Foreseeing of Fracture in CFGFRP Composites by Measuring Electrical Resistance.

The relations between strain, electrical resistance and load were measured for CFGFRP (carbon fiber-glass fiber reinforced plastics) composites. Three kinds of carbon fibers made from different raw materials and four kinds of PAN-based high strength carbon fibers with different bundle numbers were used as the resistance detectors. The strain of CFGFRP composites increased linearly with the load, but changes in electrical resistance showed nonlinear curves as a function of strain. A large resistance change during load and a large residual resistance after removing load were observed in the CFGFRP containing small numbers of carbon fibers with high strength and elongation. By measuring a relation between strain and change in electrical resistance, it is possible to know the load and strain applied presently. In addition the load and strain applied previously can be estimated by measuring the residual electrical resistance. Measuring the electrical resistance was found to be a promising technique for foreseeing the fracture of CFGFRP composites.