Rotor Dynamic Analysis of Tie-Bolt Fastened Rotor Based on Elastic-Plastic Contact

Abstract

The tie-bolt fastened rotor which is assembled by rods distributed circumferentially is modeled and analyzed by finite element method with the consideration of elastic-plastic contact between discs. Based on elastic-plastic contact model between an elastic hemisphere and a rigid plane, the contact between discs is investigated by the statistical contact model of rough surfaces, and the contact stiffness is derived. The equivalent bending stiffness between discs is acquired. With the increase of the load between the two contact surfaces, the difference between the contact stiffness of purely elastic contact and elastic-plastic model is compared. With the obtained contact stiffness, the equation of motion for the tie-bolt fastened rotor system is formed and the critical speeds are calculated. It indicates that the contact stiffness between discs increases as the load increases. The contact stiffness of elastic-plastic contact model is lower than that of the elastic contact model, and the difference between the two models increases with load. With the stiffness of elastic-plastic contact, the critical speeds of tie-bolt fastened rotor are lower than that of the pure elastic contact situation.