CALIBRATION METHOD IN POTENTIAL DIFFERENCE METHOD MEASUREMENT AND POTENTIAL DIFFERENCE METHOD MEASURING DEVICE

摘要

PROBLEM TO BE SOLVED: To improve crack measurement precision by the potential difference method. SOLUTION: When a voltage drop at a crack part being generated when a constant current is allowed to flow to a conductive sample with a thickness of T where a crack K exists is set to E and a voltage drop at a site without any crack K is set to Eo, the change in a potential difference ratio E/Eo for the change in a crack depth (a) is expressed by a calibration approximation expression E/Eo=1+f(a)/(T-a). The relationship between the above potential difference ratio E/Eo and the crack depth (a) is calibrated from the calibration approximation expression.