Multivariate damage mode identification method for fiber-reinforced composites at high temperatures by acoustic emission

Carbon fiber reinforced polymers (CFRPs) often operate in high-temperature environments, which significantly influence their damage evolution behavior and mechanical performance. To investigate this effect, a multivariable damage mode identification (MDMI) method utilizing acoustic emission (AE) technology, applicable to high-temperature conditions, is proposed. Four specimen types inducing distinct primary damage modes are designed, and mechanical tests under different temperatures are conducted to accurately extract AE signal features for each damage mode, confirming the reliability of the MDMI method. Results indicate that temperature has minimal effect on the peak frequency range for each damage mode but significantly reduces the signal amplitude in the frequency domain. Using the MDMI method, the compressive performance of open-hole CFRPs is analyzed under different temperatures. As temperature rises, the dominant damage mode of open-hole CFRPs under compression transitions from fiber/matrix debonding to predominantly matrix cracking. This study provides valuable insights into damage mode identification of CFRP under different temperatures, offering significant guidance for predicting and optimizing its performance in extreme environments.