Effect of hygrothermal aging on the high-temperature interlaminar mechanical properties of CFRP under a complex stress state

In the process of long-term service, CFRP structures are often in a complex stress state, the interlaminar resin matrix is sensitive to temperature and humidity in the environment, and different test temperatures after aging also have a significant impact on the interlaminar mechanical properties of CFRPs. A hygrothermal aging environment (80 degrees C/95% RH) was selected to conduct artificial accelerated aging tests for 28 days, and the CFRP was tested at room temperature and high temperature to study the influence of different test temperatures on the failure strength of the CFRP under five complex stress states. The fracture failure morphology, glass transition temperature (T-g) and absorbance of some functional groups change after hygrothermal aging. The interlaminar failure strength of the CFRP in five stress states decreases with increasing aging time in a cubic polynomial manner, and the interlaminar failure strength at high temperature is significantly lower than that at room temperature after aging. Finally, the three-dimensional variation surface of the high-temperature quadratic stress criterion with aging time is established, which provides a reference for the durability evaluation of the CFRP high-temperature interlaminar residual strength after hygrothermal aging.