Determination of elastic constants of composite laminates using measured natural frequencies

Abstract

The identification of material elastic constants of laminated composite plates using measured natural frequencies is studied. The first three natural frequencies of the lower resonant modes of the laminated composite plates were extracted from the modal testing data of the plates. The finite element method is used to perform the modal analysis of the laminated composite plates. An error function is established to measure the differences between the experimentally and theoretically predicted natural frequencies of the laminated composite plates. The identification of the material elastic constants of the laminated composite plates is formulated as a constrained minimization problem in which the elastic constants are determined by making the error function a global minimum. Test results of a number of laminated composite plates are used to illustrate the feasibility and applications of the proposed method.