Abstract
When the piezoelectric film is glued on the surface of a cracked material subjected to mechanical load, change in distribution of electric potential is observed on the surface of piezoelectric film. Based on this phenomenon, the passive electric potential CT (computed tomography) method was proposed for identifying two- and three-dimensional cracks. This method uses passively observed electric potential distribution on piezoelectric film induced by the strain distribution of the objective body without applying electric current. Therefore, this method can be applied to develop an intelligent structure with a function of self-monitoring of flaws and defects. In this paper, the passive electric potential CT method using a piezoelectric material is applied to the identification of a through-thickness transverse crack. The effects of crack size and location on electric potential distribution were examined by using the finite element method. For the identification of cracks from electric potential distribution, an inverse method based on the least residual method is applied, in which square sum of residuals are evaluated between the measured electric potential data and those computed by using the finite element method. The crack was identified from experimentally observed electric potential distribution. It was found that the location and size of the crack can be quantitatively identified by the passive electric potential CT method.
