Micromechanical damage and degradation of polymer composites under cryo‐thermal fatigue

Abstract In this study, the micromechanical damage of polymer composites under thermal fatigue loading in cryogenic conditions is investigated using micromechanical numerical analysis. The widespread use of polymer composites in structures such as multi‐layer tanks for storing compressed gases in the food, medical, nuclear, and aerospace industries highlights the importance of analyzing mechanical property degradation and damage under cryogenic conditions. In this research, thermal fatigue loading is applied to an RVE model of carbon fiber‐reinforced polymer composite to examine mechanical property degradation and damage modes. The results show significant agreement with previous experimental studies. The findings indicate that fiber‐matrix debonding and matrix cracking are the dominant damage modes under cryogenic conditions. Moreover, short‐term fatigue cycles have approximately 40% more impact on the degradation of mechanical properties compared to long‐term cycles. Additionally, fatigue analysis reveals that more than 50% of the mechanical property degradation occurs during the initial fatigue cycles, with negligible changes in the later cycles. Highlights Micromechanical damage analysis of polymer composites under cryogenic thermal fatigue loading. Fiber‐matrix debonding and matrix cracking are identified as primary damage modes in cryogenic conditions. Numerical simulation results show significant agreement with experimental studies. Short‐term fatigue cycles cause more pronounced mechanical property degradation than long‐term cycles. Initial fatigue cycles account for the majority of damage, with negligible changes in later cycles.