Study on Member Stiffness of Bolt Joint Structure

Bolt joints are applied especially in equipment with severe temperature change during the operating. A change in the initial axial force of the bolt due to the dissimilar material of the members causes the performance deterioration of the equipment. The variation in the bolt axial force is influenced by the member stiffness. Many have studied the method of calculating the member stiffness in a bolt–nut joint. The studies have shown the same result for calculating the member stiffness in bolt joints. Bolts of sizes M4 to M8, and the thickness and material of various members were considered in the case study. Through finite element analysis, the analytical solution of member stiffness is calculated. An equivalent pressure cone model is used to calculate the theoretical solution. The analytical result and theoretical solution were almost equal. Additionally, we proposed a formula to calculate the member stiffness relatively easily in various cases.