多误差源耦合作用的飞机柔性件装配偏差模型和分析技术

Accurate variation prediction of aircraft compliant assembly is significant to optimize assembly process and improve aircraft assembly accuracy. However, modeling and analyzing of dimensional variation for compliant assembly is challenging for the coupling effects of multiple faults of parts, fixture location and riveting location subject to complex assembly forces. In this research, several issues will be addressed in dimensional variation modeling for aircraft compliant assembly. First of all, influence of contact force between linking parts on assembly dimensional variation will be explored, and a contact force model based on geometric interference analysis will be proposed. Then, a unified geometric covariance model will be developed to investigate the distribution of part form error under typical forming technology and its effect on dimensional variation of assembly. Subsequently, the assembly process is decomposed into four stages, i.e., part locating, clamping, riveting and springback. Taking account of contact force, clamping force and rebound force, the mechanistic model of dimensional variation under linear elastic deformation will be built. So, the dimensional variation model for compliant assembly coupling with multiple faults could be established by FEA technology. Furthermore, a state space model of variation stream propagation in multi-station compliant assembly process will be established by introducing the reorientation variation when assemblies is transferred between different stations. Finally, a tolerance optimization model towards aircraft compliant assembly process will be developed, optimized tolerancing for linked parts and fixtures could be achieved. The research production is expected to provide theoretical and technical support for the assembly variation prediction and tolerancing for aircraft compliant assembly process.

飞机柔性件装配偏差的准确预测对于优化装配工艺，提高飞机装配准确度意义重大。由于柔性件装配偏差在复杂装配力作用下受零件制造、夹具定位和铆接定位等多种误差因素的耦合影响，偏差建模和偏差分析的难度很大。本项目研究零件接触力对装配偏差的影响，建立基于几何干涉分析的接触力模型；建立零件几何协方差模型，分析典型成形工艺下零件形状误差分布及对装配偏差的影响；将装配过程分解为定位、压紧、连接、回弹四阶段，研究各误差因素装配过程中的几何作用和力学行为，综合考虑装配接触力、压紧力和回弹反力，建立线弹性变形下装配偏差的力学模型，通过有限元分析方法建立多误差源耦合作用的装配偏差模型；考虑多工位装配的零件重定位误差，采用状态空间法建立飞机柔性件多工位装配偏差传递模型；建立面向飞机柔性装配过程的公差优化模型，实现零件公差和夹具公差的优化设计。研究成果可为飞机柔性件装配偏差预测和公差设计提供重要的理论和技术支撑。

飞机柔性件装配中，零件在复杂的装配力作用下发生变形，由于存在多种误差源的耦合作用，其尺寸偏差的预测分析非常困难。本项目提出了飞机柔性件铆接装配偏差分析与控制的一系列新思路和方法。针对零件接触力对装配偏差的影响，提出了一种零件接触力的建模方法，基于零件网格模型的进行接触状态检测，建立接触力与接触节点间隙的力学模型，然后求解零件的接触平衡位置，从而修正装配力，为装配偏差分析时准确刻画力-位移关系打下了基础。提出了夹具卡板的定位误差计算方法，并结合零件制造误差和铆接定位误差，根据装配过程的分段线性变形假设，建立了多误差源耦合作用下的装配偏差模型。考虑材料误差和几何误差对装配偏差的影响，采用混合多项式方法从三维层面上描述柔性件的几何协方差，并结合材料误差的一阶摄动分析，建立弹性模量、泊松比误差与零件刚度和敏感度矩阵的近似线性关系，进而建立了耦合几何与材料误差的装配偏差统计分析模型，与仅考虑几何误差的装配偏差模型相比，提高了偏差预测的准确性。基于夹具与装配偏差的作用机理，提出了基于夹具主动定位补偿的飞机柔性件装配偏差优化方法，建立了考虑夹具法向定位误差的装配偏差模型，并以最小化装配误差为目标对夹具定位补偿量进行优化，实验表明该方法可显著减小柔性件的装配偏差。针对飞机壁板件装配中刚性装配和柔性装配同时存在的特点，结合确定性定位分析和超元刚度理论，建立了刚柔混合的装配偏差分析模型；在此基础上，引入了多工位装配转换中的零件重定位误差，采用状态空间法建立了多工位的装配偏差传递模型。研究多工位装配的偏差控制策略，提出了包含装配偏差理论预测、工位间装配偏差检测和夹具主动补偿的偏差控制方法。本项目的研究丰富了柔性件装配偏差的理论体系，为进一步提升我国的飞机制造质量提供了技术支撑。