Development of Innovative Simulation and Testing Methodologies for Optimizing Crankshaft Design

The objective of this study is to investigate weight and cost reduction opportunities for a forged steel crankshaft. To optimize the design we need to understand the behavior of the crankshaft when engine is running at high- speed. In past, considerable amount of research effort has gone into the investigation of dynamic characteristics of a spinning shaft with attached discs but there has been less research on the bending behavior of high-speed engine crankshaft. Literature shows that stress and stiffness estimation under static condition is sufficient for engines operating at low-speed but dynamics of crankshaft at high- speed changes stress and stiffness values considerably. Actual engine dynamics simulation and experimental measurement demands huge effort and time. The novelty of this work is to develop simplified testing and simulation methodologies for studying crankshaft behavior in both static and dynamic conditions. FEA model of crankshaft was used for estimating static stiffness where as in case of dynamic stiffness mass and inertia of magneto, clutch and counter-mass were taken in to consideration. These new methodologies showed very good correlation with actual engine running condition for the trend. This simulation helped us in estimating static and dynamic stiffness of the crankshaft with less time and cost. To identify critical areas, which are contributing for the crankshaft stiffness, topology optimization was used. Effect of various parameters on crankshaft durability and engine performance was studied in design stage itself by using this simulation models. The optimized design tested and proved for both superior durability and engine performance.