Pulse-echo acoustic properties evaluation method using high-frequency transducer

The quantitative measurement of acoustic properties is indispensable for many applications. The realization of devices for the evaluation of acoustic properties with higher accuracy and lower error is of great importance. Moreover, the ability to obtain the high-frequency acoustic characteristics of materials is also highly desirable. In this research, the pulse echo method is applied to measure a material's acoustic parameters, using a miniature transducer with a center frequency of 42.9 MHz. For this method, only one transducer is needed, and the measurement system is simple. Acoustic parameter calculation methods for three types of materials are studied, and the corresponding experiments are conducted. The experimental results show that the sound velocity of water is 1508.8 m s⁻¹, and its attenuation coefficient is 0.981 dB mm⁻¹; the results for liquid paraffin give results of 1386.8 m s⁻¹ and 2.35 dB mm⁻¹, respectively. With reference to polymer materials, thermoplastic polyurethane (TPU) thin film has a sound velocity of 1987.2 m s⁻¹ and an attenuation of 37.1 dB mm⁻¹, and polyimide thin film has a sound velocity of 2142.3 m s⁻¹ and an attenuation of 25 dB mm⁻¹. In terms of ceramics, the sound velocity of PZT-5H 3203HD is 4804.2 m s⁻¹, and its attenuation is 1.71 dB mm⁻¹; 96% alumina ceramic has a sound velocity of 9924.9 m s⁻¹ and its attenuation 1.18 dB mm⁻¹. All results pertaining to sound velocity agree well with those reported in previous works. The measured attenuation coefficients at high frequency are also in good agreement with the experimental data. All experimental results validate the feasibility, effectiveness, convenience, and accuracy of this method. (paper)