2-STEP IDENTIFICATION APPROACH FOR DAMPED FINITE-ELEMENT MODELS

The application of well-established identification procedures in the t ime domain for finite element (FE) models with a larger number of degr ees of freedom (DOF) in general causes quite severe difficulties; i.e. , the solution diverges in most cases and the procedures are computati onally too demanding. In this paper, a two-step identification approac h is presented that is especially suitable for FE models with many DOE The two complementary approaches are a least-square-based method and a special form of the Extended Kalman Filter. Both approaches use moda l decomposition as a key for avoiding the initially mentioned problems . To enable the identification of local damping phenomena, nonclassica lly damped structures are assumed throughout the computational procedu res, implying the solution of the complex eigenvalue problem. For this purpose, a subspace iteration is used for solving the eigenvalue prob lem advantageously.