复合材料双向波纹夹层结构力学性能

为改进传统单向波纹夹层结构横向力学性能较差的缺点，设计了一种新型复合材料双向波纹夹层结构。考虑复合材料双向夹层结构制备困难，研究了整套真空辅助成型工艺(VARI)工艺制备方案，实现双向波纹夹层结构的高效制备，以满足工程应用的需要。对制备出的复合材料双向波纹夹层结构与单向波纹夹层结构分别进行面外压缩、弯曲和剪切实验，分析了双向波纹夹层结构在不同载荷下的破坏模式及其失效机制，计算了该结构在不同荷载条件下的强度和模量，并将其与单向波纹夹层结构进行对比分析。结果表明，在压缩荷载作用下，玻璃纤维/环氧树脂芯子为主要承载部分，结构的失效主要体现在芯子的屈曲、断裂和分层；在弯曲荷载的作用下，由于纤维的抗压强度远小于抗拉强度，所以压头下方的上面板最先达到破坏荷载，结构的弯曲失效形式主要为上面板的断裂和脱粘；结构的剪切失效主要以泡沫与面板的脱粘和压溃为主，芯子和面板未见明显的破坏现象；与单向波纹夹层结构相比，双向波纹夹层结构力学性能显著提升。 

Mechanical properties of composite bi-directional corrugated sandwich structure

To improve the transverse mechanical heterogeneity of conventional uni-directional corrugated sandwich structures, a new type of bi-directional composite corrugated sandwich structure was designed. Considering the difficulty of manufacturing the bi-directional corrugated sandwich structure, a procese based on vacuum assistant resin infusion (VARI) was proposed for high efficiency and quality preparation. The prepared structures were subjected to compression, bending and shear tests. The failure modes and mechanism of the bi-directional composite sandwich structures were analyzed, the strength and modulus of the structure under different load conditions were obtained, and the comparison between the bi-directional and uni-directional corrugated sandwich structure was made. The results show that the glass fiber/epoxy resin core is the main bearing part under the compression load, and the failure of the structure is mainly reflected in the buckling, fracture and delamination of the core. Under the bending load, caused by the lower compressive strength than its tensile strength of fiber, the upper panel first reaches the failure load under the pressure head. The bending failure modes of the structure are mainly the fracture and debonding of upper panel. The shear failure of the structure is mainly caused by the debonding of the foam and the panel and the collapse of the foam, but the core and the panel are not obviously destroyed. Compared with uni-directional corrugated sandwich structure, the mechanical properties of bi-directional corrugated sandwich structure are significantly improved.