Materials Design for Explicit Warning of Fracturing

It was found that measurement of electrical resistance in the CFGFRP (carbon fiber-glass fiber reinforced plastic) composites during and after loading is a very promising method for monitoring residual damage. CFGFRP composites containing three types of carbon fibers along with 31.6 V% glass fibers were tested. With loading, the CFGFRP specimens were able to withstand load/strain beyond the point where carbon fibers alone were fractured. At the transition point a tremendous change in electrical resistance was seen, and this point could be controlled through suitable selection of the type of carbon fibers according to their values of ultimate elongation. The signal is very distinct and the method is very simple. The design concept for explicit warning of fracturing is to combine a conductive material with a small value of ultimate elongation and an insulating material with a large value of ultimate elongation.