| In order to deploitation the market of international,the WYZ machines can not satisfy the newest noise limit standerd of Europe ,and need to be reduced more .One Zhonggong Ltd. and Southwest Jaotong university afforded condition to measure the noise of the cab of WYZ machines outside and inside and the vibration of WYZ machines's body in locale .this measure can afford trustiness gist for the choice and design of reduce noise .By the compute , the noise outside WYZ machines is 4.8 dB higher than noise limit standerd of Europe. The outside noise mostly composed by two parts ,120.5Hz and the noise with the most important part of 392 Hz .By freguency analysis and the factual configuration of the mathine,we can estimate the noise with 120.5Hz spreaded from muffler of engine,and the noise with the most important part of 392 Hz spreaded from hydraulic pressure system.Freguency analysis indicate that outside noise mostly composed by the middle and low freguency noise , the most import part is 120.5Hz and the noise with the most important part of 392 Hz and breath of 1000 Hz. Base on the freguency characteristic of the noise and practicability demand of engineering , choose tiny perforation syntony structure as the measure to reduce the freguency of 120.5 Hz and 392 Hz of outside noise separately.Text make use of the method of optimization design, with the optimization function of absorption coefficient in 120.5 Hz and 392 Hz, compute out the optimization structure parameter of the tiny perforation syntony structure . this structure can aim at the outside noise of certain machines to absorption. Theoretically it can whole hog reduce the outside noise.Base on the reverberation coefficient of tiny perforation syntony structure and the noise signal prereduce, can compute out the noise reduced by the tiny perforation syntony structure theoretically, and then compute out the outside noise after reduced is 100.0dB. This noise after reduce can accord with newest noise limit standerd of Europe.
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