A material selection approach for protecting carbon/epoxy laminates against single and repeated low-velocity impacts

This paper evaluates the impact performance of various materials against single and repeated low-velocity impacts. The objective is to identify a lightweight, thin, and cost-effective bumper that can effectively protect a composite aircraft structure. Drop-weight impact tests were performed on eight candidate materials with similar areal densities, including three 3D woven and three 2D woven composites, an aluminium alloy (Al 7075 T6) and an aluminium foamed sandwich. To enable a comparison of impact performance across materials with different characteristics, a normalisation method was defined for both single and repeated impact loading. The relationship between single and repeated low-velocity impacts was also explored. Finally, the influence of adding a polymeric foam on the amount of energy transmitted to the composite airframe was also discussed. The results indicate that, overall, the 3D woven composites exhibited superior impact performance in all tested scenarios.