SEREP-based reduced model of higher order viscoelastic propeller shaft considering various asymmetries

The material damping of rotors causes instability by introducing tangential force to whirl orbit. Literature shows that the improvement of stability range is achieved using fibre-reinforced composites or layered rotors which are light yet strong and exhibit better damping properties. In this study, a multi-layered viscoelastic propeller shaft mounted on three journal bearings is considered. Higher order finite-element model is developed after utilizing operator-based constitutive relationship, which includes various asymmetries from several sources like gyroscopic effect, internal damping, and journal bearing support. A large number of states of the higher order model, as well as the presence of asymmetry, make the system complicated for post-processing. Modified system equivalent reduction expansion process (SEREP) is applied for model reduction that uses both right and left eigenvectors of the original propeller-shaft system. Different numerical results are compared to test the effectiveness of reduced model. Though SEREP is found in the literature, its application over most realistic and higher order asymmetric system is completely new.