AN EXPERIMENTAL TECNIQUE FOR COMPLETE DYNAMIC CARACTERISATION OF A VISCOELASTIC MATERIAL

An experimental technique for completely characterizing a viscoelastic material, by determining the Poisson ratio and the complex dynamic Young's modulus of a small beam-like specimen subject to seismic excitation is presented in this paper, together with the theoretical background. The same experimental device is used basically for both kinds of tests: the specimen is instrumented, placed into a temperature controlled chamber and excited by means of an electrodynamic shaker. The longitudinal and the transversal deformations are measured by strain gauges to get the Poisson ratio, whereas the vertical displacement of the specimen and the acceleration of the support are measured to get Young's modulus of the tested material. The experimental curves of the Poisson ratio and of Young's modulus, obtained at different temperatures, are then gathered into a unique master curve by using the reduced variables method. The two master curves, respectively, represent the Poisson ratio and Young's modulus for the tested material in a very broad frequency range.