Hydrostatic stress

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

Stress Computation in Soil Media

Abstract: The computation of soil deformations in a state of stress prior to failure, usually done by the theory of elasticity, necessitates a more general and realistic approach to the problem of stress analysis. Instead of a stress-strain relation, the theory presented is based on assumption of a statistical "normal distribution" of stress in a particulate structure. By means of the spatial conditions of equilibrium the stress caused by a single external force is computed. From this, any type of boundary load may be handled by integration. Second, a rational explanation, in terms of probability, is given to the phenomenon of contact pressure redistribution which has been observed in some tests when the foundation load increases to the point of failure. Third, the state of stress caused by body forces is examined in relation to a local symmetric or antimetric soil expansion. Thus, the variation of the "at rest" state is analyzed.

Calculated stress distribution in a PbMo/sub 6/S/sub 8/ wire performing the I/sub c/ vs. epsilon experiment

Abstract: The precompression of the superconducting filament in a PbMo/sub 6/S/sub 8/ monofilamentary wire at 4.2 K. which was experimentally observed as a prestrain in an I/sub c/ vs. epsilon experiment, was simulated with the calculation of the thermal stress distribution using a triaxial elastic stress model. The occurrence of different prestress conditions, due to the choice of different barrier materials (Ta, Nb, and Mo) and as consequence of a varying reinforcing stainless steel content, was investigated by calculations and compared with experimental results. The change of the stress state in the filament with external axial stress shows a significant amount of hydrostatic stress even at the J/sub c/ maximum, which explains the observed degradation of superconductivity. For the presently used Chevrel-phase wire configurations with the unfavorable thermal expansion of the barrier materials, the hydrostatic stress component, e.g. the radial stress in the filament. is important for achieving a good bonding at the layer interfaces and creating the wanted prestress in the filament. If no alternative methods and materials for the barrier are found in the future, enhanced mechanical wire properties can only be obtained by a reduced layer thickness of the barrier, which would additionally improve the overall critical current density of the wire.

Prediction of fatigue life to crack initiation in unidirectional plies containing voids

Abstract: In the present work, a model is proposed to predict the life to crack initiation in porous unidirectional composite plies subjected to tensile fatigue loadings. The average values of the Local Maximum Principal Stress (LMPS) and Local Hydrostatic Stress (LHS) in a control volume of the matrix are proposed to be the driving forces to the initiation of fatigue cracks in off-axis plies. The experimental fatigue curves for the life to crack initiation of laminates characterised by different void contents are found to fall in the same scatter band once plotted in terms of the proposed driving forces, thus proving the capability of the proposed model to predict the life to crack initiation in porous laminates based on the behaviour of the void-free material. Finally, a parametric analysis is carried out to study the influence of the global void content and average void size on the reduction of the life to crack initiation and the applicability of the proposed model to different void distributions and shapes is discussed.

Some aspects of barreling in sintered plain carbon steel powder metallurgy preforms during cold upsetting

Abstract: The present research establishes a relationship of bulged diameter with densification and hydrostatic stress in forming of sintered iron (Fe) powder metallurgy preforms cold upset under two different frictional conditions, namely, nil/no and graphite lubricant condition. Sintered plain carbon steel cylindrical preforms with carbon (C) contents of 0, 0.35, 0.75 and 1.1% with constant initial theoretical density of 84% and aspect ratio of 0.4 and 0.6 were prepared using a suitable die-set assembly on a 1 MN capacity hydraulic press and sintered for 90 minutes at 1200 °C. Each sintered preform was cold upset under two different frictional constraints. It is seen that the degree of bulging reduces with reducing frictional constraints at the die contact surface. Further, it is found that the bulging ratio changed as a function of relative density and hydrostatic stress, respectively, according to the power law equations.