Prediction and measurement of the transmission coefficients of transversely isotropic porous plates

Abstract

The prediction of the transmission coefficients is based on the Biot theory of elastic waves propagation in fluid-saturated porous solids. An elastic wave impinging upon an interface between a fluid and a fluid-saturated anisotropic porous solid can generate two compressional waves (one fast and one slow) and two shear waves (one horizontal and one vertical) in the porous medium. The motion in the porous plate results in coupled differential equations involving separate displacements in the skeleton and the saturating fluid. The wave speeds of the propagation modes in the porous medium were determined by seeking the solution of the equations of motion as plane acoustical waves. The transmission coefficients were finally obtained from boundary conditions at the interfaces between the fluid and the porous plate. They were experimentally determined, in the case of a porous corundum ceramic plate immersed in water, by using an ultrasonic immersion technique. The agreement between the predicted and measured transmission coefficients versus the angle of incidence for this plate is acceptable and has been achieved using adjustable and fitted parameters.