铺丝成形复合材料格栅筋条的纤维形态与弯曲性能评价

Fibre Distribution and Bending Performance of Composite Grid Stiffeners Manufactured by Automated Fibre Placement

为进一步提高复合材料格栅筋条结构承载效率,提出了基于“剪断-续铺”的格栅节点纤维形态调控方法,采用显微观察、有限元仿真、试验验证的手段,研究了不同剪断续铺层含量和分布位置对复合材料格栅节点处纤维形态和格栅筋条弯曲性能的影响。结果表明,复合材料格栅筋条铺丝成形过程中,合理的非连续铺层在提高筋条极限弯曲载荷的同时,还会在其内部引入伪韧性弯曲行为。仿真结果与试验结果误差小于8%,具有良好的一致性。利用建立的有限元模型分析了含非连续铺层的格栅结构失效机理。综合分析非连续铺层对格栅节点纤维形态、格栅结构弯曲载荷承载能力和力学行为的影响,对于常见格栅筋条,其最优的格栅筋条节点非连续层含量为25%且在节点顶部集中分布。

In order to improve the load carrying efficiency of composite stiffeners,“cut and restart”method was proposed based on the automated fibre placement process,to optimise the fibre distribution around intersection of grid stiffeners.Influences of content and distribution of discontinuous plies,induced by“cut and restart”method,on the fibre distribution and bending performance of grid stiffeners was comprehensively studied via micro-observation,finite element simulation and experimental validation.Results show that structural efficiency of grid stiffeners maybe improved significantly with appropriate ratio of discontinuous plies in the intersection of grid stiffeners.Moreover,pseudo-ductile bending behavior also maybe achieved in grid stiffeners within discontinuous plies.Corresponding finite element models were developed and good correlation with the experimental response was established.The errors between numerical and experimental results are less than 8%.Furthermore,the failure mechanism of grid stiffeners with discontinuous plies was studied based on the finite element model established herein.Taking the mechanics performance and weight reduction into account,the optimal ratio of discontinuous plies in grid stiffeners manufactured by automated fibre placement are 25%and all discontinuous plies should locate in the top region of intersection of grid stiffeners.