Modal reanalysis methods for structural large topological modifications with added degrees of freedom and non-classical damping

This paper presents two new methods for modal reanalysis of structures considering large topological modifications with added degrees of freedom. Firstly, a quite simple and efficient approximate method with the improved dynamic condensation, the Kirsch approximation and the decoupling mass orthogonality is proposed for reanalysis of real modes; then, a high-quality method which is comprised of complex eigensubspace condensation technique and Rayleigh-quotient inverse iteration is proposed for reanalysis of complex modes of structural large topological modifications. The convergence of iterative improvement will be achieved after only two or three cycles. Four numerical examples illustrate that the proposed methods are quite effective with high precision.