Applicability of CED (crack energy density) to mixed mode fracture problem

Abstract The CED (Crack Energy Density), eϕ, in an arbitrary direction is defined and has a consistent meaning without any restriction on constitutive equation. In general, eϕ can be divided into the contributions of each mode and the maximum value, eIϕmax, of eIϕ for mode I is expected to play the most important role in mixed mode fracture problems. In this paper, eϕ and eIϕ for specimens under tension with a crack inclined to the loading axis are evaluated by path-independent integrals and the method based on the relationship between eϕ and load-displacement curves through elastic finite element analyses, and a practical method to evaluate eIϕmax is proposed through comparison of the results with theoretical ones. Subsequently, eIϕmax corresponding to an experimental result of ductile fracture is evaluated by the above proposed method through elastic-plastic finite element analyses and the applicability of CED (eIϕmax) to a mixed mode fracture problem is demonstrated.