Stress relaxation

About: Stress relaxation is a research topic. Over the lifetime, 12959 publications have been published within this topic receiving 270815 citations.

Creep cavitation by vacancy diffusion in plastically deforming solid

Abstract: The diffusive growth rate of a grain boundary cavity is calculated under conditions where vacancies are created non-uniformly across the boundary. Away from the boundary, power-law creep relaxes the strain due to the diffusive atom plating which occurs preferentially near the cavity and allows increased growth rates. At high stresses the growth rate is proportional to the creep strain rate or stress to a high power and at low stresses the growth rate is proportional to stress.

A molecular approach to the spurt effect in polymer melt flow

Abstract: The Doi-Edwards theory of polymer melts, extended to include relaxation processes associated with chain-length equilibration, is used to make quantitative predictions of a discontinuity in the flow curve of a monodisperse melt in a capillary. A fluid interface between regions of high and low deformation rates is found to propagate from the former into the latter. Our results for the “spurt” and its hysteresis compare favorably with experiment using a molecular weight dependence of the ratio of “reptation time” (Td) to “equilibration time” (Teq) in agreement with that determined from nonlinear stress relaxation.

Three-dimensional strain states and crystallographic domain structures of epitaxial colossal magnetoresistive la0.8ca0.2mno3 thin films

Abstract: The evolution of three-dimensional strain states and crystallographic domain structures of epitaxial colossal magnetoresistive La0.8Ca0.2MnO3 films have been studied as a function of film thickness and lattice mismatch with two types of (001) substrates, SrTiO3 and LaAlO3. In-plane and out-of-plane lattice parameters and strain states of the films were measured directly using normal and grazing incidence x-ray diffraction techniques. The unit cell volume of the films is not conserved, and it exhibits a substrate-dependent variation with film thickness. Films grown on SrTiO3 substrates with thickness up to ∼250 A are strained coherently with a pure (001)T orientation normal to the surface. In contrast, films as thin as 100 A grown on LaAlO3 show partial relaxation with a (110)T texture. While thinner films have smoother surfaces and higher crystalline quality, strain relaxation in thicker films leads to mixed (001)T and (110)T textures, mosaic spread, and surface roughening. The magnetic and electrical tra...