Nondestructive Testing and Predictability of Microcracks in Carbon Fiber-Reinforced Composites via Terahertz Time-Domain Spectroscopy

The presence of various defects in carbon fiber-reinforced composites (CFRP) can be highly detrimental to the safety of aircrafts during their operation. Therefore, it is crucial to employ an accurate and efficient nondestructive technology to detect such defects and ensure safe operation of aircrafts. In this study, we used COMSOL Multiphysics simulation software and terahertz time-domain spectroscopy (THz-TDS) to investigate the THz spectral characteristics of manually preset microcracks in CFRP. Results showed a linear relation between the THz spectral characteristics of the microcracks, including the reflectance, time-spectral amplitude, power spectral density, absorption, and absorption coefficient, with their geometric parameters such as the length, width, and position. This relation can help predict the geometric information of the microcracks through THz-TDS, facilitating a quantitative detection of microcracks in CFRP and providing a reference for practical applications in this detection.