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Hydrostatic stress
About: Hydrostatic stress is a research topic. Over the lifetime, 1568 publications have been published within this topic receiving 37773 citations.
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TL;DR: In this article, the ground behavior is analyzed based on the motion of material points in deformed configuration, thus the geometric non-linearity of rock mass is considered, and three different types of the plastic region can develop which depends on the magnitude of the axial in-situ stress and axial plastic flow on the squeezing response.
15 citations
TL;DR: In this article, the authors presented the theoretical predictions of the stress state at the inclusion-matrix interface in discontinuous metal matrix composites by the generalized inclusion method, which was extended to the elastoplastic deformation in the matrix material.
Abstract: This paper presents the theoretical predictions of the stress state at the inclusion-matrix interface in discontinuous metal matrix composites by the generalized inclusion method. In the author's previous works, this method had been extended to the elastoplastic deformation in the matrix material. The present analysis of the ellipsoidal inclusion problem indicates that the regions at the pole and the equator of the particle/matrix interface essentially remain elastic regardless of the level of deformation, although the size of the elastic region keeps decreasing as deformation becomes larger. It was also found that, when the composite is undergoing a relatively large plastic deformation (strain), the maximum interfacial normal stress is approximately linearly dependent upon the von Mises stress and the hydrostatic stress. Based on the stress criterion for void nucleation, the author determined the void nucleation loci and nucleation strain for a composite subjected to an axisymmetric macroscopic stress state. The influences of interfacial bonding strength, inclusion shape, and volume fraction on the occurrence of void nucleation have been determined. The interfacial bonding strength in a SiC-aluminum system was re-evaluated by using existing experimental evidence.
14 citations
TL;DR: In this article, a micro-mechanics based model was proposed to account for the contribution made by hydrostatic stress, which was then incorporated into the free volume model describing viscous softening behavior and a generalized constitutive law was established.
Abstract: Previous experimental observations have demonstrated that large stress gradient results in high plasticity, while the underlying mechanism and constitutive laws are rarely reported. In this work, a micro-mechanics based model was proposed to account for the contribution made by hydrostatic stress. This micro-mechanics model was then incorporated into the free volume model describing the viscous softening behavior and a generalized constitutive law was established. Using a user material subroutine (UMAT) and von-Mises criterion, the new constitutive equations were implemented into a finite element code to simulate the material response and free volume evolution procedure under tensile and compressive loading when hydrostatic stress was taken into account. Furthermore, comparison was made between current simulation and previous theoretical or experimental results, good agreement was successfully obtained. Therefore, it is concluded that the current constitutive law is a good candidate for describing the deformation behavior of metallic glass under complex stress states.
14 citations
TL;DR: In this article, a series of plate-impact combined compression-and-shear experiments are conducted to investigate the effect of normal stress and hydrostatic pressure on the shear yield and flow behavior of a zirconium-based bulk metallic glass (BMG), Zr41.25Ti13.75Ni10Cu12.5Be22.5
14 citations
TL;DR: In this paper, the authors developed an optimum free forging process to close and consolidate internal cavities in heavy ingots by direct forging alone, internal deformation and internal stress were investigated with Plasticine models.
Abstract: For developing an optimum free forging process to close and consolidate internal cavities in heavy ingots by direct forging alone, internal deformation and internal stress were investigated with Plasticine models. First, a method to simulate the material behavior with the existence of a large temperature gradient was established. The forging processes used were the followings;1) the conventional process which uses symmetrical upper and lower anvils2) a process called the FM process in which the upper anvil is of the usual type but the lower anvil is flat and larger than the dimension of the material to be forged3) a process called the FML process-where the lower anvil is the same as that of the FM process and the upper anvil is smaller than the dimension of the material to be forged4) the so-called JTS forging process which uses the same combination of anvils as that of the FML process and is carried out with a large temperature gradient in the material.Among these processes, the conventional process can effectively cause a large deformation rate at the center and the use of wide anvils in any process is also effective for a large deformation even without a temperature gradient in the material. For attaining compressive stress, that is, a higher hydrostatic stress at the center, it is effective even without a temperature gradient to raise the value of the parameter w/h (w: width of anvil, h: height of, forging material) or to carry out unsymmetrical reductions such as that in the FM process and the FML process. A tri-axial compressive stress state is considered to be effective for closing and consolidating the central cavities.
14 citations