Effect of high temperature and hygrothermal aging on interlaminar mechanical properties of carbon fiber reinforced plastics

Abstract Carbon fiber reinforced plastics ( CFRP ) have broad application prospects in the field of automotive lightweighting. However, their performance degradation mechanisms under hygrothermal environments remain a key issue limiting their engineering applications. This study focuses on the interlaminar mechanical properties degradation mechanisms of CFRP under the coupled action of high temperature and humidity. Through accelerated aging experiments and multi‐scale characterization, the correlation between moisture absorption and interlaminar strength is analyzed. The results show that under a high temperature environment (80°C, 25% RH ), within a short‐term aging period of about 360 h, post‐curing effects lead to increases in interlaminar tensile and shear failure strength of 7.5% and 6.9%, respectively. However, after long‐term aging (about 1440 h), thermal oxygen degradation slows down the increase in failure strength. Under a high temperature/humidity environment (80°C, 95% RH ), the moisture absorption rate of CFRP increases nonlinearly with aging time, reaching equilibrium after 1080 h. The interlaminar tensile and shear strengths decrease by 34.5% and 33.5%, respectively. Additionally, based on the interlaminar strength data, an interlaminar cohesive zone model of CFRP is developed. It can predict failure at any aging time, providing a vital reference for the interlaminar performance degradation and durability design of CFRP components. Highlights Interlayer performance degradation mechanism of CFRP under high temperature and hygrothermal environments was investigated. Post‐curing effects and thermal aging are revealed as dominant mechanisms in high temperature aging. Staged quantitative correlation between moisture absorption rate and interlaminar mechanical properties of CFRP was revealed. CFRP interlayer cohesion zone model considering hygrothermal degradation factor is developed.