Stochastic Simulation of Aircraft Fuselage Assembly Considering Manufacturing Uncertainties

In aircraft production the use of rivets as permanent mechanical fastener to assemble lightweight sheet metal structures is very common. At assembly the rivet is placed in a through boring and the buck-tail is plastically deformed to create a second head. Thus rivets are positive locking and can carry axial tension loads. However, rivets are mainly used to transfer shear loads via the seating stress of their cylindrical shaft. The remaining pre-stress in the rivet and its local area after the riveting process is subject to immanent manufacturing scatter. When assembling the fuselage of commercial aircrafts additional inherent uncertainties are impacting the riveting process. The cylindrical barrels of a fuselage are typically manufactured from large thin walled shell structures underlying geometric tolerances and variations of the boundary conditions. Managing these uncertainties has a significant impact on the geometrical and structural product quality. In this paper the resulting variations of the three-dimensional residual stress condition will be analysed by simulation. To simulate the fuselage assembly process the model must be able to predict the influence of manufacturing uncertainties appropriately. Therefore these uncertainties will be considered already during the modelling by stochastic parameters and random fields. While most application examples in the literature are quite simple [1], the present paper aims to apply random ® fields in an industrial application using LS-DYNA . By utilizing non-invasive methods the approach can be adapted to different FE-Solvers without too much effort.