LOCAL WEIGHT-FUNCTIONS FOR SEMIELLIPTIC SURFACE CRACKS IN FINITE THICKNESS PLATES

Weight functions for any local point, 0 < phi < pi/2, along a semi-ell iptical surface crack in finite thickness plates were derived from an assumed approximate general weight function and two reference stress i ntensity factors. The resulting weight functions were verified using a vailable finite element results for two nonlinear stress fields and go od agreement was achieved. When used together with weight functions fo r phi = 0 and phi = pi/2, the weight functions are suitable for the ca lculation of stress intensity factors anywhere along the crack front f or semi-elliptical surface cracks in complex stress fields with aspect ratios in the range 0 less than or equal to a/c less than or equal to 1 and relative depths 0 less than or equal to a/t less than or equal to 0.8.