Impact and post-impact response of lightweight CFRP/wood sandwich composites

Lightweight CFRP/wood sandwich composites receive considerable attention because they can be tailored to satisfy many specifications. Therefore, the damage modes during low velocity impact and compression after impact (CAI) of CFRP/wood sandwich laminate with different wood core types are investigated in this article. The effect of wood fiber orientation on the specific energy dissipation and CAI strength are studied. Results demonstrated that the laminate with balsa core wood, where the wood fibers are perpendicular to the CFRP face plies, shows higher impact load and dissipated energy due to the ability of wood cells to deform during impact and hence dissipate more energy. However, the laminate with birch core, where the wood fibers are parallel to the CFRP surface plies, reveals slightly larger CAI strength due to the role of wood fibers in sharing the load during compression. The damage initiated in the balsa core sandwich laminates at the impacted face and propagate to the unimpacted CFRP surface, while the opposite damage behavior occurs for the birch core sandwich laminate. The balsa core laminate showed larger specific impact load (load/density), dissipated energy (dissipated energy/density), and CAI strength (strength/density), reaching 2.21-, 2.24-, and 1.41-fold times compared to birch core laminates.