Application of electric potential method to smart composite structures for detecting delamination

Abstract

CF/epoxy composites have been applied to many kinds of aircraft structures. The composite laminated plate compression properties, however, are easily degraded by delaminations. Thus an approach for detecting the delaminations is widely desired. In this study, an electric potential method was discussed for realtime nondestructive evaluation of delaminations because this method has several advantages in comparison with the embedded optical fiber. In order to obtain the basic properties of the CF/epoxy composites, mode I and II delamination tests were carried out and the relations between the electric resistance change and the delamination crack length were measured. As a result, the electric resistance bridge circuit approach was proven to be excellent for detecting delaminations from the inside surfaces of aircraft structures.