Determination of intrinsic fracture energy of elastoplastic materials based on plastic dissipation exclusion

Abstract

In elastoplastic fracture problems, the determination method of classical fracture toughness often incorporates plastic dissipation as part of the crack growth resistance, i.e., plastic correction method, leading to high sensitivity of the resistance to factors such as crack length, structural geometry, and loading conditions. This work proposed a method for determining the intrinsic fracture energy of elastoplastic material, which is considered a constant material parameter. This was achieved by calculating various energy components for a cracked structure via finite element modeling and excluding plastic dissipation energy from the total energy change during crack propagation. A mathematical expression for evaluating the energy was provided for common engineering materials that follow Hollomon’s hardening law. The method was validated through compact tension as well as compact tension and shear experiments on materials with varying ductility, including 316L stainless steel, 2A12 aluminum alloy, and TC4 titanium alloy. Moreover, the applicability of the HRR solution in elastoplastic fracture problems and the underlying mechanism of crack growth resistance formation were discussed.