| 摘要 |
PROBLEM TO BE SOLVED: To realize a new ultrasonic element capable of transmitting and receiv ing ultrasonic waves to not only to a conductive specimen but also to a nonconductive specimen. SOLUTION: A magnetostrictive ultrasonic element is composed of a magnetostrictive ring body 4, in which a magnetostrictive material is formed annularly, a bias coil 10 wound on the magnetostrictive ring body for forming a DC bias magnetic field B0 in the ring body 4 and a signal coil 12 wound on the ring body 4 for detecting a fluctuating magnetic fieldΔB generated through the magnetostrictive effect by the ultrasonic vibrations of the ring body 4. Ultrasonic reception sensitivity by the signal coil 12 is adjusted by the DC bias magnetic field B0, the ring body 4 is brought into contact with the surface of the body to be inspected 24, the ultrasonic vibrations of the surface of the body to be inspected are transmitted to the ring body 4, a vibration distortion generated in the ring body 4 is converted into the fluctuating magnetic fieldΔB by the magnetostrictive effect, and the fluctuating magnetic field is detected by the signal coil 12 and ultrasonic waves are received.
|
