触发机制对复合材料吸能结构轴向压溃行为的影响

Effect of trigger mechanisms on axial crushing response of composite energy-absorbing structures

考虑碳纤维增强复合材料(carbon fiber reinforced polymers,CFRP)层内和层间力学性能特点,建立CFRP圆管轴向压溃有限元模型,并与实验测试的载荷-位移曲线和失效模式对比,验证建模方法的可靠性。在此基础上,考虑机车车辆薄壁吸能装置结构特点,研究内翻触发、外翻触发、嵌入式内翻触发和嵌入式外翻触发机制对CFRP圆管轴向压溃行为的影响。研究结果表明:相比倒角触发机制,在内翻和外翻触发机制作用下,管壁材料破坏不充分导致CFRP圆管能量吸收分别下降36.5%和43.4%。嵌入式触发机制可有效提高材料利用率,内腔尺寸参数L与CFRP圆管失效模式和能量吸收性能密切相关。L由8 mm增大为16 mm,圆管压溃变形过程得到改善,结构能量吸收先上升后下降。在嵌入式内翻机制作用下,L=12 mm时CFRP圆管能量吸收效果最好,相比倒角触发机制,能量吸收提升63.1%。管壁材料向内变形可进一步提高材料利用率。

Considering its inter-ply and intra-ply mechanical properties,axial crushing finite element models of carbon fiber reinforced polymers(CFRP)tubes were established.Comparisons on tested failure modes and loaddisplacement relationships were conducted to validate the modelling methods.Considering their characteristics of energy-absorbing structures used in rail vehicles,the effects of trigger mechanisms on the axial crushing response of circular CFRP tubes were investigated using inward-splaying trigger(IS-T),outward-splaying trigger(OS-T),plug-type inward-splaying trigger(PT-IS-T)and plug-type outward-splaying trigger(PT-OS-T),separately.The results show that compared with the chamfer-end mechanism,the energy absorption efficiencies reduce approximately by 36.5%and 43.4%for the CFRP tubes under IS-T and OS-T,respectively.Plug-type triggers present excellent advantages to make full use of the destroyed CFRP bundles.The energy absorption and crushing failure mode of CFRP tubes are sensitive to the intracavity dimension parameter L for plug-type triggers.Increasing L from 8 mm to 16 mm is effective to improve the progressive crushing process,while the energy absorption performance initially increases and then decreases.The PT-IS-T with L=12 mm yields the highest energy absorption for the CFRP tube,approximately 63.1%higher than that of chamfer-end mechanism.The inward-splaying mode is more effective for achieving excellent energy absorption performance of CFRP tubes in the crashworthiness design of external triggers.