Autori: C. Boursier Niutta 
Rivista: Applied sciences
Anno di Pubblicazione: 2021
Volume:    101
Pagine:    2-16
A new approach for the nondestructive determination of the elastic properties of composite laminates is presented. The approach represents an improvement of a recently published experimental methodology based on the Impulse Excitation Technique, which allows to nondestructively assess local elastic properties of composite laminates, by isolating a region of interest through a proper clamping system. Different measures of the first resonant frequency are obtained by rotating the clamping system with respect to the material orientation. Here, in order to increase the robustness of the inverse problem which determines the elastic properties from the measured resonant frequencies, information related to the modal shape is retained, by considering the effect of a concentrated mass on the first resonant frequency. According to the modal shape and to the position of the mass, different values of the first resonant frequency are obtained. Here, two positions of the mass, i.e. two values of the resonant frequency in addition to the unloaded frequency value are considered for each material orientation. A Rayleigh-Ritz formulation based on higher order theory is adopted to compute the first resonant frequency of the clamped plate with concentrated mass. The elastic properties are finally determined through an optimization problem which minimizes the discrepancy with the frequency reference values. The proposed approach is validated on several materials taken from the literature. Advantages and possible limitations are finally discussed.