Application of ε<SUB>J</SUB>-integral to Elasto-plastic Crack Problems under Monotonic or Cyclic Loading : Physical Meanings of J (ΔJ) and Analysis of Crack Energy Density

Abstract

In former papers, a concept of crack energy density ε was proposed as the most fundamental parameter in fracture mechanics and it was shown that εεεεε can be evaluated by a path independent integral εJ without any restriction on constitutive law. In this paper, εJ -integral is applied to elasto-plastic crack problems under monotonic or cyclic loading; and the availabilities of εJ -integral are demonstrated. First, it is shown that the physical meanings and applicable ranges of J and ΔJ can be clarified in the light of εJ. Next, the method of the estimation of ε based on εJ is established through the finite element analysis of elasto-plastic crack under monotonic loading. Moreover, an analysis under cyclic loading is carried out, and the basic characteristic of ε and the relations between ε and fatigue parameters ΔK and ΔJ are discussed.