基于局部应力调整航空整体结构件变形校正理论和方法研究

NC machining distortion of aviation monolithic components is the results from the join effects of stresses coupling, evolution and equilibrium under new rigidity condition during the production process. Based on this consideration, correcting theory, method and technological process to correct the overall distortion of the monolithic components is to be investigated, it is based on the application of burnishing which can induce micro plastic and stress. In this project, the coupling mechanism and developing regularity of the bulk residual stress and machining stress in pace with machining process is to be revealed firstly; accordingly, the relational model of final residual stress status, rigidity, machining distortion of the aviation monolithic component will be established. The material and mechanics nature which causes the overall alternation of the component's shap and stress status by the local burnishing induced local micro plastic/stress layer will be revealed further. Determination principle of the burnishing acting zone which can accomplish the overall distortion correcting is to be studied. Theory and method to calculate the integrated correcting moment caused by burnishing induced micro plastic deformation layer and stress layer is to be formed. The mapping relationship among burnishing correcting process parameters and the corrected distortion values for the designated structure and rigidity of the component will be established. Burnishing correcting comprehensive decision support package for the determination of the technical parameters will be created. Burnishing correcting device adopting pressure detection and close loop controlling on line will be developed. By conducting the research work of this project, correcting theory and method system by adjusting local micro plastic deformation layer and stress status will be estabished, it will act as a guideline for correct the distorted aviation monolithic components such as frames, beams and wainscots et al. This can provide strong support for the precision manufacturing of the monolithic components usually used in big aircraft and advanced fighter.

航空整体结构件的数控加工变形是加工过程中各种应力耦合、演变及在新刚度条件下平衡的综合作用结果。基于此，研究局部滚压产生的微塑性与滚压应力层实现航空整体结构件总体变形校正的理论、方法和工艺实现。为此，首先揭示毛坯初始残余应力与加工应力耦合作用机理以及随加工过程进行的演变规律，建立工件的应力状态-刚度-变形之间的关系模型；进而揭示局部微塑性/应力层诱导工件总体应力状态改变与尺寸、形状变化的材料、力学学本质，研究变形校正滚压作用区的确定准则，建立局部滚压作用引发宏观校正力矩的计算理论和方法，构建特定结构工件滚压工艺参数与校正量之间的映射关系，创建变形校正工艺参数确定的综合决策理论。完成基于滚压力在线监测闭环控制的滚压校正装置开发。通过本项目研究，形成基于局部微塑性层/应力调整实现框、梁、壁板等航空整体结构件总体变形校正新的工艺理论和方法，为大飞机、先进战机中整体结构件的精密制造提供有力保障。

现代飞机广泛采用的整体结构件55%以上存在加工变形问题，变形校正是保证航空整体结构件尺寸精度、实现飞机无应力装配的有效手段。为避免变形校正过程中引入表层校正拉应力给工件性能带来不利影响，围绕通过滚压引入浅表层压应力的局部应力调整及其应变协调实现航空整体结构件变形校正所涉及的科学问题，进行系统的理论、方法与工艺研究。.基于裂纹柔度法板材残余应力测试基本原理，建立了铝合金预拉伸板材残余应力测试规程，构建了考虑应变采集误差和模型误差的应力计算不确定度分析方法，开发了数据处理软件和自动测试硬件系统，实现了自动化残余应力测试。.揭示了铝合金航空整体结构件数控加工过程残余应力及变形的演变规律，建立了刚度变化-残余应力演变-工件变形之间的映射关系模型。探明了铣削工艺参数和刀具结构对加工应力的影响规律，建立了综合考虑工件刚度变化、毛坯残余应力、加工应力等多因素耦合作用的航空整体结构件变形预测模型，给出了毛坯残余应力、加工应力对某梁类结构件变形的贡献率为：90%、10%。开发了大型铝合金整体结构件变形预测平台，某大型铝合金框的变形预测值与实测值误差为21.7%。.研发了双侧壁滚压校正装置，获得了双侧壁滚压对铝合金薄壁结构表面质量完整性的影响规律，揭示了滚压残余应力的组成及形成机理。基于双侧壁滚压有限元模型，研究了滚压载荷、表面应力状态、工件结构对微塑性变形及残余应力的影响规律。通过研究滚压过程中塑性应变-残余应力的内在关联机制，揭示了航空整体结构件滚压变形校正的本质为微塑性变形主导的变形协调。.提出了简化法、拆分法和分步法校正策略，将复杂整体结构件简化为简单截面零件单元。基于弯曲应变能法和等效弯矩法，实现校正载荷精准预测。采用直接应力法，实现了大型整体结构件校正仿真分析。三隔框工件校正仿真与试验变形消除率分别为92.6%和82.5%，完成了复杂壁板类零件变形校正数值分析，平面度由1.089mm降低到0.069mm。