Nondestructive sensing evaluation of surface modified single-carbon fiber reinforced epoxy composites by electrical resistivity measurement

Nondestructive sensing of a single-carbon fiber reinforced epoxy composites was evaluated by the measurement of electrical resistivity under reversible cyclic loading. For the strain–stress sensing, the strain up to the maximum load of a bare carbon fiber itself is larger than that of carbon fiber composite. As curing temperature increased, apparent modulus up to the maximum load increased and the elapsed time became shorter. Higher residual stress might contribute to the improved interfacial adhesion. The strain up to the maximum load at low temperature was larger than that at higher temperature. The strain of electrodeposition (ED) treated carbon fiber was smaller than that of the untreated carbon fiber composite until the maximum load reached. This could be due to higher apparent modulus of composite based on the improved interfacial shear strength (IFSS). Since the electrical resistivity was responded well quantitatively with various parameters, such as matrix modulus, the fiber surface modification, the electrical resistivity measurement can be a feasible method of nondestructive sensing evaluation for conductive fiber reinforced composites inherently.