Dynamic analysis of misalignment modelling with flexible damped coupling in rotor shaft system using classical approach

Abstract

Abstract Misalignment is a common practical problem during the transmission of power from one shaft to another, where the coupling plays a crucial role in determining the dynamic behaviour of the rotor-shaft system. This paper presents a dynamic analysis of two misaligned rotors coupled by a flexible coupling to accommodate both parallel and angular misalignments. A flexible coupling accommodates misalignment to solve this problem. However, in this process, the system dynamics is also influenced by the coupling characteristics, particularly the dissipation characteristics of the coupling, which rotates with the shaft and should be considered as internal damping. Among flexible couplings, segmented disc couplings are widely used in electric motors, engines, cooling towers, and in helicopter tail rotors. This work considers a segmented disc coupling featuring viscoelastic links and aims to derive the mathematical model of the restoring and dissipation behaviour in terms of non-dimensional parameters, represented as matrices. The modelling technique applies to other situations of flexible coupling; however, the stiffness and dissipation behaviour of the coupling should be found appropriately. The use of non-dimensional parameters extends their applicability to similar couplings of any specification. Next, the characteristics derived are used to study the dynamic behaviour of a coupled non-axisymmetric rotor-shaft system, including its stability limits for spin speed and rotor response amplitude due to unbalance, misalignment, and gravity. The 1X and 2X components in the frequency response, along with their interpretation, are illustrated through several examples.