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Structural Nonlinearity Identification Using Perturbed Eigen Problem and ITD Modal Analysis Method

Identification of nonlinear behavior in structural dynamics has been considered here, in this paper. Time domain output data of system are directly used to identify system through Ibrahim Time Domain (ITD) modal analysis method and perturbed eigen problem. Cubic stiffness and Jenkins element, as case studies, are employed to qualify the identification method. Results are compared with Harmonic Balance (HB) estimation of nonlinear dynamic stiffness. Results of ITD based identification are in good agreement with the HB estimation, for stiffness parts of nonlinear dynamic stiffness but for damping parts of nonlinear dynamic stiffness, method needs some additional improvements which are under investigation.