Numerical analysis of the interactive damage mechanisms in two-dimensional carbon fabric-reinforced thermoplastic composites under low velocity impacts

摘要

Damage and failure in carbon fabric-reinforced polymer (CFRP) composites under low velocity impacts is investigated using explicit finite element analyses. Three-dimensional finite element models are developed to simulate the deformation behaviour of, and damage evolution in CFRP laminates under such loading conditions. In these simulations, the onset and growth of inter-ply delamination is captured by bilinear cohesive zone elements inserted between plies of the composite. Intra-ply fabric fracture is simulated by defining a transverse layer of cohesive elements at the specimen fracture location. The energies associated with dynamic propagation of these damage mechanisms are also captured by the numerical simulations, demonstrating their potential to model the damage modes as well as their interaction. In this study, a novel damage modelling technique based on the cohesive zone method is proposed for interaction of various damage modes, which is more efficient for coupling between failure modes than a continuum damage mechanics approach. For the first time, it was observed that the pattern of interlaminar damage formation was from the front interface towards the back of the specimen, unlike the traditional back to front one in drop-weight tests. Results of experimental tests performed on a woven CFRP material under low velocity impact in Izod-type impactor at various energy levels are used for comparison with simulations. A satisfactory agreement was found between experiments and simulations confirming the validity of the numerical analyses.