中低速压缩加载下不同截面构型复合材料薄壁结构吸能特性及失效分析

为研究开剖面复合材料薄壁吸能结构的吸能特性，基于高速液压伺服试验系统，开展了开剖面复合材料薄壁结构轴向压缩试验，分析了截面构型、截面长宽比、触发模式及加载速度对其吸能特性的影响，揭示了其在压溃过程中的失效及吸能机理。研究结果表明，复合材料薄壁结构压溃过程中主要通过材料弯曲、分层、剪切破坏以及压溃区之间的摩擦吸能。截面构型对其吸能特性影响显著，其中，帽形及Ω形试件的平均压溃载荷较C形试件分别高出14.1%和14.6%，比吸能较C形试件分别高出14.3%和14.8%；截面长宽比对复合材料薄壁结构吸能特性的影响不如截面构型明显；触发模式主要影响吸能结构的初始压溃阶段，在降低峰值载荷方面，C形试件采用45°倒角触发效果更好，帽形试件采用15°尖顶触发效果更好；当加载速度从0.01 m/s提高到1 m/s时，C形、帽形及Ω形试件的平均压溃载荷分别下降了6.1%、10.9%和6.1%，比吸能分别下降了6.2%、11.0%和6.2%。

Energy absorption characteristics and failure analysis of composite thin-walled structures with different cross-sectional configurations under medium- and low-speed compression loading

In order to study the energy absorption characteristics of open-section thin-walled composite structures, axial compression tests were carried out by using a high-speed hydraulic servo test system. The loading speed was set to 0.01, 0.1 and 1 m/s. A high-speed camera was used to record the deformation and failure of the test specimens. The effects of cross-section shape, section aspect ratio, trigger mechanism, and loading speed on the energy absorption characteristics of the composite structures are analyzed. The failure and energy absorption mechanism of the structure in the crushing process is revealed. The results show that the energy absorption is mainly attributed to material bending, delamination, shear failure and friction between crushing zones during the crushing process. The cross-section shape has a significant influence on its energy absorption capacity. The average crushing loads of the hat shaped and Ω- shaped specimens are 14.1% and 14.6% higher than that of the C-channel specimens, and their specific energy absorption (SEA) are 14.3% and 14.8% higher than that of C-channel specimens, respectively. The stress concentration of C-channel specimens leads to insufficient material damage, responsible to their lower energy absorption capacity. On the other hand, the section aspect ratio has less effect on the energy absorption capacity of composite thin-walled structures. The trigger mechanism mainly affects the initial crushing stage of the structures. For the C-channel specimens, 45° chamfer trigger is more effective in reducing the initial peak load; while for the hat shaped test piece, the 15° steeple trigger is better. When the loading speed was increased from 0.01 m/s to 1 m/s, the average crushing load of the C channel, hat shaped and Ω-shaped specimens were reduced by 6.1%, 10.9% and 6.1%, respectively; while the SAE were reduced by 6.2%, 11.0% and 6.2% respectively. The increase of loading speed leads to more debris flying out, which reduces the loading area and material utilization of the structure, and it reduces the friction energy absorption of the collapse zone, too.