Water absorption test for carbon fiber epoxy resin composite based on electrical resistance

Electric contacts were inserted into a carbon fiber epoxy resin composite to research the relationship between water absorption and resistance, which allowed the diagnosis of composite water absorption in a nondestructive way. The results show that the carbon fiber in the composite form does not absorb water from the environment, and its resistance remained unchanged when immersed in water. However, the resistance of the composite increased after water was absorbed along the fiber until the specimen reached saturation, which resulted in a sudden increase in resistance. The transverse resistance changed logarithmically in relation to water absorption. The data fitting equation is y = 2.03 × lg(x)−6.26 (R2 = 0.98), where x is the transverse resistance after water absorption (Ω), and y is the weight gain rate after water absorption (%). According to this equation, the weight gain rate of the composite can be calculated from the transverse resistance.