Identification of composite material parameters of plates using vibration test data

Two methods for identifying the material parameters of laminated plates are presented, differing with respect to the type of residual vectors to be minimized. Both methods used eigenvalue residuals. In addition either weighted eigenequation residuals (method 1) or mode shape residuals (method 2) were used. The finite element model of the plate was assembled from four-noded rectangular elements with four degrees of freedom (DOF) per node. The stiffness matrix was based on Reissner-Mindlin plate theory which includes shear deformation effects. An approximate two step condensation procedure was used, instead of the dynamic condensation which is normally used in the first identification method for the large order problem. The two methods were applied to free-free composite sandwich beam and plate structures using simulated and real modal test data.