Abstract: A perturbation method for analyzing the complex frequencies and modes of non-pro-portional damped vibration systems is presented.When the mass,stiffness and damping matrices of the original system vary a little,carrying out the complex modal coordinate transformation based on the original known complex modes and using the matrix perturbation method,the fre-quencies,damping ratios and complex modes of the updated system can be obtained without re-solving a new large generalized complex eigenvalue problem.The numerical example shows that the present method is simple,economic and highly accurate.

Key words: structural dynamics, vibration analysis method, vibration characteristicsperturbation method