Contact stiffness modeling of bolted joints considering the coupling effects

This study presents the analytical normal and tangential stiffness model of bolted joints considering the coupling effects. Firstly, the stress distribution model within the contact area is proposed with the assistance of finite element analysis (FEA). Then, using the fractal theory and Hertz contact theory, the contact models of single asperity and multi asperities are derived, resulting in the normal and tangential stiffness expression of bolted joints by integrating the contact area. In this model, the largest microcontact area is solved from the contact stress model. Finally, the effects of resultant forces, fractal parameters, material property, and coupling are investigated and analyzed. The proposed model is hugely efficient for predicting the stiffness of fixed joints in machine tools and guiding the optimal functional design under the framework of virtual machine tools