Dynamic stiffness and nonconservative modal analysis

Abstract

The dynamic stiffness method and the substructure method predict more number of natural modes than the number of master coordinates retained. For nonconservative systems, the dynamic stiffness matrix may be defective. A general algorithm for response analysis is presented. Discrete finite-element system are discussed first and the unwanted coordinates are eliminated. As the number of elements increases, the formulation approaches that of the continuum modeling. Since harmonic and time responses are Fourier pair, initial discussion is concentrated on harmonic analysis and the results are applied to time response by replacing = lw by d/df. New features include the orthonormal condition, the spectral decomposition of dynamic flexibility, the mixed frequency dynamic derivative and the expansion theorem.