STRESS INTENSITY FACTORS AND WEIGHT-FUNCTIONS FOR HIGH-ASPECT-RATIO SEMIELLIPTIC SURFACE CRACKS IN FINITE-THICKNESS PLATES

Three-dimensional finite element analyses have been conducted to calcu late the stress intensity factors for high aspect ratio semi-elliptica l cracks. The stress intensity factors are presented for the deepest a nd surface points on semi-elliptic cracks with aspect ratios of 1.5 an d 2, and a/t values of 0.2, 0.4, 0.6 and 0.8. Uniform, linear, parabol ic dr cubic stress distributions were applied to the crack face. The r esults for uniform and linear stress distributions were combined with corresponding results for lower aspect ratio surface cracks to derive weight functions over the range 0.6 less than or equal to a/c less tha n or equal to 2.0 and 0.0 less than or equal to a/t less than or equal to 0.8. The weight functions were then verified against finite elemen t data for parabolic or cubic stress distributions. Differences were l ess than 3% for the surface point and 6% for the deepest point. The pr esent results complement weight functions for low aspect ratio cracks, 0.0 less than or equal to a/c less than or equal to 1.0, developed pr eviously by the authors. (C) 1997 Elsevier Science Ltd.