METHOD AND APPARATUS FOR EVALUATING THERMAL STRESS DISTRIBUTION OF SPECIMEN USING ULTRASONIC TOMOGRAPHY

摘要

PURPOSE:To make it possible to evaluate a heat resisting material by generating ultrasonic waves having wide directivity from one point on the surface of a specimen, obtaining the propagating speeds of the ultrasonic waves to receiving points based on the transmitting times of the ultrasonic waves, and obtaining the temperature of each region. CONSTITUTION:For example, when nonuniform temperature distribution is present only in the plate thickness direction (X axis) in an infinite plate having the equal thickness, laser pulses having minute spot diameters are projected on the left end. Then ultrasonic waves are generated at the projected parts by the thermal elasticity effect. The ultrasonic waves are received with receives at points S (S1-SN) at the right end. Then the propagating times of the ultrasonix waves can be measured along paths L (L1-LN). The distribution of the propagating speeds of the ultrasonic waves can be obtained based on the measured times by specified expressions. Then the temperature distribution is obtained based on the propagating speeds. Finally, the thermal stress distribution is obtained. In this way, a heat resisting material can be evaluated, and the breakdown due to the thermal stress can be evaluated.