| 摘要 |
PURPOSE:To make a sensor compact and to improve response by using an ultrasonic wave receiving element wherein columnar ceramics piezoelectric bodies which are polarized in the longitudinal direction and have slant surfaces at the upper parts are arranged in a synthetic resin matrix. CONSTITUTION:Columnar ceramics piezoelectric bodies 21 are polarized in the longitudinal direction and have the slant surfaces at the upper parts. The slant surface is inclines, e.g. at an angle of 45 degrees with respect to the horizontal plane. The piezoelectric bodies 21 are arranged on a synthetic resin matrix 22. Electrodes 23 and 24 are attached to both ends of the bodies 21 in the longitudinal direction. Thus a composite piezoelectric element 2 of the synthetic resin and ceramics is formed. When a wave receiving plate 1 is brought into close contact with a surface 7 of a body under test, the vibration of an ultrasonic wave reaching the surface 7 from the inside is transmitted to the wave receiving plate 1. The piezoelectric body 21 is compressed through the electrode 23. The potential difference is generated at both ends of the piezoelectric body 21 by the compression. The ultrasonic wave reaching the surface 7 through the electrodes 23 and 24 can be detected. Sensitivity for the lateral wave of the ultrasonic wave is almost zero, and only the longitudinal wave can be detected. Therefore, this sensor is effective for analyzing the waveform of the ultrasonic wave in acoustic emission. |
