Low-velocity impact performance of composite-aluminum tubes prepared by mesoscopic hybridization

Novel circular hybrid structures with overlapped carbon-fiber-reinforced plastic (CFRP), glass-fiber-reinforced plastic (GFRP) and/or aluminum layers were fabricated. Such structures were hybridized at the mesoscopic scale, generating multiple CFRP-GFRP or composite-aluminum interfaces. Also, aluminum foam was utilized as inner filler to further enhance the energy absorption of the thin-walled structures. The interactive effects on crashworthiness among different materials were explored by axial drop-weight impact testing. The experimental results showed a progressive failure process of all CFRP/GFRP and composite/aluminum hybrid tubes. The mean crushing force (MCF) of empty CFRP/GFRP hybrid structures were significantly improved by more than 20% when compared to pristine CFRP tube. On the other hand, the composite/aluminum hybrid design effectively reduced the peak crushing force (PCF) and improved the crushing force efficiency (CFE). However, the specific energy absorption (SEA) was decreased by about 10% owing to the moderate strength-to-weight ratio of inserted aluminum sheet. Compared to empty tubes, the filling of aluminum foam significantly enhanced MCF by more than 10%, while declining SEA due to the low weight efficiency of aluminum foam. In sum, the proposed hybrid design maximized some aspects of crashworthy performance at a low cost, thereby promising for the future design of practical light-weight energy absorbers.