Effect of hygrothermal environment on fatigue performance of CFRP strands via experiment and molecular dynamics simulation

Y Liu and MY Xi and YZ Li and KX Sun and Y Zheng and LH Tam and RY Qin, JOURNAL OF BUILDING ENGINEERING, 101, 111732 (2025).

DOI: 10.1016/j.jobe.2024.111732

Carbon fiber reinforced polymer (CFRP) strands are increasingly used in critical structural applications such as prestressed concrete due to their high strength-to-weight ratio and corrosion resistance. However, the performance degradation of CFRP strands under hygrothermal conditions and fatigue loads remains unclear, as well as the underlying degradation mechanisms. This work investigates the fatigue performance of CFRP strands in different hygrothermal environments using experimental testing and molecular dynamics (MD) simulations. Experimentally, CFRP strands were subjected to tensile fatigue tests at room temperature, high temperature, and under hygrothermal condition with high temperature and high humidity by following ASTM standards. The results indicate that the tensile strength is minimally affected under room temperature fatigue conditions, but it decreases significantly by 6.3 % under high temperature and by 7.2 % under hygrothermal condition. Microscopic analyses via scanning electron microscopy and metallurgical microscopy revealed that the micro-cracks appear primarily at the resin- fiber interface, indicating a reduction in interfacial adhesion under these conditions. MD simulations further elucidated the atomistic-level interactions and stress responses, highlighting the accelerated degradation processes under hygrothermal conditions due to aggregation of water molecules and interfacial sliding. The findings contribute to an in-depth understanding of the durability of CFRP strands under hygrothermal conditions. This research fills a significant gap in the literature and provides a foundation for designing more robust CFRP systems in critical infrastructure.

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