A hybrid approach to determine fracture resistance for mode I and mixed-mode I and II fracture specimens

This paper proposes a hybrid approach to determine the fracture resistance for mode I and mixed-mode I and II fracture specimens, combining both numerically computed and experimentally measured load (P) versus load-line displacement (LLD or delta) relationships for metallic fracture specimens. The hybrid approach predicates on the same principle as the conventional, multiple-specimen experimental method in determining the energy release rate. The hybrid method computes the P-delta curves from multiple finite element (FE) models, each with a different crack depth. The experimental procedure measures the P-delta curve from a standard fracture specimen with a growing crack. The intersections between the experimental P-delta curve and the numerical P-delta curves from multiple FE models dictate the LLD levels to compute the strain energy (U) using the area under the numerical P-delta curves. This method provides accurate estimates of the J resistance data for both SE(B) specimen under mode I loading and single-edge notched specimens under mixed-mode I and II loading.