Mixed mode stress intensity factors for deflected and inclined surface cracks in finite-thickness plates

Using three-dimensional enriched finite elements, mixed mode stress intensity factor solutions are presented for deflected and inclined surface cracks in finite-thickness plates under uniform tensile remote loading. It is demonstrated that the enriched finite element technique provides fracture solutions for these types of problems in a very direct and convenient manner without a need for post-processing the finite element solution. Mixed mode stress intensity factor solutions are generated for semi-circular surface cracks with various deflection and inclination angles ranging from 0° to 75°. The effect of plate thickness on the mixed mode fracture solution is also investigated. In the analyses presented, crack length/plate thickness (a/t) ratio ranges from 0.2 to 0.8. It is shown that decreasing the plate thickness results in magnification of mixed mode stress intensity factors along the crack front. Based on the computed mixed mode stress intensity factors, crack propagation angles along the deflected and inclined crack fronts are also determined.