ASYMPTOTIC ANALYSIS OF A COHESIVE CRACK .2. INFLUENCE OF THE SOFTENING CURVE

This paper presents a numerical method well suited to solve the integr al equation governing the asymptotic behavior of a cohesive crack, and uses it to analyze the influence of the softening curve on the cracki ng response of large specimens. The analysis is performed with two mai n objectives in mind: (1) providing criteria to determine when a simpl ified linear elastic fracture mechanics (LEFM) approach can be applied , and (2) providing possible procedures of extracting information on t he softening behavior from experimental data. The main conclusion is t hat the effective crack extension prior to peak is nearly determined b y the length of the softening curve (the critical crack opening) and s o is the deviation from LEFM. Furthermore, a simplified R-curve approa ch is proposed as an approximate alternative to solving the governing integral equation.