Showing papers on "Residual stress published in 1983"
TL;DR: In this article, the authors examined several important issues concerning the mechanical properties of coatings, films, and layers and described the conditions needed to induce buckling and subsequent spalling.
Abstract: This paper examines several important issues concerning the mechanical properties of coatings, films, and layers. Major emphasis has been placed on descriptions of residual stresses and their influence on mechanical failure of the coating. The residual stresses are shown to depend on the details of the coating or oxidation process, the general curvature of the substrate, the waviness of the coating-substrate interface, and the stress relaxation characteristics of the coating. Residual stress-induced coating failures, which consist either of coating fractures or spalling, are described. The latter is usually more serious and has been afforded primary attention. It is shown that spalling of the coating is a consequence of buckling, when the coating is subject to significant residual compression. The conditions needed to induce buckling and subsequent spalling are described.
257 citations
01 Jan 1983
TL;DR: It is indicated that there is advantageous residual stress in the artery by virtue of which the actual maximum in vivo circumferential stress is lower than what would be computed on the basis of assuming the natural configuration to be stress-free.
Abstract: Publisher Summary In characterizing the mechanical properties of the arterial tissue, it is customary to assume that the configuration that a cylindrical arterial segment assumes when the intravascular and extravascular pressures and the longitudinal force acting on it are zero is stress-free. Similarly, also in uniaxial stress tests on arterial strips it is generally assumed that the initial straight configuration of the strip prior to the application of axial load is stress-free. This crucial assumption has never been experimentally substantiated. This chapter discusses this assumption and show that it is not warranted. It presents the results that indicate that the aorta is in a state of residual strain and stress when it is in a configuration which is circumferentially intact but free from external forces. This is contrary to what is generally assumed to be the case. It is of interest to compare the residual stresses with the normal, in vivo circumferential stress. The maximum residual stress is approximately 14 to 17% of the mean in vivo circumferential engineering stress. A similar error is also implicit when an initially curved strip is straightened out prior to subjecting it to a uniaxial tensile stress test. These findings indicate that there is advantageous residual stress in the artery by virtue of which the actual maximum in vivo circumferential stress is lower than what would be computed on the basis of assuming the natural configuration to be stress-free.
189 citations
TL;DR: In this paper, the micromechanics of failure emanating from machining-induced cracks in brittle materials are investigated and two components of residual stress have been identified: a crack-wedging force due to the plastic zone beneath the strength-controlling machining groove, and a compressive surface layer due to adjacent grooves.
Abstract: The micromechanics of failure emanating from machining-induced cracks in brittle materials is investigated. In situ monitoring of crack response during breaking tests (with use of acoustic wave scattering), strength measurements and post-failure fractography all indicate that the crack response is dominated by residual stresses. Two components of residual stress have been identified: a crack-wedging force due to the plastic zone beneath the strength-controlling machining groove, and a compressive surface layer due to adjacent grooves. The wedging force dominates and causes stable equilibrium crack extension during a breaking test. The implications of the results for non-destructive evaluation of surface damage by acoustic wave scattering is discussed.
175 citations
TL;DR: In this paper, the authors used time-of-flight neutron diffraction, using the General Purpose Powder Diffractometer at the IPNS (Intense Pulsed Neutron Source) at the Argonne National Laboratory, to measure residual stresses in deformed, polycrystalline Zircaloy-2.
124 citations
TL;DR: In this paper, a new approach for using acoustic measurements to evaluate residual stresses in the presence of unknown material property variation is presented, and a practical experimental procedure is developed that permits the evaluation of the inplane components of the principal stresses in a plate exhibiting an unknown inhomogeneous initial anisotropy caused by material texture or microstructure.
Abstract: In this paper a new approach for using acoustic measurements to evaluate residual stresses in the presence of unknown material property variation is presented. Procedures previously applied to the evaluation of stress with acoustic measurements are reviewed, and it is shown that these involve using measurements with bulk waves propagating along the normal to the surface of a plate and do not provide sufficient information to separate the influences of stress and material property variations. To overcome this fundamental limitation, an alternative theory is developed that governs the propagation of shear waves polarized horizontally with respect to the surface of a plate (SH waves), but propagating at oblique angles with respect to the surface normal. The question of separating the effects of residual stress and material properties on acoustic velocity is addressed in detail. A practical experimental procedure is developed that permits the evaluation of the in‐plane components of the principal stresses in a plate exhibiting an unknown inhomogeneous initial anisotropy caused by material texture or microstructure. The procedure is then verified experimentally using an aluminum specimen with a known residual stress state, but unknown initial anisotropy.
103 citations
TL;DR: In this paper, the residual stresses after die-attachment have been studied experimentally using a test chip with diffused resistor strain gauges, and extensive measurements were reported for the following dieattachment/leadframe combinations: Au-Si/Alloy 42, epoxy adhesive/ Copper 194, and polyimide adhesive/Copper 194.
Abstract: The residual stresses after die-attachment have been studied experimentally using a test chip with diffused resistor strain gauges. Extensive measurements are reported for the following dieattachment/leadframe combinations: Au-Si/Alloy 42, epoxy adhesive/ Copper 194, and polyimide adhesive/Copper 194. Two-dimensional distributions of the stresses in the device surface are shown, and additional thickness measurements of the adhesive layer are used to assess the amount of stress relaxation occuring in adhesive die-attachment. Large variations in the measured stresses were found for die-attachment with polyimide adhesive. Thickness measurements and radiography showed that the stress variations are caused by large voids formed during the drying cycle of the adhesive. The effect of voids on die-attachment stresses is analyzed, and its potential as a cause of vertical die-cracking is discussed.
100 citations
TL;DR: In this article, a theory for the general fatigue response of brittle flaws which experience residual stress concentrations is formulated for the indentation crack, which is taken as a model flaw system for the purpose of setting up the basic fracture mechanics equations, but the essential results are expected to have a wider range of applicability in the strength characterization of ceramics.
Abstract: A theory is formulated for the general fatigue response of brittle flaws which experience residual stress concentrations. The indentation crack is taken as a model flaw system for the purpose of setting up the basic fracture mechanics equations, but the essential results are expected to have a wider range of applicability in the strength characterization of ceramics. A starting fatigue differential equation is first set up by combining an appropriate stress intensity factor for point- or line-contact flaws with a power-law crack velocity function. Analytical solutions are then obtained for the case of static fatigue. The resulting relation between lifetime and failure stress is shown to have exactly the same power-law form as the conventional solution for Griffith (residual-stress-free) flaws. This “equivalence” is used as a basis for extending the results to dynamic fatigue. A comparison of these analytical solutions with numerical counterparts defines the limits of accuracy of the theoretical procedure. However, while the form of the lifetime relation remains invariant, the values of the exponent and coefficient differ significantly for flaws with and without residual stress. Accordingly, the application of conventional fatigue theory to evaluate crack velocity parameters, without due regard for the nature of the critical flaw, can lead to serious errors. Explicit conversion formulas are given for transforming “apparent” velocity parameters for indentation flaws directly into “true” parameters. The implications of these results concerning the use of the indentation method for materials evaluation are discussed.
100 citations
89 citations
TL;DR: In this article, a new method for the analysis of multiaxial residual stress states is presented, which is based on high resolution neutron diffraction, analogous to X-ray stress analysis, but the use of neutrons instead of X-rays allows to analyse the stress distributions also in the interior of technical components in a non-destructive way.
86 citations
TL;DR: In this paper, a three-dimensional pseudo-macrostress field is described, and the stresses in the direction of the surface normal can be measured with X-rays, but only if there is a uniform plastic deformation in the sampled volume that is different from that in the rest of the material.
Abstract: True macro-stresses are measured with X-rays after material processing, only if there is auniform plastic deformation in the sampled volume that is different from that in the rest of the material. In this stress-field the components in the direction of the surface normal are usually negligible over the depth penetrated by X-rays (for example, peening). However, pseudo-macrostresses, or backstresses, arise when this condition is violated, for example, if there are second phase particles and there is a gradient of plastic deformation from particle to matrix. This pseudo-macrostress field is three-dimensional, and the stresses in the direction of the surface normal can be measured with X-rays. Equations are presented which allow estimates to be made of the magnitudes of the two kinds of stress fields.
78 citations
TL;DR: In this paper, an X-ray diffraction technique was used to measure the residual surface stresses on ground surfaces of Al2O3/ZrO2 (tetragonal) composites.
Abstract: An X-ray diffraction technique was used to measure the residual surface stresses on ground surfaces of Al2O3/ZrO2 (tetragonal) composites. To accomplish this, it was necessary to use a radiation for which the penetration depth was small (large wavelength), e.g. CrKα radiation. It was found that these materials could have compressive stresses as high as 1 GPa on their surface, which is a result of the molar volume associated with the tetragonal-to-monoclinic ZrO2 phase transformation. This transformation was induced by the grinding stresses and a reasonable correlation between the amount of ZrO2 transformed and the magnitude of the residual stresses was established. Evidence was found that the transformation depth is controlled by the amount of stabilizing oxide added to the ZrO2 and by the ZrO2 grain size. In the materials studied, transformation depths were found to be typically <20 μm.
Patent•
10 Mar 1983
TL;DR: In this article, a structure coated with graded ceramic material and methods of coating application are discussed, and techniques for maintaining low stress to strength ratios across the depth of the coating are discussed.
Abstract: Structure coated with graded ceramic material and methods of coating application are disclosed. Techniques for maintaining low stress to strength ratios across the depth of the coating are discussed. In one particular structure the coating is applied to a metal substrate (12) and comprises a metallic bond coat (14), a first interlayer (16) of metal/ceramic material, a second interlayer (18) of metal/ceramic material having an increased proportion of ceramic and an all ceramic layer. Modulation of the metal substrate temperature during the coating process establishes a desired residual stress pattern in the part.
TL;DR: In this article, the elasticity problem for a long hollow circular cylinder containing an axisymmetric circumferential crack subjected to general nonaxismmetric external loads is considered.
Abstract: The elasticity problem for a long hollow circular cylinder containing an axisymmetric circumferential crack subjected to general nonaxisymmetric external loads is considered. The problem is formulated in terms of a system of singular integral equations with the Fourier coefficients of the derivative of the crack surface displacement as density functions. The stress intensity factors and the crack opening displacement are calculated for a cylinder under uniform tension, bending by end couples, and self-equilibrating residual stresses.
TL;DR: In this paper, an analysis of the stress intensity factor due to residual stress is made for a crack perpendicular to the welding joint in a large plate, where the residual stress distribution is represented by a simple function which is chosen to satisfy the physical requirements for residual stress and to simulate the commonly observed distribution.
Abstract: An analysis of the stress intensity factor due to the residual stress is made for a crack perpendicular to the welding joint in a large plate. The residual stress distribution is represented by a simple function which is chosen to satisfy the physical requirements for the residual stress and to simulate the commonly observed distribution. The stress intensity factor is obtained using customary method based on the superposition principle. The function chosen for the residual stress distribution leads to an exact expression of the stress intensity factor in a simple closed form. The solution yields somewhat conservative values of the stress intensity factor for large cracks and it may be conveniently used for practical applications.
TL;DR: In this paper, the authors investigated the effect of normal stresses on the accuracy of traditional residual stress determination methods by X-ray and showed that appreciable error can exist in surface stresses determined by such methods, if normal stresses are present.
Abstract: The assumption, that stress components in the direction of the surface normal are negligible in traditional residual stress determination methods by X-rays, has been recently disproved. In this paper we investigate the effect of normal stresses on the accuracy of these traditional methods. It is shown that appreciable error can exist in surface stresses determined by such methods, if normal stresses are present. New procedures are proposed to minimize these errors.
TL;DR: In this article, the authors investigated the processes involved in the nucleation of grain boundary cavities in aslroloy and concluded that the same mechanism is responsible for the initial grain boundary damage in all cases.
TL;DR: In this article, the authors present an analysis of previously published turbulence data which confirms the existence of this residual stress and indicates its generation in the lowermost part of the buffer layer of turbulent shear flows.
Abstract: Bagnold's dynamic theory for sediment suspension requires that the immersed weight of suspended grains over unit bed area is supported by an upward-directed residual Reynolds stress, τyy, arising from asymmetrical shear turbulence. The present paper presents an analysis of previously published turbulence data which confirms the existence of this residual stress and indicates its generation in the lowermost part of the buffer layer of turbulent shear flows. The magnitude of τyy is estimated as about 0.3τyx. Calculations from experimental data on suspended fine sand transport over upper phase beds reveals that τyy, is in approximate equilibrium with the weight stress due to the suspended load.
TL;DR: In this article, a theoretical approach for predicting the strengthening of brittle materials subjected to a residual stress distribution represented by a polynomial series is presented, where the effect of crack closure is considered.
Abstract: A theoretical approach is presented for predicting the strengthening of brittle materials subjected to a residual stress distribution represented by a polynomial series. In the approach, the stress intensity factor for a surface crack is derived incorporating the effect of crack closure. The crack-closure distance is then calculated using an approximate approach which allows the strengthening due to the residual stresses to be estimated. Illustrating the approach using residual stresses typical of tempering, it was found the approach agreed well with previous work. The influence of partial crack closure was found to give higher values of the stress intensity factor than would be calculated if the crack were assumed to be open. This effect decreases the amount of strengthening predicted and gives a wide range of conditions for which subcritical crack-growth processes can occur. For the example of tempering it was also found that these are conditions when weakening or spontaneous failure of the body can occur.
TL;DR: The residual stresses that develop during the wear of AISI-SAE 1018 and 4340 steels have been examined in this article, where the entire three-dimensional stress tensor was obtained.
TL;DR: In this paper, the heat-to-heat variation in the creep strength and ductility of austenitic stainless steels was reviewed from the viewpoint of residual and trace element effects.
Abstract: The heat-to-heat variation in the creep strength and ductility of austenitic stainless steels was reviewed from the viewpoint of residual and trace element effects. Based on data reported in the literature, the creep strength of unstabilized alloys such as types 304 and 316 stainless steel increased with residual element and trace element content. Niobium appeared to be the most potent strengthener. There was no direct evidence that trace elements such as sulfur and phosphorus had a deleterious effect on either strength and ductility. It was assumed that the creep strength and ductility of the unstabilized grades of austenitic stainless steels are controlled by the precipitate characteristics. It follows from this that thermomechanical treatment or residual element additions that affect the precipitate characteristics influence subsequent time dependent mechanical properties. This view is consistant with most of the information in the literature. It was concluded that more systematic studies of trace and residual element effects would be beneficial to the improvement of steels. Incorporated into the studies should be quantitative characterization of evolving precipitate morphology and composition as they are influenced by residual elements. This information should be incorporated into modeling studies of non-equilibrium segregation. Ultimately, optimum elevated-temperature strength could be developed based on a materials science approach.
01 Jan 1983
TL;DR: In this article, the authors used surface acoustic wave scattering as a method of non-destructive evaluation in the context of the indentation flaw model; the technique provided direct evidence that machining induced cracks are subjected to residual stress effects.
Abstract: Recent advances in the analysis of elastic/plastic indentation fracture, as a model for contact induced damage, are reviewed The central feature of the analysis is the dominant role played by the residual stress in the evolution of the two major crack systems (one relating to strength and the other relating to material removal), and in the subsequent response of the cracks to an applied tension0 The use of surface acoustic wave scattering as a method of non-destructive evaluation is discussed in the context of the indentation flaw model; the technique provides direct evidence that machining induced cracks are subjected to residual stress effects
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 paper, computer simulations were used to study the propagation of cracks coated with thin solid films in a 2D triangular Lennard-Jones solid and the key parameter investigated was the mismatch in the interatomic distances of the film and the substrate (the eleastic moduli were kept the same).
TL;DR: In this paper, an energy dissipation model was developed to predict the residual strength of graphite-epoxy T300/5208 composite laminates from impact damage by a cantilever-type instrumented 1-inch diameter steel ball.
Abstract: This report contains the study of Low Velocity Transverse Impact Damage of graphite-epoxy T300/5208 composite laminates. The specimen, 100 mm diameter clamped plates, were impact damaged by a cantilever-type instrumented 1-inch diameter steel ball. Study was limited to impact velocity 6 m/sec. Rectangular strips, 50 mm x 125 mm, were cut from the impact-damage specimens so that the impact damage zone was in the center of the strips. These strips were tested in tension to obtain their residual strength. An energy dissipation model was developed to predict the residual strength from fracture mechanics concepts. Net energy absorbed I(a) was evaluated from coefficient of restitution concepts based on shear dominated theory of fiber-reinforced materials, with the modification that during loading and unloading the shear deformation are respectively elastic-plastic and elastic. Delamination energy I(d) was predicted by assuming that the stiffness of the laminate dropped due to debonding. Fiber-breakage energy, assumed to be equal to the difference of I(a) and I(d), was used to determine the residual strength. Predictions were compared with test results.
TL;DR: In this article, the residual stresses obtained during shot-peening are directly proportional to the treated material's hardness, and the depth of material influenced depends on the velocity of approaching shot.
Abstract: It is shown that the residual stresses obtained during shot-peening are directly proportional to the treated material's hardness, and that the depth of material influenced depends on the velocity of approaching shot. The relationship between the shot size and depth hardened is developed, and experimental evidence is provided to verify the major points of the analysis. Useful curves, enabling the variation of residual stress with depth to be estimated, are included, and this enables the shot-peening treatment to be matched to alleviate any subsequent contact-pressure loading that the material may experience during service.
TL;DR: In this article, the authors used various light microscopy and SEM techniques to study the temperature dependence of deformation structures around hardness indentations in highly brittle ceramics (including single crystals of silicon and silicon carbide and polycrystalline forms cf SiC, Si3N4 and B4C).
Abstract: SUMMARY
Various light microscopy and SEM techniques have been used to study the temperature dependence of deformation structures around hardness indentations in highly brittle ceramics (including single crystals of silicon and silicon carbide and polycrystalline forms cf SiC, Si3N4 and B4C). Nomarski differential interferometry has enabled slip steps to be resolved around high-temperature indentations, allowing identification of the dominant slip systems and measurement of the extent of surface plasticity as a function of temperature. The occurrence of indentation fracture as a function of both temperature and specimen microstructure was studied by SEM methods (including stereo imaging), Nomarski differential interferometry and polarized reflection light microscopy. Generally, radial and lateral crack sizes increased with increasing temperature, due to increasing residual stresses around indentations caused by increasing indentation plasticity. Examples of microstructural control of crack paths are given for various single crystal and polycrystalline materials.
TL;DR: In this paper, a simple mathematical model for predicting residual stresses in injection-molded parts has been constructed, using a nonlinear viscoelastic constitutive equation to yield better quantitative results than previously obtained.
Abstract: A simple mathematical model for predicting residual stresses in injection‐molded parts has been constructed. The use of a nonlinear viscoelastic constitutive equation allows the model to yield better quantitative results than previously obtained. The model fails to predict the existence of birefringence along the midplane of the molded part, which is thought to be due to inhomogeneous cooling (i.e., thermal stress).
TL;DR: In this paper, the authors analyzed the stresses and deformations in a thin ring-disk shrink fit assembly and found the interface pressure for the presumed plane stress state as a function of the interference of the fit.
TL;DR: In this paper, the residual stresses induced during sliding contact of a series of Cu-Al alloys of various stacking fault energies (SFEs) using the conventional two-exposure X-ray technique were analyzed.