航空复合材料纸蜂窝夹芯结构热成型开裂研究

Research on the crack of thermo-forming of aviation sandwich structure composed of composite materials and paper honeycomb

摘要:

飞机复合材料芳纶纸蜂窝夹芯部件在热压罐成型时处于热-力耦合工况。本文关注热成型过程中可能出现的蜂窝开裂现象，通过试验获得了蜂窝芯的拉、压、剪性能参数和芳纶纸的热性能参数，同时结合有限元分析手段和反演方法，对整体蜂窝夹芯部件的热-力顺序耦合和局部芯子抽真空导致的蜂窝胞元间压强差进行数值模拟。结果表明：成型过程中的热应力不会导致蜂窝胞元间胶层开裂，局部憋气的压差可能导致蜂窝开裂；胶层部分破坏与胶层完全破坏所需的胞元间压强差的差值与胶层初始法向断裂应力正相关；胶层完全破坏所需的胞元间压强差随着受载胞元数量的增多而减小。

Abstract:

During the forming of aramid paper honeycomb sandwich component of aircraft composites in the autoclave, the adhesive layer between honeycomb cells will crack or even be damaged, which will affect the mechanical properties of the parts. The tensile properties, compressive properties, shear properties and thermal properties of aramid paper honeycomb core were obtained by testing. Meanwhile, numerical simulation of thermo-mechanical sequential coupling of the whole honeycomb sandwich component and mechanical simulation of the local core area were carried out by combining the finite element analysis method and the inversion method. The results show that the thermal stress during the forming process will not cause the adhesive layer between honeycomb cells to crack; The difference of pressure difference between honeycomb cells required for adhesive layer’s slight destruction and complete destruction is positively related to the initial normal fracture stress of adhesive layer; When the number of loaded honeycomb cells is less than 20, the pressure difference required for the adhesive layer’s slightly destruction is independent of the number of honeycomb cells, but the pressure difference required for the the adhesive layer’s complete destruction decreases with the increase of the number of loaded cells.