自动铺丝最小间隙路径规划与复合材料锥壳结构制造

Minimum gap layup algorithms for automatic fiber placement and manufacture of conic composite structure

自动铺丝技术(AFP)是提高复合材料构件制造效率和降低其制造成本的关键技术和重要手段。铺放轨迹的设计是控制自动铺丝工艺质量的关键。对于复杂的结构形式,合理的铺丝路径对保证可制造性及铺贴质量至关重要。本文针对简化后的后机身锥壳特征结构,研究了基于固定角法、测地线法和变角度法的自动铺丝轨迹算法设计,解决了铺放复杂曲面满覆盖问题;总结对比获得了不同铺丝轨迹方法的特点和适用范围。以保证工艺性并满足结构设计铺层方向为原则,选用了带宽为6.35mm的自动铺丝预浸料完成工艺验证件制造,并通过有限元分析评估了自动铺丝轨迹算法的合理性。结果表明:该结构宜采用测地线法铺放0°方向铺层以减少褶皱;采用固定角法铺放90°方向铺层能够保证连续铺放;采用结合预浸窄带侧弯试验结果的变角度轨迹规划方法铺放此锥类构件±45°方向铺层能够保持最小间隙。铺丝间隙使锥壳结构单层等效模量下降约30%,整体强度下降约10%。因而在结构优化设计时需考虑自动铺丝工艺对安全裕度影响的因素。

Automatic fiber placement(AFP)technique is a critical manufacturing process to improve the efficiency of manufacturing components made of composite materials and reduce the cost.The AFP trajectory planning for ply layup is crucial to the quality of the fabrication process.For composite structure with complex contour,ajustified placement technique is essential to ensure the manufacturability and the paving quality.In this paper,with a prototype of the simplified tail-cone structure in aft fuselage,different algorithms based on fixed angle,geodesic and variable angle methods are investigated for different layup orientations along a curved contour.The coverage and applicability of each algorithm are revealed and summarized.Conforming to the manufacturability along different layup orientations,the tail-cone prototype is automatically laid-up using prepreg slit tapes of 6.35 mm in width.The finite element analysis method is used to evaluate and validate the algorithms.The results show that the geodesic algorithm should be adopted for the 0°direction placement of tail-cone structure to reduce wrinkles.The fixed angle algorithm is good for the 90°direction layup to ensure continuous placement.To achieve a minimum gap at±45°direction placement,a variable angle algorithm based on the results of the tow staggering test is adopted to divert the placement direction from the original one to the adjusted one which is closer to the geodesic direction in a curtain principle.For the conic structure,the fiber placement gap leads up to 30%reduction of the ply equivalent modulus and 10%reduction of the total strength.Therefore,the influential factors of AFP process on safety margin should be taken into account in the design of optimal structure.