蜂窝夹芯结构芯格节点开裂的机理研究

Study on the mechanism of the honeycomb node cracking in sandwich structure

采用二次胶接工艺成型蜂窝夹层结构,使用的芳纶纸蜂窝在胶接固化的高温高压下可能会发生节点开裂。为了对蜂窝芯节点开裂的机理进行分析与研究,本文对蜂窝芯节点处的受力进行了分析,并建立模型进行有限元仿真计算,同时对所用蜂窝芯节点的强度进行测试。研究结果表明,蜂窝芯节点开裂是从芯格节点处的剥离破坏开始的,其是在蜂窝高度方向的压应力和芯格间压力差的叠加作用下发生的,其中侧向的芯格间压力是影响节点破坏应力大小的关键因素。当蜂窝芯节点发生开裂后,蜂窝芯格壁在压应力作用下会轻易产生弯曲失稳。

The aramid honeycomb node cracking occurred in high temperature and high pressure when the honeycomb sandwich was processed by secondary bonding.The typical sandwich samples were produced and the honeycomb node cracking was observed and detected by ultrasonic C-scan and X-ray.In order to analyze and study the mechanism of the honeycomb node cracking,the article induced the forces analysis of the core grid,and the stress suffered on the node was computed by the theoretical arithmetic and finite element simulation respectively.The results indicated that the node cracking started from the seam of the node under the dual action of the compression stress and the core grid pressure difference,and the core grid pressure difference was the key factor which effected the node damage stress.In addition,the honeycomb node peel strength was tested and compared with the node damage stress.After the honeycomb joint cracking happened,the bending instability of the honeycomb core grid walls was initiated under compression stress easily.At last,some suggestions were given to avoid the honeycomb node cracking.