Numerical evaluation of the delamination behaviour in Mixed Mode Bending CFRP specimens

The raising interest in composite materials of last decades, justifed by their amazing properties, is pushing to fill the knowledge gap which constraints their employment. Damage behavioural predictions are required to be good enough in order to satisfy the strict aeronautical regulations. The study performed in this thesis work, which is located in the above described framework, aimed to supply informations about crack propagation under mixed-mode loading condition. In particular, critical forces and Strain Energy Release Rates have been determined to describe the behaviour in the range between pure mode I and II. Two different FEM approaches have been employed to analyze a CFRP Mixed Mode Bending specimen in several mode-mixing configurations. The first selected methodology is the Virtual Crack Closure Technique, but the obtained outcomes resulted to be far from expected ones. The final goal was instead achieved with the relatively new Cohesive Zone Models approach, for which an increased interest can be observed in recent years.