Estimation scheme for ductile growth of a semi-elliptical surface crack

Finite element analyses are performed on the assumption of the power-law hardening and the deformation theory of plasticity. The J-integral values under the fully plastic condition are estimated for four semi-elliptical surface cracks in a plate subjected to uniform tension. Both local and global estimations are employed, varying the manner of the virtual crack extension. Some discussions are made on the J-integral distribution along the crack front. Especially for a deep crack, the maximum J-integral value is found at some location between the deepest point and the free surface. Also, the numerical solutions are applied to the experimental results obtained by the multi-specimen method. The crack aspect ratios during ductile growth are predicted well with reasonable fracture resistance. (author)