Damage modelling strategies for unidirectional laminates subjected to impact using CZM and orthotropic plasticity law

In the present paper, the crashworthiness of a thick unidirectional carbon fibre reinforced polymer is investigated. This material is manufactured via compression moulding process. A Low-Velocity Impact (LVI) test is implemented on a quasi-isotropic laminate for the experimental evaluation of the energy absorption due to impact, while the internal failure mechanism is detected using Computerized Tomography (CT). Two different Finite Element (FE) models are applied to model the damage onset and propagation: firstly, a shell-based model and, secondly, a solid-based model using Cohesive Zone Method (CZM). In the CZM, the analytical modelling of the cohesive element properties is adopted, and the critical force evaluated experimentally is related to the energy release rate of mode II, and to the equivalent elastic properties of the laminate. The strength and weakness of the proposed approach in mimicking the impact behaviour and the actual failure mechanism, are discussed, and validated versus numerical simulation. The models are in good agreement with the experimental results; in fact, the relative error of the maximum force is about 4 per cent, and it occurs in the shell-based model.