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To improve the accuracy of engine vibration analysis, the bolt model which fastens an engine head and an engine block had been developed. In the conventional method of engine vibration analysis, the bolt was modeled with a rigid bar. However, it is seen that the power plant rigidity becomes higher in proportion to the rigid bar bolt length. So, to precisely predict the vibration property of engine parts, the elastic deformation of the bolt was considered in this paper. It is known that the parameters, which are Young's modulus, the length of bolts, the distance between bolts, the area of contact plane, the tightening torque and so on, have a great influence on the performance of the engine vibration model. This paper describes a study of FE bolt model to correlate eigenvalue and mode shapes with the test result. The effects of following parameters were investigated: 1) Bolt model with elastic material 2) Rigidity of bolted-connection in tightening plane.

This paper discusses the prediction method of engine mount vibration using multi body simulation (MBS) with FE models in power plant assembly. In this analysis, some parts of the power plant were modeled with shell type elements and solid type elements, and modal parameters from FEA were imported into MBS, which method is called “Component Mode Synthesis”. For this analysis, the computational models of Suzuki 660cc in-line 3-cylinder engine with 4-speed automatic transmission were used. The flexibility of some engine parts was considered using FE models regarding the cylinder block, the crankshaft, the transmission case, etc. Also the properties of stiffness and viscous damping of the engine mount bushings were considered and the properties of the hydrodynamic oil film at the journal bearings were modeled with “Enhanced Short Bearing Model”. Accelerations at each engine mount were calculated.

In order to optimize the balance between aerodynamics and air-cooling performances for a motorcycle, a simulation method of external flow around a vehicle has been developed. In this paper, steady-state flow calculations were performed using two types of turbulence models, the realizable k-ε and the SST k-ω, and two levels of mesh sizes of computational models and their results were compared. To validate the computational results, wind tunnel tests were conducted and CD, CL and mean velocity of flow passing through heat exchangers were measured. The computational results on drag coefficient and mean velocity show good agreements with the experimental ones.