INTERELEMENT STRESS EVALUATION BY BOUNDARY ELEMENTS

The conventional boundary element method employs piecewise shape functions which lead to stress discontinuity at the interelement boundary. This paper derives formulae for boundary stress and boundary stress gradient based on boundary element solutions, and discusses error propagation in stress evaluation due to errors in the displacement boundary values. The nature of stress discontinuity is investigated. A simple post-processing scheme is presented using continuities of stress and stress gradient along a traction boundary as two extra conditions, so that a high-order shape function can be employed for the evaluation of stress and stress gradient on the interelement boundary. Four numerical examples are used to demonstrate the accuracy of the proposed post-processing scheme. The numerical results show that as compared with the conventional method, the post-processing method can significantly improve the stress and stress gradient on the traction boundaries, especially in the area of stress concentration