To test different car’s noise in a semi-anechoic room with different engine’s speed, measure and analysis engine noise’s characteristics and the dash panel’s sound insulation quantity. The conclusion is that:the engine noise gets bigger 10 dB(A) when engine speeds up every 1000 r/min; engine noise’s frequency mainly distributed in 1600 ~ 4000 Hz; peak part concentrates in the range 100 ~ 400 Hz; engine noise has no direct relation to engine’s displacement; cab noise frequency mainly concentrated in the range 250 ~ 630 Hz and the peaks exist in the intermediate and low frequency part, the high frequency part attenuates obviously which show the car’s dash panel has a good noise insulation and absorption effect in the high frequency part but not too ideal at the intermediate and low frequency especially in the range 250 ~ 630 Hz. These results have high practical value for the design of the automotive to decline noise and vibration.
With the development of the car industry, the pace of the urban construction is accelerating as well. Cars have gradually entered the ordinary family. As the car noise has a big effect on the health of the passengers, as well as on the surroundings, one of the car industry key duties is the car noise reduction. By researching the materials applied to car, this article describe that PU material could reduce the impact of the engine noise on the cab efficiently; Polypropylene needle-spun felt could reduce the noise passed by chassis; PET material's sound absorption is poor in mid bass, however in high frequency it's sound absorption is good; sound absorbing sponge can reduce the low and high frequency noise; The combine sponge can reduce the noise from the tire and transmission system ; Cotton material could absorb the high frequency noise.
Dalian’s traffic jam becomes increasingly severe, on the one hand, serious influence of city's image, on the other hand bring a lot of inconvenience to people. "Bus priority" is already proved an effective way to solve traffic problems in lot of states and cities. This paper first analyzes Dalian public transportation present situation and reform measures, and then analyzes cost calculation formula of public transportation and private car, then comparison them, at the end advances feasible countermeasures, determining how to implement "giving priority ”to Dalian bus development.
This paper researched on four different types cars, analyzing interior noise at the same speed under different points, the same point different speeds and the same car different speed different points, it is concluded that family car interior noise distribution law; Through analysis noise spectrum curve which can get the main frequency band, that may provide theoretical basis for automotive noise reduction. In addition, this paper gets that medium low-frequency noise(0-2Brk) are the biggest to composition car’s characteristics loudness from research on characteristic loudness curve, and with speed continuously improve characteristic loudness growth is very significant.
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