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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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169 citations

Journal ArticleDOI
TL;DR: A plane of isotropy for the material properties of meniscal tissue is supported, however, the material behavior is strongly nonlinear because the compressive modulus is several orders of magnitude smaller than previously reported values for tensile modulus.

168 citations

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate that the high temperature polymorphic tantalum phase transition from the tetragonal beta phase to the cubic alpha phase causes a large decrease in the resistance of thin films and a complete stress relaxation in films that were intrinsically compressively stressed.
Abstract: We demonstrate that the high temperature polymorphic tantalum phase transition from the tetragonal beta phase to the cubic alpha phase causes a large decrease in the resistance of thin films and a complete stress relaxation in films that were intrinsically compressively stressed. 100 nm beta tantalum thin films with intrinsic stresses of 2.0×1010 dynes/cm2 (tensile) to −2.3×1010 dynes/cm2 (compressive) were deposited onto thermally oxidized (100) silicon wafers by evaporation or dc magnetron sputtering with argon. In situ stress and resistance at temperature were measured at 10 °C/min up to 850 °C in purified helium. Upon heating, the main stress mechanisms were elastic deformation at low temperature, plastic deformation at moderate temperatures and stress relief because of the beta‐to‐alpha phase transition at high temperatures. The temperature ranges over which the elastic and plastic deformation and the beta‐to‐alpha phase transition occurred varied with deposition pressure and substrate biasing. Incomplete compressive stress relaxation at high temperatures was observed if the film was initially deposited in the alpha phase or if the beta phase did not completely transform into alpha by 800 °C due to substrate biasing during the deposition. We conclude that the main stress relief mechanism for tantalum films with intrinsic compressive stresses to completely relax their stress is the beta‐to‐alpha phase transition, while for intrinsically tensile films, this transformation has a much smaller effect on the stress.

167 citations

Journal ArticleDOI
TL;DR: In this paper, the secondary creep rate of fine-grained polycrystalline magnesium was investigated in the strainrate range 3·3 × 10−1 to 3· 3 × 10 −3 sec−1.
Abstract: The temperature and stress dependence of the secondary creep rate of fine-grained polycrystalline magnesium have been investigated in the strainrate range 3·3 × 10−1 to 3·3 × 10−3 sec−1. Stress relaxation studies were combined with the creep experiments to obtain accurate values for the activation volume. They also gave evidence of long-range internal stresses. Results have been interpreted according to a model of thermally activated screw dislocation glide in which intersection jogs determine the activation volume and probably the glide-rate also. Additional experiments for creep rates less than 10−4 sec−1 indicated that in this range the recovery of athermal obstacles is rate-determining.

167 citations

Journal ArticleDOI
TL;DR: In this article, a new dissipative constraint release model was proposed for tube deformation in polymer melts, which is based on a dissipative convective constraint release process and a strain-dependent evolution equation for the molecular stress.
Abstract: The molecular stress function theory for polymer melts is extended to include a new, dissipative convective constraint release process. First the Helmholtz free energy of tube segments with strain-dependent tube diameter is established neglecting constraint release, and it is demonstrated that the molecular stress is a function of the average logarithmic stretch under these conditions. Then convective constraint release is introduced as a dissipative process in the energy balance of tube deformation, which leads to a strain-dependent evolution equation for the molecular stress function. Constraint release is considered to be the consequence of different convection mechanisms for tube orientation and tube cross section. Our new, dissipative constraint release model emphasizes that tube kinematics are fundamentally different for rotational and nonrotational flows, and therefore distinguishes explicitly between simple shear and pure shear (planar extension). For the startup of simple shear and extensional flows, the predictions of our set of constitutive equations consisting of a history integral for the stress tensor and a differential evolution equation for the molecular stress function with only two nonlinear material parameters are in excellent agreement with experimental data of a polydisperse high-density polyethylene (HDPE) and a polydisperse low-density polyethylene (LDPE) melt. Also, stress relaxation after step-shear strain is described for both the HDPE and the LDPE melt.

167 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023145
2022390
2021266
2020276
2019270
2018281