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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 paper, a mesophase of hexagonally ordered cylindrical domains is considered, and shear deformation is applied perpendicular to the cylinder axes, and a cell dynamic approach is used to simulate the system under oscillatory and step-shear strains.
Abstract: Computer simulation is carried out for microphase-separated diblock copolymers under applied shear deformation. A mesophase of hexagonally ordered cylindrical domains is considered, and shear strains are applied perpendicular to the cylinder axes. Rheological responses and structural changes of the system under oscillatory and step-shear strains are studied by using a cell dynamic approach. For small strains, the usual behavior of ordered viscoelastic solids is seen, while for large strains, anomalous behavior is observed, including (i) in the case of oscillatory shears, a nonlinear stress response which is out of phase with the applied strain in the low frequency limit and (ii) in the case of step-shear, a double stress relaxation process in which the stress first approaches a pseudoequilibrium value and then much later relaxes further toward the final equilibrium value
97 citations
Journal Article•
TL;DR: In this paper, the authors used the theory of viscoelastic behavior of amorphous polymers to describe the density gradient formation in flakeboard and applied it to predict the glass transition temperature of wood as a function of press time.
Abstract: Theories of the viscoelastic behavior of amorphous polymers are reviewed and are used to describe the density gradient formation in flakeboard. This technique utilizes measured temperature and gas pressure at discrete locations inside a flake mat during hot pressing to predict the glass transition temperature of wood as a function of press time. The difference between the flake temperature and the predicted glass transition temperature is a relative indicator of the amount of flake deformation and stress relaxation at a location in the mat. A knowledge of the stress history imposed in the mat is then used to relate flake deformation and stress relaxation to the formation of a density gradient. This analysis allows for a significant portion of the density gradient to develop after the hot press has closed. Experimental data for various density gradients support the theories presented here.
97 citations
TL;DR: In this paper, the authors analyzed room temperature stress relaxation and associated physical phenomena in passivated and unpassivated aluminum-based metallizations, subsequent to exposure to high temperatures, based both on theoretically estimated and experimentally determined thermal stresses.
Abstract: Thermal stress‐induced voiding in narrow aluminum‐based metallizations used as interconnects in microelectronic circuits has recently become a serious reliability concern. Room‐temperature stress relaxation and associated physical phenomena in passivated and unpassivated aluminum‐based metallizations, subsequent to exposure to high temperatures, are analyzed based both on theoretically estimated and experimentally determined thermal stresses. It is shown that stress relaxation at longer times involves mainly dislocation climb, while short‐term relaxation during cool down from higher temperatures, and immediately thereafter, involves significant dislocation glide. Void growth, frequently observed in passivated metallizations, provides a new source of atoms to feed stress relaxation by the same processes as in the absence of voiding.
97 citations
TL;DR: In this paper, the authors report measurements of the plastic relaxation of InGaAs layers grown above critical thickness on GaAs substrates and the relaxation is accurately hyperbolic, proportional to the reciprocal of the layer thickness, in agreement with a recent geometrical theory of critical thickness.
Abstract: We report measurements of the plastic relaxation of InGaAs layers grown above critical thickness on GaAs substrates. The relaxation is accurately hyperbolic, proportional to the reciprocal of the layer thickness, in agreement with a recent geometrical theory of critical thickness [D. J. Dunstan, S. Young, and R. H. Dixon, J. Appl. Phys. 70, 3038 (1991)]. At large thicknesses, work hardening is observed which leads to a residual strain dependent on the original misfit.
97 citations
TL;DR: In this article, the in-plane lattice constant at the film surface was measured using reflection high-energy electron diffraction, which was shown to be tensile on MgO and compressive on LaAlO3 as expected from the lattice mismatches between the film and the substrates.
Abstract: We report a real-time observation of strain relaxation during in situ growth of SrTiO3 thin films by measuring the in-plane lattice constant at the film surface using reflection high-energy electron diffraction. The initial misfit strain in the SrTiO3 film is tensile on MgO and compressive on LaAlO3 as expected from the lattice mismatches between the film and the substrates. Strain relaxation begins immediately after the deposition starts, but is not complete until the film thickness reaches 500–2500 A depending on the substrate and the deposition temperature. The strain relaxation at the growth temperature influences the film strain at room temperature, which is compressive for both substrates for thin SrTiO3 films.
97 citations