VIBRATION-BASED IDENTIFICATION OF ISOTROPIC MATERIAL PROPERTIES BY QUASI-BINARY ELECTRONIC HOLOGRAPHY AND FINITE ELEMENT MODELLING

摘要

The first objective is presenting a novel interferometric method, the quasi-binary holography, developed to assist the hybrid, experimental-numerical identification of material properties. The quasi-binary electronic holography is a vibration measurement method extending the vibration amplitude measurement range by a factor of two with respect to the well-known time-average method. The fringe contrast is also highly improved, so the reliability is higher, and the full laser power is available for the measurement, without losses as in stroboscopic techniques. The second objective is to evaluate the importance of the number of vibration modes used in the identification. Finite element updating using the first 5, 10,20 or 40 eigenfrequen-cies of a uniform rectangular plate allows finding the optimal number of nodes in the mesh, the type and shape of elements and the material properties with an average eigenfrequency error of the numerical model between 0.13 and 0.19%, depending on the number of modes being used.