ABSTRACT
The modal procedure presented here is a variant of a general method, presented in earlier publications of the author, for modal transformation of the equations of motion for multi-degree-of-freedom-systems with non-modal symmetric damping matrix. The modal decomposition of the equations of motion in state-space-formulation is performed by a real-space transformation matrix, which is derived by a combination of two complex transformations using the complex right eigenvectors of the associated quadratic eigenvalue problem. The proposed procedure retains all common advantages of the classic modal decomposition of the equations of motion. The procedure is briefly compared with the method “phase synchronisation”, developed by other authors. An application of the proposed procedure is presented on the vibration of a wind turbine rotor blade, subjected to wind thrust loads. A non-proportional damping matrix is built on the basis of Rayleigh- and aerodynamic damping approaches.
