CFRP多胞结构吸能机制及多工况耐撞性设计

将轻质高强的碳纤维增强树脂基复合材料(CFRP)应用到多胞结构设计中,有望进一步提升CFRP薄壁结构的耐撞性能及吸能效率。为了研究CFRP多胞结构在多角度加载工况作用下的能量吸收机制及耐撞性能,采用机织平纹CFRP预浸料制备CFRP单胞管以及2个不同规格的CFRP多胞管,并通过调整壁厚使所有结构的质量保持相等;随后,对上述3个试样开展准静态轴向压溃试验,通过试验揭示CFRP多胞管的耐撞性能。此外,建立CFRP多胞管的有限元模型,采用数值仿真的方法揭示多胞管的能量吸收机制,并基于试验验证的有限元模型进一步分析9种不同规格的CFRP多胞结构在多种加载角度下的压溃性能。最后,采用多指标评价方法(COPRAS)对不同构型的多胞管在多种压溃角度下的耐撞性能进行综合评价。试验结果表明:单胞管发生了不稳定的局部屈曲,多胞管发生了稳定的渐进失效,并且在等质量的条件下,多胞管的总吸能比单胞管的总吸能高约68%。仿真结果表明:层内损伤是CFRP多胞管以及单胞管的主要吸能机制,其能量耗散值约占总能量的50%;且随着加载角度的增加,各结构的总吸能逐渐下降,但各吸能机制所耗散能量的占比变化不大,增加胞数以及内壁胞壁的厚度均能小幅度提升多胞管的能量吸收特性。综合耐撞性评价结果表明:试样MT3-4胞数为9,内部胞壁厚度b为1.178 0 mm(5层),外部胞壁厚度c为0.235 6 mm(1层)]在多种压溃角度下具有更好的综合耐撞性能。

Energy-absorbing Mechanisms and Crashworthiness Design of CFRP Multi-cell Structures Under Multiple Load Cases

Combining lightweight and high-strength Carbon fiber reinforced plastics (CFRP) with multi-cell structures is expected to further improve the crash resistance and energy absorption efficiency of CFRP thin-walled structures. In the present study, CFRP single-cell and multi-cell tubes are manufactured, and the same mass for all specimens are guaranteed through allocating different thickness of each side. The crushing process and energy-absorbing capacity of all specimens are experimentally investigated under the quasi-static axial crushing load. Subsequently, numerical simulations are further conducted to provide additional insights into their energy-absorbing mechanisms. Based on the validated numerical models, the crush performance of nine different CFRP multi-cell tubes subjected to multiple load cases is studied. Finally, the multi-index comprehensive performance evaluation method (COPRAS) is used to comprehensively evaluate the crashworthiness for the different multi-cell structures under multiple load cases. According to the experimental results, it is known that the single-cell tube develops unstable local buckling mode, and the multi-cell tubes crush progressively. Total energy absorption of the multi-cell tubes is almost 68% higher than that of the single-cell tube. The numerical results indicate that the primary energy-absorbing mechanism is intra-laminar energy, accounting for about 50% of the total energy. The energy absorbed by each part in the multi-cell tubes is much higher than the corresponding part in the single-cell tube. It is found that the energy-absorbing capacity of the tubes reduced in different degrees with increasing impact angle, but the energy proportion of each part changes little. Increasing the cell number and the inner tubal wall thickness is capable to slightly improve the energy absorption characteristics of multi-cell tubes. It is found from the comprehensive evaluation results that MT3-4 (n=9, b=1.178 0 mm (5 layers), c=0.235 6 mm (1 layer)) shows excellent crush performance.