碳纤维增强复合材料钻削缺陷的形成机理与力热调控关键技术

The typical difficult to machine material, carbon fiber reinforced composites (CFRP), drilling technology will be took as the research object. There are three issues will be probed: the time-varying characteristics of the drilling defects and the mechanism of the multi-scale structure coupling, the multi-scale constitutive model, and the prediction theory of the drilling defects based on the mechanical-thermal coupling regulation and the active control process optimization method. The objective is to develop scientific research methods such as drilling multi-scale finite element analysis and defect formation mechanical-thermal regulation, to reveal the mechanism of defect formation, to establish the drilling defect prediction model based on mechanical-thermal regulation and active control process model, to realize the precise prediction and active control of the defects for the CFRP drilling. This project focuses on the multi-scale coupling mechanism of material deformation and damage under the action of the tool, and reveals the formation mechanism of CFRP drilling defects. The multi-scale coupling constitutive model and the finite element analysis method are studied to realize the multi-scale numerical simulation of CFRP drilling process. To realize the accurate prediction of defect formation, the influence of drilling force, drilling temperature and mechanical-thermal coupling on the formation of drilling defects is studied, and also the delimitation control model based on critical force and the ablation control model based on critical heat flux are established. In addition, this project studies the precise design method of drill bit structure and the acoustic emission technology of drilling defect, then optimizes the drilling process, constructs the low defect drilling process model based on the load order distribution and the thrust force adaptive control, and finally realizes the active control of the defect.

以典型难加工材料CFRP钻削为研究对象，针对钻削缺陷形成的时变特征和多尺度结构耦合机制、多尺度本构模型、基于力-热耦合调控的钻削缺陷预测理论和主动控制工艺优化方法3个关键科学问题，发展钻削多尺度有限元分析和缺陷形成力热调控等科学研究方法，揭示缺陷形成机理，建立基于力-热调控钻削缺陷预测模型和主动控制工艺模型，实现CFRP钻削缺陷的精准预测和主动控制。重点研究刀具作用下材料变形与损伤的多尺度耦合作用机制，揭示CFRP钻削缺陷形成机理；研究CFRP多尺度耦合本构模型和有限元分析方法，实现钻削过程的多尺度数值模拟；研究钻削力、钻削温度及力-热耦合对钻削缺陷形成影响规律，建立基于临界力的分层控制和基于临界热流密度的烧蚀控制模型，实现缺陷形成的精准预测；研究钻头结构的精准设计方法和钻削缺陷形成的声发射技术，优化钻削工艺，构建基于载荷顺序分布和轴向力自适应控制的低缺陷钻削工艺模型，实现缺陷的主动规避。

以典型难加工材料CFRP钻削为研究对象，针对钻削缺陷形成的时变特征和多尺度结构耦合机制，开展了基于力-热耦合作用下的钻削缺陷预测理论和主动控制工艺优化方法与技术的研究，揭示了钻削缺陷形成的机理，发展了钻削CFRP多尺度结构有限元分析方法，形成了有效控制CFRP钻削缺陷基础理论和工艺技术。主要研究内容为（1）研究钻头切削刃的作用机制，揭示了横刃的切削行为以及对CFRP孔缺陷形成的影响规律，优化了阶梯钻结构；研究了典型刃型钻头对CFRP孔缺陷形成的影响，厘清了钻头主切削刃对CFRP孔的入口剥离和出口毛刺形成机理，建立了直线刃和圆弧刃钻头的轴向力时变曲线模型；研究了钻头结构及工艺参数对CFRP、CFRP/TC4叠层制孔损伤的影响规律，发明了一种适用于碳纤维复合材料的孔加工钻头及孔加工方法。（2）研究钻削过程中热量的传递及温度场的分布规律，建立了CFRP单向层合板钻削的温度场模型；采用零厚度内聚力单元界面相，建立了CFRP微观切削有限元模型，揭示了不同纤维切削角度下的微观材料破坏机理，以及宏观切削过程切屑的形成机理；建立了CFRP/TC4叠层结构不同切削方向的三维微观斜角切削有限元模型，分析了材料破坏行为以及界面区域的损伤形成机理；建立不同叠层顺序的CFRP/TC4叠层结构的钻削有限元仿真模型，揭示了 CFRP/TC4叠层结构钻削过程的材料去除机理、CFRP层及界面区域的缺陷形成规律。（3）基于声发射检测技术，研究不同钻削参数、不同钻削孔数下的刀具后刀面磨损、声发射信号及孔出口损伤，建立了刀具后刀面磨损、声发射信号及孔出口损伤的映射关系，为实现CFRP钻削缺陷形成的预测和控制提供理论与实验基础。（4）研究了纵-扭超声振动对CFRP钻削的影响，揭示了纵扭超声振动对CFRP钻削缺陷的抑制机理；提出“超声振动+超低温液氮+由超低温环境形成的冰冻支撑层”辅助方法，实现了CFRP的低损伤钻削；提出了可降低钻削力、热的“预导孔+冷却+液氮” 辅助方法进行CFRP/TC4叠层钻削。为CFRP单向层合板以及CFRP/TC4叠层结构的高质量制孔提供实验依据和工艺技术。