Passive electric potential CT method using piezoelectric material for crack identification

When the piezoelectric film is glued on the surface of a cracked material subjected to mechanical load, change in electric potential distribution is observed on the surface of the film. Based on this phenomenon, the passive electric potential CT (computed tomography) method can be developed, which does not require electric current application for identifying cracks. This method may be applied to develop an intelligent structure with a function of self-monitoring of flaws and defects. For the crack identification from electric potential distribution, an inverse method based on the least residual method was applied, in which square sum of residuals are evaluated between the measured electric potential distributions and those computed by using the finite element method. Numerical simulations were carried out on identification of a through-thickness transverse crack. It was found that the location and size of the crack can be quantitatively identified by the proposed passive electric potential CT method.