Determining longitudinal- and shear-wave velocities in Japanese radish, watermelon and potato

Abstract

Longitudinal- and shear-wave velocities were determined for Japanese radish, watermelon and potato. Pulsed waves propagating in cylindrically shaped specimens were detected, and their phase differences obtained in specimens of different lengths yielded phase velocities in the frequency range 0.4-8 kHz at 27 kHz. The Pochhammer-Chree dispersion relation was applied to analyze the fundamental and second modes of the measured velocities, which provided the longitudinal- and shear-wave velocities in an infinite medium. Longitudinal-wave velocities of 202, 82 and 571 m s−1 and shear-wave velocities of 61, 36 and 80 m s-1 for Japanese radish, watermelon and potato, respectively, were obtained. Furthermore, the Young’s modulus and Poisson’s ratio were determined. The drying effect of the velocities obtained in the Japanese radish suggested that gas porosity substantially influenced the velocities, resulting in smaller values of the longitudinal-wave velocity compared with that in water.