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Stress relaxation
About: Stress relaxation is a research topic. Over the lifetime, 12959 publications have been published within this topic receiving 270815 citations.
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TL;DR: In this article, the structural, optical, electrical and physical properties of amorphous carbon deposited from the filtered plasma stream of a vacuum arc were investigated, and the tetrahedral coordination of the material was confirmed by measurements of stress and plasmon energy as a function of ion energy.
217 citations
TL;DR: In this article, the authors measured the residual stresses created in polycrystalline aluminum oxide as a result of its constrained anisotropic thermal contraction using the technique of piezospectroscopy using the fluorescence from trace Cr[sup 3+] impurities.
Abstract: The residual stresses created in polycrystalline aluminum oxide as a result of its constrained anisotropic thermal contraction are measured with the technique of piezospectroscopy using the fluorescence from trace Cr[sup 3+] impurities. The average residual stresses in the crystallographic a and c directions are determined as a function of grain size for a high-purity alumina, as is the width of the stress distribution (assuming it to be Gaussian). Over the range of grain sizes investigated, from 2 to 16 [mu]m, the residual stresses exhibit a dependence on grain size consistent with the prediction of the Evans-Clarke model of thermal stress relaxation by grain boundary diffusion.
215 citations
01 Oct 2015
TL;DR: In this paper, a finite element model is developed for predicting the thermo-mechanical response of Ti-6Al-4V during electron beam deposition, and both in situ distortion and post-process residual stress measurements suggest that stress relaxation occurs during the deposition of a single-bead wide, 16-layer-high wall built for model validation.
Abstract: In this work, a finite element model is developed for predicting the thermo-mechanical response of Ti-6Al-4V during electron beam deposition. A three-dimensional thermo-elasto-plastic analysis is performed to model distortion and residual stress in the workpiece and experimental in situ temperature, and distortion measurements are performed during the deposition of a single-bead-wide, 16-layer-high wall built for model validation. Post-process blind hole–drilling residual stress measurements are also performed. Both the in situ distortion and post-process residual stress measurements suggest that stress relaxation occurs during the deposition of Ti-6Al-4V. A method of accounting for such stress relaxation in thermo-elasto-plastic simulations is proposed where both stress and plastic strain are reset to 0, when the temperature exceeds a prescribed stress relaxation temperature. Inverse simulation is used to determine the values of the absorption efficiency and the emissivity of electron beam–deposited, wir...
213 citations
TL;DR: In this article, the structural relaxation process in a metallic glass on the atomic length scale was investigated using x-ray photon correlation spectroscopy, and the authors found evidence for a crossover between the supercooled liquid phase and the metastable glassy state, suggesting different origins of the relaxation process across the transition.
Abstract: We use x-ray photon correlation spectroscopy to investigate the structural relaxation process in a metallic glass on the atomic length scale. We report evidence for a dynamical crossover between the supercooled liquid phase and the metastable glassy state, suggesting different origins of the relaxation process across the transition. Furthermore, using different cooling rates, we observe a complex hierarchy of dynamic processes characterized by distinct aging regimes. Strong analogies with the aging dynamics of soft glassy materials, such as gels and concentrated colloidal suspensions, point at stress relaxation as a universal mechanism driving the relaxation dynamics of out-of-equilibrium systems.
213 citations
TL;DR: In this article, the mesomorphic form or mesophase induced by tensile drawing from the amorphous state of a polylactide material containing 4 mol % of d-stereoisomer units was investigated.
Abstract: This work deals with the study of the mesomorphic form or mesophase induced by tensile drawing from the amorphous state of a polylactide material containing 4 mol % of d-stereoisomer units. Investigations have been carried out over the draw temperature domain 45−90 °C, i.e. an interval spanning roughly ±20 °C about the glass transition temperature. In situ WAXS experiments during drawing, stress relaxation, and/or heating of stretched samples invariably showed the strain-induced occurrence of the mesophase as far as temperature did not exceed 70 °C. This seems to be the upper stability temperature of the mesophase identified in a previous study. DSC traces upon heating of drawn samples exhibit a post glass transition endothermic peak similar to the enthalpy relaxation phenomenon observed for aged polymers. The amplitude of this strain-induced endotherm proved to be strongly dependent on draw temperature and draw ratio. Draw ratio also appeared to strongly influence the temperature domain of cold crystalli...
212 citations