Energy absorption capability of carbon fiber reinforced plastic tubes with semi-circle grooved external trigger

For the purpose of improving the energy absorption performance of capped carbon fiber reinforced plastic tubes, a semi-circle grooved crush-cap is proposed and a series of experiments and improvements has been conducted. Tubes, which are respectively built by carbon fiber laminate and carbon fiber woven cloth, with semi-circle grooved crush-caps, combined (notched-end and crush-cap) failure mechanisms were investigated to identify the optimal configuration that would result in the most stable initial peak load while providing the highest possible specific energy absorption. Experimental results show that the new crush-caps lower the initial load, effectively yielding a high specific energy absorption. These results are significantly influenced by the semi-circle radii of the crush-caps. Furthermore, two failure modes have been observed in tests by changing the external trigger and tube material. The failure mode changes from splaying mode to fragmentation mode with the decrease of radii. The combined failure triggers proved the reduction in the initial load without smoothing the load-displacement curve, therefore, they reduce the energy absorption capability of carbon fiber reinforced plastic tubes. In our experiments, the tested tube which is made by T300/5208 woven cloth with R3 trigger is ground into powder, resulting in an specific energy absorption as high as 101.7 kJ/kg also with a smooth load-displacement curve.