| 摘要 |
PURPOSE:To enable the imaging of a defect by low frequency ultrasonic waves, by a method wherein ultrasonic propagation times in plural directions passing the center point of a measuring cross area, a defect part present on the measuring cross area and the distance of the defect part and the outer periphery of the cross area are respectively measured and detection is carried out on the basis of these measuring results and a reference propagation time. CONSTITUTION:Ultrasonic propagation times are measured in plural directions (P0-P7 P0'-P7') passing the center point Q of a measuring cross area 10 and a defect part H is subsequently measured from ultrasonic propagation times in plural parts of the measuring cross area 10 while the distance of the defect part H and the outer periphery of the measuring cross area 10 is further measured. By this method, a defect part is detected from these measuring results and a reference propagation time of ultrasonic waves passing the center point of the cross area (not shown by the drawing) in the normal part of an object to be measured. As mentioned above, because plural detection procedures are taken, the position and the shape of a defect part can be detected and imaged by relatively low frequency ultrasonic waves. |
