Experimental Measurement of Dynamical Young's Modulus and Shear Modulus of Low-impedance Materials

摘要

A new dynamical measurement technique that combines PVDF film piezoelectric gages with resistor strain gages in conventional SHPB is developed to study the dynamical mechanical behavior of low-impedance aluminum foam. The average value of the stresses measured by PVDF gages from the front face and the back face of the specimen at each time is taken as the effective stress history of the specimen. This effective stress history is combined with the measured axial strain history in the specimen by eliminating time t. Then the initial part of the stress-strain relationship of the material can be determined reliably. From its slope, the dynamical Young's modulus of low-impedance aluminum foam can be determined. For the aluminum foam with a density of 1.2 x 10~3 Kg/cm~3 at a given strain rate (ε =814/s), we get: E =1.15 GPa, G=0.44GPa.