A fracture evolution procedure for cohesive materials

The present paper deals with the problem of the evaluation of the softening mechanical response of cohesive materials under tensile loading. A nonline ar fracture mechanics approach is adopted. A new numerical procedure is dev eloped to study the evolution of the crack processes for 2D solids. The pro posed algorithm is based on the derivation and use of the fracture resistan ce curve, i.e., the R-curve, and it takes into account the presence of the process zone at the crack tip. In fact, assuming a nonlinear constitutive l aw for the cohesive interface, the procedure is able to determine the R-cur ve, the process zone length and hence the mechanical response of any materi al and structure. Numerical applications are developed for studying the dam age behavior of a infinite solid with a periodic crack distribution. Size e ffects are investigated and the ductile-brittle transition behavior for mat erials characterized by the same crack density is studied. The results obta ined adopting the proposed procedure are in good accordance with the result s recovered through nonlinear step by step finite element analyses, Moreove r, the developed computations demonstrate that the procedure is simple and efficient.