Compressive strength of hybrid composite tubes after low-energy impact

Hybrid composite tubes were wound with Kevlar fibers under three winding an gles and sandwiched by either hoop carbon or glass fibers. The tubes subjec ted to low-energy impact using a drop-weight impact apparatus with a round- ended impactor have been investigated. Compression after impact (CAI) stren gths were measured, and the damage tolerances of hybrid tubes were assessed by the residual strengths. Compared to compressive strengths of the tubes without low-energy impact, CAI strengths of hybrid tubes decreased signific antly due to delamination generation and propagation from the impact site. The microstructure of CAI hybrid tubes were examined, and explanations for their damage modes through the thickness were proposed. We also studied the damage mechanisms that were induced by impact and compression, and their i nteraction, which was related to winding angle and hybrid fibers. In additi on, the correlation among damage mechanisms, failure modes, and CAI strengt hs was also investigated.