Active and Passive Electric Potential CT (Computer Tomography) Methods for Identification of Defect in Inhomogeneous and Anisotropic Materials

本研究涉及扩展的电位CT方法提出了目前的研究人员在一个均匀的各向同性体的裂纹识别。主要研究结果如下：1.该方法适用于非均匀体和各向异性体中裂纹的识别。通过在使用边界元法的电势计算中考虑不均匀性和各向异性。将该方法应用于界面裂纹的识别，数值模拟和实验结果表明，该方法对界面裂纹的识别是有效的.该方法也被应用于各向异性材料分层的识别。在边界元法计算电势分布时考虑了各向异性。将该方法应用于碳纤维增强层状复合材料分层损伤的识别。数值模拟表明了该方法的适用性.迄今为止提出的电势CT方法被分类为主动方法，因为该方法使用施加电流下的电势分布。提出了一种不需要外加电流的被动电位CT方法，即在裂纹体表面粘贴压电薄膜，测量裂纹体表面的电位。考察了电极位置和尺寸对电极电位分布的影响。数值模拟和实验结果表明，裂纹的位置和尺寸可以通过压电薄膜上的电势分布来估计。

The present study deals with the extension of the electric potential CT method proposed by the present investigators for the identification of a crack in a homogeneous isotropic body. The major results obtained are summarized as follows.1. The method was made applicable to the identification of a crack in a non-homogeneous body and in an anisotropic body. by considering inhomogeneity and anisotropy in the electric potential calculations using the boundary element method. The method was applied to the identification of an interface crack in bonded dissimilar materials Numerical simulations and experiments showed that the extended method was useful for the identification of the interface crack.2. The method was also applied to the identification of delamination in anisotropic material. The anisotropy was taken into account in the boundary element calculations of the electric potential distribution. The method was applied to the identification of delamination in carbon fiber reinforced layered composite materials. Numerical simulations showed the applicability of the method.3. The electric potential CT method proposed so far is classified into an active method since the method uses the electric potential distribution under an application of electric current. A passive electric potential CT method, which did not require current application, was proposed by adhering piezoelectric film on the surface of the cracked body and measuring the electric potential on the surface. The effect of location and size on the electric potential distribution were examined. It was found from numerical simulations and experiments that the crack location and size can be estimated from the electric potential distribution on the piezoelectric film.