| The elastohydrodynamic behavior of the crankshaft/main-bearings system plays a crucial role in the performance of a multi-cylinder engine. This elastohydrodynamic behavior relates to the tribology of the main-bearings, the dynamics of the engine structure, and the dynamics of the crankshaft. It is a coupled problem where the bearing loading and crankshaft and bearing housing displacement problems must be considered simultaneously. Combining the crankshaft dynamics, journal bearing oil film hydrodynamics, and bearing housing elasticity, the elastohydrodynamic simulation of the crankshaft/main-bearings system is performed in this dissertation.; An efficient optimization search scheme is developed to find the dynamic equilibrium among the crankshaft structure, the oil film inside main-bearings, and the bearing housing structure. The contact problem of the crankshaft and main-bearings is solved by adding a penalty function to the objective function. The oil film hydrodynamic problem is analyzed by using a two-dimensional finite element model. An adaptive mesh generation scheme is used for the oil film model to increase numerical efficiency. The cavitation problem for the oil film hydrodynamics is treated by an effective 'cavitated penalty' approach. The crankshaft structure is modeled by three-dimensional finite elements and then the resulting stiffness and mass matrices are reduced in size by a Guyan coordinate reduction technique so that the system analysis becomes more efficient. The dynamics of the crankshaft/main-bearings system is performed by a direct integration approach and the dynamic effect due to the rotation of the crankshaft is considered.; Based on this research work, it is possible to provide the crankshaft/mainbearings system designer with a powerful design tool which will allow a better understanding of the coupled behavior of the crankshaft/main-bearings system. |
