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

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