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Showing papers in "Journal of Engineering Materials and Technology-transactions of The Asme in 1988"


Journal ArticleDOI
TL;DR: In this paper, the Incremental Strain, Average Stress, Power Series, and Integral methods are examined as procedures for determining non-uniform residual stress fields using strain relaxation data from the hole drilling method.
Abstract: The Incremental Strain, Average Stress, Power Series, and Integral methods are examined as procedures for determining non-uniform residual stress fields using strain relaxation data from the hole drilling method. Some theoretical shortcomings in the Incremental Strain and Average Stress methods are described. It is shown that these two traditional methods are in fact approximations of the Integral Method. Theoretical estimates of the errors involved are presented for various stress fields. Also, some simple transformations of stress and strain variables are introduced so as to decouple the stress/strain equations and simplify the numerical solution.

490 citations






Journal ArticleDOI
TL;DR: In this article, a procedure for delineating directional and isotropic hardening from uniaxial hardening data has been developed for the Bodner-Partom model and applied to a nickel-base superalloy, B1900 + Hf.
Abstract: Modeling of hardening and thermal recovery in metals is considered within the context of unified elastic-viscoplastic theories. Specifically, the choices of internal variables and hardening measures, and the resulting hardening response obtained by incorporating saturation-type evolution equations into two general forms of the flow law are examined. Based on the analytical considerations, a procedure for delineating directional and isotropic hardening from uniaxial hardening data has been developed for the Bodner-Partom model and applied to a nickel-base superalloy, B1900 + Hf. Predictions based on the directional hardening properties deduced from the monotonic loading data are shown to be in good agreement with results of cyclic tests.

155 citations



Journal ArticleDOI
TL;DR: In this article, high temperature mechanical properties of discontinuous, whisker and particulate, SiC reinforced aluminum composites, including 2124 and 6061 alloy matrices, are reviewed.
Abstract: High temperature mechanical properties of discontinuous, whisker and particulate, SiC reinforced aluminum composites, including 2124 and 6061 alloy matrices, are reviewed. It is shown that the behavior of these composites is similar to conventional oxide dispersion strengthened alloys. Namely, they exhibit a low strain rate senstivity and a high apparent activation energy for creep deformation. Despite the fact that the addition of SiC significantly improves the mechanical properties of aluminum at room temperature, the mechanical strength of the composite at elevated temperatures is dominated by the strength of the aluminum matrix This is because the SiC dispersoids are, in general, too coarse and they are not effective barriers for dislocation motion. It is also demonstrated that SiC particulate composites are less creep resistant than SiC whisker composites.

121 citations




Journal ArticleDOI
Y. C. Liu1
TL;DR: In this paper, the intermediate restraining process has been developed to form high quality flanged channels in one single operation, which is displacement controlled and can be applied to any material once its physical properties are known.
Abstract: Quantitative relationships have been obtained between restraining force and shape deviations, such as springback and side wall curl, in flanged channels made of SKDQ and high strength streets. It is observed that shape deviation is greatly reduced if the applied restraining force is beyond the yield strength of the material. However, due to the restriction of die entrance and punch corners, this condition cannot be readily achieved in the conventional bead system as side wall fracture intervenes. To circumvent this constraint, a so-named “intermediate restraining” process has been developed to form high quality flanged channels in one single operation. The suggested process is displacement controlled and, in practice, should be applicable to any material once its physical properties are known.


Journal ArticleDOI
TL;DR: In this article, an equivalent strain energy density (EDE) concept for elastic-plastic notch strain-stress analysis has been developed, which does not require any input data other than the material stress-strain relation and the elastic stress concentration factor.
Abstract: For the evaluation of the local elastoplastic strains and stresses at the notch root suitable approximation formulas of sufficient accuracy are often used. In the present study the “equivalent strain energy density” concept for elastic-plastic notch strain-stress analysis has been developed. It was found that the evaluation of the strain energy density in the notch tip plastic zones does not require any input data other than the material stress-strain relation and the elastic stress concentration factor. The concept was verified on the basis of the results obtained from plane strain elastic-plastic finite element analysis using the material model after Mroz. Comparison of the two sets of results revealed satisfactory accuracy of the equivalent strain energy concept. It was also shown that all stress and strain components in the notch tip can be calculated by complementing the method with Hencky’s equations. Neuber-based calculations were also included in the study. It was found that the energy concept was superior to Neuber’s rule, especially in the presence of high inelastic strains in the notch tip.









Journal ArticleDOI
TL;DR: Abrasion and wear ageing, Physical Chemically Resistant Polymers Composites Composites, Fabrications Composites and Testing Crazing Dynamic Mechanical Properties Engineering Plastics Fatigue Fibers Engineering Fracture Hardness Heat resistant Polymers Impact Resistance Liquid Crystalline Polymers Mechanical Properties.
Abstract: Abrasion and Wear Ageing, Physical Chemically Resistant Polymers Composites Composites, Fabrications Composites, Testing Crazing Dynamic Mechanical Properties Engineering Plastics Fatigue Fibers Engineering Fracture Hardness Heat Resistant Polymers Impact Resistance Liquid Crystalline Polymers Mechanical Properties.

Journal ArticleDOI
TL;DR: In this paper, l'utilite des mesures de deplacement de surface pour reveler la nature de la deformation plastique de subsurface par une analyse de la zone transformee aux alentours des fissures.
Abstract: On montre l'utilite des mesures de deplacement de surface pour reveler la nature de la deformation plastique de subsurface par une analyse de la zone transformee aux alentours des fissures. On montre que la zone transformee presente un degre non uniforme de transformation des particules de la phase quadratique


Journal ArticleDOI
TL;DR: In this article, an experimental method is described whereby the dynamic fracture initiation toughness of ceramics and ceramic composites can be measured in pure tension or pure torsion at stress intensity factor rates of 100,000 to 1,000,000 MPA sq rt m/s.
Abstract: : An experimental method is described whereby the dynamic fracture initiation toughness of ceramics and ceramic composites can be measured in pure tension or pure torsion at stress intensity factor rates of 100,000 to 1,000,000 MPA sq rt m/s. In this procedure, circumferentially-notched cylindrical rods are subjected to uniaxial cyclic compression at room temperature to introduce a self-arresting, concentric Mode I fatigue pre-crack, following the technique presented by Suresh et al. (1987) and Suresh and Tschegg (1987). Subsequently, dynamic fracture initiation is effected by stress wave loading with a sharp- fronted pulse which subjects the specimen to a dynamic load inducing either Mode I or Mode III fracture. Instrumentation appropriate to the loading mode provides a record of average stress at the fracture site as a function of time. The capability of this method to yield highly reproducible dynamic fracture initiation toughness values for ceramics is demonstrated with the aid of experiments conducted on a polycrystalline aluminum oxide.

Journal ArticleDOI
TL;DR: In this article, a pseudo-amorphe de structure is defined, which permet d'etendre des resultats d'eirage uniaxial contrainte vraie-deformation vRAie a des etats plus complexes de contraintes.
Abstract: Modele pseudo-amorphe de structure qui permet d'etendre des resultats d'etirage uniaxial contrainte vraie-deformation vraie a des etats plus complexes de contrainte. Rupture et criteres de rupture


Journal ArticleDOI
TL;DR: In this article, a method of estimating the fatigue life of adhesively bonded lap joints on the basis of the stress analysis in adhesive layer with finite element method was described. But the results were evaluated from the viewpoint of the maximum values of both tensile and shear stress obtained numerically, instead of the apparent stress.
Abstract: This paper describes a method of estimating the fatigue life of adhesively bonded lap joints on the basis of the stress analysis in adhesive layer with finite element method. First, cyclic tensile fatigue tests were conducted for adhesively bonded lap joints with different lap length and adhesive layer thickness. The results were evaluated from the viewpoint of the maximum values of both tensile and shear stress obtained numerically, instead of the apparent stress. Then these standardized fatigue strength were compared with those of adhesively bonded butt joints of a thin wall tube under cyclic tensile and fully reversed torsional load conditions. The results indicate that fatigue strength of lap joints evaluated from the maximum tensile stress of the adhesive layer agrees well with the fatigue strength of adhesively bonded butt joints of thin wall tube under cyclic tensile load condition. It is confirmed that fatigue strength of lap joints can be estimated adequately based on the fatigue strength of the butt joint of thin wall tube and the numerical results for the stress state of adhesive layer.

Journal ArticleDOI
TL;DR: In this paper, the thermo-viscoelastic behavior of composite material is studied analytically using a special finite-element formulation and numerical results on stress and deformation histories are obtained for both unnotched and notched graphite/epoxy composites subjected to mechanical and thermal spectrum loads.
Abstract: The thermo-viscoelastic behavior of composite material is studied analytically using a special finite-element formulation. Numerical results on stress and deformation histories are obtained for both unnotched and notched graphite/epoxy composites subjected to mechanical and thermal spectrum loads. The results indicate that time-dependent effects are important in composites with matrix-dominated layup orientations. Such effects also strongly depend on the specific environment condition and load spectrum applied.