Ultrasonic contact pulse transmission for elastic wave velocity and stiffness determination: Influence of specimen geometry and porosity

► Sample geometry and porosity govern ultrasonically tested elastic properties. ► Only bars with slenderness ratio greater than 10 reveal Young's moduli. ► Characterization of porous solids depends on the pore-diameter-over-wavelength ratio d/λ. ► Normal and shear stiffnesses are “felt” at d/λ < 0.01 and d/λ < 0.1, respectively. ► Ultrasound test results are consistent with various homogenization schemes.