Exact limit pressure of high-speed couplings of micro gas turbines for interference fits

Abstract

Interference fits, which are widely used in the high-speed couplings of micro gas turbines, can transfer large torques while avoiding unbalance. Elastic limit pressure is an important parameters for determining the maximum load capacity of high-speed couplings of rotating elastic interference fits. In this paper, we developed a model to study the dependence of the maximum load capacity of rotating elastic interference fits upon the torques. Then we obtained the exact solutions of radial stress, tangential stress and shear stress of the coupling and shaft under plane stress condition. The formulas of the elastic limit pressures of interference fits were derived. Taking a 100kW micro gas turbine as example, the maximum load capacity in case of consideration of torques could decrease approximately 20% compared with that without this consideration under two parameters, one is the static friction coefficient; the other is the ratio of inner radius to outer radius of the coupling and shaft.