Non-linear vibration analysis of mechanical system (Analysis with consideration of non-linear sensitivity)

A method to solve a complex nonlinear vibration system is proposed by using both substructure synthesis method (SSM) and perturbation method to save computation cost, The system is divided into some components and those are approximately transformed to modal coordinates. The perturbed equations are synthesized to the overall system and the solution for the overall system is obtained. Sensitivity is defined with varying the nonlinear parameter and corresponding design variable to evaluate the effect of component nonlinearity. This method is applied to the dynamic analysis of nonlinear rotor-casing system as a large mechanical structure system. In order to illustrate the accuracy and computation efficiency of the proposed method, the results of responses are compared with those obtained by the finite element method. The effects of nonlinearity between rotor and bearing to the overall system are also observed by evaluating the sensitivity of nonlinearity.