Hydrostatic stress

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

Stress and Stress Voiding in Cu/Low -k Interconnects

Abstract: Through comparing stress state of TEOS and SiLK-embedded structures, the effect of low-k materials on stress and stress distribution in via-line structures were investigated using three-dimensional finite element analyses. In the case of TEOS-embedded via-line structures, hydrostatic stress was concentrated at the via and the top of the lines, where the void was suspected to nucleate. On the other hand, in the via-line structures integrated with SiLK, large von-Mises stress is maintained at the via, thus deformation of via is expected as the main failure mode. A good correlation between the calculated results and experimentally observed failure modes according to dielectric materials was obtained.

Modelling of the Ductile Damage Behaviour of a Beta Solidifying Gamma Titanium Aluminide Alloy during Hot-Working

Abstract: Gamma titanium aluminides are innovative materials for high temperature and light weight applications [1]. On the other hand, their hot workability can be limited by failure during hot deformation processes. The prediction of ductile damage in metallic materials can be performed by macromechanical ductile damage criteria [2-4]. If the calculated damage D parameter exceeds a critical value Dc, the material fails. Some macromechanical ductile damage criteria are shown in Table 1, with σ as effective stress, e as effective strain, σmax as maximum principal stress, σm as hydrostatic stress (mean stress) and ef as equivalent fracture strain. The damage responds to strain localization and thus, to multiaxial stress concentration that increases fracture probability.

Model for estimation of stress field in the earth's crust

Abstract: Stress field or in-situ stress, beside rock mass strength, determines stability or instability of underground openings. It plays key role of every rock engineering project, and has been subject of many researches. There are many theoretical models of the stress field of the Earth's crust which have more or less limited domain of applicability. However, those models usually express horizontal stresses as ratio with vertical stress component. On the other side, it is well known that deformation modulus of the rock mass is dependent on the lateral stress it is subjected to. This dependence is, herein, coupled with practical findings of the stress field behavior and incorporated into the stress filed model. As the result new formulation for the stress filed components is obtained.

Consistent Modelling of Expansive and Collapsive Response of Unsaturated Soils

Abstract: In unsaturated soil modelling, collapse is viewed as an ordinary response, whereas swelling upon an increase of moisture is considered as a special class of problems. However, an investigation based on fundamentals of plasticity indicates that the two seemingly opposite responses are unified within the same ordinary elastoplasticity framework. In fact, similar to the well-known contractive and dilative responses in the critical state framework, the collapsive and expansive responses of unsaturated soils differ only in the sign of the dissipative hydrostatic stress. For a soil with a low applied net stress, the dissipative mean normal stress during wetting is likely to be negative, and the plastic volumetric strain is kept negative (swelling) as well, such that the dissipation is always positive, complying with the second law of thermodynamics. When the applied net stress is high, the dissipative mean normal stress may turn to be positive, resulting in a positive plastic volumetric strain (collapse). This paper explains the concept of this ‘ordinary’ modelling framework, and uses a bounding surface triaxial model to demonstrate the concept. The numerical results are compared with experimental observations reported in the literature.