On lateral compression of circular aluminum, CFRP and GFRP tubes

Thin-walled structures made of lightweight materials, e.g. aluminum, fiber reinforced composites, have been increasingly used as energy absorption structures in vehicles. This work aimed to characterize the lateral crushing behaviors of circular aluminum, glass fiber reinforced plastics (GFRP) and carbon fiber reinforced plastics (CFRP) tubes with different geometric configuration such as diameter-to-thickness (D/T) ratio or thickness. In the experimental investigation, four different D/T ratios varied from 10.78 to 48.02 were considered here for the aluminum, GFRP and CFRP tubes. Crushing behaviors such as force-displacement curves, deformation histories, and crushing force were quantified. The experimental results revealed that the load carrying capacities, energy absorption (EA) and specific energy absorption (SEA) of the circular tubes decline with increasing D/T ratio. It was found that better crashworthy characteristics of thicker composites, with a smaller D/T ratio, were due to the more favorable failure modes occurring throughout lateral compression. The lateral crashworthy performance of the GFRP tubes was marginally better than that of the CFRP counterparts. Due to ductile behavior of aluminum tubes and brittle behavior of composites, aluminum tubes showed much better lateral crashworthiness than that of the composite counterparts. Moreover, with the increase in the D/T ratio, aluminum tubes exhibited greater advantage on crashworthiness than the composite tubes. On the basis of the experimental data, explicit finite element analysis was further carried out for modeling the lateral crushing behavior of aluminum, GFRP and CFRP tubes. The numerical results were in good agreement with the experimental data, demonstrating the validity of these finite element (FE) models in predicting lateral crushing responses of aluminum, GFRP and CFRP tubes. The proposed FE models can be exploited to further study similar thin-walled metal and composite structures for design optimization.