An efficient numerical approach to the prediction of laminate tolerance to Barely Visible Impact Damage

An efficient numerical approach for the prediction of the Compression After Impact (CAI) strength of aerospace-grade CFRP laminates when exposed to Barely Visible Impact Damage (BVID) is proposed. The approach is based on mapping relevant BVID features, i.e. delaminations, onto an efficient CAI finite element model based on continuum shell discretization, and can be used on Low-Velocity Impact (LVI) results obtained experimentally or by means of high-fidelity virtual tests. It is proposed that delaminations may be represented by simplified shapes, and only the ones at critical through-thickness locations need to be mapped, allowing the clustering of several plies in a single shell layer. General guidelines, that are potentially valid for a wide range of unidirectional CFRP laminates, are proposed to identify relevant and critical BVID features to be mapped onto the efficient CAI modelling. The approach was validated for five laminates of AS4/8552 material, covering a range of different thicknesses, overall achieving CAI strength predictions within 5% of the experimental results. In comparison with the alternative high-fidelity CAI virtual testing approach, this method leads to computational efficiency gains of an order of magnitude. Moreover, the full simulation of the sequence LVI plus CAI steps can be accelerated by a factor of four.