先进飞机复合材料柔性件保形加工中变形控制的基础研究

Carbon fiber reinforced plastics (CFRPs) are widely used in the advanced aircraft manufacturing, especially in the main components of the aircraft, to improve the structure efficiency, which is inevitable for the advanced aircraft. These advanced-composite-material parts are always so thin and weakly rigid that named as the flexible component. The shape machining of these flexible parts is the finishing process in manufacturing, and the machining precision is the main influence on the assembly accuracy and the reliability of the aircraft. However, these flexible parts deform easily in shape machining. Meanwhile, the deformation behavior is complex, which under the combined condition with the physical factors e.g. the variable stiffness, the time-varying loads, and the geometrical factors e.g. the curved surface, the variable thickness. In this case it is so difficult to the deformation control that it is hardly to ensure the machining accuracy. Thus, how to control the deformation is the key to ensure the accuracy. The fundamental research on the deformation control in machining of the CFRP flexible components will be done on the foundation of the research findings on the CFRP cutting mechanism, combining with the finite element method and the experiment design method. The material mechanical behavior of the flexible component will be analyzed to clarify the deformation mechanism of the CFRP flexible component. In addition, the correlation models will be established between the component pose, the machining error and the location condition, machining parameters. The machining processing window of the CFRP flexible component will be obtained, and the control strategy for the machining tolerance will be formulated. Finally, the machining theory and foundation data will be collected for the high-precision shape machining of the CFRP flexible component of the advanced aircraft.

先进飞机制造中，大量使用碳纤维增强树脂基复合材料（CFRP）整体制造主承力零部件，以提高结构效率，成为提高飞机先进性的必然趋势。此类零部件多为具薄壁、弱刚性特征的复合材料柔性件；保形加工作为该类柔性件制造的最后环节，其精度直接影响飞机装配准确度及可靠性。然而，复材柔性件加工中易变形，且变刚度、时变载荷等物理因素和具曲面、变厚度等几何因素共同作用下的变形行为复杂，难控制，加工精度难保证。可见，如何控制加工变形，是保证加工精度的关键。本项目基于前期的复材切削基础研究成果，结合有限元与实验设计方法，研究多物理、几何因素作用下材料的力学行为，阐明保形加工中复材柔性件的变形机制；构建柔性件位姿、加工误差与工装条件、加工工艺间关联模型体系，挖掘薄壁、弱刚性复材柔性件的加工工艺窗口，进而制定出典型复材柔性件加工容差的控制策略；为突破飞机复材柔性件的数字化高精度保形加工技术提供理论依据和关键基础数据支撑。

先进飞机制造中，具薄壁、弱刚性特征复材柔性件的高质高效保形加工直接影响着飞机装配准确度及可靠性。变刚度、时变载荷等物理因素和具曲面、变厚度等几何因素共同作用下的变形行为复杂，致使保形加工易变形、难控制问题突出。针对此问题，本项目开展了复材柔性件保形加工装夹方案与工装设计及仿真建模，研究了随形装夹工装及等效加工载荷作用下复杂的力学行为，搭建了复材柔性件保形加工工装测试台架；开展了自由状态下、装夹状态下以及等效载荷作用下的柔性件变形测试与仿真实验，阐明了复材柔性件加工中多物理因素和几何因素共同作用下的变形机制，获得了加工变形的敏感因素；提出柔性件装夹中的吸盘应遵循“随形-就近”分布原则，采用带有刚性定位件的定位吸盘与真空吸盘组合的方式。建立了可实现平面及曲面复材柔性件保形加工过程仿真的有限元模型，搭建了集整体分布式吸附装夹与集中局部支撑于一体的保形加工实验平台，构建了加工误差、表面质量与工装条件、加工工艺各参量间关联模型与实验体系，获得了薄壁、弱刚性复材柔性件保形、高质加工工艺参数，提出典型复材柔性件保形加工参数制定中应遵循“最大瞬时切深小于20μm，切削速度不易超过3m/s”原则。面向典型复材柔性件的加工容差控制需求，开发了复材柔性件保形加工工艺数据库系统，可实现加工变形、损伤预测及加工工艺优化。结合典型复材柔性件的保形加工及修复需求，开展了某型飞机典型复材柔性件试验件的现场加工实验，相关基础模型与关键数据可为突破飞机复材柔性件的数字化高精度保形加工技术提供理论依据和关键基础数据支撑。

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