta<3\\alpha$ in the stress-response function for simplicity. In this paper, we revisit the impact problem and consider the propagation of impact-induced tensile waves for all values of the parameters $\\alpha$ and $\\beta$. The physical solutions for all levels of loading are obtained completely.

  3. Tearing analysis of a new airship envelope material under uniaxial tensile load

    Wang, F. X.; Xu, W.; Chen, Y. L.; Fu, G. Y.


    This paper experimentally investigated the tearing properties of a new kind of coated woven fabrics, GQ-6, made of ultra-high molecular weight polyethylene fiber. Such material can be used for the envelope materials of a stratospheric airship. First, the uniaxial tearing tests were carried out. Effects of the stretching rate, the initial crack length, and the initial crack orientation on the material's tearing tensile strength were investigated. Experimental results showed that the initial crack length and the initial crack orientation can be represented by the equivalent initial crack length while the stretching rate has a slight influence on tearing behavior of the uniaxial tensile specimens. Then analytical studies using three methods, i.e. Griffith energy theory, the stress intensity factor theory, and Thiele's empirical theory, among which, the stress intensity factor theory gives the best correlation with the test data. Finally, a 48mm threshold of the equivalent initial crack length was recommended to the envelope material in operation.

  4. Tensile properties, collagen content, and crosslinks in connective tissues of the immature knee joint.

    Sriram V Eleswarapu

    Full Text Available BACKGROUND: The major connective tissues of the knee joint act in concert during locomotion to provide joint stability, smooth articulation, shock absorption, and distribution of mechanical stresses. These functions are largely conferred by the intrinsic material properties of the tissues, which are in turn determined by biochemical composition. A thorough understanding of the structure-function relationships of the connective tissues of the knee joint is needed to provide design parameters for efforts in tissue engineering. METHODOLOGY/PRINCIPAL FINDINGS: The objective of this study was to perform a comprehensive characterization of the tensile properties, collagen content, and pyridinoline crosslink abundance of condylar cartilage, patellar cartilage, medial and lateral menisci, cranial and caudal cruciate ligaments (analogous to anterior and posterior cruciate ligaments in humans, respectively, medial and lateral collateral ligaments, and patellar ligament from immature bovine calves. Tensile stiffness and strength were greatest in the menisci and patellar ligament, and lowest in the hyaline cartilages and cruciate ligaments; these tensile results reflected trends in collagen content. Pyridinoline crosslinks were found in every tissue despite the relative immaturity of the joints, and significant differences were observed among tissues. Notably, for the cruciate ligaments and patellar ligament, crosslink density appeared more important in determining tensile stiffness than collagen content. CONCLUSIONS/SIGNIFICANCE: To our knowledge, this study is the first to examine tensile properties, collagen content, and pyridinoline crosslink abundance in a direct head-to-head comparison among all of the major connective tissues of the knee. This is also the first study to report results for pyridinoline crosslink density that suggest its preferential role over collagen in determining tensile stiffness for certain tissues.

  5. Mechanical Characterization of Electroplated Ni Films by Micro-tensile Testing

    ZHANG Duanqin; CHU Jinkui


    Mechanical properties of structural materials are particularly important for design, performance realization and reliability analysis of microelectromechanical systems (MEMS). Furthermore,accurate database of mechanical properties at the micro scale can provide indispensable reference for establishing MEMS standard. Electroplated nickel film is one of the most favored structural materials used in MEMS, thus its mechanical properties has been studied for many years. However, the measured values show large scatter in Young's modulus of nickel film. Young's modulus and yield stress of electroplated nickel film are measured by using a micro-tensile testing instrument. The tensile load applied on the specimen is measured by a load cell with accuracy 0.25 mN directly, without additional friction. Through measuring the axial stiffness coefficient of the tensile instrument in situ, the tensile strain of the specimen is obtained by using two-serial spring model. The electroplated nickel films were fabricated from sulfamate baths, and the gauge section is 500 μm long and 10 μm wide nominally, and thickness range between 25 μm and 50 μm. The obtained Young's modulus from tensile testing is 83±6 GPa for nickel specimens electroplated at current density of 20 mA/cm~2 and it increases to 124±5 GPa as current density is decreased to 10 mA/cm~2. The phenomena are interpreted in terms of porosity of microstructure. The higher current density produced microstucture with low density and high volume fraction of pores, and the microstructure of high porosity corresponds to a lower modulus. The measured values of Young's modulus are consistent with those of calculated from the exponential empirical formula between Young's modulus and porosity. The micro-tensile testing instrument can also be used for mechanical measurement of other MEMS films.

  6. High-Strain Rate Tensile Behavior of Pure Aluminum Single and Multi-Crystalline Materials with a Tensile Split Hopkinson Bar

    Ha, Sangyul [Samsung Electro-Mechanics, Suwon (Korea, Republic of); Jang, Jin Hee; Yoon, Hyo Jun; Kim, Ki Tae [Pohang Univ. of Science and Technology, Pohang (Korea, Republic of)


    In this study, we modified the conventional tensile split Hopkinson bar(TSHB) apparatus typically used for the high strength steel to evaluate the tensile deformation behavior of soft metallic sheet materials under high strain rates. Stress-strain curves of high purity single and multi-crystalline materials were obtained using this experimental procedure. Grain morphology and initial crystallographic orientation were characterized by EBSD(Electron Backscattered Diffraction) method measured in a FE-SEM(Field emission-scanning electron microscopy). The fractured surfaces were observed by using optical microscopy. The relationship between plastic deformation of aluminum crystalline materials under high-strain rates and the initial microstructure and the crystallographic orientations has been addressed.

  7. Tensile trabeculae--myth or reality?

    Sverdlova, N


    Understanding of the functional role of the trabecular bone is very important for the analysis and computer-aided simulations of bone remodelling processes. The aspired wide clinical applications remain a remote future despite a great number of developed up-to-date approaches and theories and collected data on both material properties of the trabecular bone and its reaction to various stimuli. It is widely accepted that the mechanical loading plays the major role for the structure of the cancellous bone. The in vivo loading conditions of the cancellous bone are not known. Hence, for the computer-aided analysis and modelling of the trabecular bone specimens, simplified loading conditions are used. Also for the analysis of the cancellous bone as a part of a whole bone simplified loading conditions are assumed based on previous research without questioning its accuracy or relevance to the real in vivo conditions. In particular, the bending loading of the bone, which originates from the well-known observations made more than a century ago that have evolved in the trajectorial theory or "tensile trabeculae tradition", is often assumed to reflect the physiological loading conditions of bones. Some studies show that the bending or tensile-compressive orthogonal loading conditions for the cancellous bone may lead to plausible results. However, some other research works suggest that the presence of the tensile trabecular structures (particularly in the proximal femur) is doubtful and the bending loading conditions in bone should be treated with caution. Moreover, the loading conditions with compensated (or minimised) bending also produce results that correlate with the material distribution in the bone. The purpose of this review is to analyse some of the data and ideas available in the literature and to discuss the question of the major factors that define the shape and structure of the trabecular bone during the process of functional adaptation.

  8. Maximum Likelihood Associative Memories

    Gripon, Vincent; Rabbat, Michael


    Associative memories are structures that store data in such a way that it can later be retrieved given only a part of its content -- a sort-of error/erasure-resilience property. They are used in applications ranging from caches and memory management in CPUs to database engines. In this work we study associative memories built on the maximum likelihood principle. We derive minimum residual error rates when the data stored comes from a uniform binary source. Second, we determine the minimum amo...

  9. Maximum likely scale estimation

    Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo


    A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and....../or having different derivative orders. Although the principle is applicable to a wide variety of image models, the main focus here is on the Brownian model and its use for scale selection in natural images. Furthermore, in the examples provided, the simplifying assumption is made that the behavior...... of the measurements is completely characterized by all moments up to second order....

  10. Comparative Analysis Of The Tensile Strength Of Bamboo And Reinforcement Steel Bars As Structural Member In Building Construction



    Full Text Available Abstract This study aims at testing and comparing the tensile strength of bamboo and steel reinforcement bars as structural material for building construction. Tensile strength tests were carried out on various sizes steel and bamboo categories of reinforcement bars such as 10mm 12mm 16mm 20mm and 25mm of both high-yield and mild-yield steel reinforcement bars were both tested along with same sizes of bamboo with 10mm cross-sectional thickness. Results are presented in tables and graphs and show that the tensile strength of high-yield steel bars outstrips that of mild-yield and bamboo respectively. The study finds that the breaking force FB for 10mm HY 24.42KN tensile strength 457.13Nmm2 yield stress 379.02 Nmm2 and breaking elongation 39.67mm respectively. For 12mm HY breaking force FB 52.14 KN tensile strength 689.12 Nmm2 yield stress 551.30Nmm2 and breaking elongation 36.58mm. 16mm HY results in breaking force FB 126.67KN tensile strength 771.61Nmm2 yield stress 494.10Nmm2 and breaking elongation 70.87mm. The same factors for 20mm yields breaking force FB 163.97KN tensile strength 713.40Nmm2 yield stress 614.74Nmm2 and breaking elongation 61.57mm. While the 25mm HY produces breaking force FB 306.17KN tensile strength 792.90Nmm2 yield stress 678.46Nmm2 and breaking elongation 52.36mm respectively. Mild Steel MY 10mm yields breaking force FB 14.76KN tensile strength 290.49Nmm2 yield stress 233.17Nmm2 and breaking elongation 78.86mm. 12mm MY results in breaking force 40.35KN tensile strength 508.08Nmm2 yield stress 376.17Nmm2 and breaking elongation 84.10mm. 16mm MY yields breaking force FB 79.72KN tensile strength 508.71Nmm2 yield stress 349.10Nmm2 and breaking elongation 111.39mm respectively. For 20mm mild steel breaking force FB 83.04KN tensile strength 372.98Nmm2 yield stress 284.64Nmm2 and breaking elongation 47.40mm. While the 25mm MY steel bar results show breaking force FB 163.04KN tensile strength 701.74Nmm2 yield stress 599.77Nmm2 and

  11. Stability of germanene under tensile strain

    Kaloni, Thaneshwor P.


    The stability of germanene under biaxial tensile strain and the accompanying modifications of the electronic properties are studied by density functional theory. The phonon spectrum shows that up to 16% strain the germanene lattice is stable, where the Dirac cone shifts towards higher energy and hole-doped Dirac states are achieved. The latter is due to weakening of the Ge-Ge bonds and reduction of the s-p hybridization. Our calculated Grüneisen parameter shows a similar dependence on the strain as reported for silicene (which is different from that of graphene). © 2013 Elsevier B.V. All rights reserved.

  12. Tensile Strength of Snow using Centrifugal Technique

    Agraj Upadhyay


    Full Text Available Tensile strength of snow was determined using indigenously developed automated centrifugalmachine. Processed snow (sintered at 20 °C for 4 days samples of dia: 65 mm andheight:130 mm were tested using this machine.The experiments were conducted on sieved snowat four temperature levels of 0 °C, 3 °C,6 °C and 9 °C at density ranging from 200-460 kg/m3.Results of these experiments have been compared with the earlier  suggested models. Probabilitydistribution of snow strength on the basis of current experimental data has also been presented.

  13. Hydraulically Driven Grips For Hot Tensile Specimens

    Bird, R. Keith; Johnson, George W.


    Pair of grips for tensile and compressive test specimens operate at temperatures up to 1,500 degrees F. Grips include wedges holding specimen inside furnace, where heated to uniform temperature. Hydraulic pistons drive wedges, causing them to exert clamping force. Hydraulic pistons and hydraulic fluid remain outside furnace, at room temperature. Cooling water flows through parts of grips to reduce heat transferred to external components. Advantages over older devices for gripping specimens in high-temperature tests; no need to drill holes in specimens, maintains constant gripping force on specimens, and heated to same temperature as that of specimen without risk of heating hydraulic fluid and acuator components.

  14. Stress-magnetization properties of a silicon iron single crystal under stress

    Saito, Akihiko; Hashimoto, Masaaki; Kawaguchi, Eiji; Murashige, Shinichi


    The effects of tensile and compressive stress on magnetization changes in a Si-Fe single crystal with a (110) surface and longitudinal directions declined from the [001] direction were investigated. We found a peculiar magnetization change, namely a reversible magnetization change due to stress consisting of two peak values in a constant magnetic field. The double peak characteristic appears in samples with angle smaller than 55° for compressive stress and with angle larger than 60° for tensile stress.

  15. Parametric Analysis of Tensile Properties of Bimodal Al Alloys by Finite Element Method

    W.L. Zhanga; S. Li; S.R. Nutt


    An axisymmetrical unit cell model was used to represent a bimodal Al alloy that was composed of both nano-grained (NG) and coarse-grained (CG) aluminum. Effects of microstructural and materials parameters on tensile properties of bimodal Al alloy were investigated by finite element method (FEM). The parameters analyzed included aspect ratios of CG Al and the unit cell, volume fraction of CG Al (VFCG), and yield strength and strain hardening exponent of CG Al. Aspect ratios of CG Al and the unit cell have no significant influence on tensile stress-strain response of the bimodal Al alloy. This phenomenon derives from the similarity in elastic modulus and coefficient of thermal expansion between CG Al and NG Al. Conversely, tensile properties of bimodal Al alloy are extremely sensitive to VFCG, yield strength and strain hardening exponent of CG Al.Specifically, as VFCG increases, both yield strength and ultimate tensile strength (UTS) of the bimodal Al alloy decreases, while uniform strain of bimodal Al alloy increases. In addition, an increase in yield strength of CG Al results in an increase in both yield stress and UTS of bimodal Al alloy and a decrease in uniform strain of bimodal Al alloy. The lower capability in lowering the increase of stress concentration in NG Al due to a higher yield strength of CG Al causes the lower uniform strain of the bimodal Al alloy. When strain hardening exponent of CG Al increases, 0.2% yield stress, UT5, and uniform strain of the bimodal Al alloy increases. This can be attributed to the increased work-hardening ability of CG Al with a higher strain hardening exponent.

  16. Stress distribution in the cervical region of an upper central incisor in a 3D finite element model

    Isis Andréa Venturini Pola Poiate


    Full Text Available The aim of this study was to evaluate the stress distribution in the cervical region of a sound upper central incisor in two clinical situations, standard and maximum masticatory forces, by means of a 3D model with the highest possible level of fidelity to the anatomic dimensions. Two models with 331,887 linear tetrahedral elements that represent a sound upper central incisor with periodontal ligament, cortical and trabecular bones were loaded at 45º in relation to the tooth's long axis. All structures were considered to be homogeneous and isotropic, with the exception of the enamel (anisotropic. A standard masticatory force (100 N was simulated on one of the models, while on the other one a maximum masticatory force was simulated (235.9 N. The software used were: PATRAN for pre- and post-processing and Nastran for processing. In the cementoenamel junction area, tensile forces reached 14.7 MPa in the 100 N model, and 40.2 MPa in the 235.9 N model, exceeding the enamel's tensile strength (16.7 MPa. The fact that the stress concentration in the amelodentinal junction exceeded the enamel's tensile strength under simulated conditions of maximum masticatory force suggests the possibility of the occurrence of non-carious cervical lesions such as abfractions.

  17. Tensile properties of Inconel 718 after low temperature neutron irradiation

    Byun, T. S.; Farrell, K.


    Tensile properties of Inconel 718 (IN718) have been investigated after neutron irradiation to 0.0006-1.2 dpa at 60-100 °C in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). The alloy was exposed in solution-annealed (SA) and precipitation-hardened (PH) conditions. Before irradiation, the yield strength of PH IN718 was about 1170 MPa, which was 3.7 times higher than that of SA IN718. In the SA condition, an almost threefold increase in yield strength was found at 1.2 dpa, but the alloy retained a positive strain-hardening capability and a uniform ductility of more than 20%. Comparisons showed that the strain-hardening behavior of the SA IN718 is similar to that of a SA 316LN austenitic stainless steel. In the PH condition, the IN718 displayed no radiation-induced hardening in yield strength and significant softening in ultimate tensile strength. The strain-hardening capability of the PH IN718 decreased with dose as the radiation-induced dissolution of precipitates occurred, which resulted in the onset of plastic instability at strains less than 1% after irradiation to 0.16 or 1.2 dpa. An analysis on plastic instability indicated that the loss of uniform ductility in PH IN718 was largely due to the reduction in strain-hardening rate, while in SA IN718 and SA 316LN stainless steel it resulted primarily from the increase of yield stress.

  18. Modeling the tensile behavior of human Achilles tendon.

    Lewis, G; Shaw, K M


    Uniaxial quasi-static tensile stress, sigma versus strain, epsilon, data were obtained from 29 cadaveric Achilles tendons (donor ages: 36 to 100 years), at a strain rate of either 10 or 100%/s. These results were then used in modeling the elastic component of the tensile deformational behavior of this tissue. Two approaches were taken. In the first, it was shown that the following constitutive relation provided an excellent fit to the elastic section of the sigma-epsilon curve, sigma = C epsilon exp[D epsilon + F epsilon 2], with C, D and F being material constants, whose values for the present dataset were found to be C = 2.00 +/- 0.99, D = 0.089 +/- 0.087 and F = -0.0047 +/- 0.0095. The values of these coefficients were not statistically significantly affected by either donor age or test strain rate. In the second approach, the value of the modulus of elasticity of a filamentary polymer matrix composite material was computed as a function of various combinations of values of the modulus of elasticity of the fiber, the modulus of elasticity of the matrix, and angle of orientation of the principal material axes with respect to the reference coordinate axes (theta) for a fiber volume fraction of 0.6 and a material Poisson's ratio of 0.4. By comparing these results with the experimentally-obtained values of the tangent modulus of elasticity of the tendons (defined as the slope of the linear section of the post-toe zone in the sigma-epsilon plot), and assuming that the tendon may be idealized as a filamentary polymer matrix composite material, the suggestion is made that the winding angle of the fibers (collagen fibrils) in the tendon (taken to be equal to theta) is about 6 degrees.

  19. Microstructure and phase stress partition of Mo fiber reinforced CuZnAl composite

    Yang, Feng [State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing 102249 (China); Department of Materials Science and Engineering, China University of Petroleum-Beijing, Beijing 102249 (China); Ni, Dingrui [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Hao, Shijie [State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing 102249 (China); Department of Materials Science and Engineering, China University of Petroleum-Beijing, Beijing 102249 (China); Li, Sirui [Department of Materials Science and Engineering, China University of Petroleum-Beijing, Beijing 102249 (China); Ma, Zongyi [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Liu, Yinong [School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, WA 6009 (Australia); Feng, Chun [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Cui, Lishan, E-mail: [State Key Laboratory of Heavy Oil Processing, China University of Petroleum-Beijing, Beijing 102249 (China); Department of Materials Science and Engineering, China University of Petroleum-Beijing, Beijing 102249 (China)


    A Mo fiber reinforced CuZnAl composite was prepared by means of friction stir processing and wire drawing. Reinforcing effect of the Mo fiber and phase stress partition in the composite were investigated by means of in-situ synchrotron X-ray diffraction. The maximum elastic strain of the Mo fiber achieved was 1.8%, implying a component stress of 550 MPa on the fibers. The Mo fibers, with a volume fraction of 10%, carried 80% of stress fraction during tensile deformation. The change of modulus caused by stress-induced martensitic transformation strain resulted in redistribution of the phase stress partition between Mo fibers and CuZnAl matrix.

  20. Residual Tensile Property of Plain Woven Jute Fiber/Poly(Lactic Acid Green Composites during Thermal Cycling

    Hideaki Katogi


    Full Text Available This study investigated the residual tensile properties of plain woven jute fiber reinforced poly(lactic acid (PLA during thermal cycling. Temperature ranges of thermal cycling tests were 35–45 °C and 35–55 °C. The maximum number of cycles was 103 cycles. The quasi-static tensile tests of jute fiber, PLA, and composite were conducted after thermal cycling tests. Thermal mechanical analyses of jute fiber and PLA were conducted after thermal cycling tests. Results led to the following conclusions. For temperatures of 35–45 °C, tensile strength of composite at 103 cycles decreased 10% compared to that of composite at 0 cycles. For temperatures of 35–55 °C, tensile strength and Young’s modulus of composite at 103 cycles decreased 15% and 10%, respectively, compared to that of composite at 0 cycles. Tensile properties and the coefficient of linear expansion of PLA and jute fiber remained almost unchanged after thermal cycling tests. From observation of a fracture surface, the length of fiber pull out in the fracture surface of composite at 103 cycles was longer than that of composite at 0 cycles. Therefore, tensile properties of the composite during thermal cycling were decreased, probably because of the decrease of interfacial adhesion between the fiber and resin.

  1. Change in tensile properties of neoprene and nitrile gloves after repeated exposures to acetone and thermal decontamination.

    Gao, Pengfei; Tomasovic, Beth


    This study investigated the change in tensile properties of neoprene and nitrile gloves after repeated cycles of exposure to acetone, followed by thermal decontamination. The glove was exposed to acetone (outer surface in contact with chemical), subjected to thermal decontamination, and tested for the tensile strength and the ultimate elongation. Thermal decontamination was carried out inside an oven for 16 hours at 100 degrees C. The exposure/decontamination procedure was repeated for a maximum of 10 cycles. For neoprene versus acetone, the mean tensile strength consistently decreased after each exposure/decontamination cycle. Multiple comparisons indicated that the mean tensile strengths between the new swatches and each exposure/decontamination group were significantly different (p 0.05). The mean tensile strength for the new swatches was 37.1 MPa and the mean tensile strength after nine exposure/decontamination cycles was 36.0 MPa, with a loss less than 3%. The largest single cycle loss for ultimate elongation occurred during the first exposure/decontamination cycle for both glove materials. In our previous study, decisions regarding the effectiveness of the decontamination process were based on having no discernible change in the breakthrough time and steady-state permeation rate. The results of this study indicate that the effectiveness of the decontamination process cannot be based on permeation parameters alone but must also take into account the change in physical properties.

  2. Façade Greening: High-rise apartment building in Milan using pre-stressed concrete slab

    Sun, Wenning; Li, Mingxin; Han, Yinong; Wang, Moqi; Ansourian, Peter


    In this project, one single level of the Façade Greening was designed and modelled using finite element method in Strand7. A static analysis was performed in order to understand the deflection and the stress due to the extra loads imposed by the soil and plants. The results produced by the linear static solver are compared with the strength of the materials and the European limitations. The maximum tension stress which exceeds the tensile strength in concrete is found in the root of the cantilever balcony. An alternative design of the cantilevered balcony with pre-stressed concrete slab is modelled separately for the balcony. Decrease is found in the tension stress and the significant improvement of deflection of the balcony with pre-stressed concrete slab. The dynamic loads such as wind and earthquake did not suggest significant effect on the pre-stressed concrete slab.

  3. Determination of Tensile Strength and Fracture Toughness of Granite Using Notched Three-Point-Bend Samples

    Wang, Yusuo; Hu, Xiaozhi


    Direct tensile strength and fracture toughness of rock and concrete, important properties for many applications, are cumbersome to measure directly. In this study, granite is chosen as an example to show how the tensile strength and fracture toughness can be measured from small three-point-bend samples of a single size but with different notches. An existing fracture mechanics model has been extended to include the stable fictitious crack growth before peak loads, which is then linked to the granite grain size. Both tensile strength and fracture toughness of granite can be estimated by the maximum load measurements from those notched three-point-bend samples. In total, 72 three-point-bend granite samples with different notches have been tested, and the estimated tensile strength and fracture toughness are compared with those available in the literature. The modified fracture mechanics model is then used to predict the fracture behaviour of smaller samples of the same granite. The theoretical prediction is confirmed by the experimental results of those smaller samples. Finally, the fracture model and its relation with the American Society for Testing and Materials (ASTM) standard on fracture toughness are discussed.

  4. Tensile and tribological properties of high-crystallinity radiation crosslinked UHMWPE

    Bistolfi, Alessandro; Turell, Mary Beth; Lee, Ying-Lung; Bellare, Anuj; (BWH)


    Osteolysis due to particulate wear debris associated with ultrahigh molecular weight polyethylene (UHMWPE) components of total joint replacement prostheses has been a major factor determining their in vivo lifetime. In recent years, radiation crosslinking has been employed to decrease wear rates in PE components, especially in acetabular cups of total hip replacement prostheses. A drawback of radiation crosslinking is that it leads to a crosslinked PE (or XPE) with lower mechanical properties compared with uncrosslinked PE. In contrast, high-crystallinity PEs are known to have several mechanical properties higher than conventional PE. In this study, we hypothesized that increasing the crystallinity of radiation crosslinked and remelted XPE would result in an increase in tensile properties without compromising wear resistance. High-pressure crystallization was performed on PE and XPE and analyzed for the resulting morphological alterations using differential scanning calorimeter, low voltage scanning electron microscopy, and ultrasmall angle X-ray scattering. Uniaxial tensile tests showed that high-pressure crystallization increased the tensile modulus and yield stress in both PE and XPE, decreased the ultimate strain and ultimate stress in PE but had no significant effect on ultimate strain or ultimate stress in XPE. Multidirectional wear tests demonstrated that high-pressure crystallization decreased the wear resistance of PE but had no effect on the wear resistance of XPE. In conclusion, this study shows that high-pressure crystallization can be effectively used to increase the crystallinity and modulus of XPE without compromising its superior wear resistance compared with PE.

  5. Tensile and tribological properties of high-crystallinity radiation crosslinked UHMWPE.

    Bistolfi, Alessandro; Turell, Mary Beth; Lee, Ying-Lung; Bellare, Anuj


    Osteolysis due to particulate wear debris associated with ultrahigh molecular weight polyethylene (UHMWPE) components of total joint replacement prostheses has been a major factor determining their in vivo lifetime. In recent years, radiation crosslinking has been employed to decrease wear rates in PE components, especially in acetabular cups of total hip replacement prostheses. A drawback of radiation crosslinking is that it leads to a crosslinked PE (or XPE) with lower mechanical properties compared with uncrosslinked PE. In contrast, high-crystallinity PEs are known to have several mechanical properties higher than conventional PE. In this study, we hypothesized that increasing the crystallinity of radiation crosslinked and remelted XPE would result in an increase in tensile properties without compromising wear resistance. High-pressure crystallization was performed on PE and XPE and analyzed for the resulting morphological alterations using differential scanning calorimeter, low voltage scanning electron microscopy, and ultrasmall angle X-ray scattering. Uniaxial tensile tests showed that high-pressure crystallization increased the tensile modulus and yield stress in both PE and XPE, decreased the ultimate strain and ultimate stress in PE but had no significant effect on ultimate strain or ultimate stress in XPE. Multidirectional wear tests demonstrated that high-pressure crystallization decreased the wear resistance of PE but had no effect on the wear resistance of XPE. In conclusion, this study shows that high-pressure crystallization can be effectively used to increase the crystallinity and modulus of XPE without compromising its superior wear resistance compared with PE.

  6. Microstructure and texture evolution during tensile deformation of symmetric/asymmetric-rolled low carbon microalloyed steel

    Cai, Minghui, E-mail: [Institute for Frontier Materials (IFM), Deakin University, Geelong VIC 3217 (Australia); Wei, Xing [R & D Centre of Wuhan Iron & Steel (Group) Corp (WISCO), Wuhan 430080 (China); Rolfe, Bernard [Institute for Frontier Materials (IFM), Deakin University, Geelong VIC 3217 (Australia); Hodgson, Peter D., E-mail: [Institute for Frontier Materials (IFM), Deakin University, Geelong VIC 3217 (Australia)


    The deformation and fracture mechanisms of a low carbon microalloyed steel processed by asymmetric rolling (AsR) and symmetric rolling (SR) were compared by microstructural and texture evolutions during uniaxial tensile deformation. A realistic microstructure-based micromechanical modeling was involved as well. AsR provides more effective grain refinement and beneficial shear textures, leading to higher ductility and extraordinary strain hardening with improved yield and ultimate tensile stresses as well as promoting the occurrence of ductile fracture. This was verified and further explained by means of the different fracture modes during quasi-static uniaxial deformation, the preferred void nucleation sites and crack propagation behavior, and the change in the dislocation density based on the kernel average misorientation (KAM) distribution. The equivalent strain/stress partitioning during tensile deformation of AsR and SR specimens was modeled based on a two-dimensional (2D) representative volume element (RVE) approach. The trend of strain/stress partitioning in the ferrite matrix agrees well with the experimental results.

  7. Dynamic tensile deformation behavior of Zr-based amorphous alloy matrix composites reinforced with tungsten or tantalum fibers

    Lee, Hyungsoo; Kim, Gyeong Su; Jeon, Changwoo; Sohn, Seok Su; Lee, Sang-Bok; Lee, Sang-Kwan; Kim, Hyoung Seop; Lee, Sunghak


    Zr-based amorphous alloy matrix composites reinforced with tungsten (W) or tantalum (Ta) continuous fibers were fabricated by liquid pressing process. Their dynamic tensile properties were investigated in relation with microstructures and deformation mechanisms by using a split Hopkinson tension bar. The dynamic tensile test results indicated that the maximum strength of the W-fiber-reinforced composite (757 MPa) was much lower than the quasi-statically measured strength, whereas the Ta-fiber-reinforced composite showed very high maximum strength (2129 MPa). In the W-fiber-reinforced composite, the fracture abruptly occurred in perpendicular to the tensile direction because W fibers did not play a role in blocking cracks propagated from the amorphous matrix, thereby resulting in abrupt fracture within elastic range and consequent low tensile strength. The very high dynamic tensile strength of the Ta-fiber-reinforced composite could be explained by the presence of ductile Ta fibers in terms of mechanisms such as (1) interrupted propagation of cracks initiated in the amorphous matrix, (2) formation of lots of cracks in the amorphous matrix, and (3) sharing of loads and severe deformation (necking) of Ta fibers in cracked regions.

  8. Maximum Entropy Fundamentals

    F. Topsøe


    Full Text Available Abstract: In its modern formulation, the Maximum Entropy Principle was promoted by E.T. Jaynes, starting in the mid-fifties. The principle dictates that one should look for a distribution, consistent with available information, which maximizes the entropy. However, this principle focuses only on distributions and it appears advantageous to bring information theoretical thinking more prominently into play by also focusing on the "observer" and on coding. This view was brought forward by the second named author in the late seventies and is the view we will follow-up on here. It leads to the consideration of a certain game, the Code Length Game and, via standard game theoretical thinking, to a principle of Game Theoretical Equilibrium. This principle is more basic than the Maximum Entropy Principle in the sense that the search for one type of optimal strategies in the Code Length Game translates directly into the search for distributions with maximum entropy. In the present paper we offer a self-contained and comprehensive treatment of fundamentals of both principles mentioned, based on a study of the Code Length Game. Though new concepts and results are presented, the reading should be instructional and accessible to a rather wide audience, at least if certain mathematical details are left aside at a rst reading. The most frequently studied instance of entropy maximization pertains to the Mean Energy Model which involves a moment constraint related to a given function, here taken to represent "energy". This type of application is very well known from the literature with hundreds of applications pertaining to several different elds and will also here serve as important illustration of the theory. But our approach reaches further, especially regarding the study of continuity properties of the entropy function, and this leads to new results which allow a discussion of models with so-called entropy loss. These results have tempted us to speculate over

  9. Study of the theoretical tensile strength of Fe by a first-principles computational tensile test

    Liu Yue-Lin; Zhang Ying; Hong Rong-Jie; Lu Guang-Hong


    This paper employs a first-principles total-energy method to investigate the theoretical tensile strengths of bcc and fcc Fe systemically. It indicates that the theoretical tensile strengths are shown to be 12.4, 32.7, 27.5 Gpa for bcc Fe, and 48.1, 34.6, 51.2 Gpa for fcc Fe in the [001], [110] and [111] directions, respectively. For bec Fe, the [001] direction is shown to be the weakest direction due to the occurrence of a phase transition from ferromagnetic bcc Fe to high spin ferromagnetic fcc Fe. For fcc Fe, the [110] direction is the weakest direction duc to the formation of an instable saddle-point 'bct structure' in the tensile process. Furthermore, it demonstrates that a magnetic instability will occur under a tensile strain of 14%, characterized by the transition of ferromagnetic bcc Fe to paramagnetic fcc Fe. The results provide a good reference to understand the intrinsic mechanical properties of Fe as a potential structural material in the nuclear fusion Tokamak.

  10. Optimization of tensile strain-hardening cementhious composites for tensile strain capacity

    Shionaga, R.; Pansuk, W.; Grunewald, S.; den Uijl, J.A.; Walraven, J.C.


    The synergistic action of a cementitious matrix and fibres can result in strain hardening in tension. The accompanied tensile strain capacity can be an important design parameter for strain-hardening cementitious composites in order to prevent the localization in a single crack and to assure that th

  11. Regularized maximum correntropy machine

    Wang, Jim Jing-Yan


    In this paper we investigate the usage of regularized correntropy framework for learning of classifiers from noisy labels. The class label predictors learned by minimizing transitional loss functions are sensitive to the noisy and outlying labels of training samples, because the transitional loss functions are equally applied to all the samples. To solve this problem, we propose to learn the class label predictors by maximizing the correntropy between the predicted labels and the true labels of the training samples, under the regularized Maximum Correntropy Criteria (MCC) framework. Moreover, we regularize the predictor parameter to control the complexity of the predictor. The learning problem is formulated by an objective function considering the parameter regularization and MCC simultaneously. By optimizing the objective function alternately, we develop a novel predictor learning algorithm. The experiments on two challenging pattern classification tasks show that it significantly outperforms the machines with transitional loss functions.

  12. Effect of parameters on local stress field in single-lap bolted joints with the interference fit

    Jiefeng Jiang


    Full Text Available From the interference fit bolt installation to tensile loading stage in single-lap joint with a hi-lock bolt, the stress and strain fields were studied experimentally and numerically. A three-dimensional finite element model was generated to simulate the experimental setup, which was validated using the experimental data. The fatigue behavior of the bolted joint is influenced by the local stress fields on the faying surface near the holes in single-lap joints. Therefore, with the aim to improve design awareness, the effects of the parameters on the local stress fields were investigated by means of finite element simulation. With an increase in the interference fit size, the occurred position of the maximum stress values on the upper plate faying surface moves away from the hole edge gradually. As the clamping force or friction coefficient increases, the position of larger stress area is changed to the side of bearing load from the transverse direction. The lap geometry of the bolted joint as well as the amplitude of tensile load has apparent impact on the maximum stress value.

  13. Effects of mechanical tensile properties of plastic film on plastic recycling method%农田地膜拉伸性能变化对缠绕式回收的影响

    张佳喜; 王学农; 张丽; 喻晨; 蒋永新; 张海春; 刘旋峰; 乔园园; 王祥金


    field experiments. The series tests were conducted in Da West village, YuLi County in Korla, Xinjiang from March to October in 2014, including the test of tensile properties of plastic film changes in different thickness, time and direction by 0.01 mm plastic film enwinding recycling. The methods were as follows: Firstly, each sampling point, which are not very far with previous sampling point, were carried on hard, dry and flat land, and taken complete plastic film without damage. The sampling work should be conducted on the large space line, and the sampling point be as close as to the plants. Four plastic films with different thickness were selected with the width and length were 600 mm and 200 mm respectively. The tensile properties of plastic films were tested with CMT6000 electronic universal testing machine. Secondly, three-dimensional modeling and motion analysis were completed for the machine of retrieving by solid works software. According to the measure of maximum tensile force with payback time, the tensile force was contrasted with the sum of ground and slope in wrapping recovery. The result showed that the maximum tensile force was less than the twine. Finally, the recycling test was carried out with wrapping in 0.01 mm film, but the film fractured from time to time. The wrapping recovery could not meet the demand of 0.001 mm film. The results of field experiments showed that the tensile strength of used plastic film had dropped obviously for the wind and ultraviolet irradiation after 30 to 60 days laying the plastic film. The maximum tensile stress of 0.01 mm plastic film was 1.52 N, which was close to the plants and 1.305 N, which was far from the plants; and the stress was 1.4 times and 1.22 times of 0.008 mm plastic film, respectively. The maximum tensile strength of mulch film on the longitudinal direction was generally higher about 1/3 than the transverse direction of the mulch film. So the recycling aparts should be along the direction of laying the

  14. Influence of thermo-mechanical treatment on the tensile properties of a modified 14Cr–15Ni stainless steel

    Vijayanand, V.D., E-mail:; Laha, K.; Parameswaran, P.; Nandagopal, M.; Panneer Selvi, S.; Mathew, M.D.


    The titanium modified 14Cr–15Ni austenitic stainless steel is used as clad and wrapper material for fast breeder nuclear reactor. Thermo-mechanical treatments consisting of solution annealing at two different temperatures of 1273 and 1373 K followed by cold-work and thermal ageing have been imparted to the steel to tailor its microstructure for enhancing strength. Tensile tests have been carried out on the thermo-mechanically treated steel at nominal strain rate of 1.6 × 10{sup −4} s{sup −1} over a temperature range of 298–1073 K. The yield stress and the ultimate tensile strength of the steel increased with increase in solution treatment temperature and this has been attributed to the fine and higher density of Ti(C,N) precipitate. Tensile flow behaviour of the steel has been analysed using Ludwigson and Voce constitutive equations. The steel heat treated at higher solution temperature exhibited earlier onset of cross slip during tensile deformation. The rate of recovery at higher test temperatures was also influenced by variations in solution heat treatment temperature. In addition, dynamic recrystallization during tensile deformation at higher temperatures was profound for steel solution heat-treated at lower temperature. The differences in flow behaviour and softening mechanisms during tensile testing of the steel after different heat treated conditions have been attributed to the nature of Ti(C,N) precipitation.

  15. Tensile and Bending Properties of Surface Strengthened Sliced Wood Sheets%表面强化刨切薄板拉伸、弯曲性能



    Sliced wood sheets of Populus ussuriensis were dipped in water under normal temperature until water-saturated, then were compressed perpendicular to grain without heat softening pretreatment. Tensile and bending properties of the wood sheets after hot compression and fixation for 1 ~24 h under 160 or 180 degrees C were analyzed before and after compression in order to probe the feasibility of this strengthening method of wood sheets. Results show that the tensile strength and tensile elastic modulus of the wood are greatly improved compared to the uncompressed strengthened material. The bending elastic modulus decreases with increasing heat treatment duration. The bending strength and fracture stress are both substantially reduced compared to the uncompressed strengthened material. The average strain at maximum stress and the average strain at fracture stress both decrease with increasing heat treatment duration.%以黑龙江产大青杨刨切薄板为研究对象,用常温水浸泡至饱水状态,不经热软化预处理即进行横纹压缩强化,通过160、180℃高温定型处理1~24 h,分析横纹压缩强化前、后木材的拉伸、弯曲性能的变化,探讨此方法强化木材薄板的可行性和有待改进、完善之处.结果表明:与未压缩强化素材相比,木材的拉伸强度和拉伸弹性模量均有较大幅度提高;弯曲弹性模量随着热处理时间的增加而下降;弯曲强度和断裂应力有所降低;最大应力时应变平均值、断裂应力时应变平均值都随着热处理时间的增加而下降.

  16. Effect of Taper on Stress Distribution of All Ceramic Fixed Partial Dentures: a 3D-FEA Study

    F. Gerami-Panah


    Full Text Available Statement of Problem: Mechanical failure of ceramic materials is controlled by brittle fracture, mostly occurred in tension. In 3-unit all-ceramic FPDs the connector area is considered to be at fracture risk because of tensile stress concentrations.Purpose: The aim of this FE analysis was to evaluate the effect of taper on stress distribution in all-ceramic FPDs.Materials and Methods: In this experimental study two 3-D finite element models of thee-unit IPS-Empress 2 FPDs replacing mandible second premolar were created by means of finite element software. The digital images were obtained from CT scan of human skull. Abutment was reduced with 12 and 22 degrees of taper. The cement layer,PDL, cancellous bone and cortical bone were also modeled. Frameworks of core material were fabricated. A static load of 100 N was applied at mid pontic area.Resolved stresses were calculated according to the Von Mises criterion and principal stresses.Results: In both models stresses were concentrated at the connectors. The maximum stresses were lower in the model with larger taper. The maximum Von Mises stress was recorded at the connector region of the premolar and the pontic. In model with larger taper the patterns of stresses were also more distributed and less concentrated.Conclusion: The highest Von Mises and principal stress were recorded at the connectors. Tensile stresses developed at the gingival connector of premolar and pontic was higher than molar. The stress level in model with 22-degree taper was lower compare to 12-degree and the stress pattern was more distributed, lowered the risk ofconcentrations.

  17. Stress Analysis of ZnO Film with a GaN Buffer Layer on Sapphire Substrate

    CUI Jun-Peng; WANG Xiao-Feng; DUAN Yao; HE Jin-Xiao; ZENG Yi-Ping


    A 5.35-μm-thick ZnO film is grown by chemical vapour deposition technique on a sapphire (0001) substrate with a GaN buffer layer. The surface of the ZnO film is smooth and shows many hexagonal features. The full width at half maximum of ZnO (0002) w-rocking curve is 161 arcsec, corresponding to a high crystal quality of the ZnO film. From the result of x-ray diffraction θ - 2θ scanning, the stress status in ZnO film is tensile, which is supported by Raman scattering measurement. The reason of the tensile stress in the ZnO film is analysed in detail. The lattice mismatch and thermal mismatch are excluded and the reason is attributed to the coalescence of grains or islands during the growth of the ZnO film.

  18. Validatin of miniaturised tensile testing on DMLS TI6AL4V (ELI specimens

    Van Zyl, Ian


    Full Text Available Direct metal laser sintering (DMLS is a relatively new technology that is developing rapidly. Since DMLS material is created by melting/solidifying tracks and layers from powder, even building geometry can influence the mechanical properties. To certify a material, the testing specimens must be designed and manufactured according to the appropriate standards. Miniaturised tensile DMLS samples could be a good alternative for express quality control, and could reduce the cost of DMLS-specific testing. In this study, as-built and stress-relieved miniaturised tensile DMLS Ti6Al4V (ELI specimens with different surface qualities were investigated. The fracture surfaces and mechanical properties of the mini-tensile specimens were analysed and compared with standard full-sized specimens also manufactured by DMLS. The obtained data showed the applicability of mini-tensile tests for the express analysis of DMLS objects if a correction factor is applied for the calculation of the load-bearing cross-section of the specimen.

  19. Development of Yield and Tensile Strength Design Curves for Alloy 617

    Nancy Lybeck; T. -L. Sham


    The U.S. Department of Energy Very High Temperature Reactor Program is acquiring data in preparation for developing an Alloy 617 Code Case for inclusion in the nuclear section of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code. A draft code case was previously developed, but effort was suspended before acceptance by ASME. As part of the draft code case effort, a database was compiled of yield and tensile strength data from tests performed in air. Yield strength and tensile strength at temperature are used to set time independent allowable stress for construction materials in B&PV Code, Section III, Subsection NH. The yield and tensile strength data used for the draft code case has been augmented with additional data generated by Idaho National Laboratory and Oak Ridge National Laboratory in the U.S. and CEA in France. The standard ASME Section II procedure for generating yield and tensile strength at temperature is presented, along with alternate methods that accommodate the change in temperature trends seen at high temperatures, resulting in a more consistent design margin over the temperature range of interest.

  20. The MDI-Mediated Lateral Crosslinking of Polyurethane Copolymer and the Impact on Tensile Properties and Shape Memory Effect

    Chung, Yong Chan; Chung, Hyang Mi [The University of Suwon, Hwasung (Korea, Republic of); Choi, Jae Won; Chun, Byoung Chul [Inje University, Gimhae (Korea, Republic of)


    The maximum stress and strain at break remained high and stable after MDI-mediated crosslinking. Similarly, shape recovery and shape retention tests also showed excellent and reproducible results. The MDI-mediated crosslinking was responsible for the interesting tensile and shape memory results. Therefore, it was demonstrated in this investigation that the allophanate type crosslinking, unlike previous misleading information, was possible under the mild reaction conditions. Polyurethane (PU) has long been investigated due to its excellent mechanical properties, shape memory effect, and biocompatibility, and was grafted with pendant functional groups to tailor the polymer characteristics without affecting their basic structure. Actually, polyethyleneglycol has been grafted to polyurethane to improve biocompatibility in biomedical applications, and low temperature flexibility could be improved by the pendant naphthol group grafted to PU. In the field of shape memory polyurethane, mechanical and shape memory properties could be improved by terminal crosslinking with glycerol, pentaerythritol, and dextrin. Alternatively, a flexible crosslinking method was devised to demonstrate both high mechanical strength and shape recovery.

  1. Effect of Sett and Construction on Uniaxial Tensile

    Prabir Kumar Banerjee, Ph.D.


    Full Text Available The tensile behavior of woven fabrics is known to be affected by its sett and construction. This influence, when clearly understood, would make engineering of fabrics for tensile properties easier. Hence, this work is aimed at understanding the interdependence between the sett, construction and tensile behavior of woven fabrics. Experiments have been conducted to study the effect of number of load bearing and interlacing yarns, the spacing between them and their interlacement pattern on the tensile behavior of the fabric, typically characterized by the percent yarn strength utilization in the fabric. The results reveal that the factors mentioned above along with the crimp of the constituent yarns and their interchange during the tensile deformation process, influence the tensile properties of the fabric. It is also observed that there is a significant influence of the distribution of interlacement.

  2. Evaluating Freeze-Thaw Deterioration with Tensile Strength

    Komar, A. J. K.; Boyd, A. J.


    Freeze-thaw damage is one of the leading contributors to infrastructure deterioration in temperate northern climates. Deterioration caused by freeze-thaw cycling is primarily induced by hydraulic pressures within the hydrated cement paste matrix that cause tensile cracking. Such damage should, therefore, be more effectively detected with tensile testing. This work presents the detection and evaluation of ongoing freeze-thaw (F/T) damage in plain concrete cylinders using the pressure tensile strength test, as it compares to compressive strength evaluation. Pressure tension test results exhibited significantly higher levels of deterioration compared to compression testing, with the samples losing up to 90% of their undamaged tensile capacity. Moreover, it was shown that tensile strength testing is far more sensitive to freeze-thaw deterioration, evidenced by a significant drop in the tensile to compressive strength ratio to below 5%.

  3. Elastic interaction between twins during tensile deformation of austenitic stainless steel

    Juul, Nicolai Ytterdal; Winther, Grethe; Dale, Darren


    In austenite, the twin boundary normal is a common elastically stiff direction shared by the two twins, which may induce special interactions. By means of three-dimensional X-ray diffraction this elastic interaction has been analysed and compared to grains separated by conventional grain boundaries....... However, the components of the Type II stress normal to the twin boundary plane exhibit the same large variations as for the grain boundaries. Elastic grain interactions are therefore complex and must involve the entire set of neighbouring grains. The elastic-regime stress along the tensile direction...

  4. Tensile and fatigue behaviour of self-piercing rivets of CFRP to aluminium for automotive application

    Kang, J.; Rao, H.; Zhang, R.; Avery, K.; Su, X.


    In this study, the tensile and fatigue behaviour of self-piercing rivets (SPRs) in carbon fibre reinforced plastic (CFRP) to aluminium 6111 T82 alloys were evaluated. An average maximum lap-shear tensile load capacity of 3858 N was achieved, which is comparable to metal-to-metal SPR lap-shear joints. The CFRP-Al SPRs failed in lap-shear tension due to pull-out of the rivet head from the CFRP upper sheet. The CFRP-Al SPR lap- shear specimens exhibited superior fatigue life compared to previously studied aluminium-to- aluminium SPR lap-shear joints. The SPR lap-shear joints under fatigue loads failed predominantly due to kinked crack growth along the width of the bottom aluminium sheet. The fatigue cracks initiated in the plastically deformed region of the aluminium sheet close to the rivet shank in the rivet-sheet interlock region. Scatter in fatigue life and failure modes was observed in SPR lap-shear specimens tested close to maximum tensile load.

  5. Equalized near maximum likelihood detector


    This paper presents new detector that is used to mitigate intersymbol interference introduced by bandlimited channels. This detector is named equalized near maximum likelihood detector which combines nonlinear equalizer and near maximum likelihood detector. Simulation results show that the performance of equalized near maximum likelihood detector is better than the performance of nonlinear equalizer but worse than near maximum likelihood detector.

  6. Effect of Sett and Construction on Uniaxial Tensile

    Prabir Kumar Banerjee, Ph.D.; Swapna Mishra; Thiyagarajan Ramkumar


    The tensile behavior of woven fabrics is known to be affected by its sett and construction. This influence, when clearly understood, would make engineering of fabrics for tensile properties easier. Hence, this work is aimed at understanding the interdependence between the sett, construction and tensile behavior of woven fabrics. Experiments have been conducted to study the effect of number of load bearing and interlacing yarns, the spacing between them and their interlacement pattern on the t...

  7. Generalized Maximum Entropy

    Cheeseman, Peter; Stutz, John


    A long standing mystery in using Maximum Entropy (MaxEnt) is how to deal with constraints whose values are uncertain. This situation arises when constraint values are estimated from data, because of finite sample sizes. One approach to this problem, advocated by E.T. Jaynes [1], is to ignore this uncertainty, and treat the empirically observed values as exact. We refer to this as the classic MaxEnt approach. Classic MaxEnt gives point probabilities (subject to the given constraints), rather than probability densities. We develop an alternative approach that assumes that the uncertain constraint values are represented by a probability density {e.g: a Gaussian), and this uncertainty yields a MaxEnt posterior probability density. That is, the classic MaxEnt point probabilities are regarded as a multidimensional function of the given constraint values, and uncertainty on these values is transmitted through the MaxEnt function to give uncertainty over the MaXEnt probabilities. We illustrate this approach by explicitly calculating the generalized MaxEnt density for a simple but common case, then show how this can be extended numerically to the general case. This paper expands the generalized MaxEnt concept introduced in a previous paper [3].

  8. On the tensile strength of insect swarms

    Ni, Rui; Ouellette, Nicholas T.


    Collective animal groups are often described by the macroscopic patterns they form. Such global patterns, however, convey limited information about the nature of the aggregation as a whole. Here, we take a different approach, drawing on ideas from materials testing to probe the macroscopic mechanical properties of mating swarms of the non-biting midge Chironomus riparius. By manipulating ground-based visual features that tend to position the swarms in space, we apply an effective tensile load to the swarms, and show that we can quasi-statically pull single swarms apart into multiple daughter swarms. Our results suggest that swarms surprisingly have macroscopic mechanical properties similar to solids, including a finite Young’s modulus and yield strength, and that they do not flow like viscous fluids.

  9. Tensile Behaviour of Spun Yarns under Static State

    B. R. Das


    Full Text Available The tensile properties of spun yarn are accepted as one of the most important parameters for assessment of yarn quality. The tensile properties decide the performance of post spinning operations; warping, weaving and knitting and the properties of the final textile structure; hence its accurate technical evaluation carries much importance in industrial applications. There is no doubt that all the studies related to tensile behaviour of spun yarns are invaluable both in theory and practice. In this article, a critical review of the theoretical and practical aspect of static tensile behaviour of staple yarns has been discussed.

  10. Cervical Rotatory Manipulation Decreases Uniaxial Tensile Properties of Rabbit Atherosclerotic Internal Carotid Artery

    Qi, Ji; Zhang, Lei; Chen, Chao; Mondal, Shubhro; Ping, Kaike; Chen, Yili


    Objective. To investigate the effects of one of the Chinese massage therapies, cervical rotatory manipulation (CRM), on uniaxial tensile properties of rabbit atherosclerotic internal carotid artery (ICA). Methods. 40 male purebred New Zealand white rabbits were randomly divided into CRM-Model group, Non-CRM-Model group, CRM-Normal group, and Non-CRM-Normal group. After modeling (atherosclerotic model) and intervention (CRM or Non-CRM), uniaxial tensile tests were performed on the ICAs to assess the differences in tensile mechanical properties between the four groups. Results. Both CRM and modeling were the main effects affecting physiological elastic modulus (PEM) of ICA. PEM in CRM-Model group was 1.81 times as much as Non-CRM-Model group, while the value in CRM-Model group was 1.34 times as much as CRM-Normal group. Maximum elastic modulus in CRM-Model group was 1.80 times as much as CRM-Normal group. Max strains in CRM-Model group and Non-CRM-Model group were 30.98% and 28.71% lower than CRM-Normal group and Non-CRM-Normal group, respectively. However, whether treated with CRM or not, the uniaxial tensile properties of healthy ICAs were not statistically different. Conclusion. CRM may decrease the uniaxial tensile properties of rabbit arteriosclerotic ICA, but with no effect on normal group. The study will aid in the meaningful explanation of the controversy about the harmfulness of CRM and the suitable population of CRM. PMID:28303160

  11. Fracture and Tensile Properties of Polyvinyl Alcohol Fiber Reinforced Cementitous Composites

    XU Shilang; GAO Shuling


    Experiments were carried out to design polyvinyl alcohol(PVA)fiber reinforced cementitous composites(PVA-FRCCs)holding high ductility and energy consumption ability.Besides,the properties of each ingredients in composites,mixing method and technology for fresh mixture were described in detail.Then,the pseudo-strain-hardening(PSH)behavior was investigated in uniaxial tension test.As a result,them maximum ultimate tensile strain can reach 0.7 percent.On the other hand,the single edge notch(SEN)thin sheet specimens were employed to gain the normal tensile load via crack mouth opening displacement(CMOD)curves,which can show obvious PSH behavior.In addition,the curves can be divided into four zones whose fracture toughness calculation methods were discussed.The wedge splitting(WS)test method can be applied to discuss the fracture toughness.Moreover,fracture energy of SEN and WS specimens were both approximately evaluated.

  12. Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

    Lee, Jinwoo; Kim, Se-Jong; Lee, Myoung-Gyu; Song, Jung Han; Choi, Seogou; Han, Heung Nam; Kim, Daeyong


    The uniaxial tensile and compressive stress-strain responses of AZ31B magnesium alloy sheet under pulsed electric current are reported. Tension and compression tests with pulsed electric current showed that flow stresses dropped instantaneously when the electric pulses were applied. Thermo-mechanical-electrical finite element analyses were also performed to investigate the effects of Joule heating and electro-plasticity on the flow responses of AZ31B sheets under electric-pulsed tension and compression tests. The proposed finite element simulations could reproduce the measured uniaxial tensile and compressive stress-strain curves under pulsed electric currents, when the temperature-dependent flow stress hardening model and thermal properties of AZ31B sheet were properly described in the simulations. In particular, the simulation results that fit best with experimental results showed that almost 100 pct of the electric current was subject to transform into Joule heating during electrically assisted tensile and compressive tests.

  13. In-situ scanning electron microscopy (sem) observations of the tensile and tensile-creep deformation of Titanium-8Aluminum-1mo-1v (wt.%) alloy

    Ghosh Dastidar, Indraroop

    Titanium (Ti) and titanium alloys (Ti alloys) are attractive for structural applications, such as in the aerospace and automotive industries due to their high specific strength, excellent corrosion resistance and good ability to withstand elevated temperatures. To develop Ti alloys with better mechanical properties, it is necessary to comprehend the deformation behavior of available Ti alloys. Previous studies performed by another graduate student, Dr. Hongmei Li, involved investigation of the deformation behavior of commercially pure (CP) Ti, Ti-5Al-2.5Sn (wt.%), Ti-3Al-2.5V (wt.%) and Ti-6Al-4V (wt.%) alloys. The current thesis focused on investigating the deformation behavior of Ti-8Al-1Mo-1V (wt.%). In-situ tensile and tensile-creep experiments were performed at temperatures ranging from room temperature (RT) to 650OC inside a scanning electron microscope (SEM), which allowed for the observation of the surface deformation evolution. Electron Back Scattered Diffraction (EBSD) was used to identify the distribution of the active deformation systems. In this thesis efforts were made to characterize the various deformation modes of the Ti-8Al-1Mo-1V (wt.%) alloy as a function of the testing conditions (stress and temperature). It was observed that prismatic slip made up the majority of the observed slip systems during the RT tensile deformation, while basal and prismatic slip were almost equally active during the 455OC tensile deformation. Grain boundary ledges were observed during the elevated temperature tensile-creep deformation and from this observation it was suggested that grain boundary sliding was an active deformation mode. This work also involved estimating the Critical Resolved Shear Stress (CRSS) ratios of the alpha-phase deformation modes. The CRSS ratios were compared with the CRSS ratios of CP Ti and other Ti alloys. Overall, this work was intended to add more data to the scientific literature of Ti alloys in order to better comprehend their

  14. Effects of p38MAPK signaling pathway on cyclic tensile stress-induced fibroblast apoptosis%周期性张应力诱导成纤维细胞凋亡中p38MAPK信号通路的作用

    仇静; 张广耘; 田臻; 张月; 于江波; 袁晓


    BACKGROUND: When the teeth affected abnormal biting force, tooth absorption and periodontium would be greatly damaged. OBJECTIVE: To study whether periodontal membrane fibroblast affected apoptosis following cyclic tensile stress stimulation and whether p38MAPK signaling pathway participated in apoptosis. METHODS: Fibroblasts at passages from 4 to 7 were randomly assigned to control, loading and SB203580 groups after synchronization. In the loading and SB203580 groups, 12% strain was applied at a loading frequency of 6 cycles per minute, i.e. 5 seconds for tension and 5 seconds for relaxation. In the SB203580 group, cells were treated with 20 mmol/L p38MAPK inhibitor SB203580 at 1 hour before loading. At 6, 12 and 24 hours after loading, cells from each group were harvested, and cell apoptosis was detected using a flow cytometry. Expression of bax mRNA was determined using reverse transcription-polymerase chain reaction. RESULTS AND CONCLUSION: Compared with the control group, apoptotic rate of fibroblasts and bax mRNA expression were increased after loading (P < 0.05), and enhanced over time, and peaked at 12 hour following loading, and then decreased gradually. Compared with the loading group, cell apoptosis was reduced at corresponding time points in the SB203580 group (P < 0.05), and bax mRNA expression was diminished. These results indicated that cells affected apoptosis after mechanics stimulation, and mitogen activated protein kinase p38MAPK signaling pathway participates in the process of apoptosis.%背景:当牙齿受异常咬合力时会导致牙体吸收、牙周组织的大量破坏.目的:研究牙周膜成纤维细胞在受到周期性张应力刺激后是否发生凋亡及p38MAPK信号通路是否参与该凋亡过程.方法:取4~7代成纤维细胞,同步化后随机分为对照组、加力组和SB203580组.加力组和SB203580组细胞加载力值为12%表面应变率,加力频率为6个循环/min,即5 s拉伸,5 s松弛.SB203580

  15. Residual stress measurement on propellant tank of 2219 aluminum alloy and study on its weak spot

    Huang, Chaoqun; Li, Huan; Li, Jianxiong; Luo, Chuanguang; Ni, Yanbing [Tianjin University, Tianjin (China)


    This paper presented residual stress measurement on two circumferential Variable polarity plasma arc welding (VPPAW) joints and one circular closed Friction stir welding (FSW) joint on the propellant tank of 2219 aluminum alloy using the indentation strain-gauge method. Quite large tensile residual stresses were attached to the center and inner areas of the circular closed FSW joint. There were very large tensile stresses in some points of the two circumferential VPPAW joints, among these points, the maximum value was +253 MPa, which was about 63 % of the yield strength of 410 MPa measured in the base material. In addition, the peak of compressive residual stress was about -160 MPa. Above all, there were two typical peaks of residual stress in the circumferential VPPAW joints, one was located in the middle part while the other one was near the start/end position of the joints. Combining the result of residual stress measurement with the characteristics of the tank structure, it can be concluded that circular closed FSW joint around the flange was a weak spot on the propellant tank. And the most vulnerable point on the circular closed FSW joint has also been found.

  16. Finite Element Modelling for Tensile Behaviour of Thermally Bonded Nonwoven Fabric

    Gao Xiaoping


    Full Text Available A nonwoven fabric has been widely used in geotextile engineering in recent years; its tensile strength is an important behaviour. Since the fibre distributions in nonwoven fabrics are random and discontinuous, the unit-cell model of a nonwoven fabric cannot be developed to simulate its tensile behaviour. This article presents our research on using finite element method (FEM to study the tensile behaviour of a nonwoven fabric in macro-scale based on the classical laminate composite theory. The laminate orientation was considered with orientation distribution function of fibres, which has been obtained by analysing the data acquired from scanning electron microscopy with Hough Transform. The FE model of a nonwoven fabric was developed using ABAQUS software; the required engineering constants of a nonwoven fabric were obtained from experimental data. Finally, the nonwoven specimens were stretched along with machine direction and cross direction. The experimental stress-strain curves were compared with the results of FE simulations. The approximate agreement proves the validity of an FE model, which could be used to precisely simulate the stress relaxation, strain creep, bending and shear property of a nonwoven fabric.

  17. Scale effects on the transverse tensile strength of graphite epoxy composites

    Obrien, T. Kevin; Salpekar, Satish A.


    The influence of material volume on the transverse tensile strength of AS4/3501-6 graphite epoxy composites was investigated. Tensile tests of 90 degree laminates with 3 different widths and 5 different thicknesses were conducted. A finite element analysis was performed to determine the influence of the grip on the stress distribution in the coupons and explain the tendency for the distribution of failure locations to be skewed toward the grip. Specimens were instrumented with strain gages and extensometers to insure good alignment and to measure failure strains. Data indicated that matrix dominated strength properties varied with the volume of material that was stressed, with the strength decreasing as volume increased. Transverse strength data were used in a volumetric scaling law based on Weibull statistics to predict the strength of 90 degree laminates loaded in three point bending. Comparisons were also made between transverse strength measurements and out-of-plane interlaminar tensile strength measurements from curved beam bending tests. The significance of observed scale effects on the use of tests for material screening, quality assurance, and design allowables is discussed.

  18. Dynamic tensile behavior of AZ31B magnesium alloy at ultra-high strain rates

    Geng Changjian


    Full Text Available The samples having {0001} parallel to extruding direction (ED present a typical true stress–true strain curve with concave-down shape under tension at low strain rate. Ultra-rapid tensile tests were conducted at room temperature on a textured AZ31B magnesium alloy. The dynamic tensile behavior was investigated. The results show that at ultra-high strain rates of 1.93 × 102 s−1 and 1.70 × 103 s−1, the alloy behaves with a linear stress–strain response in most strain range and exhibits a brittle fracture. In this case, {10-12}  extension twinning is basic deformation mode. The brittleness is due to the macroscopic viscosity at ultra-high strain rate, for which the external critical shear stress rapidly gets high to result in a cleavage fracture before large amounts of dislocations are activated. Because {10-12} tension twinning, {10-11} compressive twinning, basal slip, prismatic slip and pyramidal slip have different critical shear stresses (CRSS, their contributions to the degree of deformation are very differential. In addition, Schmid factor plays an important role in the activity of various deformation modes and it is the key factor for the samples with different strain rates exhibit various mechanical behavior under dynamic tensile loading.

  19. Tensile Deformation Behavior of Fe-Mn-Al-C Low Density Steels

    Xiao-feng ZHANG; Hao YANG; De-ping LENG; Long ZHANG; Zhen-yi HUANG; Guang CHEN


    Room temperature tensile tests of Fe-Mn-Al-C low density steels with four different chemical compositions were conducted to clarify the dominant deformation mechanisms.Parameters like product of strength and elongation, as well as specific strength and curves of stress-strain relations were calculated.The microstructures and tensile frac-ture morphologies were observed by optical microscope,scanning electron microscope and transmission electron mi-croscope.The tensile behavior of low density steel was correlated to the microstructural evolution during plastic de-formation,and the effects of elements,cooling process and heat treatment temperature on the mechanical properties of the steels were analyzed.The results show that the tensile strength of steels with different cooling modes is more than 1 000 MPa.The highest tensile strength of 28Mn-12Al alloy reached 1 230 MPa,with corresponding specific strength of 189.16 MPa.cm3 .g-1 ,while the specific strength of 28Mn-10Al alloy was 178.98 MPa.cm3 .g-1 , and the excellent product of strength and elongation of 28Mn-8Al alloy was over 69.2 GPa.%.A large number of ferrite reduced the ductility and strain hardening rate of the alloy,while the existence ofκcarbides may improve the strength but weaken the plasticity.Some fineκcarbides appeared in the water-quenched specimen,while coarseκcarbides were observed in the air-cooled specimen.High temperature heat treatment improved the decomposition ki-netics ofγphase and the diffusion rate of carbon,thus speeded up the precipitation of fineκcarbides.The dominant deformation mechanism of low density steel was planar glide,including shear-band-induced plasticity and microband-induced plasticity.

  20. Tensile Properties and Microstructure of DS NiAl-28Cr-5.8Mo-0.2Hf Alloy


    A multiphase alloy NiAl-28Cr-5.8Mo-0.2Hf was directionally solidified in Ar atmosphere in an Al2O3-SiO2 mold by standard Bridgman method. The fracture toughness and tensile properties at 980℃ as well as tensile creep at 1050℃were studied. It was found that the strength of the present alloy is higher than that of many NiAl-based alloy and the stress exponent n for creep is about 6.69. Then the possible strengthening mechanism and creep mechanism are also discussed.

  1. Notch effects on room temperature tensile and bend properties of Ni3Al and Ni3Al+B

    Khadkikar, P. S.; Rigney, J. D.; Lewandowski, J. J.; Vedula, K.


    The notched mechanical properties of Ni3Al and Ni3Al+B prepared by powder metallurgy techniques have been determined in both tension and bending at room temperature. Tensile tests performed using double-notched specimens containing relatively blunt notches produced intergranular fracture in both Ni3Al and Ni3Al+B, with evidence of fracture initiating in an intergranular manner ahead of the blunt notch in both cases. Estimates of notched fracture toughness from bend tests and of local grain boundary fracture stress from the notched tensile tests suggest an increase in these values with boron addition.

  2. Static tensile and tensile creep testing of five ceramic fibers at elevated temperatures

    Zimmerman, Richard S.; Adams, Donald F.


    Static tensile and tensile creep testing of five ceramic fibers at elevated temperature was performed. J.P. Stevens, Co., Astroquartz 9288 glass fiber; Nippon Carbon, Ltd., (Dow Corning) nicalon NLM-102 silicon carbide fiber; and 3M Company Nextel 312, 380, and 480 alumina/silica/boria fibers were supplied in unsized tows. Single fibers were separated from the tows and tested in static tension and tensile creep. Elevated test temperatures ranged from 400 C to 1300 C and varied for each fiber. Room temperature static tension was also performed. Computer software was written to reduce all single fiber test data into engineering constants using ASTM Standard Test Method D3379-75 as a reference. A high temperature furnace was designed and built to perform the single fiber elevated temperature testing up to 1300 C. A computerized single fiber creep apparatus was designed and constructed to perform four fiber creep tests simultaneously at temperatures up to 1300 C. Computer software was written to acquire and reduce all creep data.

  3. Optimization of high filler loading on tensile properties of recycled HDPE/PET blends filled with rice husk

    Chen, Ruey Shan; Ahmad, Sahrim; Ghani, Mohd Hafizuddin Ab; Salleh, Mohd Nazry


    Biocomposites of recycled high density polyethylene / recycled polyethylene terephthalate (rHDPE/rPET) blend incorporated with rice husk flour (RHF) were prepared using a corotating twin screw extruder. Maleic anhydride polyethylene (MAPE) was added as a coupling agent to improve the fibre-matrix interface adhesion. The effect of high filler loadings (50-90 wt%) on morphology and tensile properties of compatibilized rHDPE/rPET blend was investigated. The results of our study shown that composite with 70 wt% exhibited the highest tensile strength and Young's modulus, which are 22 MPa and 1752 MPa, respectively. The elongation at break decreased with increasing percentage of RHF. SEM micrograph confirmed fillers dispersion, morphological interaction and enhanced interfacial bonding between recycled polymer blends and rice husk. It can be concluded that the optimum RHF content is 70 wt% with maximum tensile strength.


    J.Zhang; J.J.Yu; H.Z.Fu


    The high-temperature tensile fracture behavior of the Ni, Cr, Al-TaC eutectic superalloy directionally solidified under high temperature gradient is investigated. The hightemperature tensile fracture of this in situ composite has ductile character with lots of ductile nests whose diameters decrease with the increasing solidification rates. The maximum σb and δ are respectively 668.5MPa and 19.6%. There is a TaC whisker in the center of each nest, and the deformation of γ' and TaC is uneven. The hightemperature tensile behavior cannot be explained by the rule of mixtures but is decided by the formation of the plastic deforrmation band. The crack extension model is given.

  5. Non-linearities in tensile creep of concrete at early age

    Hauggaard-Nielsen, Anders Boe; Damkilde, Lars


    A meterial model for creep is proposed which takes into consideration some of the couplings in early age concrete. The model is in incremental form and reflect the hydration process where new layers of cement gel are formed in a stress free state. In the present context attention is on non......-linear creep at high stress levels. The parameteres in the model develop in time as a result of hydration. The creep model has been used to analyse the tensile experiments at different stress levels carried out in the HETEK project. The tests were made on dogbone shaped specimen and the test procedure...... is described. Furthermore, compressive creep at high stress levels are fitted....

  6. Finite element analysis of thermal residual stresses at cemented carbide rock drill buttons with cobalt-gradient structure

    HUANG Zi-qian; HE Yue-hui; CAI Hai-tao; XIAO Yi-feng; HUANG Bai-yun


    The aim of this study is to apply the concept of functionally graded materials (FGMs) to cemented carbides and to develop high-performance rock drill buttons.Cobalt-gradient structure was introduced to the surface zone of the buttons by carburizing process.Finite element method and XRD measurement were used to decide the distribution of thermal residual stress.Constitutive parameters were determined by constraint factor.Numerical results show that residual stresses of gradient buttons mainly concentrate in cobalt-gradient zone.There is compressive stress in the surface zone and tensile stress in the cobalt-rich zone.The maximum value of surface compressive stress is 180 MPa for WC-6Co cemented carbides.And the numerical results agree with the results of XRD measurement.

  7. Swelling and tensile properties of neutron-irradiated vanadium alloys

    Loomis, B.A.; Smith, D.L.


    Vanadium-base alloys are candidates for use as structural material in magnetic fusion reactors. In comparison to other candidate structural materials (e.g., Type 316 stainless and HT-9 ferritic steels), vanadium-base alloys such as V-15Cr-5Ti and V-20Ti have intrinsically lower long-term neutron activation, neutron irradiation after-heat, biological hazard potential, and neutron-induced helium and hydrogen transmutation rates. Moreover, vanadium-base alloys can withstand a higher surface-heat, flux than steels because of their lower thermal stress factor. In addition to having these favorable neutronic and physical properties, a candidate alloy for use as structural material in a fusion reactor must have dimensional stability, i.e., swelling resistance, and resistance to embrittlement during the reactor lifetime at a level of structural strength commensurate with the reactor operating temperature and structural loads. In this paper, we present experimental results on the swelling and tensile properties of several vanadium-base alloys after irradiation at 420, 520, and 600{degree}C to neutron fluences ranging from 0.3 to 1.9 {times} 10{sup 27} neutrons/m{sup 2} (17 to 114 atom displacements per atom (dpa)).

  8. The growth and tensile deformation behavior of the silver solid solution phase with zinc

    Wu, Jiaqi, E-mail: [Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697-2660 (United States); Materials and Manufacturing Technology, University of California, Irvine, CA 92697-2660 (United States); Lee, Chin C. [Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697-2660 (United States); Materials and Manufacturing Technology, University of California, Irvine, CA 92697-2660 (United States)


    The growth of homogeneous silver solid solution phase with zinc are conducted at two different compositions. X-ray diffraction (XRD) and Scanning electron microscope/Energy dispersive X-ray spectroscopy (SEM/EDX) are carried out for phase identification and chemical composition verification. The mechanical properties of silver solid solution phase with zinc are evaluated by tensile test. The engineering and true stress vs. strain curves are presented and analyzed, with those of pure silver in comparison. According to the experimental results, silver solid solution phase with zinc at both compositions show tempered yield strength, high tensile strength and large uniform strain compared to those of pure silver. Fractography further confirmed the superior ductility of silver solid solution phase with zinc at both compositions. Our preliminary but encouraging results may pave the way for the silver based alloys to be applied in industries such as electronic packaging and structure engineering.

  9. Crystal plasticity extend FEM implementation of thermal-tensile aluminum alloy

    Liu Yang


    Full Text Available Multi-level approach has been used to simulate the thermal deformation of aluminium alloy at different temperature and strain rate. The crystal plasticity model is extended in the finite element method and the thermal behaviour is integrated in the constitutive equations. Moreover, the damage evolution is also reflected in the simulation using continuum damage mechanics model. Thus, the void evolution and thermal effect could both be shown in the simulation. A new shear strain rate model is constructed with the thermal activated mechanism to describe the rate dependent behaviours during tensile test. The thermal parameters are determined in a fitting test of representative volume element to compare with the experimental data. The results prove that the mechanical tensile behaviour of 5052 aluminium alloy could be well described at different temperatures. The damage evolution process is expressed by the stress concentration and strain concentration in the finite element simulation, which are also confirmed by the experiments.

  10. In situ micro-tensile testing on proton beam-irradiated stainless steel

    Vo, H. T.; Reichardt, A.; Frazer, D.; Bailey, N.; Chou, P.; Hosemann, P.


    Small-scale mechanical testing techniques are currently being explored and developed for engineering applications. In particular, micro-tensile testing can add tremendous value, since the entire stress-strain curve, including the strain to failure, can be measured directly. In this work, 304 stainless steel specimens irradiated with 2 MeV protons to 10 dpa (full-cascade setting in the Stopping and Range of Ions in Matter, SRIM, software) at 360 °C was evaluated using micro-tensile testing. It was found that even on the micron scale, the measured strain corresponds well with macroscopic expectations. In addition, a new approach to analyzing sudden slip events is presented.

  11. Influence of NdFeB Fillers on Tensile and Electromagnetic Properties of Natural Rubber



    Full Text Available Tensile and electromagnetic properties of hard magnetic natural rubber composites were studied. In a fabrication stage, neodymium-iron-boron (NdFeB magnets were recycled from electronic wastes, broken and then ball-milled for 1 - 3 h. The NdFeB powder was then incorporated into natural rubber (NR by a 2-roll mill technique. Since the NdFeB powder behaved as a non-reinforced filler, thus, it inhibited cross-linking and stress-induced recrystallization. Therefore, the cure time and the tensile strength of the NdFeB-NR composites were reduced compared to the control sample without magnetic fillers. The addition of NdFeB fillers improved the electrical permittivity of NR and the magnetic moment in NdFeB-NR composites could be measured by a fluxmeter.

  12. Combined spectrophotometry and tensile measurements of human connective tissues: potentials and limitations.

    Ernstberger, Markus; Sichting, Freddy; Baselt, Tobias; Hartmann, Peter; Aust, Gabriela; Hammer, Niels


    Strain-dependent transmission data of nine iliotibial tract specimens are determined using a custom-built optical setup with a halogen light source and an industrial norm material testing machine. Polarized light microscopy and hematoxylin-eosin staining indicated that lateral contraction of collagen structures is responsible for total intensity variations during a 20-cycle preconditioning and a 5-cycle tensile test. Tensile force progress is opposite to total transmission progress. Due to dehydration, wavelength-specific radiation intensity shifting is determined during the test, primarily noticeable in a water absorption band between 1400 and 1500 nm. The results show the capability of integrating spectrophotometry technology into biomechanics for determining structural alterations of human collagen due to applied strain. Being more sensitive to drying, spectrophotometry may likely serve as a quality control in stress-strain testing of biological structures.


    W. Huang; X. Nie; X. Zan; Y.M. Xia


    A new experimental technique has been developed for the performance of high temperature, high-strain rate tensile experiments in the self-designed tensile impact apparatus. This technique uses rapid contact heating method to heat the specimen to the desired temperature, thus avoids a significant temperature rise in incident and transmitted bars, and at the same time it is capable of retaining a nearly homogeneous temperature field within the specimen. As an illustration of its application, the hightemperature response of the forging die steel 5CrMnMo at high strain rates has been examined. Stress-strain curves are obtained for this material at strain rates ranging from 230s-1 to 1200s-1 and at temperature ranging from 25 to 600℃, respectively.For comparison, quasi-static experiments are performed over a slightly smaller range of temperatures.

  14. Slow Strain Rate Tensile Testing to Assess the Ability of Superalloys to Resist Environment-Assisted Intergranular Cracking

    Gabb, Timothy P.; Telesman, Jack; Banik, Anthony; McDevitt, Erin


    Intergranular fatigue crack initiation and growth due to environmental degradation, especially at notched features, can often limit the fatigue life of disk superalloys at high temperatures. For clear comparisons, the effects of alloy composition on cracking in air needs to be understood and compared separately from variables associated with notches and cracks such as effective stress concentration, plastic flow, stress relaxation, and stress redistribution. The objective of this study was to attempt using simple tensile tests of specimens with uniform gage sections to compare the effects of varied alloy composition on environment-assisted cracking of several powder metal and cast and wrought superalloys including ME3, LSHR, Udimet 720, ATI 718Plus alloy, Haynes 282, and Inconel 740. Slow and fast strain-rate tensile tests were found to be a useful tool to compare propensities for intergranular surface crack initiation and growth. The effects of composition and heat treatment on tensile fracture strain and associated failure modes were compared. Environment interactions were determined to often limit ductility, by promoting intergranular surface cracking. The response of various superalloys and heat treatments to slow strain rate tensile testing varied substantially, showing that composition and microstructure can significantly influence environmental resistance to cracking.

  15. The influence of the weld toe grinding and wig remelting weld toe rehabilitation techniques, on variable stresses, in case of cross fillet welds, reinforced with additional welding rows

    Babis Claudiu


    Full Text Available Variable stresses where the load value varies between a maximum and a minimum value, or varies the position in time, cause after accumulating a large number of load cycles in those structures, the emergence of drug fatigue. Fatigue is characterized by failure on values of the applied stress from the load cycles, below the material flow, values which in case of static stress would not have caused problems. Knowing that the variable stressed structures are sensitive to stress concentrators, the paper aims to highlight the influence of two techniques to reduce stress concentrator weld toe grinding and WIG remelting weld toe, on the behavior of variable tensile test of cross corner welded specimens, reinforced with additional welding rows.

  16. Tensile Strength of Water Exposed to Pressure Pulses

    Andersen, Anders Peter; Mørch, Knud Aage


    It is well known that pressurization for an extended period of time increases the tensile strength of water, but little information is available on the effect of pressure pulses of short duration. This is addressed in the present paper where we first measure the tensile strength of water...

  17. New Scanning Electron Microscope Used for Cryogenic Tensile Testing

    Maximilien Brice


    At CERN engineering department's installation for cryogenic tensile testing, the new scanning electron microscope (SEM) allows for detailed optical observations to be carried out. Using the SEM, surface coatings and tensile properties of materials can investigated in order to better understand how they behave under different conditions.

  18. Relating tensile properties with flexural properties in SHCC

    Qian, S.; Li, V.C.; Zhou, J.


    Strain hardening cementitious composites (SHCCs) have seen increasing field applications in past decade, yet existing quality control test methods for tensile properties are sometime difficult to implement. This paper presents a new simple inverse method for quality control of tensile strain

  19. Relating tensile properties with flexural properties in SHCC

    Qian, S.; Li, V.C.; Zhou, J.


    Strain hardening cementitious composites (SHCCs) have seen increasing field applications in past decade, yet existing quality control test methods for tensile properties are sometime difficult to implement. This paper presents a new simple inverse method for quality control of tensile strain capacit

  20. Dynamic test devices for analyzing the tensile properties of concrete

    Forquin, P.; Riedel, W.; Weerheijm, J.


    Owing to their low tensile failure strain, concrete is a difficult material to test under dynamic tensile loading. Indeed, conventional testing apparatuses such as high-speed hydraulic presses or Split Hopkinson Bar facilities rely on a mechanical balance of the specimen implying a short round-trip

  1. Relationship between tensile strength and porosity for high porosity metals

    刘培生; 付超; 李铁藩; 师昌绪


    An analysis model has been established according to the structure feature of high porosity metals, and the mathematical relationship between the tensile strength and porosity for this material has been derived from the model. Moreover, the corresponding theoretical formula has been proved good to reflect the variation law of tensile strength with porosity for high porosity metals by the example experiment on nickel foam.

  2. Polystyrene cryostat facilitates testing tensile specimens under liquid nitrogen

    Shogan, R. P.; Skalka, R. J.


    Lightweight cryostat made of expanded polystyrene reduces eccentricity in a tensile system being tested under liquid nitrogen. The cryostat is attached directly to the tensile system by a special seal, reducing misalignment effects due to cryostat weight, and facilitates viewing and loading of the specimens.

  3. Tensile behaviour of polyethylene and poly(p-xylylene) fibres

    van der Werff, Harm


    This thesis deals with the tensile behaviour of fibres prepared from high molecular weight polymers.The tensile strength of a polymeric fibre is in general much lower than the corresponding theoretical value. In case of ultra-high molecular weight polyethylene (UHMWPE), fibres can be prepared by gel

  4. Impact Tensile Testing of Stainless Steels at Various Temperatures

    D. K. Morton


    Stainless steels are used for the construction of numerous spent nuclear fuel or radioactive material containers that may be subjected to high strains and moderate strain rates during accidental drop events. Mechanical characteristics of these base materials and their welds under dynamic loads in the strain rate range of concern (1 to 300 per second) are not well documented. However, research is being performed at the Idaho National Laboratory to quantify these characteristics. The work presented herein discusses tensile impact testing of dual-marked 304/304L and 316/316L stainless steel material specimens. Both base material and welded material specimens were tested at -20 oF, room temperature, 300 oF, and 600 oF conditions. Utilizing a drop weight impact test machine and 1/4-inch and 1/2-inch thick dog bone-shaped test specimens, a strain rate range of approximately 4 to 40 per second (depending on initial temperature conditions) was achieved. Factors were determined that reflect the amount of increased strain energy the material can absorb due to strain rate effects. Using the factors, elevated true stress-strain curves for these materials at various strain rates and temperatures were generated. By incorporating the strain rate elevated true stress-strain material curves into an inelastic finite element computer program as the defined material input, significant improvement in the accuracy of the computer analyses was attained. However, additional impact testing is necessary to achieve higher strain rates (up to 300 per second) before complete definition of strain rate effects can be made for accidental drop events and other similar energy-limited impulsive loads. This research approach, using impact testing and a total energy analysis methodology to quantify strain rate effects, can be applied to many other materials used in government and industry.

  5. Tensile properties of the modified 13Cr martensitic stainless steels

    Mabruri, Efendi; Anwar, Moch. Syaiful; Prifiharni, Siska; Romijarso, Toni B.; Adjiantoro, Bintang


    This paper reports the influence of Mo and Ni on the tensile properties of the modified 13Cr martensitic stainless steels in tempered condition. Four steels with different content of Mo and Ni were prepared by induction melting followed by hot forging, quenching and tempering. The experimental results showed that the addition of about 1% and 3% Mo has a beneficial effect to increase both the tensile strength and the elongation of the steels. On the contrary, the addition of about 3% Ni into the martensitic stainless steel results in decreasing of both the tensile strength and the elongation. Among the alloys investigated the 13Cr3Mo type steel exhibited largest tensile strength of 1348 MPa and largest elongation of 12%. The observation on the tensile fractured surfaces by using scanning electron microscope supported these findings.

  6. Tensile behavior and tension stiffening of reinforced concrete

    Choun, Young Sun; Seo, Jeong Moon


    For the ultimate behavior analysis of containment buildings under severe accident conditions, a clear understanding of tensile behaviors of plain and reinforced concrete is necessary. Nonlinear models for tensile behaviors of concrete are also needed. This report describe following items: tensile behaviors of plain concrete, test results of reinforced concrete panels in uniaxial and biaxial tension, tension stiffening. The tensile behaviors of reinforced concrete are significantly influenced by the properties of concrete and reinforcing steel. Thus, for a more reliable evaluation of tensile behavior and ultimate pressure capacity of a reinforced or prestressed concrete containment building, an advanced concrete model which can be considered rebar-concrete interaction effects should be developed. In additions, a crack behavior analysis method and tension stiffening models, which are based on fracture mechanics, should be developed. The model should be based on the various test data from specimens considering material and sectional properties of the containment building.

  7. The elevated temperature tensile properties of S-200E commercially pure beryllium

    Henshall, G.A.; Torres, S.G.; Hanafee, J.E.


    The tensile properties of commercially pure beryllium are sensitive to temperature, impurity content, texture, grain size, and prior processing. Therefore, tensile tests have been conducted using the commercially pure S-200E Be commonly employed at Lawrence Livermore National Laboratory. These experiments were performed at temperatures ranging from 300 to 1100{degrees}C in the longitudinal and transverse orientations at the quasi-static strain rate of 5.5 x 10{sup -4} s{sup -1}. The results of these experiments reveal that the stress-strain curve is smooth, ie. without yield points or serrations, over the entire temperature range studied. The yield stress (YS) and ultimate tensile stress (UTS) decrease monotonically with increasing temperature. Similar strengths were measured for both the longitudinal and transverse orientations, with the latter exhibiting slightly lower YS and UTS values. The measured failure elongation (e{sub f}) vs. temperature curve is complex due to the competing effects of increasing basal-plane fracture stress with increasing temperature combined with the presence of hot shortness at intermediate temperatures. The latter is believed to be caused, at least partially, by the presence of free aluminum impurities at the grain boundaries. This hypothesis is supported by the measured increase in e{sub f} at 700{degrees}C following a 100-hr anneal at 750{degrees}C, which would remove free Al from the grain boundaries. Texture also was found to influence e{sub f}. The favorable orientation of the basal planes for initiation and propagation of cleavage cracks in longitudinal specimens results in a significantly decreased failure elongation compared with the transverse orientation. The effects of testing temperature and specimen orientation on the reduction in area were found to be similar to those described for e{sub f}.

  8. Knitting Technologies And Tensile Properties Of A Novel Curved Flat-Knitted Three-Dimensional Spacer Fabrics

    Li Xiaoying


    Full Text Available This paper introduces a knitting technique for making innovative curved three-dimensional (3D spacer fabrics by the computer flat-knitting machine. During manufacturing, a number of reinforcement yarns made of aramid fibres are inserted into 3D spacer fabrics along the weft direction to enhance the fabric tensile properties. Curved, flat-knitted 3D spacer fabrics with different angles (in the warp direction were also developed. Tensile tests were carried out in the weft and warp directions for the two spacer fabrics (with and without reinforcement yarns, and their stress–strain curves were compared. The results showed that the reinforcement yarns can reduce the fabric deformation and improve tensile stress and dimensional stability of 3D spacer fabrics. This research can help the further study of 3D spacer fabric when applied to composites.

  9. Effect of recrystallization on tensile behavior, texture, and anisotropy of Ti-3Al-2.5 V cold pilgered tubes

    Bayona-Carrillo, Nicolas; Fundenberger, Jean-Jacques; Wagner, Francis [LETAM-Laboratoire d' Etude des Textures et Applications aux Materiaux CNRS FRE 3143 Universite Paul Verlaine de Metz, F57000 Metz (France); Bozzolo, Nathalie [MINES ParisTech, CEMEF - Centre de Mise en Forme des Materiaux CNRS UMR 7635, BP 207 1 rue Claude Daunesse, 06904 Sophia Antipolis Cedex (France); Thomas, Bertrand; Camelin, Patrick; Lenarduzzi, Emmanuel [PFW SPECITUBES Hameau de Letoquoi 1402, rue de Neufchatel, F62830 Samer (France)


    The recrystallized volume fraction of Ti 3Al 2.5 V seamless tubes is measured using electron BackScatter diffraction (EBSD) after annealing under various conditions. Standard tensile tests and contractile strain ratio (CSR) measurements are carried out in order to analyze the effect of recrystallization on the tensile behavior and the anisotropy of the tubes. The tensile tests show anomalous yield-point phenomena, which become stronger when the recrystallized fraction is increased. CSR value changes through recrystallization, from 0.8 in the cold worked stress relieved (CWSR) state to 1.1 in the fully recrystallized structure. Orientation distribution functions (ODFs) calculated from X-ray data reveal a decay in the intensity of the crystallographic texture as recrystallization advances. This can explain the tendency toward isotropy when complete recrystallization is achieved. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Effect of prior creep at 1365 K on the room temperature tensile properties of several oxide dispersion strengthened alloys

    Whittenberger, J. D.


    An experimental study was conducted to determine whether oxide dispersion-strengthened (ODS) Ni-base alloys in wrought bar form are subject to creep degradation effects similar to those found in thin-gage sheet. The bar products evaluated included ODS-Ni, ODS-NiCr, and advanced ODS-NiCrAl types; the alloys included microstructures ranging from an essentially perfect single crystal to a structure consisting of very small elongated grains. Tensile test specimens were exposed to creep at various stress levels at 1365 K and then tensile tested at room temperature. Low residual tensile properties, change in fracture mode, appearance of dispersoid free bands, grain boundary cavitation, and/or internal oxidation are interpreted as creep degradation effects. The amount of degradation depends on creep strain, and degradation appears to be due to diffusional creep which produces dispersoid free bands around grain boundaries acting as vacancy sources.


    Yagi, Hiroshi; Tamamura, Kouji; Uneda, Atsushi; Domon, Tsuyoshi; Nishimura, Kazuo

    This paper reports the experiential result about the applications of the high tensile strength bolts as a countermeasure for the displacement, considered about the denaturalization of the large cross sectional tunnel in mudstone layer. In Kanaya Tunnel of the New Tomei Expressway, the soft rock section appeared where we cannot restrain support denaturizi ng and internal displacement by materials of the standard design. Then fore, we adopted the high tensile strength bolts (748kN) replacing with of the standard design, and improved the support proof for stress. As the result, we got possible to control the displacement and execute the work safety and economi cally. We compared the analysis result (FEM) by the limited element method with the measure result on the spot, and inspected the supportability effect of the higt tensile strength bolts.

  12. Finite element analysis of steel fiber-reinforced concrete (SFRC): validation of experimental tensile capacity of dog-bone specimens

    Islam, Md. Mashfiqul; Chowdhury, Md. Arman; Sayeed, Md. Abu; Hossain, Elsha Al; Ahmed, Sheikh Saleh; Siddique, Ashfia


    Finite element analyses are conducted to model the tensile capacity of steel fiber-reinforced concrete (SFRC). For this purpose dog-bone specimens are casted and tested under direct and uniaxial tension. Two types of aggregates (brick and stone) are used to cast the SFRC and plain concrete. The fiber volume ratio is maintained 1.5 %. Total 8 numbers of dog-bone specimens are made and tested in a 1000-kN capacity digital universal testing machine (UTM). The strain data are gathered employing digital image correlation technique from high-definition images and high-speed video clips. Then, the strain data are synthesized with the load data obtained from the load cell of the UTM. The tensile capacity enhancement is found 182-253 % compared to control specimen to brick SFRC and in case of stone SFRC the enhancement is 157-268 %. Fibers are found to enhance the tensile capacity as well as ductile properties of concrete that ensures to prevent sudden brittle failure. The dog-bone specimens are modeled in the ANSYS 10.0 finite element platform and analyzed to model the tensile capacity of brick and stone SFRC. The SOLID65 element is used to model the SFRC as well as plain concretes by optimizing the Poisson's ratio, modulus of elasticity, tensile strength and stress-strain relationships and also failure pattern as well as failure locations. This research provides information of the tensile capacity enhancement of SFRC made of both brick and stone which will be helpful for the construction industry of Bangladesh to introduce this engineering material in earthquake design. Last of all, the finite element outputs are found to hold good agreement with the experimental tensile capacity which validates the FE modeling.

  13. A Study of Influencing Factors on the Tensile Response of a Titanium Matrix Composite With Weak Interfacial Bonding

    Goldberg, Robert K.; Arnold, Steven M.


    The generalized method of cells micromechanics model is utilized to analyze the tensile stress-strain response of a representative titanium matrix composite with weak interfacial bonding. The fiber/matrix interface is modeled through application of a displacement discontinuity between the fiber and matrix once a critical debonding stress has been exceeded. Unidirectional composites with loading parallel and perpendicular to the fibers are examined, as well as a cross-ply laminate. For each of the laminates studied, analytically obtained results are compared to experimental data. The application of residual stresses through a cool-down process was found to have a significant effect on the tensile response. For the unidirectional laminate with loading applied perpendicular to the fibers, fiber packing and fiber shape were shown to have a significant effect on the predicted tensile response. Furthermore, the interface was characterized through the use of semi-emperical parameters including an interfacial compliance and a "debond stress;" defined as the stress level across the interface which activates fiber/matrix debonding. The results in this paper demonstrate that if architectural factors are correctly accounted for and the interface is appropriately characterized, the macro-level composite behavior can be correctly predicted without modifying any of the fiber or matrix constituent properties.

  14. Morphology, stresses, and surface reactivity of nanoporous gold synthesized from nanostructured precursor alloys

    Rouya, Eric

    , and finally remains tensile over longer times. An increase in Ni content overall resulted in (i) an increase in maximum compressive stress, (ii) a decrease in compressive-to-tensile transition thickness, and (iii) an increase in steady-state tensile stress. The stress profile recorded in situ during Au-Ni and Au-Ag dealloying exhibits an initial rise in tensile stress followed by a steady-state compressive stress over longer times. The former is due to void formation, while the latter is indicative of a stress relaxation mechanism, which may occur either via cracking, a consequence tensile stress build-up from the dissolution of the more reactive alloy component, and/or Au atom clustering, which reduces the curvature of Au ligaments and hence coarsens the overall NPG surface. Up to 55% and 71% stress relaxation were measured for dealloyed Au-Ni and Au-Ag, respectively. Au oxidation can additionally inhibit tensile stress relaxation by kinetically hindering Au atom diffusivity, further contributing to a structurally unstable NPG film. The surface area (SA) of NPG films was quantified using Cu underpotential deposition (UPD), Au oxidation, electrochemical impedance spectroscopy (EIS), and Ag UPD. While the SA was found to increase linearly with NPG thickness, the EIS-based values were larger than those determined from Cu UPD and Au oxidation by ˜60%. This discrepancy was ascribed partly to the presence of residual Ag atoms on the NPG surface, which act to inhibit Cu reduction and Au oxidation. The EIS probes the entire NPG surface irrespective of surface chemistry, as supported by the negligible change in SA when NPG was additionally modified with UPD Ag. An electrocatalysis study revealed a de-polarization in the ORR, and therefore an enhancement in the electrocatalytic activity of NPG relative to planar Au. This is consistent with NPG's activity towards the reduction of a H2O2 intermediate, whereas planar Au only partially reduces O2 to H2O2. Modification of NPG with

  15. Effect of boron on post irradiation tensile properties of reduced activation ferritic steel (F-82H) irradiated in HFIR

    Shiba, Kiyoyuki; Suzuki, Masahide; Hishinuma, Akimichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Dept. of Materials Science and Engineering; Pawel, J.E. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.


    Reduced activation ferritic/martensitic steel, F-82H (Fe-8Cr-2W-V-Ta), was irradiated in the High Flux Isotope Reactor (HFIR) to doses between 11 and 34 dpa at 400 and 500 C. Post irradiation tensile tests were performed at the nominal irradiation temperature in vacuum. Some specimens included {sup 10}B or natural boron (nB) to estimate the helium effect on tensile properties. Tensile properties including the 0.2% offset yield stress, the ultimate tensile strength, the uniform elongation and the total elongation were measured. The tensile properties were not dependent on helium content in specimens irradiated to 34 dpa, however {sup 10}B-doped specimens with the highest levels of helium showed slightly higher yield strength and less ductility than boron-free specimens. Strength appears to go through a peak, and ductility through a trough at about 11 dpa. The irradiation to more than 21 dpa reduced the strength and increased the elongation to the unirradiated levels. Ferritic steels are one of the candidate alloys for nuclear fusion reactors because of their good thermophysical properties, their superior swelling resistance, and the low corrosion rate in contact with potential breeder and coolant materials.

  16. Experimental and Numerical Analysis of the Effects of Curing Time on Tensile Mechanical Properties of Thin Spray-on Liners

    Guner, D.; Ozturk, H.


    The effects of curing time on tensile elastic material properties of thin spray-on liners (TSLs) were investigated in this study. Two different TSL products supplied by two manufacturers were tested comparatively. The "dogbone" tensile test samples that were prepared in laboratory conditions with different curing times (1, 7, 14, 21, and 28 days) were tested based on ASTM standards. It was concluded that longer curing times improves the tensile strength and the Young's Modulus of the TSLs but decreases their elongation at break. Moreover, as an additional conclusion of the testing procedure, it was observed that during the tensile tests, the common malpractice of measuring sample displacement from the grips of the loading machine with a linear variable displacement transducer versus the sample's gauge length had a major impact on modulus and deformation determination of TSLs. To our knowledge, true stress-strain curves were generated for the first time in TSL literature within this study. Numerical analyses of the laboratory tests were also conducted using Particle Flow Code in 2 Dimensions (PFC2D) in an attempt to guide TSL researchers throughout the rigorous PFC simulation process to model support behaviour of TSLs. A scaling coefficient between macro- and micro-properties of PFC was calculated which will help future TSL PFC modellers mimic their TSL behaviours for various tensile loading support scenarios.

  17. Comparative tensile strength study of the adhesion improvement of PTFE by UV photon assisted surface processing

    Hopp, B.; Geretovszky, Zs.; Bertóti, I.; Boyd, I. W.


    Poly(tetrafluoroethylene) (PTFE) is notable for its non-adhesive and non-reactive properties. A number of technologies can potentially benefit from the application of PTFE, but these characteristics restrict the ability to structuring its surface. In this paper, we present results on two ultraviolet photon assisted treatments of PTFE. The originally poor adhesion was significantly improved by both 172 nm excimer lamp and 193 nm excimer laser assisted surface treatments. While Xe2∗ lamp irradiation, applied in a modest vacuum environment, was sufficient by itself to improve adhesion, the ArF laser process was only effective when the irradiated interface was in contact with 1,2-diaminoethane photoreagent. It was found that the tensile strength of an epoxy resin glued interface created on treated surfaces depended strongly on the applied number of laser pulses and lamp irradiation time. Laser treatment caused fast tensile strength increase during the first 50-500 pulses, while after this it saturates slowly at about 5.5 MPa in the 500-2500 pulse domain. The excimer lamp irradiation resulted in a maximum tensile strength of approximately 10 MPa after 2 min irradiation time which reduced to about 65% of the peak value at longer times.

  18. Influence of Tm:YAP laser irradiation on tensile strength for bracket debonding

    Dostalova, Tatjana; Jelinkova, Helena; Sulc, Jan; Koranda, Petr; Nemec, Michal; Fibrich, Martin; Jelinek, Michal; Michalik, Pavel; Miyagi, Mitsunobu


    The investigation of tensile strength needed for bracket debonding was the aim of study. A diode pumped Tm: YAP microchip laser generating a continuous 2um radiation with the maximum output power of 4W was used for debonding purposes. The group of 60 brackets was debonded using classical and laser irradiation methods - the doze from 1W to 4 W, 60s. The tensile strength without laser irradiation was in the range from 39.6 N (full ceramic bracket group) to 63.7 N (ceramic bracket with metal slot group). After irradiation the tensile strength was decreased from 35.1 N (full ceramic bracket group) to 48.8 N (ceramic bracket with metal slot group). The results of our study generally agree with the previous studies, substantiating the fact that lasers can be used effectively to thermally soften the adhesive resin for removal of ceramic brackets. From the practical point of view is conclusion that during laser irradiation, thermal ablation occurs and the bracket is removed from the enamel together with the rest of the adhesive resin. Laser debonding is easier and little heat diffusion occurred.

  19. Influence of macrostructure on tensile properties of multipass SAW C-Mn steel deposits

    Yongyuth, P.; Ghosh, P. K.; Gupta, P. C.; Patwardhan, A. K.; Prakash, Satya


    Blocks of 'all weld' metal were prepared by a multipass submerged arc process, using a C-Mn filler wire, at different welding currents and speeds by keeping the arc voltage constant. The variation in welding parameters was found to alter the macrostructure primarily by influencing its co-axial dendrite content. The chemical composition and hardness of the dendritic and the heat affected regions were affected little by the welding parameters. A dendrite content up to 37%, had no significant effect on the tensile properties. However an increase in it beyond 37% was found to enhance the UTS and YS and reduce percent elongation. The tensile strength was found to be a maximum in the L orientation and a minimum in the S direction. The use of post-weld heat treatment (PWHT) at 873 K caused spheroidization of cementite there by somewhat reducing the hardness and strength. The treatment while not affecting the basic dendritic morphology reduced the observed difference in tensile properties along the L, T and S directions. Implications of the data vis-a-vis industrial applications have been discussed.

  20. Influence of laser power on tensile properties and material characteristics of laser-sintered UHMWPE

    Khalil Yas


    Full Text Available Ultra High Molecular Weight Polyethylene (UHMWPE has excellent properties, such as high mechanical performance, low friction, high wear and chemical resistance but so far there has been limited use in additive manufacturing (AM. Laser sintering of polymers is one of the most promising AM technologies due to its ability to produce complex geometries with accurate dimensions and good mechanical properties. Consequently, this study investigates the influence of laser power on physical and mechanical properties of UHMWPE parts produced by laser sintering. In particular mechanical properties, such as Ultimate Tensile Strength (UTS, Young’s Modulus and elongation at break were evaluated alongside relative density, dilation and shrinkage. Finally, the fracture surface of the tensile test specimens was examined by electron microscopy. Results show that within a laser power range of 6–12 W there appears to be an optimum where tensile strength and relative density reach a maximum, dilation is minimised and where elongation increases with laser power. UTS up to 2.42 MPa, modulus up to 72.6 MPa and elongation at break up to 51.4% were observed. Relative density and part dimensions are also influenced by laser power.

  1. Contraction stresses of composite resin filling materials.

    Hegdahl, T; Gjerdet, N R


    The polymerization shrinkage of composite resin filling materials and the tensile stresses developed when the shrinkage is restrained were measured in an in vitro experiment. This allows an estimation to be made of the forces exerted upon the enamel walls of cavities filled with the resin in the acid etch technique. The results indicate that the stresses acting on the enamel are low compared to the tensile strength of the enamel.

  2. Laser solder repair technique for nerve anastomosis: temperatures required for optimal tensile strength

    McNally-Heintzelman, Karen M.; Dawes, Judith M.; Lauto, Antonio; Parker, Anthony E.; Owen, Earl R.; Piper, James A.


    Laser-assisted repair of nerves is often unsatisfactory and has a high failure rate. Two disadvantages of laser assisted procedures are low initial strength of the resulting anastomosis and thermal damage of tissue by laser heating. Temporary or permanent stay sutures are used and fluid solders have been proposed to increase the strength of the repair. These techniques, however, have their own disadvantages including foreign body reaction and difficulty of application. To address these problems solid protein solder strips have been developed for use in conjunction with a diode laser for nerve anastomosis. The protein helps to supplement the bond, especially in the acute healing phase up to five days post- operative. Indocyanine green dye is added to the protein solder to absorb a laser wavelength (approximately 800 nm) that is poorly absorbed by water and other bodily tissues. This reduces the collateral thermal damage typically associated with other laser techniques. An investigation of the feasibility of the laser-solder repair technique in terms of required laser irradiance, tensile strength of the repair, and solder and tissue temperature is reported here. The tensile strength of repaired nerves rose steadily with laser irradiance reaching a maximum of 105 plus or minus 10 at 12.7 When higher laser irradiances were used the tensile strength of the resulting bonds dropped. Histopathological analysis of the laser- soldered nerves, conducted immediately after surgery, showed the solder to have adhered well to the perineurial membrane, with minimal damage to the inner axons of the nerve. The maximum temperature reached at the solder surface and at the solder/nerve interface, measured using a non-contact fiber optic radiometer and thermocouple respectively, also rose steadily with laser irradiance. At 12.7, the temperatures reached at the surface and at the interface were 85 plus or minus 4 and 68 plus or minus 4 degrees Celsius respectively

  3. Tensile Property of Bi-axial Warp Knitted Structure



    The tensile property of bi-axial warp knitted fabrics is tested and compared with that of the plain weave fabric. The results show that there are obvious differences between the tensile property of a bi-axial warp knitted fabric and that of a plain weave fabric.The former can give fuller play to the property of a high modulus yarn than the latter. The tensile strength of a bi-axial warp knitted fabric is linear with the number of yarns in the direction of force.

  4. Tensile Stiffness Analysis on Ocean Dynamic Power Umbilical

    汤明刚; 阎军; 王野; 岳前进


    Tensile stiffness of ocean dynamic power umbilical is an important design parameter for functional implementation and structural safety. A column with radial stiffness which is wound by helical steel wires is constructed to predict the tensile stiffness value of umbilicals in the paper. The relationship between the tension and axial deformation is expressed analytically so the radial contraction of the column is achieved in the relationship by use of a simple finite element method. With an agreement between the theoretical prediction and the tension test results, the method is proved to be simple and efficient for the estimation of tensile stiffness of the ocean dynamic power umbilical.

  5. Elevated Temperature Tensile Tests on DU–10Mo Rolled Foils

    Schulthess, Jason [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    Tensile mechanical properties for uranium-10 wt.% molybdenum (U–10Mo) foils are required to support modeling and qualification of new monolithic fuel plate designs. It is expected that depleted uranium-10 wt% Mo (DU–10Mo) mechanical behavior is representative of the low enriched U–10Mo to be used in the actual fuel plates, therefore DU-10Mo was studied to simplify material processing, handling, and testing requirements. In this report, tensile testing of DU-10Mo fuel foils prepared using four different thermomechanical processing treatments were conducted to assess the impact of foil fabrication history on resultant tensile properties.

  6. Effect of a shear modified Gurson model on damage development in a FSW tensile specimen

    Nielsen, Kim Lau; Tvergaard, Viggo


    For a friction stir welded aluminum plate the resistance to ductile failure is studied by analyzing tensile test specimens cut out across the weldline. As the stress triaxiality is rather low in these tests, the Gurson material model is not expected to give a very accurate description of the void...... growth to coalescence. A recently proposed modified version of the Gurson model is used, in which an extra term in the damage evolution law allows for the prediction of failure even at zero or negative values of the mean stress. This modification of the Gurson model is purely phenomenological......, such that the damage parameter does not really represent the void volume fraction. Various amounts of the additional damage evolution are compared with predictions of the original Gurson model. The analyses are carried out for different yield stress profiles transverse to the weld and for different specimen widths...

  7. Overall bolt stress optimization

    Pedersen, Niels Leergaard


    The state of stress in bolts and nuts with International Organization for Standardization metric thread design is examined and optimized. The assumed failure mode is fatigue, so the applied preload and the load amplitude together with the stress concentrations define the connection strength....... Maximum stress in the bolt is found at the fillet under the head, at the thread start, or at the thread root. To minimize the stress concentration, shape optimization is applied. Nut shape optimization also has a positive effect on the maximum stress. The optimization results show that designing a nut......, which results in a more evenly distribution of load along the engaged thread, has a limited influence on the maximum stress due to the stress concentration at the first thread root. To further reduce the maximum stress, the transition from bolt shank to the thread must be optimized. Stress reduction...

  8. In-situ electron microscopy studies on the tensile deformation mechanisms in aluminium 5083 alloy

    Motsi, G


    Full Text Available In this study tensile deformation mechanisms of aluminium alloy 5083 were investigated under observations made from SEM equipped with a tensile stage. Observations during tensile testing revealed a sequence of surface deformation events...

  9. Energy absorption behavior of polyurea coatings under laser-induced dynamic tensile and mixed-mode loading

    Jajam, Kailash; Lee, Jaejun; Sottos, Nancy


    Energy absorbing, lightweight, thin transparent layers/coatings are desirable in many civilian and military applications such as hurricane resistant windows, personnel face-shields, helmet liners, aircraft canopies, laser shields, blast-tolerant sandwich structures, sound and vibration damping materials to name a few. Polyurea, a class of segmented block copolymer, has attracted recent attention for its energy absorbing properties. However, most of the dynamic property characterization of polyurea is limited to tensile and split-Hopkinson-pressure-bar compression loading experiments with strain rates on the order of 102 and 104 s-1, respectively. In the present work, we report the energy absorption behavior of polyurea thin films (1 to 2 μm) subjected to laser-induced dynamic tensile and mixed-mode loading. The laser-generated high amplitude stress wave propagates through the film in short time frames (15 to 20 ns) leading to very high strain rates (107 to 108 s-1) . The substrate stress, surface velocity and fluence histories are inferred from the displacement fringe data. On comparing input and output fluences, test results indicate significant energy absorption by the polyurea films under both tensile and mixed-mode loading conditions. Microscopic examination reveals distinct changes in failure mechanisms under mixed-mode loading from that observed under pure tensile loading. Office of Naval Research MURI.

  10. Preparation and Dynamic Tensile Behavior of C200 Green Reactive Powder Concrete

    ZHANG Yunsheng; SUN Wei; LIU Sifeng; JIAO Chujie; LAI Jianzhong


    A new type of green reactive powder concrete (GRPC) with compressive strength of 200 MPa is prepared by utilizing composite mineral admixtures,natural fine aggregates,and short and fine steel fibers.The quasi-static mechanical properties (mechanical strength,toughness,fracture energy and interracial bonding strength) of GRPC specimens,cured in three different types of regimes,are investigated.The experimental results show that the mechanical properties of the C200 GRPC made with the powder binders that is composed of 40% of Portland cement,25% of ultra fine slag,25% of ultra fine fly ash and 10% of silica fume are better than the others'.The corresponding compressive strength,flexural strength and fracture energy are more than 200 MPa,and 30 000 J/m2 respectively.The dynamic tensile behavior of the C200 GRPC is also investigated through the split Hopkinson pressure bar (SHPB) according to the spalling phenomenon.The dynamic testing results demonstrate that strain rate has an important effect on the dynamic tensile behavior of GRPC.With the increase of strain rate,its peak stress and relevant strain increase.The GRPC exhibits an excellent strain ratio stiffening effect under the dynamic tensile Ioad with high strain ratio,resulting in a significant change of the fracture pattern.

  11. A tensile test to facilitate identification of defects in dentine bonded specimens.

    Nakabayashi, N; Watanabe, A; Arao, T


    To determine the efficacy of a miniaturized dumbbell test procedure designed to more easily identify defect(s) in bonded dentine test specimens. Extracted human dentine substrates were pre-conditioned with 10-3 solution for 10, 30 or 60 s prior to dentine bonding with 4-META/MMA-TBB resin. Miniaturized dumbbell-shaped test specimens were prepared from the resin bonded samples. After 24 h storage in 37 degrees C water, the specimens were tensile-loaded to failure. Fractured surfaces and cross-sections were examined and compared under scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Cohesive failure within the bonding resin was observed in specimens pre-conditioned for 10 s. The tensile bond strength of these was excellent. Bond strengths of specimens that were pre-conditioned for 30 and 60 s were significantly lower, and defects in these specimens, formerly difficult or impossible to identify, were readily identified under SEM and TEM microscopy. The proposed method of tensile stressing to failure and microscopically examining fractured miniaturized dumbbell-shaped test specimens is a simple and reproducible test procedure. The protocol is capable of clearly elucidating defective resin infiltration of demineralized dentine in bonded interfaces. These defects are difficult to visualize by conventional and/or ISO recommended methods.

  12. Tensile properties of a titanium modified austenitic stainless steel and the weld joints after neutron irradiation

    Shiba, K.; Ioka, I.; Jitsukawa, S.; Hamada, A.; Hishinuma, A. [and others


    Tensile specimens of a titanium modified austenitic stainless steel and its weldments fabricated with Tungsten Inert Gas (TIG) and Electron Beam (EB) welding techniques were irradiated to a peak dose of 19 dpa and a peak helium level of 250 appm in the temperature range between 200 and 400{degrees}C in spectrally tailored capsules in the Oak Ridge Research Reactor (ORR) and the High Flux Isotope Reactor (HFIR). The He/dpa ratio of about 13 appm/dpa is similar to the typical helium/dpa ratio of a fusion reactor environment. The tensile tests were carried out at the irradiation temperature in vacuum. The irradiation caused an increase in yield stress to levels between 670 and 800 MPa depending on the irradiation temperature. Total elongation was reduced to less than 10%, however the specimens failed in a ductile manner. The results were compared with those of the specimens irradiated using irradiation capsules producing larger amount of He. Although the He/dpa ratio affected the microstructural change, the impact on the post irradiation tensile behavior was rather small for not only base metal specimens but also for the weld joint and the weld metal specimens.

  13. Effect of dimethylpolysiloxane liquid on the cryogenic tensile strength and thermal contraction behavior of epoxy resins

    Yi, Jin Woo; Lee, Yu Jin; Lee, Sang Bok; Lee, Wonoh; Um, Moon Kwang


    Dimethylpolysiloxane liquid was blended with diglycidyl ether of bisphenol-A epoxy resin including anhydride curing agent to improve the tensile strength of the epoxy resin at 77 K without any increase in its coefficient of thermal expansion (CTE). A bifunctional polymer, silicone-modified epoxy resin (SME), was also added to the mixture as a compatibilizer. The results of UV transmittance for the blend resin showed that the incorporation of the SME could stabilize effectively spherical domains of the siloxane liquid which was immiscible with the epoxy matrix. The tensile strengths of the blend resins at both room temperature and 77 K were measured and SEM analysis for the fractured cross sections was carried out to verify the toughening behavior of the liquid droplets. The results indicated that even small amount of addition of the siloxane liquid (0.05 phr) coupled with SME (20 phr) could enhance the tensile strength at 77 K by 77.6% compared to that of the neat epoxy resin. This improvement is attributed to the fact that the solid and s droplets can disperse the localized stress and interrupt the crack propagation by cavitation mechanism followed by multiple generation of numerous micro-deformation. From the CTE measurement, the siloxane liquid has no influence on the thermal contraction behavior of the blend resin.

  14. Research on differences and correlation between tensile, compression and flexural moduli of cement stabilized macadam

    Yi Yang


    Full Text Available In order to reveal the differences and conversion relations between the tensile, compressive and flexural moduli of cement stabilized macadam, in this paper, we develop a new test method for measuring three moduli simultaneously. By using the materials testing system, we test three moduli of the cement stabilized macadam under different loading rates, propose a flexural modulus calculation formula which considers the shearing effect, reveal the change rules of the tensile, compression and flexural moduli with the loading rate and establish the conversion relationships between the three moduli. The results indicate that: three moduli become larger with the increase of the loading rate, showing a power function pattern; with the shear effect considered, the flexural modulus is increased by 47% approximately over that in the current test method; the tensile and compression moduli of cement stabilized macadam are significantly different. Therefore, if only the compression modulus is used as the structural design parameter of asphalt pavement, there will be a great deviation in the analysis of the load response. In order to achieve scientific design and calculation, the appropriate design parameters should be chosen based on the actual stress state at each point inside the pavement structure.

  15. High strain rate tensile behavior of Al-4.8Cu-1.2Mg alloy

    Bobbili, Ravindranadh, E-mail:; Paman, Ashish; Madhu, V.


    The purpose of the current study is to perform quasi static and high strain rate tensile tests on Al-4.8Cu-1.2Mg alloy under different strain rates ranging from 0.01–3500/s and also at temperatures of 25,100, 200 and 300 °C. The combined effect of strain rate, temperature and stress triaxiality on the material behavior is studied by testing both smooth and notched specimens. Johnson–Cook (J–C) constitutive and fracture models are established based on high strain rate tensile data obtained from Split hopkinson tension bar (SHTB) and quasi-static tests. By modifying the strain hardening and strain rate hardening terms in the Johnson–Cook (J–C) constitutive model, a new J–C constitutive model of Al-4.8Cu-1.2Mg alloy was obtained. The improved Johnson–Cook constitutive model matched the experiment results very well. With the Johnson–Cook constitutive and fracture models, numerical simulations of tensile tests at different conditions for Al-4.8Cu-1.2Mg alloy were conducted. Numerical simulations are performed using a non-linear explicit finite element code autodyn. Good agreement is obtained between the numerical simulation results and the experiment results. The fracture surfaces of specimens tested under various strain rates and temperatures were studied under scanning electron microscopy (SEM).

  16. One-dimensional tensile constitutive equation cannot be directly generalized to deal with two-dimensional bulging mechanical problems

    SONG; Yuquan(宋玉泉); LIU; Shumei(刘术梅)


    Superplastic forming has been extensively applied to manufacture parts and components with complex shapes or high-precisions. However, superplastic formation is in multi-stress state. In a long time, uniaxial tensile constitutive equation has been directly generalized to deal with multi-stress state. Whether so doing is feasible or not needs to be proved in theory. This paper first summarizes the establishing processes of superplastic tensile and bulging constitutive equation with variable m, and, using the analytical expressions of equivalent stress ? and equivalent strain rateof free bulge based on the fundamentals of continuum medium plastic mechanics, derives the analytical expressions of optimum loading rules for superplastic free bulge. By comparing the quantitative results on typical superplastic alloy ZnAl22, it is shown that one-dimensional tensile constitutive equations cannot be directly generalized to deal with two-dimensional bulging quantitative mechanical problems; only superplastic bulging constitutive equation based on bulging stress state can be used to treat the quantitative mechanical problems of bulge.

  17. Influence of isothermal transformation dwell on tensile and fatigue properties of austempered ductile iron

    Vechet, S.; Hanzlikova, K. [Brno Univ. of Technology, Brno (Czech Republic); Kohout, J. [Military Academy in Brno, Brno (Czech Republic)


    Two ADI heats transformed at temperatures of 400 and 380 C during temporal range from 2 minutes to 9 hours were studied in details, with emphasis on structure composition and mechanical properties (tensile and fatigue properties were determined). In the case of the shortest dwells the level of mechanical properties is influenced by martensite, which occurs in the structure as a result of subsequent cooling. UTS and yield stress increase slightly with the dwell of isothermal transformation while the values of elongation to fracture as well as of fatigue limit are very closely dependent on the amount of the retained austenite in the microstructure. (orig.)

  18. Dynamic tensile behavior of electron beam additive manufactured Ti6Al4V

    Rodriguez, O.L. [Department of Mechanical Engineering, University of Alabama, Tuscaloosa, AL 35487 (United States); Allison, P.G., E-mail: [Department of Mechanical Engineering, University of Alabama, Tuscaloosa, AL 35487 (United States); Whittington, W.R.; Francis, D.K. [Department of Mechanical Engineering, Mississippi State University, Starkville, MS 35759 (United States); Rivera, O.G.; Chou, K.; Gong, X. [Department of Mechanical Engineering, University of Alabama, Tuscaloosa, AL 35487 (United States); Butler, T.M. [Department of Metallurgical Engineering, University of Alabama, Tuscaloosa, AL 35487 (United States); Burroughs, J.F. [Geotechnical & Structures Laboratory, US Army ERDC, Vicksburg, MS 39180 (United States)


    High rate and quasi-static tensile experiments examined strain rate dependence on flow stress and strain hardening of additive manufactured Ti6Al4V. Variations on strain-hardening coefficient indicate that the rate of thermal softening is greater than strain hardening during plastic deformation. Strain rate sensitivity calculations within the plastic strain regime suggest changes in deformation mechanisms. Fractography revealed cup-and-cone fracture for quasi-static samples and shear mechanisms for high rate samples. As-deposited microstructure consisted of bimodal α+β with the presence of secondary martensitic phase.

  19. A molecular mechanics approach for analyzing tensile nonlinear deformation behavior of single-walled carbon nanotubes

    Yu Wang; Daining Fang; Ai Kah Soh; Bin Liu


    In this paper, by capturing the atomic informa-tion and reflecting the behaviour governed by the nonlin-ear potential function, an analytical molecular mechanics approach is proposed. A constitutive relation for single-walled carbon nanotubes (SWCNT's) is established to describe the nonlinear stress-strain curve of SWCNT's and to predict both the elastic properties and breaking strain of SWCNT's during tensile deformation. An analysis based on the virtual internal bond (VIB) model proposed by P. Zhang et al. is also presented for comparison. The results indicate that the proposed molecular mechanics approach is indeed an acceptable analytical method for analyzing the mechanical behavior of SWCNT's.

  20. Evolution of cleared channels in neutron-irradiated pure copper as a function of tensile strain

    Edwards, D.J.; Singh, B.N.


    , and that channels were present in a low number even before the macroscopic yield. New primary channels and secondary channels continued to form with increasing strain, suggesting the increase in stress was related directly to the initiation of new channels as earlier sources were exhausted. (C) 2004 Elsevier B......% of the macroscopic yield, at 1.5% and 5% elongation, and near the ultimate tensile strength at 14.5% elongation, with the 5th specimen tested to failure (e(T) = 22%). SEM and TEM characterization of the deformed specimens revealed that the plastic strain was confined primarily to the 'cleared' channels only...

  1. Microstructural and Residual Stress Development due to Inertia Friction Welding in Ti-6246

    Attallah, Moataz M.; Preuss, Michael; Boonchareon, Chatri; Steuwer, Axel; Daniels, John E.; Hughes, Darren J.; Dungey, Christopher; Baxter, Gavin J.


    A thorough investigation has been performed to assess the microstructural properties, mechanical properties (hardness and elastic modulus), and residual stress development in Ti-6Al-2Sn-4Zr-6Mo (Ti-6246) inertia friction welds in the as-welded and postweld heat-treated conditions. It was evident that the thermomechanical deformation in the weld region occurred above the β transus, forming dynamically recrystallized β grains and precipitating acicular α within the β grains, which resulted in a localized hardness increase. In the heat-affected zone, a ghost microstructure of the base metal formed because of the absence of sufficient time for diffusion, resulting in Mo segregation in the prior primary α plates. Energy-dispersive synchrotron X-ray diffraction and neutron diffraction were used to assess the residual stress development in the three principal directions. The variation in the unstrained lattice parameters across the weld regions was established by imposing a stress balance on the axial stress component in the radial direction. It was found that the maximum stresses occurred in the hoop direction, with significantly lower stresses present in the radial and axial directions. The maximum tensile hoop stresses were located at ~4 mm from the weld centerline and not at the dynamically recrystallized β-rich weld zone. This was associated with the α → β phase transformation and the subsequent acicular α precipitation within the region surrounding the weld centerline.

  2. Feeding a diet contaminated with ochratoxin A for broiler chickens at the maximum level recommended by the EU for poultry feeds (0.1 mg/kg). 2. Effects on meat quality, oxidative stress, residues and histological traits.

    Pozzo, L; Cavallarin, L; Antoniazzi, S; Guerre, P; Biasibetti, E; Capucchio, M T; Schiavone, A


    The European Commission Recommendation 2006/576/EC indicates that the maximum tolerable level of ochratoxin A (OTA) in poultry feeds is 0.1 mg OTA/kg. Thirty-six 1-day-old male broiler chicks were divided into two groups, a control (basal diet) and an OTA (basal diet + 0.1 mg OTA/kg) group. The OTA concentration was quantified in serum, liver, kidney, breast and thigh samples. The thiobarbituric acid reactive substances (TBARS) content were evaluated in the liver, kidney, breast and thigh samples. The glutathione (GSH) content, and catalase (CAT) and superoxide dismutase (SOD) activity were measured in the liver and kidney samples. Histopathological traits were evaluated for the spleen, bursa of Fabricius and liver samples. Moreover, the chemical composition of the meat was analysed in breast and thigh samples. In the OTA diet-fed animals, a serum OTA concentration of 1.15 ± 0.35 ng/ml was found, and OTA was also detected in kidney and liver at 3.58 ± 0.85 ng OTA/g f.w. and 1.92 ± 0.21 ng OTA/g f.w., respectively. The TBARS content was higher in the kidney of the ochratoxin A group (1.53 ± 0.18 nmol/mg protein vs. 0.91 ± 0.25 nmol/mg protein). Feeding OTA at 0.1 mg OTA/kg also resulted in degenerative lesions in the spleen, bursa of Fabricius and liver. The maximum tolerable level of 0.1 mg OTA/kg, established for poultry feeds by the EU, represents a safe limit for the final consumer, because no OTA residues were found in breast and thigh meat. Even though no clinical signs were noticed in the birds fed the OTA-contaminated diet, moderate histological lesions were observed in the liver, spleen and bursa of Fabricius.

  3. Tensile deformation of NiTi wires.

    Gall, Ken; Tyber, Jeff; Brice, Valerie; Frick, Carl P; Maier, Hans J; Morgan, Neil


    We examine the structure and properties of cold drawn Ti-50.1 at % Ni and Ti-50.9 at % Ni shape memory alloy wires. Wires with both compositions possess a strong fiber texture in the wire drawing direction, a grain size on the order of micrometers, and a high dislocation density. The more Ni rich wires contain fine second phase precipitates, while the wires with lower Ni content are relatively free of precipitates. The wire stress-strain response depends strongly on composition through operant deformation mechanisms, and cannot be explained based solely on measured differences in the transformation temperatures. We provide fundamental connections between the material structure, deformation mechanisms, and resulting stress-strain responses. The results help clarify some inconsistencies and common misconceptions in the literature. Ramifications on materials selection and design for emerging biomedical applications of NiTi shape memory alloys are discussed.

  4. The Effects of Post Diameter on Stress Distribution in Maxillary Central Incisor, A Three Dimensional Finite Element Study

    A. Monzavi


    Full Text Available Statement of Problem: Currently there are three recognized theories about the diameter of prepared dowel space in endodontically treated teeth. Diameter of the dowel is commonly contributed to the root fracture.Purpose: This study used a 3 dimensional (3D finite element method to predict stress distribution in endodontically treated central maxillary tooth with cast post and core with various post diameter according to three philosophies about post diameter (Conservational,Proportional, Preservational.Materials and Methods: In this study three 3D models of central maxillary incisors with different post diameter were created and depend on the size of post called narrow, medium and thick model with post diameter of 1.1mm, 1.7 mm and 2.6 mm of in (CEJrespectively. A load of 100 N was applied to cingulum fossa from lingual direction with 45-degree angle to long axis of tooth and maximum tensile, compressive and Von Misses stresses and their distribution in dentin and post was studied.Results: The post in narrow, medium and thick models produced a similar magnitude of tensile, compressive and Von Misses stresses in dentin. Stress distribution was also similar in all models. Peak stresses in dentin were slightly decreased when post diameter increased from narrow to thick model. In all models peak tensile stresses in dentin occurred in the coronally one third of the lingual surface of the root, whereas peak compressive stresseswere evident in the coronal one third of the facial surface of the root.Conclusion: There were not significant differences stress distribution pattern and magnitude in dentin between the three theories of post diameter.

  5. A comparative study on the elastic modulus of polyvinyl alcohol sponge using different stress-strain definitions.

    Karimi, Alireza; Navidbakhsh, Mahdi; Alizadeh, Mansour; Razaghi, Reza


    There have been different stress-strain definitions to measure the elastic modulus of spongy materials, especially polyvinyl alcohol (PVA) sponge. However, there is no agreement as to which stress-strain definition should be implemented. This study was aimed to show how different results are given by the various definitions of stress-strain used, and to recommend a specific definition when testing spongy materials. A fabricated PVA sponge was subjected to a series of tensile tests in order to measure its mechanical properties. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) were used to determine the elastic modulus. The results revealed that the Almansi-Hamel strain definition exhibited the highest non-linear stress-strain relation and, as a result, may overestimate the elastic modulus at different stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress). The Green-St. Venant strain definition failed to address the non-linear stress-strain relation using different definitions of stress and invoked an underestimation of the elastic modulus values. Engineering stress and strain definitions were only valid for small strains and displacements, which make them impractical when analyzing spongy materials. The results showed that the effect of varying the stress definition on the maximum stress measurements was significant but not when calculating the elastic modulus. It is important to consider which stress-strain definition is employed when characterizing the mechanical properties of spongy materials. Although the true stress-true strain definition exhibits a non-linear relation, we favor it in spongy materials mechanics as it gives more accurate measurements of the material's response using the instantaneous values.

  6. Tensile Bond Strength of Latex-Modified Bonded Concrete Overlays

    Dubois, Cameron; Ramseyer, Chris


    The tensile bond strength of bonded concrete overlays was tested using the in-situ pull-off method described in ASTM C 1583 with the goal of determining whether adding latex to the mix design increases bond strength. One slab of ductile concrete (f'c > 12,000 psi) was cast with one half tined, i.e. roughened, and one half steel-troweled, i.e. smooth. The slab surface was sectioned off and overlay mixtures containing different latex contents cast in each section. Partial cores were drilled perpendicular to the surface through the overlay into the substrate. A tensile loading device applied a direct tensile load to each specimen and the load was increased until failure occurred. The tensile bond strength was then calculated for comparison between the specimens.

  7. A Simple Method for Measuring Tensile Force with Piezoelectric Patch

    ZHANG Zhi-Wen; JIANG Zhong-Wei; Testuya Morisaki


    @@ We propose a simple method for monitoring the axial tensile and compressive force in a structure by using a piezoelectric patch with the piezoelectric impedance based measurement. A simple approximate equation for estimating the tensile force in two different conditions, which can be calculated easily if the natural frequencies in two different states are measured, is explained in detail. On another front, the natural frequency can be very easily measured by a piezoelectric element by bonding it on the measuring subject structure, because its electric impedance of piezoelement is related to the structural mechanical impedance. Furthermore, an experiment for measuring a tensile force in a simple supported beam is carried out for validating the proposed method. The results show a good accuracy in estimating the tensile force variation by the natural frequency change measured from the piezoelement.

  8. Tensile strength of woven yarn kenaf fiber reinforced polyester composites

    A.E. Ismail


    Full Text Available This paper presents the tensile strength of woven kenaf fiber reinforced polyester composites. The as-received yarn kenaf fiber is weaved and then aligned into specific fiber orientations before it is hardened with polyester resin. The composite plates are shaped according to the standard geometry and uni-axially loaded in order to investigate the tensile responses. Two important parameters are studied such as fiber orientations and number of layers. According to the results, it is shown that fiber orientations greatly affected the ultimate tensile strength but it is not for modulus of elasticity for both types of layers. It is estimated that the reductions of both ultimate tensile strength and Young’s modulus are in the range of 27.7-30.9% and 2.4-3.7% respectively, if the inclined fibers are used with respect to the principal axis.

  9. Tensile Fracture Behavior of Progressively-Drawn Pearlitic Steels

    Jesús Toribio; Francisco-Javier Ayaso; Beatriz González; Juan-Carlos Matos; Diego Vergara; Miguel Lorenzo


    In this paper a study is presented of the tensile fracture behavior of progressively-drawn pearlitic steels obtained from five different cold-drawing chains, including each drawing step from the initial hot-rolled bar...

  10. Aluminum/steel wire composite plates exhibit high tensile strength


    Composite plate of fine steel wires imbedded in an aluminum alloy matrix results in a lightweight material with high tensile strength. Plates have been prepared having the strength of titanium with only 85 percent of its density.

  11. Stress Domains in Si(111)/a-Si{sub 3}N{sub 4} Nanopixel: Ten-Million-Atom Molecular Dynamics Simulations on Parallel Computers

    Omeltchenko, Andrey; Bachlechner, Martina E.; Nakano, Aiichiro; Kalia, Rajiv K.; Vashishta, Priya; Ebbsjoe, Ingvar; Madhukar, Anupam; Messina, Paul


    Parallel molecular dynamics simulations are performed to determine atomic-level stresses in Si(111)/Si {sub 3}N{sub 4}(0001) and Si(111)/a-Si {sub 3}N{sub 4} nanopixels. Compared to the crystalline case, the stresses in amorphous Si{sub 3}N {sub 4} are highly inhomogeneous in the plane of the interface. In silicon below the interface, for a 25 nm square mesa stress domains with triangular symmetry are observed, whereas for a rectangular, 54 nmx33 nm , mesa tensile stress domains ({approx}300 Angstrom) are separated by Y-shaped compressive domain wall. Maximum stresses in the domains and domain walls are -2 GPa and +2 GPa , respectively. (c) 2000 The American Physical Society.

  12. Comparison of Some Mechanical and Physical Methods for Measurement of Residual Stresses in Brush-Plated Nickel Hardened Gold and Silver Coatings

    Harri LILLE


    Full Text Available Hard gold and silver are applied in coating owing to their high hardness, good wear and corrosion resistance for engineering application (e.g. on generators slip rings, sliding contacts and small machine parts and are typically plated on copper (mostly, brass and bronze. The studied nickel-hardened gold and silver coatings were brush plated on open thin-walled copper ring substrates. Residual stresses in the coatings were calculated from the curvature changes of the substrates. Biaxial intrinsic residual stresses were also determined by nanoindentation testing and by the X-ray technique. The values of the residual stresses represented tensile stresses and when determined by the techniques used they were comparable within a maximum limit of measurement uncertainty. These stresses relax; the dependence of relaxation time was approximated by a linear-fractional function.DOI:


    Umar A.H.


    Full Text Available Umar A.H1, Zainudin E.S1,2 and Sapuan S.M.1,21Department of Mechanical and Manufacturing EngineeringFaculty of Engineering, Universiti Putra MalaysiaSelangor, Malaysia.2Biocomposite LaboratoryInstitute of Tropical Forestry and Forest Product (INTROPUniversiti Putra Malaysia, Selangor, Malaysia.Email: ABSTRACTIn this study, a high-density polyethylene composite reinforced with kenaf (Hibiscus Cannabinus L. bast fibres (K-HDPE was fabricated and tested for durability with regard to weather elements. The material consists of 40% (by weight fibres and 60% matrix. Other additives, such as ultraviolet (UV stabiliser and maleic anhydride grafted polyethylene (MaPE as a coupling agent were added to the composite material. The biocomposite was subjected to 1000 hours (h of accelerated weathering tests, which consisted of heat, moisture and UV light, intended to imitate the outdoor environment. The tensile properties of the K-HDPE composite were recorded after 0, 200, 400, 600, 800 and 1000 h of exposure to the accelerated weathering. Compared with neat high-density polyethylene (HDPE, the K-HDPE composite has 22.7% lower tensile strength when produced but displays a less rapid rate of strength deterioration under weathering (After 1000 h of exposure the tensile strength of K-HDPE drops 29.4%, whereas, for neat HDPE, it falls rapidly by 36%. Due to better stiffness, the Young’s modulus of the K-HDPE composite is much higher than that of neat HDPE. The fibres on the surface of the K-HDPE composite gradually start to whiten after 200 h of exposure and become completely white after 600 h of exposure. For neat HDPE, micro-cracking on the surface can be observed after 200 h of exposure and the stress-strain curve obtained from the tensile test indicates its increase in brittleness proportional to the amount of weathering time.

  14. The Stress Pattern of Iceland

    Ziegler, Moritz; Rajabi, Mojtaba; Heidbach, Oliver; Páll Hersir, Gylfi; Ágústsson, Kristján; Árnadóttir, Sigurveig; Zang, Arno


    Iceland is one of the few places on earth where an active spreading can be observed onshore, yet the contemporary crustal stress state has not been investigated intesively. We compiled the first comprehensive stress map of Iceland from different stress indicators and analysed data from 57 Icelandic geothermal boreholes. In total we interpreted appox. 37 km of acoustic image logs for stress indicators, i.e. borehole breakouts and drilling induced tensile fractures. Furthermore we revised the 38 data records for Iceland from the World Stress Map 2008 and conducted an extensive literature research to compile all available focal mechanism solutions and geological stress indicators. The new stress compilation consists of 495 data records for the orientation of the maximum horizontal stress (SHmax) in and around Iceland with 318 data records of A-D qualities according to the World Stress Map ranking scheme. Most of the data records are derived from focal mechanism solutions (35%) and geological fault inversions (26%). Borehole related indicators (breakouts, drilling induced fractures, hydro-fractures) have a share of 20%. Minor contributions to the dataset are provided by the alignment of volcanic vents and fissures and overcoring measurements. The mean orientation of SHmax is 17° ± 39° for all A-D quality data. A closer look at subregions reveals four different provinces with fairly consistent SHmax orientation. They are in the Capital area and Southern Lowlands (mean SHmax = 38° ± 29°), the eastern Highlands and Eastfjords (mean SHmax = 8° ± 25°), the Tjörnes Fracture Zone and Akureyri (mean SHmax = 151° ± 21°), and the Westfjords (mean SHmax = 137° ± 17°). This distribution of SHmax orientations is in agreement with the prevailing tectonic structure. At the spreading ridges Reykjanes and Kolbeinsey in the South and North respectively an orientation of SHmax parallel to the plate boundary is observed. The same is observed in the Northern and Eastern

  15. Tensile Properties of Fiber Materials under Different Strain Rates

    XIONG Jie; GU Bo-hong; WANG Shan-yuan


    The quasi-static and dynamic tensile tests of aranid and high strength PVA fiber bundles are carried out under a wider range of strain rate by use of MTS (Materials Testing System) and bar-bar tensile impact apparatus.The influences of strain rate on mechanical properties of aramid and high strength polyvinyl alcohol fibers ar estudied. Micro failure mechanisms of fibers at different strain rates are examined by means of SEM.

  16. Tensile Behavior of Low Density Thermally Bonded Nonwoven Material

    Xiaonan Hou


    Full Text Available A discontinuous and non-uniform microstructure of alow-density thermally bonded nonwoven materialdisplays in a complicated and unstable tensilebehavior. This paper reports uniaxial tensile tests of alow density thermally bonded nonwoven toinvestigate the effect of the specimen size and shapefactor, as well as the cyclic tensile loading conditionsemployed to investigate the deformational behaviorand performance of the nonwoven at differentloading stages. The experimental data are comparedwith results of microscopic image analysis and FEmodels.

  17. Covalent Crosslinking of Carbon Nanotube Materials for Improved Tensile Strength

    Baker, James S.; Miller, Sandi G.; Williams, Tiffany A.; Meador, Michael A.


    Carbon nanotubes have attracted much interest in recent years due to their exceptional mechanical properties. Currently, the tensile properties of bulk carbon nanotube-based materials (yarns, sheets, etc.) fall far short of those of the individual nanotube elements. The premature failure in these materials under tensile load has been attributed to inter-tube sliding, which requires far less force than that needed to fracture individual nanotubes.1,2 In order for nanotube materials to achieve their full potential, methods are needed to restrict this tube-tube shear and increase inter-tube forces.Our group is examining covalent crosslinking between the nanotubes as a means to increase the tensile properties of carbon nanotube materials. We are working with multi-walled carbon nanotube (MWCNT) sheet and yarn materials obtained from commercial sources. Several routes to functionalize the nanotubes have been examined including nitrene, aryl diazonium, and epoxide chemistries. The functional nanotubes were crosslinked through small molecule or polymeric bridges. Additionally, electron beam irradiation induced crosslinking of the non-functional and functional nanotube materials was conducted. For example, a nanotube sheet material containing approximately 3.5 mol amine functional groups exhibited a tensile strength of 75 MPa and a tensile modulus of 1.16 GPa, compared to 49 MPa and 0.57 GPa, respectively, for the as-received material. Electron beam irradiation (2.2x 1017 ecm2) of the same amine-functional sheet material further increased the tensile strength to 120 MPa and the modulus to 2.61 GPa. This represents approximately a 150 increase in tensile strength and a 360 increase in tensile modulus over the as-received material with only a 25 increase in material mass. Once we have optimized the nanotube crosslinking methods, the performance of these materials in polymer matrix composites will be evaluated.

  18. Dynamic response and residual stress fields of Ti6Al4V alloy under shock wave induced by laser shock peening

    Sun, Rujian; Li, Liuhe; Zhu, Ying; Zhang, Lixin; Guo, Wei; Peng, Peng; Li, Bo; Guo, Chao; Liu, Lei; Che, Zhigang; Li, Weidong; Sun, Jianfei; Qiao, Hongchao


    Laser shock peening (LSP), an innovative surface treatment technique, generates compressive residual stress on the surface of metallic components to improve their fatigue performance, wear resistance and corrosion resistance. To illustrate the dynamic response during LSP and residual stress fields after LSP, this study conducted FEM simulations of LSP in a Ti6Al4V alloy. Results showed that when power density was 7 GW cm-2, a plastic deformation occurred at 10 ns during LSP and increased until the shock pressure decayed below the dynamic yield strength of Ti6Al4V after 60 ns. A maximum tensile region appeared beneath the surface at around 240 ns, forming a compressive-tensile-compressive stress sandwich structure with a thickness of 98, 1020 and 606 μm for each layer. After the model became stabilized, the value of the surface residual compressive stress was 564 MPa at the laser spot center. Higher value of residual stress across the surface and thicker compressive residual stress layers were achieved by increasing laser power density, impact times and spot sizes during LSP. A ‘Residual stress hole’ occurred with a high laser power density of 9 GW cm-2 when laser pulse duration was 10 ns, or with a long laser pulse duration of 20 ns when laser power density was 7 GW cm-2 for Ti6Al4V. This phenomenon occurred because of the permanent reverse plastic deformation generated at laser spot center.

  19. Flux-pinning-induced stress and magnetostriction in a functionally graded long rectangular superconductor slab

    Feng, W. J.; Han, X.; Ma, P.


    The flux-pinning-induced stress and magnetostriction of a functionally graded type-II superconductor shaped as a rectangular slab are analyzed. By using the plane strain approach, the exact solution of the three-dimensional (3D) magneto-elastic problem is found. All the stresses, strains, and magnetostriction in the graded direction are first expressed in terms of the flux-density profile in the slab, and all these expressions are valid for any critical-state model jc=jc(B ). Then, based on the Bean model, i.e., jc=const, an extensive analysis is made for three cases of applied magnetic fields, i.e., increasing field, decreasing field, and field cooling. And the emphasis is put on the effects of both the applied magnetic field and the graded index of the slab on the maximum tensile stress and the magnetostriction.

  20. Tensile characteristics of metal nanoparticle films on flexible polymer substrates for printed electronics applications

    Kim, Sanghyeok; Won, Sejeong; Sim, Gi-Dong; Park, Inkyu; Lee, Soon-Bok


    Metal nanoparticle solutions are widely used for the fabrication of printed electronic devices. The mechanical properties of the solution-processed metal nanoparticle thin films are very important for the robust and reliable operation of printed electronic devices. In this paper, we report the tensile characteristics of silver nanoparticle (Ag NP) thin films on flexible polymer substrates by observing the microstructures and measuring the electrical resistance under tensile strain. The effects of the annealing temperatures and periods of Ag NP thin films on their failure strains are explained with a microstructural investigation. The maximum failure strain for Ag NP thin film was 6.6% after initial sintering at 150 °C for 30 min. Thermal annealing at higher temperatures for longer periods resulted in a reduction of the maximum failure strain, presumably due to higher porosity and larger pore size. We also found that solution-processed Ag NP thin films have lower failure strains than those of electron beam evaporated Ag thin films due to their highly porous film morphologies.