Application of Computer Simulation Using FEM and Experimental Techniques for the Reduction of Noise in Air Cooled Engine and Crankcase Cover of Motorcycle

Measurement of sound intensity techniques has very good application in the source identification of a particular noise character. It has been applied effectively along with modal analysis and FE experimental excitation techniques to find out root cause of a particular noise character in small gasoline engine. A FEM shell model was used to make cylinder block and cylinder head model. FEM simulation was carried out which matched with experimental results. It helped to remove the noise character from engine.

The other part of the paper describes the noise reduction of the crankcase cover used for the same motorcycle. It houses crankcase as well as two speed gearbox. The methodology involves very effective combination of experimental harmonic analysis, FE model with the shell element for the 3 piece crankcase cover, and experimental measurements. A particular sequence of this experimental techniques along with computer simulation techniques gives extremely good results. It has an effect on the passby noise reduction as well as the noise character elimination of the transmission cover.

The paper describes the results carried on one of the motorcycle crankcase structure, the combination of the techniques for NVH control in the motorcycle which has brought out tremendous improvements in the noise character by fine tuning the structure.