Abstract
Fundamental study is carried out to investigate accuracy for evaluating the defect size in the circular rods in water by using the ultrasonic caustics. It is shown that the defect can be evaluated by employing not only shear wave but also longitudinal wave and the general relationship between the angle β_0 of receiver and the value of a/D, which is used to determine the crack length, is given. Moreover it is revealed that the minimum defect size which can be evaluated by this technique is approximately 4mm under the experimental condition used in this study.
