Design of intelligent materials with self-diagnosing function for preventing fatal fracture

Hybrid composites containing both conductive fibres with a small value of ultimate elongation and insulating fibers with a large value of ultimate elongation show promise as intelligent materials with a self-diagnosing function for preventing fatal fracture. Three types of carbon fiber and one type of glass fibre were tested as conductive fibers and insulating fibers, respectively. A tremendous change in electrical resistance was seen at the transition point where the conductive fibers fractured, and this point could be controlled through suitable selection of the type of conductive fiber according to its value of ultimate elongation. Permanent residual electrical resistance was observed even after the removal of load, and the change was dependent on the maximum strain applied in the past trials. In the application of this method, changes in the electrical resistance of CFGFRP-reinforced concretes were measured during and after loading.