Analysis of Pressure Distribution of the Bolted Joints Based on the Finite Element Method

Bolted joints widely exist in the field of the national defense industry. However, its nonlinear stiffness degradation will occur under tangential load which may lead to the reliability reduction. According to Coulomb friction theory, the pressure distribution is the key in the tangential degradation of bolted joints. Therefore, this paper aims to analyze the pressure distribution of bolted joints. Firstly, we established a threaded bolt model and two simplified models. Secondly, the accuracy of the three models describing the contact area is verified, and the influence of preload and material properties on the contact radius is analyzed. Thirdly, we compared the pressure distribution of the three models, and results show that the smooth bolt model is more suitable for pressure analysis. Finally, the accuracy of several different functions to characterize the pressure distribution of bolted joints is analyzed, and results indicated that the Fernlund function is optimal. This paper provides a feasible simplified bolt model for finite element analysis, and the optimal pressure distribution function can be applied in the tangential stiffness degradation modeling.