3D effects on crack front core regions, stress intensity factors and crack initiation angles

Results pertaining to three dimensional finite element analysis of a mixed mode edge crack in a tension specimen are presented. Considering three values for the crack inclination angle, the effect of thickness is investigated on the predicted crack tip plastic zone size, stress intensity factors and crack initiation angles at the surface and the mid plane. The crack initiation angles are calculated using two crack initiation criteria: MTS and R-criterion. In general, the effect of thickness is noted for low values of thickness over crack length ratio at the surface. The finite element results are optimized through mesh convergence and validated by experiments. The experimental set up is designed and used to measure the crack initiation angle in mixed mode SENT specimen and estimate the stress intensity factors for different crack inclination angles and specimen thicknesses.