Shape Optimization of Engine Moving Components with Hyper-Study Integration

Computer aided optimization techniques find broad application recently in order to search for structural optimized design. Engine components such as cylinder head, cylinder block and bed plate are subjected to many optimization studies, since the loading conditions are clearly defined and easy to evaluate as a unique characteristic constraint or objective. However for the connecting rod, which is subjected to a load cycle comprising tensile load and static compressive load, the integral evaluation is required in the various aspects such as fatigue safety factor, big end stiffness and buckling safety factor. And for the crankshaft, the change of the mass needs to be considered as the loading condition for the reliable optimized design. This study introduces the two structural optimization case studies of engine components using ABAQUS, FEMFAT with Hyper-Study integration. First, the durability of the connecting rod is optimized. The objective of the study is to increase fatigue safety factor below the evaluation criteria. For the integral evaluation, weight, big end stiffness and buckling safety factor are defined as constraints and the full simulation and optimization process is automated. The results show that more than 10% fatigue safety factor increase is possible without any increase in weight and satisfying the other constraints. Second, the weight of the crankshaft is optimized. The objective of the study is to reduce mass and moment inertia of the crankshaft with the least possible effect on the durability. For precise definition of boundary conditions and loading history, multi body simulations using substructuring method are embedded into the optimization procedure. The weight reduction is updated in the simulation loop automatically. The results show that more than 7% mass and mass inertia reduction is possible satisfying the durability criteria.

 

The Author

Mr. SANGWOO CHA
Senior Research Engineer
Hyundai motors company