Initial gap modeling for wing assembly analysis

The aircraft wing is a complex structure consisting of many joined components. Because of the inevitable variability of the component shapes, different deviations may occur in the joining process including unreduced gaps between parts which can negatively affect the quality of further assembly. When developing the assembly process, the influence of these variations can be taken into account by considering the initial gap between the parts. For the variation analysis of the aircraft assembly process, a large set of random initial gaps between the parts is needed. To get this set without initial gap measurements it is proposed to use the method of modeling the initial gap based on the mode shape decomposition. The initial gap is represented as a sum of orthonormal mode shapes with random coefficients. This paper describes the method for estimating parameters and generating initial gap samples for such cases without initial gap measurements. The application of this method is illustrated for the wing assembly process. The effectiveness of the initial gap modeling based on residual gap measurements is studied and the application of this initial gap model for fastening pattern optimization is performed.