A study of non-uniform stress distribution to predict stress intensity factors of Two Edge Cracks

Abstract

The parameter known as the Stress Intensity Factor (SIF) K is used within Linear Elastic Fracture Mechanics (LEFM) to predict crack propagation rate knowing the appropriate material properties. Unfortunately the number of SIF solutions for two cracks is very small especially for real engineering cases. One of the methods to determine K value that can be further developed for two interacting cracks is the weight function method. The calculation of SIF using the weight function equation requires stress distribution profile at the potential crack plane. Under uniform applied stress, the stress distributions at the potential crack plane for a single crack will be uniform but not for the case of two cracks. Twodimensional FE models were constructed to study the nonuniform stress distribution due to the presence of a single edge crack, along the crack plane of a potential second edge crack. The objective of the study was to examine the relationship between the crack-line stresses and the interaction effect between cracks. Two-dimensional FE models were also constructed to calculate SIFs of two parallel edge cracks in a sheet under uniform tension. Results of stress distributions along the potential crack plane shows that their variation is similar to the characteristics of the interaction effects as illustrated by the SIF results. The non-uniform stress distributions were used to establish the crack interaction in a general form. With this general form the weight function method which are normally used for a single edge crack, can be applied to predict the SIFs of two edge cracks in a finite body under uniform tension.