Hydrostatic stress

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

Thermographic Stress Field Investigation of a Multiply-Loaded Disk

Abstract: Hybrid thermoelastic stress analysis (Hybrid-TSA) is an experimental thermographic method that has been successfully utilized for the stress analysis of numerous structures with various geometries, discontinuities and loading situations. Previous work has shown the capacity of such approach to separate stresses on diametrically loaded disks with known loading conditions. The objective of the present work is to investigate the capacity of such hybrid experimental-analytical approach in the stress analysis of two-dimensional granular materials. Previously, thermography has been successful at determining the hydrostatic stress network in cohesionless bidisperse granular systems (composed of cylinders placed in parallel) under confined compression. However, the analysis remained tricky because of the large number of cylinders considered, leading to a reduced number of thermal data per cylinder. The method which is proposed here relies heavily on analytical expressions of stress, which arise from mechanical compatibility and equilibrium conditions. It enables us to reconstruct a stress field on granular materials with low special resolution (few TSA points available per cylinder), and thus to analyze more precisely the mechanical state of tested granular systems.

An Elastic Solution for Twin Circular Tunnels’ Stress in Hydrostatic Stress Field

Abstract: In order to present an elastic solution for twin circular tunnels’ stress distribution in hydrostatic stress field, based on the complex variable theory and the superposition principle, the stress field of twin tunnels under static hydraulic pressure is decomposed into two parts: the original stress field and the secondary stress field. According to the symmetry of the structural form and the load distribution, the secondary stress filed can be simplifyed into a half-plane model. Therefore, the stress filed can be analyzed with the complex variable theory conveniently. Finally, the elastic solution of the twin tunnels under static hydraulic pressure is demonstrated by the superposition of the original stress field and the secondary stress field. In order to verify the analytical solution, a finite element model is adopted as the comparative test.. The result of the finite element simulation shows that the stress concentration at the middle rock wall is most obvious. And the stress concentration factor keeps increasing when the twin tunnels’ spacing distance and supporting pressure are decreasing. Besides, the maximum tangential stress appears at the tunnel boundary. The farther away from the tunnel’s boundary, the tangential stress gets lower. Furthermore, the supporting pressure leads to the increasing of radial stress and the decreasing of tangential stress. The analytical results are highly consistent with the numerical results with finite element method.

Numerical simulations of plastic deformation and fracture effects in two phase {gamma}-TiAl+{alpha}{sub 2} - Ti{sub 3}Al lamellar microstructures

Abstract: Deformation characteristics of fully lamellar (FL) and nearly lamellar (NL) morphologies in two phase {gamma}- TiAl(Ll{sub 0}) + {alpha}{sub 2} - Ti{sub 3}Al(DO{sub 19}) polycrystalline aggregates are simulated by Finite Element Methods. Polycrystalline stress-strain response is accurately predicted using, as input parameters, the range of soft ({tau}{sub crss}{sup soft}) and hard ({tau}{sub crss}{sup hard}) mode critical resolved shear stresses obtained from single poly-synthetically twined (PST) lamellar crystals, for shear parallel and perpendicular to the lamella. The deformation is severely inhomogeneous, due in part to the large difference in {tau}{sub crss}{sup soft} and {tau}{sub crss}{sup hard} with the largest strain accumulations being encountered at grain boundaries, particularly at triple points. Such deformation incompatibilities between adjacent crystals create large hydrostatic stress concentrations at grain boundaries, which are likely nucleation sites for fracture, as experimentally verified for both tension and compression loading. Incorporating small volume fractions of {gamma} - TiAl (with compliant deformation characteristics, at least at small strains) at grain boundaries, as in the case for NL microstructures, greatly reduces the magnitude of the peak hydrostatic stresses, and consequently mitigates fracture initiation. This provides a suitable explanation for the increase in ductility as associated with an increasing volume fraction of {gamma} -more » TiAl in lamellar microstructures. It is shown that numerically computed plots of hydrostatic stress vs strain provide a more logical and direct correlation between microstructure and ductility response, over the current, more traditional stress-strain plots.« less