Hydrostatic stress

About: Hydrostatic stress is a research topic. Over the lifetime, 1568 publications have been published within this topic receiving 37773 citations.

Fold zone analysis in wiping die bending process by using experimental and numerical approaches

Abstract: This paper deals with an analysis of the fold zone of bent parts within the sheet thickness by means of micro hardness measurement and numerical modelling. The failure risk has to be accurately predicted by using a continuum damage mechanics in order to avoid some expensive experiments. In this reason, a 3D numerical model, based on Lemaitre damage formulations, has been developed. The scalar damage variable D as well as the hardening law are taken to be isotropic within the sheet. The numerical approach is based on an incremental integration scheme of the constitutive equations coupled with ductile damage and von Mises criteria. The corresponding numerical algorithm is implemented into ABAQUS/Standard code. During bending operation, the damage variable evolution is computed and the hydrostatic stress effect is investigated within the sheet thickness. The hardening and plastic strain evolutions have been compared with the micro hardness one deduced from experimental tests. The comparison between experimental and numerical results illustrates the capability of the model in 3D process simulation, particularly in bending processes. Copyright © 2004 John Wiley & Sons, Ltd.

Dynamics of a linearly inhomogeneous incompressible isotropic elastic half-space

Abstract: The study presented in this paper treats the harmonic and transient wave motion of an incompressible isotropic semi-infinite elastic medium with a shear modulus increasing linearly with depth. The medium has a constant mass density and an initial hydrostatic stress distribution due to a constant gravity. In particular, attention is given to the case of a vanishing top rigidity. For this case it is shown that the governing equations resemble the equations governing the deep water motion, and that under normal loading the behaviour of the upper surface resembles that of the upper surface of (deep) water.

Studying the effect of a hydrostatic stress/strain reduction factor on damage mechanics of concrete materials

Abstract: In the Nonlinear Finite Element Analysis (NFEA) of concrete materials, Continuum Damage Mechanics (CDM) provide a powerful framework for the derivation of constitutive models capable of describing the mechanical behavior of such materials. The internal state variables of CDM can be introduced to the elastic analysis of concrete to form elastic-damage models (no inelastic strains), or to the elastic-plastic analysis in order to form coupled/uncoupled elastic-plastic-damage models. Experimental evidence that is well documented in literature shows that concrete’s susceptibility to damage and failure is distinguished under deviatoric loading from that corresponding to hydrostatic loading. A reduction factor is usually introduced into a CDM model to reduce the susceptibility of concrete to hydrostatic stresses/strains. In this work, the effect of a hydrostatic stress reduction factor on the performances of two NFEA concrete models will be studied. These (independently published) models did not provide any results showing such effect. One of these two models is an elastic-damage model while the other is an uncoupled elastic-plastic-damage model. Comparisons are carried out between the performances of the two models under tensile and compressive loadings, clearly showing the effect of the reduction factor on the numerically depicted behaviors of concrete materials. In order to have rational comparisons, the hydrostatic stress reduction factor applied to each model is chosen to be a function of the internal state variables common to both models. Therefore, once the two models are calibrated to simulate the experimental behaviors, their corresponding reduction factors are readily available at every increment of the iterative NFEA procedures.