大型飞机壁板装配中约束作用机理及工艺策略

The thin-walled large aircraft panel structure is weak in rigidity, which easily causes static deformation and dynamic instability during its assembly process. Therefore, to create stable and reliable assembly condition is the primary requirement for guaranteeing panel assembly quality. In this project, in order to optimize the assembly constraint process of drilling and riveting, the mechanism of deformation and instability of thin-walled skin will be analyzed and the effect of discrete constraints on skin mechanical properties and assembly quality will be investigated: 1) The essential relations between physical and geometrical properties of the skin will be analyzed, and the evolution of deformation and stress of the skin driven by the discrete constraints will be studied; 2) So as to analyze the influence of the discrete constraints on the skin dynamic behavior, the differential quadrature method for handling discrete constraints will be introduced, and thin-walled skin elasto-dynamic model will be established. Accordingly, considering the effects of the discrete constraints on skin deformation, static and dynamic behavior, a criterion and approach for constraint design will be put forward; 3) The residual stress release causes skin deformation when the skin is separated from framework after drilling. So it is difficult to reset the deformed skin toward the framework. Analyzing skin deformation energy between the assembly and the discrete and its threshold for appropriate assembly, we will present a novel method to reset the deformed skin to framework by arranging discrete constraints on the deformed skin to correct the deformation; 4) Focusing on the skin deformation during riveting, the suppressing effect of constraints on rivet deformation propagation will be emphasized. Based on the analysis, a method of rivet region partition and riveting sequence optimization in each region will be proposed. Research findings will provide theoretical guidance and technical support for establishing the constraint design criterion and process strategy for high-quality aircraft panel assembly.

大型飞机壁板为弱刚度薄壁结构，在装配过程中易产生静态变形与动态失稳现象，因此，保障壁板装配质量的首要前提是创建稳定、可靠的装配约束条件。本项目以制孔、铆接过程中装配约束工艺优化为突破点，重点分析薄壁蒙皮的变形与动态失稳产生机理，对多点离散约束作用下蒙皮力学性能及装配质量的影响规律进行研究：分析薄壁蒙皮物理属性与几何内蕴量间的本质关系，提出几何约束引导的蒙皮变形与内应力演化分析方法；研究薄壁蒙皮的约束处理方法，分析约束对蒙皮动态稳定性的作用机理，提出综合考虑蒙皮变形及其动静态力学性能的制孔约束设计方法；计算壁板分离前后蒙皮变形能，研究从引导约束的保守状态逐渐释放约束的变形能演化规律，提出基于变形能阈值的引导约束布局的拓扑优化方法；研究约束对铆接变形传播的抑制作用，提出壁板铆接区域划分及区域自治铆接顺序优化方法。本项目研究成果将为飞机壁板高质量装配中约束设计准则建立及约束布局优化奠定理论基础。

本项目研究主要是围绕壁板装配中预连接工艺的作用展开，对壁板单元内层间间隙的消除、单元间间隙的流动、壁板刚度增强作用、壁板稳定制孔、铆接应力及变形等进行了系统研究，为建立静动态统一的预连接优化方法提供理论依据。.在预连接分布对壁板变形影响方面：根据蒙皮和长桁连接区域几何结构和约束作用的相似性对壁板进行预连接单元划分，建立了单元内的蒙皮、长桁装配间隙等效分析模型；应用最小势能原理分析了预连接约束作用下蒙皮长桁残余间隙，以预连接残余间隙满足容差要求为目标对预连接数量及其分布进行优化；建立了预连接单元之间的间隙流动模型，提出一种面向整块壁板的预连接工艺优化方法。.在预连接分布对壁板稳定制孔方面：提出描述壁板预装配后动态性能的刚度评价指标，建立了面向壁板刚度性能增强的预连接分布优化模型；构建了考虑间隙的预连接动力学模型，获得了不同初始间隙分布在预连接作用下的壁板单元频率预测。分析了机器人低阶固有频率的空间分布及其随机器人姿态的变化规律，提出了面向机器人精准和高效制孔的弱刚度机器人加工方法；针对飞机机身对接区域环向360°制孔装配，创新设计了环形轨五轴联动制孔系统，分析了不同约束支撑定位方案对系统的静动态力学性能影响。.在壁板铆接变形分析方面：构建了双机器人钻铆系统，建立了双机器人气动铆接系统动力学模型，分析了气动压力和机器人末端姿态对系统动力学性能的敏感性；研究了顶铁支撑弹簧刚度、铆枪输入气压和铆接时间对铆钉镦头成形的影响，获得了墩头成形的最佳工艺参数；建立了单个铆钉成型后的孔壁应力分布，获得了沿孔壁轴线方向上的干涉量比值；通过将大量铆接对壁板变形的影响简化为一定量弯矩载荷作用的结果，提出了壁板铆接变形的简化预测方法。.本项目研究取得了一系列创新成果，发表和录用SCI/EI论文8篇，获授权国家发明专利2项，另有2项国家发明专利处于公示期，多项研究成果已经在我国大型飞机自动化装配中得到成功应用。