Modelling and Prediction of Riveting Surface Deformation of Aircraft Thin-Walled Parts Based on the Spring Damping Method

Currently, deformation modelling of a riveted assembly of aircraft thin-walled parts typically assumes that the riveted surfaces of thin-walled parts are smooth.However, in engineering practice, the riveted surfaces of thin-walled parts are not smooth.Therefore, in this study, the relationships among the pressing riveting force, the fractal characteristics of the riveting surface, and the riveting deformation are precisely quantified and a new modelling method for predicting the deformation of the riveted assembly of thin-walled components is proposed based on the spring damping method.The method enhances the prediction accuracy of the riveting deformation of aircraft thin-walled components.Through the analysis of the riveted assembly of thin-walled components, the pressing riveting force of the standard pier head is obtained.By examining the microscopic features of the riveting surface, a fractal model capable of capturing the surface complexity at the microscopic scale is established, revealing the geometric and topological properties of the surface.The structural function method is employed to derive the fractal parameters of the equivalent riveting surface topography that characterise the surface roughness.A micro-asperity contact model considering the interactions between micro-asperities is established to simulate the actual contact conditions.By extending the size distribution function of the micro-asperity contact area, a normal contact stiffness and damping model describing the mechanical response of the surface under normal loading is established, incorporating the elastic and dissipative properties of the contact interface.Spring elements representing normal contact stiffness and damping are arranged on the riveting surface to establish a simulation model for the riveted assembly of thin-walled components based on the spring damping method.Simulation and experimental results indicate that, compared with the smooth surface model, the spring damping method model reduces the two indicators of overall relative error by 16% each, and the local relative error of each measuring point by over 8%, thus significantly improving the prediction accuracy.This study integrates the fractal contact theory with the spring damping equivalent method to quantify the influence mechanism of the microscopic topography of the riveting surface on macroscopic deformation, breaking through the limitations of the traditional smooth surface assumption.