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A criterion to predict under what conditions EAC would initiate in cracks in a high-sulfur steel in contact with low-oxygen water was recently proposed by Wire and Li (1996). This EAC initiation criterion was developed using transient analyses for the diffusion of sulfides plus experimental test results. The experiments were conducted mainly on compact tension-type specimens with initial crack depths of about 2.54 mm. The present paper expands upon the work of Wire and Li by presenting results for significantly deeper initial semi-elliptical surface cracks. In addition, in one specimen, the surface crack penetrated weld-deposited cladding into the high-sulfur steel. The results for the semi-elliptical surface cracks agreed quite well with the EAC initiation criterion, and provide confirmation of the applicability of the criterion to crack configurations with more restricted access to water.

As a part of the welding fabrication procedure development for the next generation space shuttle external tank, aluminum-lithium wide-panel specimens were used to assess the interactions between repair weld residual stresses and external loading conditions. The detailed residual stress development in the wide panel specimens with a repair weld was analyzed using an advanced finite element procedure. External tension loading effects were then incorporated in the residual stress model to study the interactions between the residual stress field and external tensile loading. Wide-panel tensile tests were also performed to extract photo strain and strain-gage results. A good agreement between the finite element and experimental results was obtained. The results demonstrate that the presence of high tensile residual stresses within a repair weld has a drastic impact on the stress/strain distribution in the wide panel specimens subjected to external loading. Its implications on structural integrity are discussed in light of the wide-panel results. The effects of post-welding mechanical treatment such as planishing were also examined.

The knowledge of residual stresses introduced in the tubes of heat exchangers during their expansion in the tubesheet holes is important because of their effect on the structural integrity of components. This paper presents a simplified theoretical method to calculate the maximum residual stresses introduced in the transition zone of expanded tube-to-tubesheet joint. The higher positive values of tensile residual stresses and their corresponding axial locations are determined by using a standard deviation analysis. The validation of the proposed equations was accomplished by comparing their results to those obtained by the finite element method for some arbitrary cases. An upper limit has been imposed on the expansion pressure level, depending on the combination of the geometrical and material parameters that are involved in the design of the tube-to-tubesheet joints.

Structures subjected to strong earthquake ground shaking may be left in a displaced condition. The amount of this residual or permanent displacement is determined by structural characteristics, including mass and hysteretic behavior, as well as ground motion. Residual displacement is undesirable because it presents problems during repair and reconstruction after an earthquake. This paper describes analyses of many single-degree-of-freedom bilinear oscillators, with different natural periods, damping ratios, ductility factors, bilinear factors, and input ground motions. These analyses were carried out in order to obtain a method of estimating the likely residual displacements of real single-degree-of-freedom structures. The residual displacement was normalized by the maximum possible residual displacement. Although there was scatter in the normalized residual displacement for different earthquake records, trends in behavior were dominated by the slope of post-yielding branch of bilinear loop. A residual displacement response spectrum is presented for design of a single-degree-of-freedom structures and a design application is also provided.

A numerical study of an aircraft fuselage's residual strength was conducted in the presence of both multiple site damage (MSD) and multiple element damage. This was done by developing a software package for the automated analysis of the fuselage panels at widespread fatigue damage conditions. Elastic-plastic analyses showed that the fuselage's residual strength was reduced in the presence of MSD. In addition, the location of the two-bay crack were seen to affect residual strength. Results highlighted the need for elastic-plastic fracture mechanics in the assessment process.

This paper focuses on developing a full-state observer that can be used to obtain unmeasurable reaction forces in a flexible structure. In the context of modal truncation of a distributed parameter system, accurate representation of reaction forces is discussed and is shown to require a more comprehensive model than for displacement representation. This fact, coupled with the difficulty in directly measuring reaction forces in many applications points to the need for accurate estimation of forces with reduced-order models. The residual flexibility, a term from past literature, is used to recapture some of the lost force information in a truncated model. This paper presents numerical and experimental results of a study where the residual flexibility is used in conjunction with a Kalman filter so that accurate force information may be obtained from a small set of displacement measurements with a reduced-order model. The motivation for this paper is to be able to obtain accurate information about dynamic bearing loads in a rotating machine for diagnostic and control purposes.

A negative Poisson's ratio is observed for 69% of the cubic elemental metals when stretched along the [110] direction. For these metals, there are correlations between the work function and the extremal values of Poisson's ratio for the stretch direction. This can be explained using a simple electron-gas model. There is practical significance associated with the existence of negative Poisson's ratios for the cubic metals, particularly as a negative Poisson's ratio reverses the compensation effects of positive Poisson's ratios on the volume and area changes created by a uniaxial stress.

Bending fatigue tests were conducted to investigate the fatigue strength of small-diameter socket welded pipe joints. In most cases of large-diameter socket joints, a fatigue crack started from the root of the fillet weld, though the stress amplitude at the root was smaller than that at the toe of the fillet weld. Additionally, the fatigue strength was affected by the weld bead sequence. The residual stress was considered to be one of the important parameters governing fatigue strength; therefore, its effects were investigated. In several types of pipe joints, the local stress and residual stress distributions were calculated by finite element analysis. The residual stresses were compressive at the toe and tensile at the root of the socket welded joints. Based on these results, the effects of residual stresses on the fatigue strength are discussed for small-diameter welded pipe joints in the present work.

The development and accuracy of an appropriate analytical model to predict the behavior of cold-formed steel (CFS) structural members necessitate a correct representation of the corresponding material characteristics. The results of two series of experimental investigations to evaluate the mechanical properties and the built-in residual stresses of CFS sections are reported in this paper. These investigations were performed on channel-shaped CFS sections manufactured using the cold-roll forming technique. Tensile coupon tests were used to evaluate the mechanical properties at different locations such as fiat area, and the comer areas, of the channel sections. Electrical resistance strain gauges with an 'electrical discharge machining' cutting technique were used to establish the magnitudes and the distributions of residual stresses within the channel sections. Based on the experimental results, appropriate analysis models for the stress-strain relationship, the variation of the yield strength, and the residual stresses in CFS channel sections have been established. The proposed analysis models for material properties have been incorporated within a large deformation shell finite element to form an analysis model for CFS sections. The efficiency and accuracy of the proposed material properties models have been evaluated by comparing the finite-element analysis results against corresponding experimental results of CFS sections subjected to axial compressive loads.

Byline: R. Skalak (1), D. A. Farrow (1), A. Hoger (1) Keywords: Key words:aGrowth; Horns; Shells; Residual stress Abstract: aIn this paper a general mathematical framework is developed to describe cases of fixed and moving growth surfaces. This formulation has the mathematical structure suggested by Skalak (1981), but is extended herein to include discussion of possible singularities, incompatibilities, residual stresses and moving growth surfaces. Further, the general theoretical equations necessary for the computation of the final form of a structure from the distribution of growth velocities on a growth surface are presented and applied in a number of examples. It is shown that although assuming growth is always in a direction normal to the current growth surface is generally sufficient, growth at an angle to the growth surface may represent the biological reality more fully in some respects. From a theoretical viewpoint, growth at an angle to a growth surface is necessary in some situations to avoid postulating singularities in the growth velocity field. Examples of growth on fixed and moving surfaces are developed to simulate the generation of horns, seashells, antlers, teeth and similar biological structures. Author Affiliation: (1) Department of Bioengineering - 0412, University of California, San Diego, La Jolla, CA 92093-0412, USA (e-mail: rskalak@ucsd.edu), US (2) Department of Applied Mechanics and Engineering Sciences, University of California, San Diego, La Jolla, CA 92093-0412, USA, US Article note: Received 20 February 1996 received in revised form 15 October 1996

Linear elastic solution of an axisymmetric boundary value problem is used as a basis to generate its inelastic solution. This method treats the material parameters as field variables. Their distribution is obtained as a part of solution in an iterative manner. Two schemes of updating material parameters are discussed and compared. A procedure for calculation of residual stress field is presented. Application of the method to autofrettage is presented. Residual stress calculation based on actual material curve, isotropic and kinematic hardening models, and variable Bauschinger effect factor (BEF) is carried out. It is concluded that consideration of dependency of BEF on plastic strain makes significant changes to residual hoop stress near the bore for low-level autofrettage. However, this dependency is insignificant for high-level autofrettage. Results obtained here are shown to be in good agreement with experimental and finite element results.

Heat conduction and diffusion equations were computed to determine the residual stresses in plastic integrated circuits packages during the surface mounting process preceded by moisture soaking test. Results reveal that temperature, moisture content and moisture vaporization pressure may cause residual stresses such as micro-cracking or delamination. Furthermore, these residual stresses are found to be time-dependent and are influenced by the soldering temperature cycle.

Three-dimensional scans of residual stress within intact weldments provide insight into the consequences of various welding techniques and stress-relieving procedures. The neutron diffraction method for nondestructive evaluation of residual stresses has been applied to a circumferential weld in a ferritic steel pipe of outer diameter 114 mm and thickness 8.6 mm. The maximum tensile stresses, 250 MPa in the hoop direction, are found at mid-thickness of the fusion gone. The residual stresses approach zero within 20 mm from the weld center. The residual stresses caused by welding zirconium alloy components are partially to blame for failures due to delayed-hydride cracking. Neutron diffraction measurements in a GTA-welded Zr-2.5Nb plate have shown that heat treatment at 530 [degrees] C for 1 h reduces the longitudinal residual strain by 60 percent. Neutron diffraction has also been used to scan the residual stresses near circumferential electron beam welds in irradiated and unirradiated Zr-2.5Nb pressure tubes. The residual stresses due to electron beam welding appear to be lower than 130 MPa, even in the as-welded state. No significant changes occur in the residual stress pattern of the electron-beam welded tube, during a prolonged exposure to thermal neutrons and the temperatures typical of an operating nuclear reactor.

A test chip which allows the experimental study of the influence of die residual stresses on MOS transistor matching, in a standard 0.7 [[micro]meter] CMOS technology, is described. The influence of eutectic die bonding on transistor matching is found to be a major degradation factor. Polyimide bonded dies do not significantly affect the matching performance of MOS transistors.

Microcracks were mechanically induced in the CVD coating layers on two types of cemented carbides with different thermal expansion coefficients, and one type of cermet. The microcracks were found to have beneficial effects on residual stress, transverse rupture strength, and chipping resistance during interrupted cutting. Residual stress in the coating on cemented carbide is tensile. Tensile residual stress decreases with increasing microcrack width and decreasing microcrack distance. Induction of 20 [[micro]meter]-distant and 0.025 [[micro]meter]-wide cracks relieves tensile residual stress by about 0.5 GPa, increases transverse rupture strength by about 0.70 GPa, and almost doubles the chipping resistance. Residual stress in the coating on cermet is compressive. Microcracks in the coating layer do not change residual stress or transverse rupture strength.

Residual stress is observed in many parts of the cardiovascular system and is thought to reduce transmural stress gradients due to intravascular pressure. Its development is closely associated with normal growth and pathological remodeling, although there appear to be few previous reports of the relationship between aging and residual stress. We have estimated residual strain (an indicator of the magnitude of residual stress) at ten sites along the aorta of rats aged 2.5 to 56 weeks by measuring the degree to which rings of vessel spring open when cut (opening angle). At all ages the opening angle decreased along the aorta, reaching a minimum near the renal arteries and increasing toward the aorto-iliac bifurcation, a result that confirms previous studies. During growth, although the unloaded circumference of the aorta increased steadily, the wall thickness and medial surface area fell to a minimum at the age of 6 weeks before continuing a steady increase. Similarly, the opening angle decreased between the ages of 2.5 and 6 weeks, thereafter increasing with age. In the abdominal aorta, a strong correlation between opening angle and wall thickness relative to midwall radius (h/R) was seen; whereas in the thoracic segment, in which no increase in h/R with age occurred, no such relationship was found. These observations are in keeping with a recently proposed hypothesis that residual stress will change in response to growth-related changes in vessel geometry driven by a tendency to minimize the nonuniform stress distribution inevitably found in pressurized thick-walled cylinders.

Microstructure and residual stresses were investigated in 100 nm tungsten thin films deposited by ion beam sputtering on silicon substrates. The atomic peeping model is suggested as an explanation for the mechanical state of these films. Ar+ ion irradiation was found to cause a total stress relaxation, a return of the stress-free lattice parameter to the bulk one, a large reduction of the microdistortions and an increase of the coherently diffracting domain sizes.

Three failure criteria were used to forecast the residual strength of unstiffened aluminum panels with multiple site damage. The damage involves perpendicularly aligned holes that caused through-the-thickness cracks. The analyses were compared with the results of residual strength tests of 2024-T3 aluminum panels. Results show the accuracy of the failure criterion that featured plastic zone considerations. Results also indicate that multiple site damage cracking decreases residual strength.

A technique for the estimation of the residual flexibility between nonexcited structural degrees of freedom (DOF) from experimental modal data is applicable to reciprocal residual flexibility problems. A general solution satisfies modal orthogonality when the unknown matrix lies in the nullspace of the global stiffness matrix, with the functioning of all DOF. A specific rank-deficient solution enables the use of the residual in the computation of the flexibility matrix. Application of the method to both the flexibility matrix convergence and component mode synthesis is discussed.

A thermal, phase transformation and residual stress estimation of multi-layer materials involves an analytical method based on the analysis of an inclusion embedded in a matrix. The method uses cylindrical coordinates to predict the stress behavior in cylindrical or flat shaped layers. Two layers are increamented at a time in the problem solving process. The thermal and residual stress estimations are in good agreement with the finite element method.

The cyclic residual stresses ahead of fatigue cracks are known to play an important role in the fatigue fracture response of engineering materials. The size of these residual stresses are directly affected by the stress state of the component. In this paper, we examine the effect of stress state for fully compressive and fully tensile cyclic loading of polycarbonate. The role of stress state is studied using two different specimen thicknesses, one thickness will represent a near-plane stress condition and the other will represent a near-plane strain condition. In cyclic compressive loading, it will be shown that the near-plane stress specimen with its larger zone of residual tension will exhibit enhanced crack saturation lengths. While for cyclic tensile loading, the larger zone of residual compression upon unloading will result in crack retardation for the same unloading stress intensity. A series of systematic experiments on the effects of mean stress on fatigue fracture is reported, and the results of the experiments are rationalized with the aid of scanning electron microscopy of the fracture surfaces. The results of this study have strong implications for both constant amplitude fatigue loading and variable amplitude fatigue loading as well as applicability to other engineering materials., INTRODUCTION Cyclic near-tip stresses ahead of fatigue cracks are known to have a pronounced effect on the fracture behavior of engineering materials. Within the cyclic damage zone directly in front [...]

The solidification of a molten layer of amorphous thermoplastic between cooled parallel plates is used to model the mechanics of part warpage in the injection-molding process. Flow effects are neglected, and a thermorheologically simple thermoviscoelastic material model is assumed. The model allows material to be added to fill the space created by the pressure applied during solidification so that this model can be used to assess packing-pressure effects in injection molding. Parametric results are presented on the effects of the mold temperatures and the packing pressure - the pressure applied during solidification to counteract the effects of volumetric shrinkage of the thermoplastic - on the in-plane and through-thickness shrinkages, on warpage, and on residual stresses in plaque-like geometries. The packing pressure is shown to have a significant effect on part warpage. While the results are presented in terms of normalized variables based on the properties of bisphenol-A polycarbonate, they can be interpreted for other amorphous thermoplastics, such as modified polyphenylene oxide, polyetherimide, and acrylonitrile-butadiene-styrene., INTRODUCTION This paper addresses the warpage of plastic parts induced by forming processes, such as injection molding, in which molten resin is injected into a relatively cold mold. As the [...]

The effects of hypertension on the stress and strain distributions through the wall thickness were studied in the rat thoracic aorta. Goldblatt hypertension was induced by constricting the left renal artery for 8 weeks. Static pressure-diameter-axial force relations were determined on excised tubular segments. The segments were then sliced into thin ring specimens. Circumferential strain distributions were determined from the cross-sectional shape of the ring specimens observed before and after releasing residual stresses by radial cutting. Stress distributions were calculated using a logarithmic type of strain energy density function. The wall thickness at the systolic blood pressure, [P.sub.sys], significantly correlated with [P.sub.sys]. The mean stress and strain developed by [P.sub.sys] in the circumferential direction were not significantly different between the hypertensive and control aortas, while those in the axial direction were significantly smaller in the hypertensive aorta than in the control. The opening angles of the stress-free ring specimens correlated well with [P.sub.sys]. The stress concentration factor in the circumferential direction was almost constant and independent of [P.sub.sys], although the stress distributions were not uniform through the wall thickness. Histological observation showed that the wall thickening caused by hypertension is mainly due to the hypertrophy of the lamellar units of the media, especially in the sub-intimal layer where the stress increase developed by hypertension is larger than in the other layers. These results indicate that: (a) the aortic wall adapts itself to the mechanical field by changing not only the wall dimensions but also the residual stresses, (b) this adaptation is primarily related to the circumferential stress but not to the axial stress, and (c) the aortic smooth muscle cells seem to change their morphology in response to the mechanical stress.

This paper presents a finite-element technique for the analysis of tubular member stability under combined external pressure and structural loads. A tube element is developed for the purposes of this research. While polynomial (quadratic) interpolation is used in the longitudinal direction, Fourier series expansions of the displacement components are adopted at the nodal cross sections. The formulation accounts for large inelastic deformation and recognizes initial imperfections and residual stresses. To trace unstable equilibrium paths, arc-length procedures are implemented. A simple, yet effective estimate of the contribution of external pressure to the tube element stiffness matrix, particularly significant in the analysis of slender tubes, is included. Preliminary results regarding the behavior of tubular members subjected to pressure and bending are reported and discussed. The effects of initial imperfections and residual stresses on the response to pressure along with bending are summarized. Finally, the influence of residual stresses on thrust-moment interaction in tubular beam-columns is examined briefly.

The flow-induced and thermally induced residual stresses during injection molding of a thin part with complex geometries are predicted. The injection molding process was considered to consist of a filling and a post-filling stage (packing coupled with cooling). Additionally, the analyses were applied to successive stages of the process. The model takes into account the viscoelasticity of the molding polymer, which has been neglected in most previous works, because of the complexity of its inclusion. A unified K-BKZ viscoelastic constitutive model, capable of modeling both the fluid-rubbery state and the glass state of amorphous polymers, was employed for simulating this problem. For the flow-induced residual stress predictions of the filling stage, a quasi-steady state approximation was employed for each element of the part, for the calculation of stress profile and subsequent stress relaxation after cessation of flow. Stress calculations were provided for the thermally induced residual stress predictions of the post-filling stage. These explicit calculations led to the results of pressure and temperature distributions of the part during the post-filling stage into the viscoelastic constitutive model. Additionally, the pressure and asymmetric temperature profiles of the post-filling stage were based on finite element packing analysis coupled with a boundary element cooling analysis of the molding process. Finally, the total residual stress in the part was obtained via superposition of the flow-induced and thermally induced residual stresses. An example is provided to demonstrate the entire concept. The results indicate that thermally induced residual stress is higher than the flow-induced residual stress by one to two orders of magnitude., INTRODUCTION Some of the problems associated with injection molding (e.g., warpage, molecular orientation, or part birefringence) can be caused by residual stresses. These involve both the flow-induced and thermally induced [...]

Compressive residual stresses and surface flaws cause considerable reduction in the tensile strength of conventional glass samples. The inverse problem of measuring residual stresses using fracture mechanics leads to an experimental method which bears a significant edge over the traditional residual stress measurement methods. The experimental results are quantified on the basis of linear elastic fracture mechanics. The crack closure under the impact of surface compressive stresses is discussed.

The treatment of weld residual stress in the fracture assessment of cylindrical pressure vessels is considered through partitioning the stress into membrane, bending, and self-balancing through-wall components. The influence of each on fracture behavior is discussed. Stress intensity factor solutions appropriate to each type of stress are presented. Short-range, medium-range, and long-range stress categories are identified according to simple rules relating the effect of increasing crack length to stress intensity factor and ligament net stress. Proposals are made on how the stress in tensity factor from these stress types may be incorporated into a Kr, Lr-based fracture assessment.

An analysis of the sensitivity of the hole drilling method of residual stress estimation to errors in experimental strain and hole diameter measurements shows that choice of an appropriate calculation step and an approximate number of measurement points can increase its reliability. This new procedure also makes it possible to give numerical estimates of the uncertainty associated with the measurements.

The use of overlapping piecewise functions instead of continuous functions to model the unknown residual stress field in the crack compliance method of residual stress estimation gives better predictions. Each function corresponds to a portion of the region of interest, and a least square fitting of the strains observed when cutting provides estimates for the unknown parameters. Simulations also show that the estimates are more reliable than those obtained by layer removal as they are not distorted by the introduction of random errors or by zero shift.

Experiments show that estimates of shot-peening induced near-surface residual stress made using the compliance method closely match those made using the X-ray method. The two methods also agree on the whole when used on laser-treated specimens but the compliance method detects stresses unnoticed by the X-ray method. Results also showed that the compliance method can substitute a circular bottomed cut with a flat bottomed cut if the depth of the cut is greater than or equal to half the width of the cut.

Stresses produced by a thermal gradient in the wall of a partially filled horizontal cylindrical vessel are presented. Three different thermal gradients are considered: 1) a discontinuous temperature change; 2) a hyperbolic temperature change; and 3) a linear temperature change at the liquid level. Thermal shock effects are also presented.

An 820-Watt clamshell module was fabricated and tested in order to assess the feasibility of cooling future high heat flux avionic hardware via subcooled phase change. One half of the module was constructed from aluminum 7075-T6 and populated with 16 heat sources simulating microelectronic chips. The other half was substituted with a transparent plastic cover to facilitate optical access to the boiling taking place in the module cavity. A dielectric coolant, Fluorinert FC-72, was supplied to, and rejected from the module via sleeveless quick connection couplers. Tests were performed with an inlet coolant pressure of 1.52 bar (22 psia) and inlet temperatures ranging from 27 to 47 [degrees] C. These tests yielded power dissipation exceeding 410 W per half module for coolant flow rates and pressure drops as small as 0.023 kg/s (0.221 gpm) and 0.149 bar (2.16 psia), respectively, and the device and rib guide temperatures were maintained below 80 and 60 [degrees] C, respectively. The pressure drop remained constant with increasing module power proving, as was confirmed visually, it is possible to condensate all the vapor within the module cavity, allowing only liquid to exit the module. Thus, coolant conditioning external to the module can be greatly simplified by employing a simple single-phase liquid flow loop.

Results of torsional ring shear tests on cohesive soils reveal that the drained residual strength is related to the type of clay mineral and quantity of claysize particles. The liquid limit is used as an indicator of clay mineralogy, and the clay-size fraction indicates quantity of particles smaller than 0.002 mm. Therefore, increasing the liquid limit and clay-size fraction decreases the drained residual strength. The ring shear tests also reveal that the drained residual failure envelope is nonlinear and the nonlinearity is significant for cohesive soils with a clay-size fraction greater than 50% and a liquid limit between 60% and 220%. This nonlinearity should be incorporated into stability analyses. An empirical correlation for residual friction angle is described that is a function of liquid limit, clay-size fraction, and effective normal stress. Previous residual strength correlations are based on only one soil index property and provide a residual friction angle that is independent of effective normal stress. For slope stability analyses, it is recommended that the residual strength be modeled using the entire nonlinear residual strength envelope or a residual friction angle that corresponds to the average effective normal stress on the slip surface.

Material property models for poly(etheretherketone) (PEEK) have been combined with a residual stress model to provide a means for investigating the effect of crystallization process on the residual stress development in semicrystalline materials. The analysis shows that crystallization causes an increase in the residual stress levels. This increase is affected through an increase in the resin modulus values and through the resin modulus build-up at higher temperatures. The shrinkage due to crystallization was found to have no effect on the residual stress development in neat PEEK.

The influence of surface residual stress on the surface flashover behavior of polycrystalline alumina in vacuum is investigated. The samples for the present investigation were prepared by using SiC and diamond abrasives of particle size ranging from 268 to 0.25 micrometer. Two types of polishing procedures, namely forward and reverse sequence polishing, are adopted in the present work. The surface residual stress of the specimens is determined by the two-exposure X-ray diffraction method. The flashover strength and the surface stress of the samples, subjected to forward sequence polishing (i.e., coarse to fine finish), are found to exhibit a random behavior with respect to the surface finish. Interestingly, a linear dependence between flashover strength and surface stress with respect to the surface finish is observed for the samples subjected to reverse sequence polishing (i.e., fine to coarse finish). The observed dependence between the residual stress and the flashover strength is discussed in terms of the high energy defect centers (e.g., deep traps) formed within the forbidden gap of the alumina insulator.

A simple model predicts the strain change on the surface near the cut that occurs during Electric Discharge Wire Machining (EDWM). A modified least square fit minimizes the effect of EDWM in residual stress calculation. The value of residual stress near the area of a curved beam obtained with EDWM correction corresponds closely to the value predicted by the bending test. EDWM does not affect a stress-specimen comprising titanium alloy.

The effects of thermal oxidation on residual stress distribution through the thickness of a p+ silicon wafer doped with boron are studied. A positive curvature or negative binding moment is exhibited by as diffused p+ silicon with a residual stress without being influenced by thermal oxidation. The residual stress distribution can be changed by thermal oxidation in the surface regions of p+ silicon film.

This paper presents the results obtained from the residual stress relief tests on 21 welded structural steel joints: 17 butt-welded, two tee, and two corner joint specimens. The A572 grade 50 structural steel plates of two different thicknesses, 15 and 32 mm, were used. All specimens were welded by the submerged arc welding (SAW) process and were designed according to the prequalified welded joints specified by the American Welding Society. In this study, a controlled low-temperature stress-relief method was used for residual stress relief. The experimental results show that by using an appropriate combination of the heating temperature, heating distance, and cooling method, the original high-tensile residual stresses near the weld of the joint can be reduced effectively. The residual stresses before and after the heat treatment were measured by using the blind hole-drilling method. A reduction of more than 50% of the original tensile residual stresses adjacent to the weld was observed.

We have detailed the effects of annealing and temperature on the residual microstress at the matrix interface in rubber-filled and glass bead-filled epoxy resin systems. We found that annealing renders changes in residual microstress. The closer the annealing temperature to the glass transition temperature of the sample, the more pronounced the annealing effect on the stress. Also, we examined the interfacial residual microstress and found a linear relationship with annealing temperature. A description of the mechanism of the interfacial microstress buildup is proposed.

Fifteen representative bridges throughout the state of Illinois were instrumented with foil strain gages to determine their frequencies of loading and the magnitudes of stresses induced by traffic over a 3- to 8-hour period, depending on traffic volume. Fatigue prone details, such as cover-plated wide flanges, were instrumented. For each stress range increment gathered by the data-acquisition system, the cumulative damage sustained over an extended number of years is compared with the number of available fatigue cycles for that stress range using published S = f(N) data for various details and the Palmgren-Miner linear damage rule. A new equation for factor of safety for welded structures subject to fatigue is proposed, taking dead load, live load, and bridge detail fatigue strengths into account. A new method of assessing future fatigue damage in bridges that takes traffic growth and increased truck weights into account is also proposed.

In the cooldown phase of the deposition process, plasma-sprayed ceramic barrier coatings generate large residual stresses. In this paper, a scheme for the analysis of the thermal stresses is given, which accounts for the nonuniformity of the temperature field, and for the microstructure of the coating. The considered microstructural data include the morphology and orientation pattern of the porosities. The case of a coated sphere is studied, as an application. In this connection, the coating structure is computer-simulated, and the temperature profile is numerically determined.

The combination of experimental, analytical and statistical methods to define equations for solving for ejection temperatures is proposed to determine the cooling time for an injection molding part in early design stages. Based on properties of materials, thickness of parts and molding conditions such as injection and mold temperatures, the ejection temperature is necessary to obtain cooling time.

An analysis of the behavior of residual soils shows that effective cohesion may be the best explanation for red clay soil stability, despite other factors such as root reinforcement, undisturbed residual clay, bonding and other factors. Compaction behavior of soils should be considered along with other factors depending on the soil type or construction project involved. While lateral and horizontal stress factors are important, soil stress history is not always significant. The liquidity index is an effective parameter in the study of certain soil types, however, the normalized and undisturbed void ratios may be more significant for varied soil types.