A Novel Tangential Friction Modelling Approach Considering Multi-scale Contact Pressure Distribution for Predicting the Nonlinear Dynamics of a Bolted Joint

Bolted joints are widely used to connect the components owing to the advantages of high reliability and ease of disassembly. Under dynamic loading, friction contact behavior of connection interfaces has a significant impact on the dynamic response of jointed structures. In this paper, a multi-scale tangential friction modelling approach, considering both the non-uniform contact pressure distribution and the multi-scale characteristics of rough surfaces, is proposed to predict the frictional hysteresis of the jointed interfaces. This method is based on the framework of Iwan model and provided a new way to explicitly determine the density function of slider critical slip force. Specifically, the multi-scale modelling approach combines the non-uniform contact pressure distribution in the contact region and the microscopic contact pressure distribution induced by surface roughness. The contact pressure distribution of a bolted joint interface is described by the twofold Weibull mixture model. Then, the Iwan density function is determined based on the local Column friction. Finally, the explicit expression between the tangential friction force and the relative displacement is derived. The Iwan density function determined by the contact pressure distribution is more direct and physical than those artificially assumed. The effectiveness of the proposed method is validated by comparing the simulation results with the experimental results. The comparative analysis illustrates the application potential of the proposed modelling approach in bolted joint structures. The proposed model is integrated into a numerical model of a bolted joint structure to study its applicability in dynamics analysis. The frequency response of a bolted joint structure is solved by combining the multi-harmonic balance method (MHBM) and the alternating frequency/time (AFT) method. The frequency response is also compared with experiment results, which illustrate that the proposed modelling approach is capable of capturing the nonlinear friction hysteresis behavior and predicting the dynamic response of jointed structures.