Stress field

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

An analytical model of joint contact.

Abstract: The stress distribution in the region of contact between a layered elastic sphere and a layered elastic cavity is determined using an analytical model to stimulate contact of articulating joints. The purpose is to use the solution to analyze the effects of cartilage thickness and stiffness, bone stiffness and joint curvature on the resulting stress field, and investigate the possibility of cracking of the material due to tensile and shear stresses. Vertical cracking of cartilage as well as horizontal splitting at the cartilage-calcified cartilage interface has been observed in osteoarthritic joints. The current results indicate that for a given system (material properties mu and nu constant), the stress distribution is a function of the ratio of contact radius to layer thickness (a/h), and while tensile stresses are seen to occur only when a/h is small, tensile strain is observed for all a/h values. Significant shear stresses are observed at the cartilage-bone interface. Softening of cartilage results in an increase in a/h, and a decrease in maximum normal stress. Cartilage thinning increases a/h and the maximum contact stress, while thickening has the opposite effect. A reduction in the indenting radius reduces a/h and increases the maximum normal stress. Bone softening is seen to have negligible effect on the resulting contact parameters and stress distribution.

Induced stresses and fault potential in eastern Canada due to a realistic load: a preliminary analysis

Abstract: SUMMARY In order to understand the causal relation between postglacial rebound and earthquakes, a simple disc load model is used to: (1) calculate stresses induced in the lithosphere and mantle by glacial loading, melting and postglacial rebound; and (2) evaluate the effect of glacial loading/rebound on the failure potential for earthquakes in the upper crust. The dependence of the failure potential and the actual mode of failure on the coefficient of friction, the ambient tectonic stress magnitude/direction, the stress due to the overlying rocks, and lithospheric thickness are investigated. Prominent features of this paper are the inclusion of: (1) a viscoelastic mantle and thus the migration of stress; and (2) the ambient tectonic stress and overburden stress contributions in the calculation of the total stress field. It is assumed that, throughout the Earth, there are optimally oriented pre-existing virtual faults that are initially close to but not at failure; thus, a time-dependent quantity called dFSM (related to the Coulomb-Mohr failure criterion) can be defined such that a negative value of dFSM would advocate faulting or earthquake activities whereas a positive value of dFSM would promote stability. The results indicate that, under all combinations of tectonic stress magnitude and overburden stress, crustal loading promotes fault stability directly underneath the load. Upon the removal of the load, thrust faulting is predicted within the ice margin if the horizontal stress (S,) induced by the overburden is greater than or equal to the vertical component (S,) of the overburden stress (121, where (=SJS,). Under this condition, theory predicts that faulting or earthquake activity should have reached a maximum immediately after deglaciation. If the horizontal stress induced by the overburden is less than the vertical component of the overburden stress (1 < l), then theory predicts fault stability within the ice margin. The theory predicts fault instability both north and south of the ice margin. The mode of failure, however, is completely determined by the value of i. The trade-off between the tectonic stress magnitude and the overburden stress parameter (1) is also investigated. It is shown that a larger tectonic stress magnitude can be used to compensate a smaller value of 1. The results of this analysis show that variations in the coefficient of friction, lithospheric thickness and a ductile zone below the upper crust do not significantly affect the above conclusions.

High-Angle Tilt Boundary—A Dislocation Core Model

Abstract: The dislocation model of a symmetric tilt boundary is modified to take into consideration the stress field of the cores of the dislocations. It is found that such modification enables discussion of many properties of high‐angle tilt boundaries including porosity, strain energy, intergranular fracture, grain boundary shearing, void formation, preferential melting, preferential diffusion, boundary migration, segregation, precipitation, amorphous behavior, continuous and discontinuous transition, etc., in terms of the interaction among the cores of the dislocations and the properties of the cores themselves. This is a first attempt to devise a working model capable of interpreting all the properties of grain boundaries. Unlike other models which are designed to have a few particular properties in a limited angular range, this model has the advantage of reducing to the dislocation model at low angles and of providing for amorphous behavior at high angles. The characteristic of a grain boundary of behaving as ...