A vibration model for the parallel misalignement of rotating shafts conneted by a flexible coupling

Abstract

It is surprising to find that although shaft misalignment is generally accepted as one of the major sources of vibration in rotating machinery much mystery still surrounds the exact nature of the associated excitation forces and the resulting vibration response. In real rotating machinery the relationship between misalignment and vibration is further confused by the fact that different vibration characteristics have been observed in apparently similar misalignment conditions. Unfortunately, much of the relevant published work in this field is of a qualitative nature with little emphasis placed on the creation and assessment of suitably representative models. In an attempt to improve this situation this paper presents a simple model which enables investigation of two misaligned and flexibly-coupled Jeffcott rotors. The model helps provide some insight into rotor-system vibration response when shaft parallel misalignment and mass unbalance are present.