Showing papers on "Stress–strain curve published in 1990"
TL;DR: The principal findings were that the ultimate strain and the work under the stress-strain curve declined sharply with mineralisation, as did the stress and strain appearing after the specimen had yielded.
226 citations
TL;DR: In this paper, the deformation theory of plasticity is used to model the stress-strain characteristics of the adhesive, with the stressstrain curve itself being approximated by any continuous mathematical function.
151 citations
151 citations
TL;DR: In this article, the stress-strain curves of MDPE samples show strong evidence that yielding involves two thermally activated rate processes operating co-operatively, but having different activation parameters relative to both the temperature dependence and the strain-rate dependence.
Abstract: The stress-strain curves of MDPE samples show strong evidence that yielding of MDPE involves two thermally activated rate processes operating co-operatively, but having different activation parameters relative to both the temperature dependence and the strain-rate dependence
97 citations
TL;DR: In this paper, the strain-rate sensitivity of the cement paste and mortar constituents of concrete is studied experimentally, in terms of the initial elastic moduli, maximum stress, and corresponding strain.
Abstract: The strain-rate sensitivity of the cement paste and mortar constituents of concrete is studied experimentally. Saturated cement paste and mortar specimens are loaded in compression to 15,000 microstrains, 27 to 29 days after casting, using strain rates ranging from 0.3 to 300,000 microstrains/sec. Water-cement ratios of 0.3, 0.4, and 0.5 are used. Strain-rate sensitivity of the material is measured in terms of the initial elastic moduli, maximum stress, and corresponding strain. The initial elastic moduli and the strength of cement paste and mortar increase by 7% and 15%, respectively, with each order of magnitude increase in strain rate. The strain at the maximum stress is the greatest for the lowest strain rate. With an increase in strain rate, the strain at the maximum stress first decreases and then increases.
90 citations
TL;DR: In this paper, mixed-mode elastic-plastic fracture tests were carried out by using A5083-O aluminum alloy compacttension-shear specimens, in which the angle between the loading axis and the crack surface was varied from 90° (mode I) to 0°(mode II) by employing a special loading device.
Abstract: M ixed mode elastic-plastic fracture tests were carried out by using A5083-O aluminum alloy compacttension-shear specimens, in which the angle between the loading axis and the crack surface was varied from 90° (mode I) to 0° (mode II) by employing a special loading device. A fractographic investigation was made at various stages of crack tip blunting and stable crack growth. Under mixed mode loadings, opposite deformations appeared at the crack tip: sharpening and blunting. With increasing mode II component, cracks due to shear type fracture initiated at the sharpened corner of the crack tip near the surfaces of the specimen, and then another crack due to dimple type fracture occurred at the blunted corner of the crack tip near the midthickness of the specimen. These experimental results were explained qualitatively by taking account of the stress and strain singularities and triaxial stress distributions near the surface and midthickness of the specimen. Fracture mechanics parameters appropriate for mixed mode elastic-plastic fractures were also studied based on the experimental data.
89 citations
TL;DR: In this article, the authors present plane-stress crack-tip stress and strain fields for pressure-sensitive dilatant materials, where a hydrostatic stress-dependent yield criterion and the normality flow rule are used to account for pressure sensitive yielding and plastic dilatancy.
Abstract: Abstraet--In this paper we present plane-stress crack-tip stress and strain fields for pressure-sensitive dilatant materials. A hydrostatic stress-dependent yield criterion and the normality flow rule are used to account for pressure-sensitive yielding and plastic dilatancy. The material hardening response is specified by a power-law relation. The plane-stress mode I singular fields are found in a separable form similar to the HRR fields (Hutchinson, J. Mech. Phys. Solids 16, 13-31 and 337-347, 1968; Rice and Rosengren, J. Mech. Phys. Solids 16, l-12, 1968). ‘Ihe angular variations of the fields depend on the material hardening exponent and the pressure sensitivity parameter. Our low-hardening solutions for d&rent degrees of pressure sensitivity agree well with the corresponding perfectly plastic solutions. An important aspect of the eRecta of pressure.-sensitive yielding and plastic dilatancy on crack-tip fields is the lowering of the opening stress and the hydrostatic stress directly ahead of the crack tip. This effect, similar to that under plane-strain conditions (Li and Pan, to appear in J. Appl. Mech. 1989), has implications in the material toughening observed in some ceramic and polymeric composites.
89 citations
TL;DR: In this paper, a series of experiments involving a wide range of principal stress axes directions were carried out on hollow cylindrical specimens of Toyoura sand using a torsional shear test apparatus.
84 citations
TL;DR: In this article, the relationship between midgap interface state density (Dit) and thickness-averaged stress in thermally grown SiO2 thin films has been investigated by infrared spectroscopy, an optical beam deflection technique, and capacitance-voltage measurements.
Abstract: Correlations between midgap interface state density (Dit) and thickness‐averaged stress in thermally grown SiO2 thin films have been investigated by infrared spectroscopy, an optical beam deflection technique, and capacitance‐voltage measurements. We find no correlations between Dit and either (i) the maximum stress in the Si or SiO2 at the Si/SiO2 interface or (ii) the stress gradient in the SiO2 film. By direct measurements of the strain‐induced bending of the Si wafer, and by calculating the microscopic strain from the SiOSi bond‐stretching vibrational frequency, we have established linear relationships between Dit and the thickness‐averaged stress and strain in the oxide.
77 citations
TL;DR: In this article, the authors evaluated the effective modulus of continuous fiber reinforced brittle matrix composite systems in which debonding and slipping between the constituents occurs and showed that the composite effective stiffness tensor becomes unsymmetric under certain interfacial conditions.
64 citations
TL;DR: In this paper, the authors investigated the compression yield stress behavior of engineering polycarbonates in the glassy state with a wide range of strain rates (10−4−4500 sec−1 and temperatures (−40 to 60°).
TL;DR: In this paper, the applicability of the uniform strain assumption is evaluated by comparing the results from the micro-structural continuum method to those from the computer simulation method, and two types of granular solids, viz. with linear bonded contacts and with nonlinear frictional contacts, are studied to investigate the influence of contact behavior on the heterogeneity of the strain field.
Abstract: The micro‐ and the macro‐mechanical measures of heterogeneous granular solids are investigated using two methods, namely a computer simulation method, and a micro‐structural continuum method. The micro‐structural continuum method used in this study is based on a uniform strain assumption. The applicability of the uniform strain assumption is evaluated by comparing the results from the micro‐structural continuum method to those from the computer simulation method. Two types of granular solids, viz. with linear bonded contacts and with nonlinear frictional contacts, are studied to investigate the influence of contact behavior on the heterogeneity of the strain field. It is observed that packings with bonded contacts have a reasonably homogeneous strain field, implying that the uniform strain assumption is applicable for this condition. Packings with frictional contacts have a heterogeneous strain field, except at low levels of deviatoric stress. The natures of inhomogeneity for the particle rotation, stress...
Book•
01 Apr 1990
TL;DR: Stress and strain transformation plane elasticity theory structures with symmetry bending of beams and plates theories of torsion moment distribution flexural shear flow energy methods instability of columns and plates finite elements yield and strength criteria plasticity and collapse creep and visco-elasticity high and low cycle fatigue fracture mechanics as discussed by the authors.
Abstract: Stress and strain transformation plane elasticity theory structures with symmetry bending of beams and plates theories of torsion moment distribution flexural shear flow energy methods instability of columns and plates finite elements yield and strength criteria plasticity and collapse creep and visco-elasticity high and low cycle fatigue fracture mechanics. Appendices: properties of areas matrix algebra stress concentrations.
TL;DR: In this article, the stress-strain behavior of saturated, remoulded clay has been investigated in a cuboidal plane strain apparatus and the most important properties refer to: the dependence of the stress response on the stress level, the asymptotic property of clay, the influence of the history of straining on stress response, and the dependence that the stress paths reaching the state boundary surface may move along this surface.
Abstract: The stress-strain behaviour of saturated, remoulded clay has been investigated in a cuboidal plane strain apparatus. The tests covered a variety of strain paths ranging from proportional paths starting from a slurry state to complex paths with up to two sharp bends. Both normally consolidated and overconsolidated samples were investigated. As a result of these observations, a list of material properties has been formulated. The most important properties refer to: the dependence of the stress response on the stress level, the asymptotic property of clay, the influence of the history of straining on the stress response, and the ohservation that the stress paths reaching the state boundary surface may move along this surface. The list of material properties is thought to be a guideline for development of constitutive theories. It provides also a useful framework within which the behaviour of natural clays may be qualitatively described. Le comportement contrainte/deformation de l'argile saturee remanise a et...
TL;DR: In this paper, a grid technique was used to determine the inhomogeneous strain field associated with a steadily growing neck and an extension of photoelasticity was used in obtaining the stress variation along the line of symmetry in the neck.
TL;DR: In this paper, the authors investigated the behavior of the material system over two length scales which are physically relevant, namely, distances comparable to the dominant plastic zone and the crack tip opening displacement.
Abstract: In previous analyses [1, 2, 13], and full-field computational investigations, we found that the near tip plastic fields of cracks on a bimaterial interface do not have a separable form of the HRR type. Nevertheless they appear to be nearly separable in an annular region well within the plastic zone. Asymptotically, as the crack tip is approached, the material system responds like that of a plastically deforming solid bonded to a rigid substrate; in particular, the stress and strain fields in the more compliant (lower hardening) material behave like those of a material with identical plastic properties bonded to a rigid substrate. Furthermore, the asymptotic fields of the interface crack bear strong similarities to mixed mode HRR fields for the homogeneous medium characterized by the plastic properties appropriate to the more (plastically) compliant material. In this investigation, we elucidate the behaviour of the material system over two length scales which are physically relevant, namely, distances comparable to the dominant plastic zone and the crack tip opening displacement. The latter is approximately given by the plastic zone size times and the relevant yield strain. Over length scales comparable to the dominant plastic zone, the stress fields are governed by the characteristics of the weaker (lower yield strength) material. On the other hand, the near tip plastic fields are governed by the strain hardening characteristics of the more plastically compliant (lower hardening) material.
TL;DR: In this article, the authors present plane-stress crack-tip stress and strain fields for pressure-sensitive dilatant materials, where a hydrostatic stress-dependent yield criterion and the normality flow rule are used to account for pressure sensitive yielding and plastic dilatancy.
TL;DR: In this article, an experimental investigation on the strength and behavior of short confined, reinforced concrete columns with and without steel fibers has been carried out, where the columns were subjected to monotonic axial compression until failure.
Abstract: An experimental investigation on the strength and behavior of short confined, reinforced concrete columns with and without steel fibers has been carried out. The columns were subjected to monotonic axial compression until failure. The volume fraction, 1.5 % and aspect ratio, 70 of steel fibers used, were the same in all the confined steel fiber reinforced concrete (SFRC) columns. The primary variable considered in this study was the amount of lateral steel. Four different percentages of volumetric ratio of lateral reinforcement, namely, 0.6, 0.8, 1.6, and 2.4 %, were used. The stress-strain characteristics and equivalent confinement conditons of confined SFRC and confined reinforced concrete columns were compared. As the earlier models proposed for confined reinforced concrete did not compare satisfactorily with the experimental values of confined SFRC specimens, an analytical model for confined SFRC was proposed. From the experimental study, it was observed that the addition of steel fibers improved the strength and strain at peak load of confined reinforced concrete columns significantly.
TL;DR: In this paper, as-solidified eutectic Pb-Sn solder joints exhibit superplastic behavior in shear creep loading, and the total shear deformation of joints in stress-rupture tests performed at 65° C are found to exceed 150%.
Abstract: This paper presents experimental evidence that as-solidified eutectic Pb-Sn solder joints can exhibit superplastic behavior in shear creep loading. Stepped load creep tests of as-solidified joints show a change in the stress exponent from a high value typical of con-ventional creep at high stress and strain rate to a superplastic value near 2 at lower stress and strain rates. In addition, the change in stress exponent is accompanied by a change in the activation energy for creep from a value near that for bulk self-diffusion (20 kcal/mol) to a value near that for grain boundary diffusion (12 kcal/mol). The total shear deformation of joints in stress-rupture tests performed at 65° C are found to ex-ceed 150%. The concomitant observation that quenched solder joints creep faster than air-cooled ones is attributed to a grain, or phase, size dependence of the strain rate. The source of superplastic behavior is a fine, equiaxed microstructure. It is not yet clear whether the superplastic microstructure is present in the as-solidified joint, or develops during the early stages of plastic deformation.
TL;DR: In this paper, the tensile load elongation curves to failure of samples cut along different directions from a extruded sheet of short-glass-fibre-reinforced polypropylene having good fibre alignment along the extrusion direction, were obtained at a strain rate of 0·01 min−1.
TL;DR: In this paper, the adaptation of the Iosipescu test as a method for determination of the stress and strain to failure and the shear modulus of adhesives under uniform shear conditions is described.
Abstract: The adaptation of the Iosipescu test as a method for determination of the stress and strain to failure and the shear modulus of adhesives under uniform shear conditions is described. The design and performance of a number of special purpose instruments and jigs to facilitate sample preparation, bond line thickness measurement, and shear displacement determinations are also described. Representative shear stress-strain curves of a nylon-epoxy film adhesive are presented.
TL;DR: Analysis of the elasticity tensor relating stress and strain within a solid shows that if the induced strain is restricted, then a greater stress is required to produce the same strain; it appears stiffer.
Abstract: If a solid body is deformed along one direction, by a uniaxial applied stress for instance, then strains will also be induced in perpendicular directions. The negative ratio of the induced strain to the applied strain is known as the Poisson ratio. Analysis of the elasticity tensor relating stress and strain within a solid shows that if the induced strain is restricted, then a greater stress is required to produce the same strain; it appears stiffer. Many biological materials with a mechanical function are subject to forces which are primarily uniaxial. This mechanism appears to be used to maximize the uniaxial load-bearing properties of some of these materials. Muscles are commonly surrounded by strong sheets of connective tissue which will constrain the lateral expansion of the muscle as it contracts. This increases the stress in the muscle for a given strain, and hence the load it can support. Similarly, cancellous bone is normally surrounded by a shell of much stronger compact bone and this effectively increases the stiffness of the cancellous bone without the penalty of increasing the mass, as would be the case if the same stiffening was produced by increasing the degree of calcification. It also has important implications for the failure of bone, which is largely a function of strain rather than stress.
TL;DR: In this paper, cylindrical compression samples were machined from the gauge section of their tensile specimens and tested in air at 1300 K. While microscopy indicates that rapid solidification technology can produce fine dispersions of TiB2, TiC and HfC in a NiAl matrix, the mechanical property data reveal that only hfC successfully strengthens the intermetallic matrix.
Abstract: To examine the potential of rapid solidification technology (RST) as a means to fabricate dispersion-strengthened aluminides, cylindrical compression samples were machined from the gauge section of their tensile specimens and tested in air at 1300 K. While microscopy indicates that RST can produce fine dispersions of TiB2, TiC and HfC in a NiAl matrix, the mechanical property data reveal that only HfC successfully strengthens the intermetallic matrix. The high stress exponents (above 10) and/or independence of strain rate on stress for NiAl-HfC materials suggest elevated temperature mechanical behavior similar to that found in oxide dispersion-strengthened alloys. Furthermore, an apparent example of departure side pinning has been observed, and as such, it is indicative of a threshold stress for creep.
TL;DR: In this paper, tensile impact testing was performed on both AS4 carbon/3501-6 epoxy and S2 glass composite unidirectional composites, and the neat (unreinforced) Hercules 3501 6 epoxy, using an apparatus designed and fabricated specifically for composite materials.
Abstract: Tensile impact testing was performed on both AS4 carbon/3501-6 epoxy and S2 glass/3501-6 epoxy unidirectional composites, and the neat (unreinforced) Hercules 3501-6 epoxy. Static tensile tests were also performed. The impact testing was conducted using an apparatus designed and fabricated specifically for composite materials. Impact test results indicated relatively little influence of varying the impact velocity from static to 5 m/s, a range of practical interest in design.
TL;DR: In this paper, local fatigue strength characteristic values for spot welded joints are compiled in the form of endurable local strains, structural stresses and stress intensity factors on the basis of an evaluation of published material.
TL;DR: In this article, the authors used microboudinaged competent piedmontite grains within a ductile quartz matrix to measure relative differential stress and strain in metamorphic belts in Japan.
TL;DR: In this article, the authors analyzed the dominant singularity solutions of the stress and strain field near an interface crack in a pure power-hardening bimaterial and showed that the crack stress singularity is −1/(nII+1) for hardening power of nI and nII(nI
Abstract: Analytical and numerical analysis of the dominant singularity solutions of the stress and strain field near an interface crack in a pure power-hardening bimaterial indicates that the crack stress singularity is −1/(nII+1) for hardening power of nI and nII(nI
TL;DR: In this article, the authors demonstrated how cushioning curves can be predicted from constant-strain rate measurements and a limited number of stress-relaxation or drop experiments, for rate-independent and rate-dependent foams, respectively.
Abstract: This study demonstrated how cushioning curves can be predicted from constant-strain rate measurements and a limited number of stress-relaxation or drop experiments. For rate-independent foams, only one stress-strain curve and the proposed dynamic model are required. For rate-dependent foams, however, a computer and appropriate software are also needed to predict accurately cushioning curves.
01 Jan 1990
22 Jan 1990
TL;DR: In this paper, the authors report on the strain distribution in optical fibers measured using Brillouin Optical-Fiber Time Domain Analysis (BOTDA) both before and after installation into the field conduit.
Abstract: The strength of optical fibers is lowered by stress applied to them especially at the point of maximum stress. Hence, it is necessary to measure, not only the average strain value along the whole fiber length(1), but also its spatial distribution, in order to guarantee the long term reliability of optical transmission lines(2). This is the first paper to report on the strain distribution in optical fibers measured using Brillouin Optical-Fiber Time Domain Analysis (BOTDA) (3)(4) both before and after installation into the field conduit.