Assessment of the SIF, T-stress and higher-order coefficient values of the cracked specimens with two interacting cracks or notches under mixed mode loadings by digital photoelasticity method

Abstract

The purpose of this work is to determine experimentally and computationally the coefficients of the Williams series expansion in the vicinity of two interacting cracks or notches. In this study, the multi-parameter description of the crack-tip fields for digital processing of the experimental data obtained from photoelastic experiments is complied. The special programming tool for digital processing of the experimental data is elaborated. The Williams expansion is introduced for approximation of the stress/displacement distribution. The over-deterministic method is used for calculation of the coefficients of the power series terms because it requires only a conventional FE analysis. Results determined via finite element analysis are compared to those calculated by means of the stress distribution expressed via the Williams expansion under consideration of various numbers of initial terms of the series. It is shown that the higher-order terms of the Williams expansion can be significant when the extent of the isochromatic fringe is far enough in comparison to the crack length. It is shown that the use of higher order terms leads to increase of the domain where the Williams series expansion can be used.