Ultrasonic characterization of the anisotropic behavior of air-saturated porous materials

摘要: Abstract This paper provides a comprehensive review of the propagation ultrasonic waves in anisotropic porous materials. The equivalent fluid model (or Allard-Johnson theory) which is relevant for air-saturated media described. It takes into account viscous and thermal losses occurring during movement within motionless solid frame. When skeleton moving as well, coupled Biot theory should instead be used. becomes intricate when anisotropy considered due to very large number physical parameters determined. A strong formal correspondence between wave dynamic thermoelasticity non-porous outlined. Standard methods, generally used at low frequency (i.e. 20–500 kHz) are effective order characterize media. Both reflection transmission configurations have been Special attention has devoted measurements tortuosity, but also characteristics lengths. Finally, some inverse problems related these solved others, still open, presented.