Equivalent End-Weakening Governing Crushing Modes and Crashworthiness of CFRP Tubes with Different End Triggers Under Quasi-Static Axial Compression

Quasi-static axial crushing tests were carried out on CFRP tubes with various end triggers (chamfer, tulip, crown, notch), aiming to reveal the joint regulation mechanism of geometric configuration and equivalent end-weakening on the crushing behavior of the tubes. Load–displacement responses, crashworthiness indicators and post-crushing failure morphologies were analyzed. Results indicate that the chamfer trigger can effectively reduce the initial peak load at the expense of mean crushing force and total energy absorption. Moderate tulip and crown triggers form cantilever petals and exhibit desirable two-stage crushing responses. However, excessive cutting intensifies the end-weakening effect, leading to simultaneous petal bending and matrix crushing and yielding a distinct unimodal response. Under the present test conditions, the notch trigger exhibits an inherent unimodal crushing characteristic. It delivers a high total energy absorption of up to 2186.2 J but suffers from a higher peak crushing load and lower crushing force efficiency, which reveals a clear performance trade-off. These observations demonstrate that geometric configuration and equivalent end-weakening exert a bidirectional coupled regulatory effect on crushing behavior. Furthermore, numerical simulation results show that the finite-element model can well predict the crushing load–displacement responses of tubes with different end modifications, while it fails to reproduce the typical petalling opening morphology of triggered specimens, which clarifies the application boundary of the simulation model. The results of this study can provide experimental references for the optimization design of end-triggered CFRP energy-absorbing tubes.