Engine-Component Wear Modeling With Consideration of Growth and Removal of Surface Films: Computational Framework and Preliminary Results

The life of an automotive engine is often limited by the ability of its components to resist wear. The ability to predict wear, particularly for the effects of lubricant and additive characteristics, would greatly aid the development process of both engine components and lubricants. This paper addresses the development and function of thin solid films on rough surfaces and their effect on surface wear, as that occurring between contacting engine component surfaces. Completely deterministic modeling of such films may not be possible due to the complex interactions between the numerous mechanical, thermal, and chemical variables over disparate magnitudes of time and length scales. However, it is believed that useful predictions can be made by constructing a mechanistic model in which all of the most important effects are included, even if only at an approximate level. This work outlines the early stages of such a modeling effort in the context of zinc dialkyl-dithiophosphate (ZDDP) antiwear films on iron surfaces. The key concepts behind the theoretical model will be introduced, while its numerical implementation will be the focus of the discussion. Preliminary results from this effort are presented to illustrate feasibility and functionality on a qualitative level.