Theoretical Prediction of Fracture of Initially Crack-Free Brittle Materials

Accurate determination of failure is crucial for designing engineering structures as their failure may cause not only economic loss but also loss of human life. Brittle fracture is a type of material failure, and literature on brittle fracture mainly focuses on fracture of bodies with pre-existing crack. In this study, however, a new brittle fracture criterion (of tensile mode) that is applicable at quasi-static loading conditions is proposed for initially crack-free bodies. The fracture criterion is based on the continuum modeling of energy release rates and it is developed using Karr-Akçay energy balance concept. The criterion can be implemented to determine (Mode I) fracture toughness of a material as well as (fracture) strength of a material if its characteristic length is known, whereas the characteristic length of a material can be obtained (using the proposed criterion) if its (fracture) strength is known. Tensile strength of a gray cast iron is determined using the proposed criterion and compared to the results in the literature. Theoretical result is in good agreement with the experimental result published in the open literature.