A new multiphysics coupling analysis method and research on exhaust valve wear failure of marine engines

The application of new low-carbon fuels, such as LNG, has introduced wear failure issues in key engine components, especially in the exhaust valve-seat friction pair. However, there is currently limited targeted research on this topic. In this study, a thermal-mechanical-chemical coupling model for the exhaust valve is developed. First, using molecular dynamics theory, the impact of different oxide film thicknesses on the friction and wear of valve materials is investigated, and a wear model for the exhaust valve-seat interface is proposed. Next, the heat transfer process within the exhaust valve-seat system is analyzed, and a mathematical model for the exhaust valve’s temperature field is established. Then, the forces and constraints acting on the exhaust valve are analyzed, and a thermos-elastodynamics model is established. Finally, by coupling the above models, the influence of multiphysics coupling on exhaust valve wear failure is examined. The results indicate that as the oxide film thickness increases, both the friction and wear coefficients rise. Moreover, the temperature field has a significant effect on the contact and wear status of the exhaust valve-seat friction pair. The wear volume under multiphysics coupling is substantially higher than that calculated without considering the temperature field. Furthermore, the thicker the oxide film, the more severe the valve wear.