Application of the virtual fields method to the identification of material properties using vibrating plates

The paper presents a novel procedure to derive both stiffness and damping parameters from forced vibrating isotropic plates. The theory assumes that displacement and curvature fields are measured at different times on the whole surface of the plate using a suitable optical technique. These data are processed with the Virtual Fields Method (VFM). Using finite element calculations of the harmonic response of the plate, the method is validated and its stability with respect to measurement noise is checked. A particular experimental set up is used for excitation and measurement of the kinematic fields. Measurements of the slope fields are carried out using a phase shifting treatment of images of the plate taken with a CCD camera triggered by the excitation. First results of measurements and identifications are presented.