Towards practical application of electrical resistance change measurement for damage monitoring using an addressable conducting network

This article considers the practical use of electrical resistance change method (ERCM) for damage detection in graphite/polymer composites. ERCM utilizes the high electrical conductivity of graphite fibers in the composites and can detect damage by change in electrical resistance. Since the effectiveness of ERCM has been shown extensively in the literature, it is now necessary to consider how to apply ERCM into existing structures. For practical use of ERCM, a new concept of an addressable conducting network (ACN) has been proposed, which consists of two sets of conducting lines normal to each other. One set of lines resides on the top surface of the laminate and the other resides on the bottom surface. Damage can be detected by monitoring resistance change between two lines across the laminate thickness. In this article, composite panels with several sets of conducting lines are locally loaded by a static indentation test and examined to monitor the distribution of electrical resistance changes. Monitoring the changes in resistance successfully indicated the damage occurrence, but it is sometimes difficult to pinpoint the damage location due to the resistance changes caused by compressive deformation. To improve the sensitivity of ACN to damage, the relationship between damage location and electrical conductivity was investigated using a design of experiments. The changes in resistance with various damage locations and electrical conductivities were acquired from finite element analysis, and the results suggested several ways to optimize damage detection. Depending on the damage tolerance of target structure, spacing of conducting lines and the electrical conductivities can be preferably selected toward practical application of ACN.