Method to Determine Dynamic Elastic Constants of Thin Shell Composites by Guided Ultrasonic Waves

摘要

Ultrasonic techniques are used to determine the velocities of guided waves in unidirectional metal matrix composite places. Both extensional (fundamental Lamb symmetric) and in-plane shear (SH) plate wave speeds are measured via through-transmission procedures utilizing one-half megahertz broadband transducers. The values recorded for the wave speeds and the plate density are used to calculate the four reduced stiffness coefficients of the plane stress Hooke's Law relationship of the plate. This approach allows the full set of elastic constants required by designers for the analysis of a thin orthotropic plate or shell loaded in its plane to be obtained from only four ultrasonic measurements. The accuracy of the elastic constant determinations may be increased by measuring more than four wave speeds and employing the statistical data reduction method described.