A comparison of flexible coupling models for updating in rotating machinery response

Abstract

This paper analyzes the effects of the mathematical models of flexible couplings in rotating mechanical systems in terms of their vibrational behavior. The residual unbalance of the coupled shafts is considered to be the main source of vibration in the rotating system. The moments and the frequencies of the forces, which result from these effects, are close to the natural frequencies of the mechanical system. Since the coupling is considered to be a flexible component in the power transmission system, it introduces a certain amount of mass, damping and stiffness to the system, influencing its natural frequencies. The present work shows the modeling of a mechanical rotor-bearing-coupling system, through the finite element method, used in this case to analyze the transverse vibrations of the system. Different modeling techniques were taken into account for this purpose. Such models are recommended for flexible couplings to analyze their influence on the natural frequencies of the system and on the unbalance response of the system. Afterwards, a model updating was carried out to fit the coupling stiffness and damping coefficients, using the minimum quadratic technique. Some sensitivity of the proposed models was observed in relation to the coupling parameters.