Molecular Dynamics Investigation on Micro-Friction Behavior of Cylinder Liner-Piston Ring Assembly

In the vicinity of the top dead center of a diesel engine, the piston rings operate in a low-speed, high-load, and high-temperature environment, which is detrimental to the formation of an effective lubrication oil film. Consequently, it presents significant challenges for predicting the tribological characteristics of the piston ring-cylinder liner friction (PRCL) assembly. This study explores the micro-friction behavior of PRCL assemblies near the top dead center in engines using the molecular dynamics approach. The tribological characteristics of the PRCL, especially the microscopic wear mechanisms, were analyzed under various operating conditions such as ring sliding speed, ring back load, operating temperature, and lubricant supply amount. The liner surface morphology, liner wear, and lubricant film distribution were used to evaluate the tribological characteristics. It was determined that the lubricant supply amount has the most significant impact on the micro-friction behavior of the PRCL assembly.