Analysis of Stress Singularity Field in Three-Dimensional Joints Using Three-Dimensional Boundary Element Method

Abstract

Stress singularity at a vertex in three-dimensional joints is closely related to the strength of joints. It is very important to perform an analysis for evaluating the reliability of a real three-dimensional joint. However, the stress singularity fields near the vertex and along stress singularity lines are still unclear. In the present study, we investigated the characteristics of stress singularity field at a vertex and a point located on the stress singularity line in three-dimensional joints using a three-dimensional BEM and an eigen analysis based on FEM. It was shown that the order of stress singularity at the vertex is larger than that at the point on the stress singularity line, and the order of logarithmic singularity along the singularity line is larger than that at vertex. In the present analysis, a triple root and a quintple root of eigen value, p=1, occur at the vertex and a point on the singularity line, respectively. The order of stress singularity determined from the eigen analysis was agreed with that from BEM. The value of coefficient in a power-law singularity increased as approaching to the vertex along the singularity line. The stress field along the singularity line is more influenced on the logarithmic singularity than that at the vertex. In particular, coefficients of terms in logarithmic singularity vary in the same way with the angle from an interface.