| In the multi-station assembly process of aircraft fuselage panel, the assembly variation are caused by the coupling effect of various factors such as part errors, fixture errors, and relocating errors of sub-assembly in the transfer between different stations. It is highly challenging to analyze the assembly variations. To provide an effective tool for the prediction of dimensional variations in fuselage panel assembly, the multi-station assembly variation modeling of fuselage panel is investigated systematically. The main contributions of this research are as follows:Assembly process of fuselage panel is studied, and the strategy of variation analysis is proposed. The structural characteristics of certain fuselage panel and its assembly process are firstly analyzed, which lays a foundation for the assembly variation modeling; Then, based on geometric perturbation theory, a new deterministic locating method for the analysis of part locating errors is proposed, in which the homogeneous transformation is utilized to simplify the variation calculations of multiple points; Finally, Method of Influence Coefficient(MIC) and Super Element Theory(SET) are introduced for the purpose of variation modeling in flexible parts assembly, and these methods provide a theoretical basis for the variation modeling of panel assembly.A hybrid model is developed for the analysis of single-station dimensional variation in fuselage panel assembly, which incorporating rigid assembly with flexible assembly. Firstly, the locating errors of flexible parts on the fixture with full constraints are calculated by the proposed deterministic locating method. Secondly, the deformations of the flexible parts under assembly forces are analyzed by combing MIC with SET, and a hybrid model is further established for the analysis of single-station dimensional variation. Compared with the traditional FEA methods, this theoretical model is much more efficient in calculation. Finally, a comparative analysis of a case study is conducted between the proposed theoretical model and the FEA simulation, and the results verify the effectiveness of this theoretical model.Based on the State Space method, a variation propagation model in the multi-station assembly of fuselage panel is established. Based on the single-station assembly variation model, the influence of sub-assembly relocation in different stations is investigated. By introducing the state vector and input vector in the variation modeling, as well as the deduced state matrix and input matrix, the multi-station variation propagation model in panel assembly is developed, which is more applicable and efficient in computation. Moreover, a case study is conducted to validate the proposed multi-station assembly variation model by a comparative analysis with the FEA simulation. |
