Strain and Damage Monitoring of CFRP Laminates by Means of Electrical Resistance Measurement

Abstract

This review discusses the use of electrical resistance and potential change in various methods for monitoring Carbon Fiber Reinforced Plastic (CFRP) composites. CFRP composites have electrical conductivity as they contain carbon fibers. When fibers and fiber networks break within the structure its electrical resistance changes; the electrical resistance of carbon fiber changes with the applied strain just as physical resistance varies in a conventional strain gage. Using these changes in electrical resistance damage to CFRP composites can be monitored and applied strain measured without implementation of additional sensors. This makes CFRP a self-sensing material. The electrical resistance change method has been applied for decades to detect carbon fiber breakages. As regards the measurement of applied strain, there is divergence of opinion amongst researchers about the piezoresistance of CFRP. This discrepancy is discussed in detail in this review. For monitoring damage such as delamination cracks, the electrical resistance change method can accurately estimate the location and dimension of the damage. This review also discusses electrical potential change and eddy current methods for monitoring CFRP composites.