| Abstract Scope |
A large structural size-effect on brittle fracture energy was observed in historical studies of Charpy impact fracture of steels by Stanton, Batson, and Docherty, circa 1920-35. Interestingly, these detailed studies were performed prior to A. A. Griffith’s famous publication on energy release rate theory for fracture. Neither the Griffith’s crack theory nor the fracture mechanics framework developed by G. R. Irwin is able to explain these elaborate results. In this presentation, a novel net-section mechanics based approach is used to explain the size effects observed by Stanton, Batson, and Docherty. It is shown that the change in net-section strain energy predicts well the size effect on fracture energy under the constant load condition of cleavage crack initiation at the notch root. The analysis provides a rigorous method to quantity size effects in notched bar impact and in fracture toughness testing of structural materials. |