A finite-element model of mixed-mode delamination in laminated composites with an R-curve effect

A finite-element model is proposed for mixed-mode delamination of composites which takes into account R-curve effects like fibre bridging at cracked interfaces or plastic deformation at crack tips. An elastic/ideal-plastic damage model is used to describe the initiation and propagation of interfacial cracks. The laminate is modelled as a set of monolayers separated by zero-thickness imperfect interfaces with finite stiffness. Under external loading, plastic yielding in interfaces is assessed according to a stress-based criterion while delamination initiation and propagation are governed by a fracture-mechanics-based criterion taking the interaction effects of mixed-mode loading into account. The R-curve effect is modelled as a linear damageable spring. The proposed method is implemented into the general finite-element code SAMCEF. Numerical simulation of standard delamination tests is compared with experimental results showing the efficiency of the method.