Laser-Induced Thermoelastic Wave Technique to Evaluate Hygrothermal Aging in CFRP Composites

Abstract

The interaction of heat and moisture with fiber-reinforced polymer composites over a long duration is known to cause physical and mechanical degradation. In this paper, an attempt was made to evaluate physical and mechanical changes in carbon fiber–reinforced polymer (CFRP) by an unconventional nondestructive approach before and after varied duration of exposures to hygrothermal (HT) treatment at an elevated temperature (80 °C/353 K) up to 800 h. As a novel approach, laser-induced thermoelastic waves were utilized for characterization of the material. Wave characteristics, such as wave amplitude and velocity of propagation, were studied over different duration exposures of HT treatment to detect and quantify HT-induced property changes in the material. Results show that the aging effect attenuated the wave to a factor of 2.75 and significantly reduced the velocity of wave propagation by 20% compared to that of the pristine material, revealing the degradation in the material caused by HT exposure. The proposed methodology has the potential to monitor the health of fiber-reinforced polymer composite structures that have undergone hygrothermal aging.