The influence of thermal aging on the interlaminar mechanical properties and failure mechanisms of CFRP under complex stress states

The fiber/matrix interlayer structure of carbon fiber reinforced polymer (CFRP) is temperature-sensitive, so the aging is likely to cause degradation of interlayer performance. Aging experiments were conducted under high-temperature and thermal-cycling environments. The aged CFRP were performed to investigate the variation patterns of interlayer failure strength under different temperatures and stress states. The study found that thermal-cycling aging resulted in less severe degrees of post-curing and thermal oxidative aging. The failure of aged CFRP was a combined effect of fibers and matrix, and high temperature exacerbated the damage. A surface equation of the quadratic stress failure criterion was established.