Hydrostatic stress

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

Stress concentration around a strongly oblate spheroidal cavity in a transversely isotropic medium

Abstract: Expressions for the Eshelby tensor of a strongly oblate spheroidal region in a transversely isotropic medium are given explicitly. Based on the equivalent inclusion method, three dimensional stress concentration around the spherodal cavity subjected to remote uniform loading is analyzed and the associated stress concentration factor is determined. Analogously to two-dimensional blunted cracks, the so called stress rounding factor is introduced so that the connection between the crack tip stress and the stress intensity factor in linear fracture mechanics is established. Numerical values of the stress rounding factor for several representative cases of transversely isotropic symmetry are given.

Micro‐statics and micro‐kinematics of capillary phenomena in dense granular materials

Abstract: A capillary stress tensor and an effective stress tensor are defined in DEM simulations of spheres packings with capillary effect. It is shown that induced fabric anisotropy results in an anisotropy of the capillary stress, so that any stress‐like variable used to represent the effect of capillarity in granular materials should be represented by a non‐spherical tensor. The response of a sample to small isotropic stress increments is also presented, the loading being imposed either by a small variation of the stress imposed at boundaries (method A) or by a variation of matric suction (method B). The comparison of the results, with emphasis on micromechanical aspects, shows some differences between the results obtained with methods A and B, even though the increment of effective stress is the same in both cases. The effective stress concept in unsaturated granular materials is questionned on the basis of these results.

Deformation state effects on the Jc of BSCCO tapes

Abstract: Developing long-length, high- J c superconducting tapes has been a major world-wide effort in recent years because of their potential applications in power-transmission lines, motors, and other devices. The superconducting tape is usually produced by co-deforming a ductile silver sheath containing a superconducting oxide. Since the conventional thermomechanical process has failed to yield sufficient J c values for most liquid-nitrogen temperature applications, new approaches are needed to improve the criticalcurrent density, J c . This study investigated the feasibility of improving J c by increasing the shear and compressive stresses in the silver-sheathed Bi 2 Sr 2 Ca 2 Cu 3 O 10 + x (BSCCO-2223) tapes during the rolling. To investigate the effects on the J c of the stress state during rolling, specific stress states were imposed by rolling the BSCCO tapes embedded at different locations within thick steel blocks. Pure compression loading was achieved in the center plane of the blocks, while a combined compression-shear loading state was produced away from the center plane. Higher compressive hydrostatic stress at the tape edge was obtained by confining the tape width. Tapes deformed with a shear stress component exhibited higher J c values than tapes subjected to pure compression. In addition, the compressive hydrostatic stress reduced the porosity in the oxide near the tape edge and, as a consequence, increased the J c value.

Constraint Evaluation And Effects On J-R Resistance Curves For Pipes Under Combined Load Conditions

Abstract: Single edge cracked under tension (SENT) specimens appear as an alternative to conventional fracture specimens to characterize fracture toughness of circumferentially cracked pipes. The similarities of stress and strains fields between SENT specimens and cracked pipes are now well known. However, these similarities are not so well established for the case of circumferentially cracked pipes under combined loading conditions (i.e. internal pressure plus bending). This work presents a numerical analysis of crack-tip constraint of circumferentially surface cracked pipes and SENT specimens using full 3D nonlinear computations. The objective is to examine combined loading effects on the correlation of fracture behavior for the analyzed crack configurations. The constraint study using the J-Q methodology and the h parameter gives information about the fracture specimen that best represents the crack-tip conditions on circumferentially flawed pipes under combined loads. Additionally, simulations of ductile tearing in a surface cracked plate under biaxial loading using the computational cell methodology demonstrate the negligible effect of biaxial loadings on resistance curves. Introduction Structural defects in pressurized piping systems are very often surface cracks that form during fabrication or during in-service operation. The fracture conditions of these crack configurations contrast sharply to fracture conditions present in conventional deeply cracked specimens (i.e. CT or SENB). Single edge cracked under tension specimens (SENT) appear as an alternative to conventional fracture specimens to characterize fracture toughness of circumferentially cracked pipes. The similarities of stress and strains fields between SENT specimens and cracked pipes are now well determined. However, these similarities are not so well established for the case of circumferentially cracked pipes under combined load conditions (i.e. internal pressure plus tension, internal pressure plus bending, etc.). Heating and cooling cycles, ground movement and frost heave are examples of situations that produce yielding in the pipe metal when it is submitted to biaxial loading. To further understand the effects of combined loading conditions on fracture behavior of flawed pipes, this work presents a numerical investigation of crack-tip constraint of circumferentially surface cracked pipes and SENT specimens using full 3D nonlinear computations. The primary objective is to examine combined loading effects on the correlation of fracture behavior for the analyzed crack configurations using the Q [1, 2] and h [3] parameters. The Q parameter measures the deviation of the stress field of the studied geometry from a reference stress solution (i.e. the boundary layer model [4]). On the other hand, the h parameter is defined as the ratio of the hydrostatic stress level ahead of the crack front over the effective Von Mises stress and it characterizes the growth of micro voids in a triaxial stress field. Furthermore, simulations of ductile tearing in a surface cracked plate under biaxial loading using the computational cell methodology allow the study of biaxial effects on tearing behavior. The constraint study and the crack growth