FREQUENCIES AND MODES OF ROTATING FLEXIBLE BLADED DISC-SHAFT ASSEMBLIES - A GLOBAL CYCLIC SYMMETRY APPROACH

It is now increasingly necessary to predict accurately, at the design stage and without excessive computer costs, the dynamic behaviour of r otating parts of turbomachines, in order to avoid resonant conditions at operating speeds. In this study, the global non-rotating mode shape s of flexible bladed disc-shaft assemblies are used in a modal analysi s method for evaluating the dynamic characteristics (frequencies and m ode shapes) of the corresponding rotating systems. The non-rotating mo des are calculated by using a finite element cyclic symmetry approach. Rotational effects, such as centrifugal stiffening and gyroscopic eff ects are accounted for, and all the possible couplings between the fle xible parts are allowed. An application is presented in order to asses s the mathematical model by comparison of the computed results with re ference values. (C) 1996 Academic Press Limited