| 摘要 |
PURPOSE:To measure a stress value produced on the surface of an object to be measured under a nondestructive condition, by previously measuring and preparing the relation between the acoustic velocity changing ratio and stress value of the material of the object to be measured and measuring the velocity of the surface wave sound of the object to be measured. CONSTITUTION:If the relation of the acoustic velocity and the stress of the same material or approximate material of an object to be measured is previously found, a produced stress value is found by measuring the acoustic velocity of the object to be measured. By applying this principle, a wave transmitting terminal 2 and wave receiving terminal 3 are pressed against the surface 1a of the object 1 to be measured with an optional interval L between them. When the pulse current of an ultrasonic transmitter/receiver 4 is supplied to the terminal 2, ultrasonic waves are produced from the terminal 2 and propagated on the surface 1a of the object 1 in the direction shown by the arrow 6. The ultrasonic waves are converted into electric signals by means of the wave receiving terminal 3 and amplified by an ultrasonic receiver. Then the acoustic velocity between the terminals 2 and 3 is calculated from the propagating time T of the ultrasonic waves propagated along the distance L between the terminals 2 and 3 by means of an acoustic velocity measuring instrument 5 and, therefore, produced stress can be known.
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