Thermodynamic Properties of the Interface in Carbon Fiber/Epoxy Resin Matrix Composites: A Molecular Dynamics Simulation Approach

Carbon fiber/epoxy resin matrix composites have gained widespread application in aerospace, automotive, and electronics industries due to their excellent mechanical properties, lightweight characteristics, and corrosion resistance. However, due to the significant difference in thermal expansion coefficients between carbon fibers and the epoxy resin matrix, these composites are prone to thermal stresses during temperature changes, which can adversely affect their mechanical properties and long-term stability. Therefore, investigating the thermodynamic properties of the composite interface, especially the thermal expansion behavior and the evolution of interface thermal stresses, is of great theoretical and practical significance. Current studies on the thermodynamic theoretical analysis, experimental testing, and numerical simulations. However, due to the complex microstructure of the composites, existing research methods have limitations in capturing the interface-level thermal stress and thermal expansion characteristics. In particular, traditional finite element analysis methods are unable to precisely capture thermal stresses and expansion properties at the interface level. To address this, molecular dynamics simulation, as a fine-scale research tool, effectively simulates the micro-level interactions within composites and provides more accurate predictions of thermodynamic properties. This study uses molecular dynamics simulations to explore the thermal expansion properties and interface thermal stresses of carbon fiber/epoxy resin matrix composites, revealing the thermodynamic behavior at the interface level. By integrating finite element analysis and cohesive zone model (CZM), Athis paper further conducts multiscale simulations of the interface thermodynamic properties, systematically studying the evolution of thermal stresses and their impact on interface failure. This research not only provides a theoretical basis forAa deeper understanding of the thermodynamic behavior of composites but also offers important references for optimizing the design and application of composite materials.