Exact Solution of High-Speed Couplings for Interference Fits

Abstract

High-speed couplings are the key parts of micro-turbomachinerys. They are assembled to shafts by interference fits, which can transfer large torque, are easy to produce and offer significant cost advantages. Considering of the influences of the torque, rotational speed and temperature variation, the interference fits between couplings and shafts have to be analyzed accurately in order to save the construction cost and reducing risk of invalidation accidents. In this paper, a model of the interference fit between a coupling and a shaft is developed to study the determine parameters of the interference value. Using the classic elastic plane stress theory, the exact solutions of the radial stresses, hoop stresses and radial displacements are obtained. Three determine parameters (the torque, angular velocity and temperature variation correction terms) are derived in order to calculate the interference value. Taking a high-speed microturbomachinery for example, the numerical results show that the interference value is dependent of the ratios of inner radius to outer radius of the coupling and shaft significantly. The torque, angular velocity and temperature variation correction terms are in the same order of magnitude. The present analytical solutions are expected to be useful in the structure design of the interference fit between a high-speed coupling and a shaft.