The conventional Modal Strain Energy method (MSE is briefly discussed. Several indices are proposed to characterize a viscoelastically damped system. An Overall Error Index is proposed to assess the accuracy of the solution. A Modified MSE method is developed for a better evaluation of modal damping. Instead of neglecting the damping stiffness matrix in the determination of the eigenvectors, as is the case in the conventional MSE method, the authors used a weighted matrix to solve a real eigenvalue problem. With such modification the estimation of the modal damping is often improved. Numerical simulation of multi degree-of-freedom systems are reported using the proposed Modified MSE method and the indices.

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