Prediction of riveting deformation for thin-walled structures using local-global finite element approach

Riveting is a crucial manufacturing process and widely used in the assembly of aeronautical thin-walled structures, such as wing panels and fuselage panels. However, the dimensional errors of final products often violate the allowed tolerance due to riveting-induced deformation, which significantly degrades the dynamic performance of aircraft and decreases the productivity. In this study, a two-step computational approach, which combines a full 3D dynamic explicit finite element model (FEM) and a local-global FEM with consideration of local bulging, is proposed to evaluate the riveting deformation for thin-walled structures. Firstly, a freedom expanding method was developed to eliminate additional stress, emerging in general connection of solid element and shell element. In addition, the plastic zone after riveting was determined by the cold expansion of hole. Secondly, the inherent deformations of nodes in typical riveted joints involved in thin-walled structure were calculated using the 3D dynamic explicit FEMs and their characteristics were also examined. Thirdly, based on the improved connection method and estimated plastic zone, the local-global FEM was built through equivalent model. Finally, three representative thin-walled riveted structures were simulated using the proposed method. By comparing predicted results and measurements, the accuracy and efficiency of the two-step computational approach are verified.