In the present research, we attempted a basic comparison between the actions of crushing by high-powered ultrasonic vibrations of 28 kHz and of 50 kHz, using a biological soft-tissue crushing model. The crushing model was a mixture of agar, the base material, graphite powder, plastic powder, and ethanol as a sound velocity regulator. We placed the mixture in water, and experimentally investigated and verified the crushing process to the amplitude of high-powered ultrasonic vibration with the driving frequency used as a parameter. As the vibration amplitude increases, both the ultrasonic output and the velocity increase, and the crushing multiplies in each case. However, the crushing rate was higher at 50 kHz than at 28 kHz. Acceleration reached the peak at an ethanol concentration of approximately 33 weight percent, and the crushing rate showed the maximum value. This result implies that the crushing action of acceleration, in particular, exerts a great effect on the crushing of biological soft tissues, and that an improvement in the crushing effect is expected from a higher frequency.
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