Monitoring delamination of laminated CFRP using the electric potential change method: Application of normalization method and the effect of the shape of a delamination crack

Abstract

Monitoring for delamination is indispensable for carbon fiber reinforced plastic (CFRP) structures. The authors previously reported delamination monitoring using the electric resistance change method; which provides excellent estimations. However, the method requires complicated electric circuits and uses a two-probe method, in which electric resistance change at the electrodes has a significant effect. To overcome these problems, the present study adopted an electric potential change method. Since this method had poor estimation performance in our previous study, here we employed a normalization method that showed significant improvements in the estimations using the electric resistance change method. Moreover, the effect on the estimation performance of delamination with a zigzag shape caused by matrix cracking is investigated using FEM analyses. In the results, the electric potential change method shows good performance of estimations for delaminations located near the edges of the specimen but poor performance near the middle of the specimen. The zigzag shape has a large effect on the performance of the estimations when the delamination crack locates near the middle of the specimen. FEM analysis shows that a small electric current through the thickness direction near the middle of the specimen causes large effects on estimation performance.