Abstract
The present authors proposed the passive electric potential CT method using an electric potential distribution appearing due to the direct piezoelectric effect on a piezoelectric film pasted on a structure subjected to mechanical load. By applying an electric pulse on the film for emitting pulse-echo due to the inverse piezoelectric effect, the active pulse-echo method was proposed. In this paper a simultaneous application of the passive and the active methods using the piezoelectric film with multi-electrodes was made for the quantitative identification of through-cracks. The electric potential was measured on the film of a cracked specimen subjected to a varying load. The electric pulse was applied to an electrode on the piezoelectric film and reflection waves were received at several electrodes on the piezoelectric film. Inverse analysis was made to identify the cracks from the observed electric potential distributions and the reflected waves. It was found that the active/passive method was useful for the estimation of the crack depth, for which the passive method was not efficient. The effectiveness of the active/passive method was shown.