In this study, we measured temperature dependences of longitudinal and shear wave velocities in some acoustic lens materials using the sing-around method. The materials we tested were silicone rubber (SR) and polymerization acrylic resin (PAR). The velocities were measured in the temperature range from 5℃ to 30℃. The temperature of material immersed in water was maintained by using a water tank that could be kept at a constant temperature while the velocities were measured. The PAR material was made by stacking two thin plates and cementing them together with polymerizing adhesive. We assumed that this material will be used for making large acoustic lenses which cannot be realized with a single plate of PAR. For example, the aperture of such a lens is greater than 1.0 m, and the thickness is over 0.25 m. After measurement of sound velocities of materials, the data of velocities were approximated to the linear function of temperature using regression analysis. The results of PAR were then compared with those of the simple PAR material with a single plate used in the previous studies. In the PAR material, the temperature coefficient of the longitudinal wave was −2.822 [m/s・℃], and that of the shear wave −2.107 [m/s・℃]. On the other hand, the temperature coefficient of the longitudinal wave was −2.545 [m/s・℃], and that of the shear wave was −2.189 [m/s・℃] in the simple PAR material. In the SR material, the temperature coefficient of the longitudinal wave was −2.893 [m/s・℃].
抄録全体を表示