动态非均衡变形影响的薄壁CFRP/Ti结构钻削表面缺陷成形机理与抑制方法研究

Thin-wall CFRP/Ti stacks are widely used in wings and fuselages of aircrafts, as the application of these stacks meets the trends of large-size, light-weight, and long-life in the area of aviation. Though interference fit could effectively improve strength and fatigue resistance of aircraft components, it requires strictly high surface quality of connecting hole. However, features of the stack, different-material and low-stiffness, easily induce hole’s surface defects such as geometrical deviation and surface damage. This project intends to experimentally and theoretically analyze the diameter deviation, wall slope, axis offset, surface roughness, interface damage, and delamination in drilling thin-wall CFRP/Ti stacks. The whole-stage drilling forces prediction model is firstly developed for laminated construction with different materials. Then, the coupling rule between drilling force and deformation is studied in drilling thin-wall structures.Geometrical deviation of hole wall and forming mechanism of surface damage are also investigated considering the effect of dynamic non-uniform deformation. At last, a method is proposed to reduce surface defects of drilling by synthetically control parameters of tool, clamping, and cutting. Thus, thin-wall CFRP/Ti stacks could be drilled with low-damage and high-accuracy, which provides the base of theory and method for high reliability and long life connection of the components.

薄壁CFRP/Ti叠层结构契合航空领域大型化、轻质化、长寿命的发展趋势，被广泛用于机身和机翼等部件，其干涉连接能有效提高部件连接强度和抗疲劳性能，但对连接孔表面质量提出了极为严苛的要求，而该结构的异质性和弱刚性极易导致孔壁几何偏差和表面损伤等表面缺陷。对此，本项目以薄壁CFRP/Ti叠层结构为对象，结合理论探索和实验研究，分析钻削中孔径偏差、孔壁倾斜、轴线偏移等几何偏差以及孔壁微观不平、层间积屑损伤、出口分层撕裂等表面损伤，建立异质叠层结构全阶段钻削力预测模型，探究薄壁叠层结构钻削力-变形耦合规律，研究钻削刃和变形综合影响的钻削孔壁几何偏差预测方法，揭示动态非均衡变形作用下的钻削表面损伤成形机理，提出刀具、装夹、切削参数等多变量协同钻削表面缺陷抑制方法，实现薄壁CFRP/Ti叠层结构高精度、低损伤钻削工艺优化设计，为该结构高可靠、长寿命连接提供理论基础与方法。

薄壁CFRP/Ti叠层结构契合航空领域大型化、轻质化、长寿命的发展趋势，被广泛用于机身和机翼等部件，其干涉连接能有效提高部件连接强度和抗疲劳性能，但对连接孔表面质量提出了极为严苛的要求，而该结构的异质性和弱刚性极易导致孔壁几何偏差和表面损伤等表面缺陷。.本项目围绕薄壁CFRP/Ti叠层结构力-变形耦合变化过程的钻削力变化、结构变形响应、几何偏差特征及孔壁质量等展开研究。构建了CFRP直角切削细观数值模型，分析了不同纤维方向及不同工艺参数下的切削力系数变化规律；在分析层间变形与出口变形的基础上，通过微元法构建了全阶段钻削力演变模型。分析了轴向力作用下的弱刚性叠层结构变形响应规律；探究了轴向力作用下的层间间隙形成规律并建立了层间间隙预测模型。分析了包含孔圆柱度、同轴度等几何偏差的形成过程，并实现基于数值模拟方法几何偏差预测。在分析刀具与材料间动态接触关系的基础上，建立了过渡域制孔缺陷演变模型，提出了以临界压脚力预测为核心的层间缺陷抑制方法，以提高钻孔表面质量与刀具性能为目标，提出了叠层结构制孔表面质量评价体系与控制方法。本研究对薄壁CFRP/Ti叠层结构的高精度、低损伤制孔的实现具有重要的科学意义与应用价值。