Showing papers on "Stress–strain curve published in 1983"
Book•
01 Jan 1983TL;DR: In this paper, the authors present sheet metal properties including stress and strain, tension, and strain hardening, and anisotropic anisotropy for sheet metal forming, as well as other sheet forming operations.
Abstract: 1. Stress and strain 2. Plasticity 3. Strain hardening 4. Plastic instability 5. Temperature and strain-rate dependence 6. Work balance 7. Slab analysis and friction 8. Friction and lubrication 9. Upper-bound analysis 10. Slip-line field analysis 11. Deformation zone geometry 12. Formability 13. Bending 14. Plastic anisotropy 15. Cupping, redrawing and ironing 16. Forming limit diagrams 17. Stamping 18. Hydroforming 19. Other sheet forming operations 20. Formability tests 21. Sheet metal properties.
1,126 citations
TL;DR: In this paper, a continuum description is introduced for an elastic solid which contains particles that undergo an irreversible stress-induced dilatant transformation, and the behaviors of the composite solid considered range from abrupt complete transformation at a critical mean stress to strain controlled transformation at constant stress.
548 citations
TL;DR: In this article, a review of the tensile impact testing of composite materials is given and a new method, using a modified version of the standard tensile split Hopkinson's pressure bar (SHPB), is described.
Abstract: A brief review is given of techniques which have been employed in attempts to determine the mechanical properties of composite materials under tensile impact loading. The difficulties encountered in the design of a satisfactory tensile impact testing machine for composite materials are discussed and a new method, using a modified version of the standard tensile split Hopkinson's pressure bar (SHPB), is described. Dynamic stress-strain curves for unidirectionally-reinforced carbon/epoxy composite, in which failure occurs in less than 30 μsec at a mean strain rate of about 400 sec−1, are presented and their validity is established. An extension of the technique to allow the testing of wovenroving reinforced glass/epoxy composites is described and dynamic stress-strain curves obtained for which the times to failure approach 100 μsec and the average strain rate is of the order of 1000 sec−. Comparative stress-strain curves at low and intermediate rates of strain are obtained and the effect of strain rate, over about 7 orders of magnitude, on the tensile modulus, and strength, fracture strain and energy absorbed in fracturing is determined. The limitations of the technique are discussed.
400 citations
TL;DR: In this article, a detailed microscopical study revealed several deformation and fracture modes for /3-Ti alloy Ti-10V-2Fe-3Al microstructures with different yield stresses was established by combinations of forging and heat treatment.
Abstract: In the /3-Ti alloy Ti-10V-2Fe-3Al a variety ofα-andω-aged microstructures with different yield stresses was established by combinations of forging and heat treatment. Tensile tests have shown that plastic deformation and fracture are strongly influenced by the morphology, size, and volume fraction of the different types of a-phase (primary a, secondaryα, grain boundaryα), as well as by the-phase. A detailed microscopical study revealed several deformation and fracture modes. It appears that at several sites stress and strain concentrations and subsequent void nucleation can occur and that the quantitative combinations of the differentα-types determine which sites are active. The dominant deformation mode for the (α +gb) solution treated andα-aged conditions was a strain localization in theα-aged matrix leading to voids at the interface between aged matrix and primary a-phase. In case of theβ-solution treated andα-aged microstructures the grain boundaryα leads to a strain localization in the softα-film and to void nucleation at grain boundary triple points at low macroscopic strains. Based on the above mechanisms it is discussed in detail how varying size, volume fraction, and morphology of theα-phase affect the ductility. The embrittling effect ofω-particles can be largely reduced by a grain refinement.
157 citations
TL;DR: In this paper, the authors examined the nonlinear elastic behavior of fabric composites, including shear deformation of fill threads, extensional deformation and transverse cracking of warp regions.
Abstract: This paper examines the non-linear elastic behavior of fabric composites Three types of non linearity including the shear deformation of fill threads, the extensional deformation of the pure matrix regions and transverse cracking of the warp regions have been taken into considerations The non-linear constitutive relation developed by Hahn and Tsai is adopted in this analysis and the fiber undulation and bridging models developed by Ishikawa and Chou are also applied Results of the analysis for a glass 8 harness satin/polyimide composite compares remarkably well with the experimental stress-strain curve The analyses also show that the nonlinear effects are less pronounced for fabrics assuming larger geometrical repeating length due to the increasing in fluence of the "bridging effect" As a result, both knee stress and strain increase with the geometrical repeating length
143 citations
TL;DR: In this paper, the yield stress of nylon 6 (Ny6) composites filled with ultrafine and micron-sized (SiO2 and glass) particles was measured as a function of temperature, rate of strain, and filler content.
Abstract: The yield stress of nylon 6 (Ny6) composites filled with ultrafine and micron-sized (SiO2 and glass) particles was measured as a function of temperature, rate of strain, and filler content. The yield stress of the composites filled with ultrafine SiO2 particles increased with filler content and decreased with filler size, whereas for composites filled with glass particles, this relation was reversed. For ultrafine SiO2 filled composites, the tensile yield stress was found to be reducible with regard to temperature, rate of strain, and filler content. At a given filler content, composite curves were obtained for yield stress plotted against the logarithm of the strain rate. The Arrhenius plot of the shift factors for composing the strain rate-temperature master curve formed a single curve irrespective of the filler content and size. The curve comprised two linear regions with a break appearing at 110[ddot], corresponding to a transition of the matrix polymer. The master curves obtained for differe...
139 citations
01 Jan 1983
116 citations
Book•
19 May 1983
TL;DR: In this paper, the authors describe the engineering description of rocks and their properties, including deformation, deformation curve, and shear resistance of discontinuity shear resistances.
Abstract: 1 Engineering Description of Rocks.- 1.1 Rock testing.- 1.2 Uniaxial or unconfined strength.- 1.3 Empirical field and laboratory tests.- 1.4 Porosity and permeability.- 1.5 Discontinuous rock.- 2 Stress and Strain.- 2.1 Stress at a point.- 2.2 Pore pressure and effective stress.- 2.3 Strain at a point.- 2.4 Representation of stress and strain.- 2.5 Relation between stress and strain.- 2.6 Geostatic stresses.- 2.7 Measurement of in situ stress.- 3 Rock Deformation.- 3.1 Rock tests in compression.- 3.2 Rock deformation in compression.- 3.3 Mechanics of microfracture.- 3.4 Rock macrofracture.- 3.5 The complete rock deformation curve.- 4 Rock Strength and Yield.- 4.1 Rock strength criteria.- 4.2 Yield criteria.- 4.3 The critical state concept.- 4.4 Triaxial testing.- 4.5 Axial and volumetric strain data.- 4.6 The Hvorslev surface in rocks.- 5 Time Dependency.- 5.1 Creep strain.- 5.2 Phenomenological models of creep.- 5.3 Time-dependent deformation.- 5.4 Time-dependent strength reduction.- 5.5 Cyclic loading.- 5.6 Rapid loading.- 6 Discontinuities in Rock Masses.- 6.1 Discontinuity measurement.- 6.2 Discontinuity orientation data.- 6.3 Shear resistance of a rock containing a discontinuity.- 6.4 Shear resistance of a discontinuity.- 6.5 A critical state model for rock discontinuity strength.- 6.6 Measurement of discontinuity shear resistance.- 7 Behaviour of Rock Masses.- 7.1 Discontinuity frequency.- 7.2 Rock mass classification systems.- 7.3 Rock mass strength criterion.- 7.4 The relevance of rock mass strength.- References.- Author Index.
114 citations
TL;DR: In this article, the authors proposed a new approach based on maximum tangential principal stress (MTPS) to predict the angle of crack extension, critical load and unstable crack paths.
Abstract: Predictions for the angle of crack extension, critical load and unstable crack paths based on the criteria of maximum tangential stress (MTS), maximum tangential strain (MTSN) and strain energy density (SED) for angled slit and elliptical cracks under uniaxial tensile loading are compared. The tangential stress associated with the MTS criterion need not be a principal stress and a new approach to this criterion is suggested. A criterion based on maximum tangential principal stress (MTPS) is proposed. Predictions by these two criteria are compared. Some difficulties associated with the application of the SED criterion are indicated. A new basis, which permits a unification of all the criteria in respect of prediction of critical load, is suggested. Some of the results have been compared with data available in the literature.
112 citations
01 May 1983
103 citations
TL;DR: The concept of the envelope curve which was based primarily on plain concrete is extended to confined concrete subjected to cyclic loading as mentioned in this paper, and analytical expressions were developed to predict the envelope curves as well as the peak strength and the corresponding strain.
Abstract: The concept of the envelope curve which was based primarily on plain concrete is extended to confined concrete subjected to cyclic loading. Spirally confined normal weight and light weight concrete specimens were subjected to stress and strain cycling loadings at low as well as high strain rates. Analytical expressions were developed to predict the envelope curve as well as the peak strength and the corresponding strain. All analytical expressions are functions of plain concrete strength (fc′) and the confinement index (fr) which is a measure of the effective confinement.
01 May 1983
TL;DR: In this article, a triaxial stress-strain relation is proposed to describe gradual strain-softening with reduction of tensile stress to zero, which is applicable under general loading, including rotating principal stress directions.
Abstract: : Dynamic fracture analysis of concrete structures necessitates a triaxial stress-strain relation that describes gradual strain-softening with reduction of tensile stress to zero. A new model which does that and is applicable under general loading, including rotating principal stress directions, is a proposed. It is based on accumulating stress relaxations due to microcracking from the planes of all orientation within the microstructure. Comparisons with tensile test data are given.
TL;DR: In this article, the incremental theory of plasticity is employed in conjunction with the finite element method for determining the stresses in a tensile specimen containing a center crack, and a net section yield is developed.
TL;DR: Physical ageing of polyethylene terephthalate (PET) is associated with the conventional glass formation process, which occurs at a more rapid rate at higher temperatures as mentioned in this paper, and is accompanied by a marked change in mechanical properties, increased tensile yield stress and drawing stress, more localized yielding of the polymer and a marked decrease in impact strength.
TL;DR: In this article, the results of mechanical tests involving uniaxial compression of isotropic ice at −5°C were analyzed and interpreted, giving much the same information about failure strains, strength, creep rates, time to failure, stress/strain-rate relations, and suchlike.
TL;DR: In this article, a review of the current state-of-the-art concerning the use of the modulus of subgrade reaction (Winkler) model indicates that there is considerable disagreement concerning the correct method for interpreting and evaluating the Modulus of Subgrade Reaction, k, k. Extension of previous work, which used the simplified continuum approach to solve a problem in the theory of elasticity, shows that the Winkler subgrade model actually defines an elastic body of finite thickness in which all stress and strain components are assumed to be zero except for the vertical normal stress
Abstract: A review of the current state-of-the-art concerning the use of the modulus of subgrade reaction (Winkler) model indicates that there is considerable disagreement concerning the correct method for interpreting and evaluating the modulus of subgrade reaction, k. Extension of previous work, which used the simplified continuum approach to solve a problem in the theory of elasticity, shows that the Winkler subgrade model actually defines an elastic body of finite thickness in which all stress and strain components are assumed to be zero except for the vertical normal stress and strain. Furthermore, the modulus of subgrade reaction, k, is defined explicitly to be a function of the Young's modulus and thickness of the elastic body. Solutions for a Young's modulus that is constant with depth, as well as one that varies linearly and with the square root of depth, are presented. Although the simplified continuum approach offers an analytically rigorous and consistent method for evaluating the modulus of subgrade re...
TL;DR: In this article, the Cottrell-Stokes relation is observed at low stresses, but deviation from it is prominent at high stresses, attributed to the plastic generation of defects which are more rate sensitive than monopole dislocations.
TL;DR: In this article, the authors derived the asymptotic stress and strain fields near the tip of a crack which propagates dynamically in a rate-sensitive solid under anti-plane shear and plane strain conditions.
Abstract: T he asymptotic stress and strain fields near the tip of a crack which propagates dynamically in a rate-sensitive solid are obtained under anti-plane shear and plane strain conditions. The problem is formulated within the context of a small-strain theory for a solid whose mechanical behavior under high strain rates is described by an elastic-viscoplastic constitutive relation. It is shown that, if the stresses are singular at the crack-tip, the viscoplastic relation is equivalent asymptotically to an elastic-non-linear viscous relation. Furthermore, for a certain range of the material parameter which characterizes the rate-sensitivity of the material, the elastic strain-rates near the propagating crack tip are shown to have the same asymptotic radial dependence near the propagating crack-tip as the inelastic strain-rates. This determines the order of the stress singularity uniquely. The governing equations for anti-plane shear and plane strain are then derived. The numerical results for the stress and strain fields are presented for anti-plane shear and plane strain. For the present model, the results suggest that under small-scale yielding conditions, there exists a minimum velocity for stable steady crack propagation. The implication that a terminal velocity for a running crack may exist is also discussed.
TL;DR: In this article, a finite element analysis of high speed silicon sheet growth was used to examine factors affecting residual stress and buckle formation for growth of silicon ribbon by the EFG method.
TL;DR: In this article, a series of static cyclic tests were performed on cubical saturated sand specimens in undrained conditions using a true triaxial test apparatus, and the analysis of stress and strain increment vectors on the octahedral plane showed that the sand manifests the deformation characteristics like an elastic body at the beginning of cyclic loading where the developed pore water pressure is still small.
TL;DR: In this paper, the elasticity of polyethylene fibres were crosslinked by means of 60Coγ-radiation and the equilibrium elasticity behavior of the thus obtained networks was studied.
Abstract: Ultra-high strength polyethylene fibres were crosslinked by means of60Coγ-radiation. The equilibrium elasticity behaviour of the thus obtained networks was studied. The elastic modulus of the dry network, from which the sol-fraction was extracted, was found to be 10 times larger than the modulus of the same network in the swollen state or in the dry state prior to the extraction. This effect, that could not be attributed to oxidative degradation, is explained by the presence of a large amount of pendant chains in the fibre-networks. In the melt, after removal of the sol-fraction, the pendant chains are thought to establish severe constraints on the network chains, resulting in an increment of the elastic modulus of the polyethylene network.
TL;DR: In this article, the influence of internal hydrogen on the multiaxial stress-strain behavior of commercially pure titanium has been studied, and a strain dependent, texture-induced strengthening effect in equibiaxial tension is observed, this effect having the form of an enhanced strain hardening rate.
Abstract: The influence of internal hydrogen on the multiaxial stress-strain behavior of commercially pure titanium has been studied. Thin-walled tubing specimens containing either 20 or 1070 ppm hydrogen have been tested at constant stress ratios in combined tension and internal pressure. The addition of hydrogen lowers the yield strength for all loading paths but has no significant effect on the strain hardening behavior at strains e ≥ 0.02. Thus, the hydrogen embrittlement of titanium under plain strain or equibiaxial loading is not a consequence of changes of flow behavior. The yielding behavior of this anisotropic material is described well by Hill’s quadratic yield criterion. As measured mechanically and by pole figure analysis, the plastic anisotropy changes with deformation in a manner which depends on stress state. Hill’s criterion and the associated flow rule do not describe the multiaxial flow behavior well because of their inability to account for changes of texture which depend on multiaxial stress path. Hence, a strain dependent, texture-induced strengthening effect in equibiaxial tension is observed, this effect having the form of an enhanced strain hardening rate.
TL;DR: In this article, the fundamental stress-strain-time relationships of soil skeletons including sand and clay caused by the deviatoric stress are theoretically formulated for various stress levels and are simulated by a mechanical model.
TL;DR: In this paper, the generalized equivalent energy method, the Neuber method and the Hardrath-Ohman method are compared for low carbon steel and the results are in good agreement with experimental data.
TL;DR: In this article, an experimental technique for directly measuring strain-induced stiffening effects in individual carbon fibers has been developed, which involves the superposition of a small amplitude oscillating strain (Δe∼10−4) on a slow linearly increasing strain (∼1.1×10−3 s−1).
Abstract: An experimental technique for directly measuring strain‐induced stiffening effects in individual carbon fibers has been developed. The technique involves the superposition of a small amplitude oscillating strain (Δe∼10−4) on a slow linearly increasing strain (∼1.1×10−3 s−1). Synchronous detection of the resultant ac component of the measured stress yields a signal proportional to the slope of the stress versus strain curve provided the modulation amplitude is small compared to the ultimate strain at failure (∼0.005). The experimental arrangement has been designed for use in conjunction with an Instron tensile test apparatus. A novel design for a fiber gripping apparatus which permits direct measurement of the strain is also described. The technique has been applied to carbon fibers produced from two different precursor materials: polyacrylonitrile and mesophase pitch. Fibers from both precursors exhibited strain‐induced stiffening. The modulus of the pitch‐based fibers increased in proportion to the squar...
TL;DR: In this paper, an unload reload cycle can be used together with the hyperbolic stress strain model to find a soil modulus at any strain level, which is shown to vary with the level of stress confinement.
Abstract: Conventionally, a first loading modulus and a limit pressure are obtained from a pressuremeter test curve. This article shows how much information on the soil modulus can be obtained from a pressuremeter test. Soil moduli vary with the strain level. The pressuremeter modulus is measured at a large strain level; it is shown how an unload reload cycle can be used together with the hyperbolic stress strain model to find a soil modulus at any strain level. Soil moduli vary With the level of stress confinement. It is shown how an unload‐reload cycle can be used together with a power law to find the stress dependency of the soil modulus. Soil moduli vary with the number of unload reload cycles. One pressuremeter test with 100 unload‐reload cycles is presented; it is shown how the modulus and the plastic strain vary with the number of cycles.
TL;DR: In this paper, a finite element method was used to study the distribution of stress and strain in the interlayer during the onset of yielding, through general yielding, to a strain of 12%.