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This paper describes how we predict the stress of engine components resulting from vibration of engine, using MBD (Multi Body Dynamics) and FEA (Finite Element Analysis). In a development of industrial engine, many engine models which are installed on various machines are developed. Depending on operating condition of machine, many kinds of components are designed. Therefore, in order to shorten a development period, it is important to predict accurately stress of components and evaluate its durability in the design phase. In this study, for exhaust silencer, the stress of engine components which are caused from of engine vibration is calculated by FEA and MBD and the accuracy of prediction is confirmed as compared with the experiment result. In addition, the stress of oil suction pipe is predicted. As vibrational characteristic of oil suction pipe is influenced by lube oil, virtual mass method is used in order to take into consideration the influence of fluid which is surrounding it.

This paper describes how we design engine mount layout, in order to isolate a machine from engine vibration. Natural frequency of vibration isolation system is calculated by Finite Element Method. We focus on the exciting force direction and mode vectors calculated by FEM, and optimize engine mount layout. In the optimization process, we use Modal Assurance Criterion (MAC) to track mode shape which is corresponded with exciting force, and create the maps of MAC value and natural frequency against design parameters. Proper engine mount layout is searched within our design parameters. Finally, multi body dynamics model of engine is constructed and the effect of mount layout which is optimized is confirmed. As a result, the transfer force is reduced 75 % against original design at maximum point.

The demand for the noise reduction of working machines, such as construction machines, tractors, and generators, has been strongly increasing. In order to achieve noise reductions, a low noise fan was developed using the CFD (Computed Fluid Dynamics) technique. The engine enclosure was developed, not only to reduce the noise emitted from the engine efficiently, but also to improve the cooling performance. Finally, the average noise level of working machines was reduced by about 10dB(A).