F.J. Gómez

Generalizations and specializations of cohesive crack models

Abstract This paper presents an overview of the cohesive crack model, one of the basic models used so far to describe the fracture of concrete and other quasibrittle materials. Recent developments and needs for further research are discussed. The displayed evidence and the discussion are based on considering the cohesive crack model as a constitutive assumption rather than an ad hoc model for the behaviour ahead of a preexisting crack. Topics addressed are fracture of unnotched specimens, mixed mode fracture, diffuse cracking, anomalous stress–strain curves, size effect and asymptotic analysis, and strength of structural elements with notches.

Fracture of components with V-shaped notches

An experimental and numerical study was performed to ascertain the influence of V-notches on the strength of different brittle materials. Critical loads were computed using the cohesive process zone model that allows extension of classical methods, based on linear elastic fracture mechanics, to rounded V-notches and contained plasticity. A large experimental programme, with more than one hundred tests, was performed with PMMA samples to support the numerical predictions. All the experimental results are reported. In addition, experimental results of notched steel samples, performed by Strandberg, [Engng. Fract. Mech. 69 (2002) 403], and notched samples made with expanded PVC foams, performed by Grenestedt, Hallstrom and Kuttenkeuler [Engng. Fract. Mech. 54 (1996) 445], are in very good agreement with the numerical computations, adding further support to the cohesive process zone model.