The effect of MWCNT concentration on the electrical resistance change characteristic of glass/fiber epoxy composites under low cycle fatigue loading

In this study, the effect of multi-walled carbon nanotube concentration on the electrical resistance change characteristics of multi-walled carbon nanotube filled glass/epoxy composites under low-cycle fatigue loading was experimentally investigated. For this purpose, multi-walled carbon nanotube concentrations of 0.2, 0.3, and 0.4wt.% within composites were utilized to ensure electrical conductivity. The rectangular specimens for fatigue tests were manufactured by vacuum bagging method. The fatigue tests were conducted in a load-controlled manner with an ultimate strength ratio of 0.6 and at a stress ratio of 0.1. The results showed that the alteration in electrical resistance within the composites experiences a sharp and exponential rise when the concentrations of multi-walled carbon nanotube reach 0.2 and 0.3wt.%, whereas the rate of this increase in electrical resistance is more gradual at 0.4wt.%. multi-walled carbon nanotube concentration. The electrical resistance change curves of multi-walled carbon nanotube filled composites at various fatigue life levels were determined for statistical analysis using the Weibull distribution method. Finally, the average stiffness loss and the average residual fatigue life were determined at the electrical resistance changes corresponding to 95, 80, and 50% Weibull reliabilities at various fatigue life levels and various multi-walled carbon nanotube concentrations.