Effect of initiator geometry on energy absorption of CFRP tubes under dynamic crushing

This study investigates the effect of initiator geometry, i.e. an inward-triggering cap (ITC), an outward-triggering plug (OTP) and a flat-surface plate (FSP), on the failure mechanisms and energy absorption of two carbon fibre reinforced polymer (CFRP) tubes, [0₃/45/−45/90/−45/45/0₃] (type U) and [0₃/90₂/0₃/(0/90)] (type W), under dynamic and quasi-static crushing in the axial direction. Under both dynamic and quasi-static crushing, the ITC induced massive transversely fractured fronds with enormous fragments, leading to high specific energy absorption, whereas the OTP produced the lowest specific energy absorption. The specific energy absorption of CFRP tubes under dynamic crushing were 32–40% and 12–69% lower than those under quasi-static crushing for the U-type tube and W-type tube, respectively. With the FSP, as compared to the U-type tube, the W-type tube had a higher specific energy absorption, though the wall thickness of the W-type tube was about 0.15 mm less than that of the U-type tube. Comparative analysis of the specific energy absorption indicated that the CFRP tubes were advantageous with the FSP when subjected to dynamic crushing, but they performed better with the ITC under quasi-static crushing.