Improved Point Load Weight Function for Stress Intensity Factor of a Surface and an Embedded Crack

This paper describes the application of weight function method for the calculation of stress intensity factors in a surface crack and an embedded crack under complex two-dimensional loading conditions. The crack shape is approximated by an ellipse.Improved formulation of the point load weight functions are proposed based on the properties of weight functions and the available weight functions for two-dimensional cracks proposed by Wang and Glinka. For a surface crack and an embedded crack of any aspect ratio, the unknown parameters in the general form can be determined from one reference stress intensity factor solution obtained by the finite element analysis with J integral method. The derived weight functions are then validated against available stress intensity factor solutions for several linear and non-linear stress distributions. The derived weight functions are particularly useful for the fatigue crack growth analysis of a planer surface crack and an embedded crack subjected to fluctuating non-linear stress.