Sub-sized short bend beam configuration for the study of mixed-mode fracture

Abstract

In this paper an angled edge cracked short beam specimen subjected to symmetric three-point bend loading was designed and examined for conducting mixed-mode I + II fracture toughness experiments. This specimen is suitable for being used in those experimental crack growth studies in which a very limited amount of raw material is available for the preparation of the test specimen. By conducting several finite element analyses, it was shown that the short bend beam specimen is able to produce full modes I and II mixities if the affecting parameters such as the crack length ratio, loading span ratio and crack inclination angle are set in suitable ranges. The practical ability of the short bend beam specimen was investigated for obtaining the mixed-mode I + II fracture toughness of bovine bone and the corresponding values of KIc and KIIc were determined for different mode mixities. While a significant discrepancy was observed between the experimental results and predictions of the conventional singular based fracture theories, it was demonstrated that the two-parameter (K &T) based fracture models such as GMTS and EMTSN criteria can provide significantly improved predictions for the fracture behavior of tested short bend beam specimen made of bone material.