| Interior noise is an indicator of high-speed train’s performance. The research ofcontrolling interior noise is far behind of the development of high-speed train. Severewheel/rail noise and aerodynamic noise will be produced when train operation at high speed.While part of there noise propagate to far away, another part penetrate through the train’s walland propagate to the compartment. Improve the performance of train’s wall transmission loss(TL) is one of means to control the interior noise. The speed of train increase and the massdecrease make more difficult to control the compartment interior noise, and demand a higherlevel of train’s wall TL. This paper takes CRH2train’s wall as subject, and focuses on the TLof windows, walls of prima compartment and seconda compartment. Combining with thecharacter of exterior coach noise and the experimental result, the spectral characteristic ofexterior coach noise was analyzed, the result show that, the total noise of exterior coachincreases with the speed increase, the composition change. Low and medium frequencyrail/wheel’s noise and medium and high frequency aerodynamic noise is the base of exteriornoise. The measurement result of interior noise shows that, the frequency of most interiornoise below8kHz, the frequency of maximum A weighting noise between100Hz and200Hz,interior noise of lead and tail compartment quite different.The train’s side wall can be simplified a combination plate which made up of double paneglass and double-layer aluminum alloy stiffened panel. While analytical method can getqualitative curve of double pane glass only, the exact TL is difficult to be gain. Move over, thedouble-layer aluminum alloy stiffened panel’s mathematical model is hard to be built. In thispaper, the FEM (Finite Element Method) was used for research the TL of double pane glassand double-layer aluminum alloy stiffened panel. First, the finite element model of windowand wall was built utilize general FEM software ANSYS. In the modeling process, the modelwas not over-simplified, the really structure was reserved. Then, the TL curve and thevibration information of window and wall were gained by solving based on professionalacoustic FEM software ACTRAN. Finally, the TL curve of whole side wall was gainedaccording to the theory of combination plate. After investigate the interior and exterior noise,the side wall’s whole sound insulation property was evaluated. Combine the law of plate’s TL,the measures was proposed for improving windows and side wall’s TL. The model waschanged based on the measures, and new model’s TL curve gives full evidence to thefeasibility of improvement approach. The TL of whole side wall was improved, and someother conclusions were gained during the research:The minimal value on window’s TL curve was caused by global structure resonance ormodal resonance, and the position of minimum value around global structure resonance frequency. The TL was increased as the damping coefficient increased.In low frequencies, TL of double-layer aluminum alloy stiffened panel is connected withits whole rigidity. Its TL decrease along with the increase of frequency. Minimal TL ofdouble-layer aluminum alloy stiffened panel was caused by local modal vibration. Thefrequency of local modal vibration varies with ribs spacing.In the low frequency region below400Hz, the TL of sidewall is much higher than thewindows’. Between400Hz and1200Hz, is the sidewall’s first TL trough. In this case, sidewall’s TL is inferior to the windows’. In the region of1200Hz~2400Hz, side wall’s TL curveat peak, so its TL is exceed the windows. TL of both side wall and windows at same between2400Hz-4000Hz, and the whole TL of combination plate get trough at this frequencies region.Side wall’s TL is inferior to windows’ in the region of4000Hz~8000Hz.At the frequencies that TL at trough, both vibrating velocity and displacement at a greatvalue, increase the damping coefficient can consume sound energy effectively, it’s a goodmeans to improve TL trough which caused by resonance. |
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