An experimental-numerical technique for evaluating the bulk and shear dynamic moduli of viscoelastic materials

An experimental/numerical technique has been implemented to determine simultaneously the bulk and shear dynamic moduli (and loss factor) of viscoelastic materials of arbitrary shape under low-frequency (0.5–2.5 kHz) harmonic excitation. The method consists of measuring the dynamic response of the sample at several points on the surface with a set of five independent laser interferometers, and matching the response with the predictions from a finite element code in which the two complex elastic moduli are the adjustable parameters. Results are presented for measurements made in air, under standard pressure and temperature conditions, and compared with predictions based on Kerner’s model.