Stress field

About: Stress field is a research topic. Over the lifetime, 11926 publications have been published within this topic receiving 226417 citations.

Maximum horizontal stress orientations in the Cooper Basin, Australia: implications for plate-scale tectonics and local stress sources

Abstract: SUMMARY Borehole breakouts and drilling-induced tensile fractures (DITFs) were interpreted in 61 wells in the Cooper Basin indicating an average maximum horizontal stress orientation of 101 ◦ N. A total of 890 borehole breakouts and 608 DITFs were interpreted in the Cooper Basin. The approximately east‐west maximum horizontal stress orientation is consistent over much of the basin, except in the Patchawarra Trough where maximum horizontal stress rotates to a northwest‐southeast orientation. This rotation in maximum horizontal stress orientation is consistent with in situ stress data to the northwest of the Cooper Basin. The stress field in the Cooper Basin appears to mark the apex of a major horseshoe-shaped rotation in maximum horizontal stress direction across central eastern Australia. Finite element modelling of the in situ stress field of the Indo‐Australian Plate (IAP) using a range of plate-scale tectonic forces is able to match the regional maximum horizontal stress orientation over most of Australia reasonably well, including the mean east‐west maximum horizontal stress orientation in the Cooper Basin. However, plate boundary‐scale modelling does not adequately match the horseshoe-shaped stress rotation across central eastern Australia. The average east‐west maximum horizontal stress orientation in the Cooper Basin indicates that stresses from tensional forces acting along the Tonga‐Kermadec subduction zone are not transmitted into the interior of the Australian plate. The majority of the tensional forces associated with the Tonga‐Kermadec subduction zone are most likely accommodated along the numerous spreading centres within the Lau‐ Havre backarc basin. A number of more localized stress anomalies have also been identified. These cannot be explained by plate-scale tectonic forces and are possibly a result of geological structure and/or density contrasts locally perturbing the stress field.

On the micromechanics of void growth by prismatic-dislocation loop emission

Abstract: Experimental evidence and recent molecular dynamics simulations of void growth indicate that prismatic dislocation loop emission by externally applied stresses is a viable mechanism of void growth under shock loading conditions when diffusive processes are given no time to operate. In this paper, the process of growth by loop emission is studied in a model system comprised of a void in an infinite linearly elastic and isotropic solid loaded axisymmetrically by remote applied stresses. First, the interaction between applied stresses, the stress field of a single dislocation loop or a pile-up of loops next to the void, the surface energy expenditure on void surface change, and the lattice resistance to the motion of loops is reviewed. The necessary condition for interstitial loop emission is used to determine the equilibrium positions of the loops as well as the maximum number of loops in a pile-up under given applied stresses. For the parameters of the model-material with purely hydrostatic loading, the numerical results yield a volume change for the void, which when normalized by the initial undeformed volume, exhibits a strong dependence on the size of the void for radii less than ∼400 times the lattice Burgers vector. For larger voids, the normalized volume change was found to be independent of the void radius.

Investigation of stress induced by CO2 laser processing of fused silica optics for laser damage growth mitigation

Abstract: Laser damage mitigation' is a process developed to prevent the growth of nanosecond laser-initiated damage sites under successive irradiation. It consists of re-fusing the damage area with a CO2 laser. In this paper we investigate the stress field created around mitigated sites which could have an influence on the efficiency of the process. A numerical model of CO2 laser interaction with fused silica is developed. It takes into account laser energy absorption, heat transfer, thermally induced stress and birefringence. Residual stress near mitigated sites in fused silica samples is characterized with specific photoelastic methods and theoretical data are compared to experiments. The stress distribution and quantitative values of stress levels are obtained for sites treated with the CO2 laser in various conditions of energy deposition (beam size, pulse duration, incident power). The results provided evidence that the presence of birefringence/residual stress around the mitigated sites has an effect on their laser damage resistance.