Non-linear vibration analysis of mechanical structure system using substructure synthesis method

In this paper, a new method of analysis of a complex nonlinear vibration system is presented. Combining substructure synthesis and perturbation methods the computation cost for large mechanical system is considerably reduced. The system is divided into components. Under the assumption that the mode shape does not change, these are approximately transformed to modal coordinate system with nonlinearity. Using perturbation method, the overall modal equations are derived and solved sequentially. These solutions are synthesized to the overall system. Solution of the overall system is obtained in the modal coordinate system and then, these are translated into the physical coordinate. This method is applied to a vibration analysis of a large mechanical structure system composed of the rotor-bearing and casing. In order to illustrate accuracy and computation time of the proposed method, the results are compared with those obtained by the finite element method