Damage and fracture in carbon fabric reinforced composites under impact bending

Carbon fabric reinforced polymer (CFRP) composites used in sports products demonstrate various modes of damage and fracture under impact bending loads. These failure modes are studied using experimental material characterisation and numerical simulations. Experimental tests are carried out to characterise the behaviour of a woven CFRP material under large-deflection dynamic bending in Izod-type impact tests at various energy levels. Three-dimensional finite element (FE) models are developed to study the deformation and damage development in the specimens under dynamic bending. In these models, initiation and progression of interlaminar delamination at the impact location is studied by employing cohesive-zone elements between each ply of the composite. Intralaminar fabric fracture of composite laminate is modelled by inserting a transverse layer of cohesive elements at the laminate fracture location. The developed numerical models are capable to simulate these damage mechanisms as well as their subsequent interaction observed in tests. FE models based on the cohesive-zone method are more efficient than those based on continuum damage mechanics approach in modelling interaction between failure modes. In this study, front-to-back damage formation was observed in specimens, unlike back-to-front one in drop-weight tests. Simulation results showed a reasonable agreement with an experimentally obtained transient response of the composites.