Modelling low-velocity impact damage and compression after impact of 3D  woven structures considering compaction

A novel finite element modelling approach is presented which incorporates representative binder yarn compaction, for simulating the low-velocity impact (LVI) and compression after impact (CAI) response of 3D woven layer-to-layer carbon/epoxy composite architectures. Simulations of out-of-plane drop-weight impact tests were performed at energies of 32 J and 42 J. Warp and weft layers were modelled as continuous plies and three different approaches were explored to model the binder reinforcement; (i) with a rectangular cross-section and non-compacted, (ii) with an elliptical cross-section and non-compacted, and (iii) an elliptical cross-section which accounts for compaction. Predictions were compared with experimental results from literature and it is shown that modelling the binder reinforcement as an elliptical cross-section with compaction leads to a predicted damage area, on the impacted side, which is within 2%, and the non-impacted side within 6% of experimental measurements. The predicted CAI strength is within 11% of the experimental values.