Research On The Deformation Accumulation Rule Of The Flexible Aircraft Panel Parts In Multi-stage Assembly Process

In the assembly process of the flexible aircraft panel parts, due to the influence of manufacturing error, positioning error, assembly tooling positioning and installation error, there inevitably exists some degree of deformation. Assembly deformation seriously affects the assembly precision of aircraft panel components, thus affects the subsequent assembly quality of the components and final assembly.In order to predict the assembly precision of the flexible components, the practical assembly process needs to be considered. In tradition, the assembly of the aircraft flexible components mostly relied on the assembly fixture to locating and clamping, and used the method of dimension chain to consider assembly deviation. This method is based on the rigid assumption, ignoring the characteristics of flexible parts which are large size, low stiffness and easy to deformation, resulting in its low efficiency and precision in analyzing the assembly deviation and often need to be adjusted repeatedly in the assembly process. With the development of digital manufacturing technology, the traditional method based on analog transmission is replaced by digital assembly technology. However, the assembly deviation modeling method for aircraft flexible components considering the flexible assembly tool has not been investigated deeply. In order to solve this problem, this thesis investigates the assembly deformation rule of the flexible aircraft panel parts considering the practical assembly process using the flexible assembly tool. The main research works are presented as follows.1. The structure of the flexible aircraft panel components is introduced, the positioning and clamping process of the flexible aircraft panel components with the flexible assembly tool is analyzed, and the assembly process is divided into four stages.2. A method of positioning and clamping of flexible parts considering the influence of contact forces is proposed. Based on the “N-2-1” positioning principle, the positioning and clamping process of the flexible parts is divided into the deterministic positioning stage and the over positioning stage. The deterministic locating method was used to calculate the position changes of parts in the deterministic positioning stage. The contact force prediction model is established in the over positioning stage, and the principle of the total complementary energy is used to solve the contact force with MATLAB. With finite element simulation, the clamping deformation of flexible parts considering the influence of the contact force is calculated.3. Based on the method of influence coefficients, a mechanistic variation model is established to reflect the relationship between the assembly deviation of key characteristic points in flexible parts before assembly and that after assembly, the method to calculate the sensitivity matrix is discussed. The contact force after the riveting and springback is concluded using the spring-back force and the global stiffness matrix of subassembly. Finally, the assembly deformation of flexible parts is evaluated in different aspects with different methods.4. With an example of riveting assembly of the skin and stringer, the proposed multi-stage analysis method to conclude the deformation of the flexible parts is verified. And the effect of different stringer riveting sequence on the assembly deformation of flexible parts is investigated.