Damage sensing of carbon nanotubes embedded glass fiber composites based on electrical resistance change

Application of composites in the primary structural parts such as aircrafts or wind turbine blades involves a great deal of mechanical joining to form a final structure. Therefore, it is essential to monitor the critical status of the joints related to the overall durability and performance of the structure. Carbon nanotubes acting as an electrical conductive network is utilized to detect the damage evolution and state in unidirectional glass fiber reinforced composite joints. In order to sense the damage evolution in the matrix, the double-lap tension test with two different electrode configurations in the Longitudinal Direction (LD) and Transverse Direction (TD) was performed. There are three stages in the change in resistance before the peak load. Initially the resistance change increase steadily, then rapidly and back to a steady increase. These steps correspond to the elastic deformation, the microcracks initiation/growth in matrix, and the saturation of crack density.