Overview of Analytical Methods for Lubricated Engine Components

Engine designs require better fuel economy, lower NVH, and longer durability. Consequently, the understanding, analysis and design for lubricated engine components that have relative moving surfaces play an important role in this objective. As the GM corporate standard analytical tool for these components, FLARE has been under continuous improvements and validations since its first rollout from GMR in the late 80s. It has also been benchmarked with the best features available in the commercial software package and research literature. There are currently more than 20 standard work procedures directly involving FLARE as solver and its applications span over: • Rod, crank, cam and balance shaft journal bearings; • Connecting rod structure; • Piston structure and scuffing; • Engine mechanical friction; • Load calculation for engine block structural analysis; • Lube system analysis; • Noise analysis. There are three levels of analysis based on requirements. Namely, level one is used in initial design stage that finds solution by interpolating the curve-fitted equations. It requires the least information about the design and runs in seconds. In level 2, a more detailed solution can be obtained by solving mixed mass-conserving lubrication governing equations using FEM with the assumption of rigid bounding surfaces. Heat transfer can be taken into account in this level and above. Level 3 has the full capability, in addition to the features in level 2, the solution is coupled with the elasticity of surface/structure which can be obtained through offline structure FEM analysis. Higher level of analysis captures more physics but requires better understanding of the input parameters and careful interpretation of the results. The unique strength of FLARE is its detailed component level analysis capability. This presentation is an overview of the latest development on FLARE technology. It includes the physics captured in FLARE, integrated solution technique and some selected results for crankshaft bearings, floating piston pins, and piston/liner impact under partial film lubrication.