The Analysis Of Noise Emitted By Stationary Motorcycle

Noise can not only reduce the comfort ability of motorcycle, but also effect theenvironment around it. Noise can be emitted mainly by the procedure of intake and exhaustthe engine and the vibration of motorcycle and so on. The frequencies of these noises are veryclose to each other, so, the digital signal process is very necessary in order to analyze anddetect characteristics of noises. Analyzing and controlling noise source is a very complicatedand systematic project.According to the noise emitted by a 200 model stationary motorcycle, the noise measurementswere completed. The application of fourier analysis, coherent analysis and powerspectrumanalysis in identification of noise source is elaborated absolutely and the MATLAB andVib'sys are chosen for compiling software. The main frequency of vibration and noise isfound out through powerspectrum. The relationship between vibration and noise is found outthrough coherent analysis. Then, the result is that when the motorcycle is in the situation ofstation, the engine is the unique reason for vibration and noise. When the engine runs at3000rpm, the noise composed by two parts: the vibration and the exhaust. Once the engineruns at 4500rpm or 6500rpm, besides the vibration of components of motorcycle, there is noother sound source.In order to identify the relationship between vibration and noise of motorcycle, the testmodel analysis is carried out by DASP. The natural frequency is calculated. The result is asfollows: when the engine runs at 3000rpm, 4500rpm and 6500rpm, there is no mechanicalresonance between the gearbox and body. The main noise source of this motorcycle isidentified accurately. Finally, it paves the way for decreasing the noise of this motorcycle.