Effective contact stiffness model for bolted flange joint with spigot

The bolted-flange joint with spigot (BFJS) is the main joint type of structures in engineering equipment such as aero-engines, however, effective theoretical model for the contact stiffness of BFJS is still absent due to the complicated contact and friction state. In this study, we propose a novel and effective contact stiffness model for BFJS. In this model, we take into account the interaction between adjacent bolts for the first time, so that a novel non-uniform pressure distribution function with respect to bolt-related parameters is proposed. We found that the pressure distribution on the connecting surface of the compact bolt flange obeys the cosine-function law. The contact stiffness for the BFJS is modeled by the fractal theory and thick-walled cylinder theory. Then we apply the proposed contact stiffness model to study the vibration of shaft-disk-shaft structures. An experimental platform for the BFJS shaft-disk-shaft structure is built and the modal tests are performed. Comparison of theoretical and experimental results shows that our proposed contact stiffness model has good accuracy. The effects of bolt-related parameters on the joint stiffness and vibration characteristics of the BFJS shaft-disk-shaft structure are revealed.