Research shows that the vibration noise frequency for most of the high-speed train bodies is 513 Hz to 1615 Hz, the vibration noise caused by the skeleton structure of the train body is within the low frequency range of 5 Hz to 30 Hz, and the vibration noise mostly caused by the wallboards is within the low frequency range of 30 Hz to 300 Hz. The noise in the carriage is from the airborne noise generated when the train runs at high speed, the friction and impact sounds of the rails, the noise of each component in the carriage, etc..
Control the vibration and noise radiated by the train body, avoid the interior resonance, prevent or eliminate the interior resonance, adjust and design the inherent frequency of the train body, effectively utilize the sound absorbing material or control the track excitement vibration transmission system, and adjust the vibration property on the noise reflection system to improve the cavity resonance in the train. In the components of the train body, the vibration of plates mostly impacts the noise of train body, because the sound radiation efficiency of the plates is higher. To reduce the vibration of the plates, the reinforced ribs can be arranged for the plates to improve the rigidity, and the damping material can be additionally installed or the vibration damping material can be stuck to increase the vibration attenuation. In addition, the water based damping material can be sprayed on the plates to reduce the sound radiation efficiency and effectively reduce the noise. The experimental conclusion is that the sound insulation effect is best when the damping coating coverage is 3 kg/m2.
More noise reduction and sound insulation measures should be taken on the structure and material in order to effectively improve the acoustic environment of the carriage, including improving the air duct structure to reduce the noise of the air conditioner, adopting the double-layer surface structure with high sound attenuation rate on the aluminum alloy train body, filling the vibration damping foamed resin in the truss between two surface layers for the room and the side wall, additionally mounting the vibration damping material on the carriage floor or installing the sound insulation steel plate on the floor, filling 50% foamed vibration damping material at the truss widening part on the bottom edge of the carriage side, etc.
In order to prevent the secondary solid sound transmission of vibration and noise source from the bogie, the traction motor, the gear box, the diesel generator and the air conditioning unit to the carriage, the sound insulation material should be added on the nearby train body key structure to increase the sound insulation property of the train body structure, and the noise propagation path can be insulated by the vibration insulation, sound insulation and sealing measures.
The vibration transmission between the vibration source and the train body can be obstructed by the elastic material and the damping material. The sound insulation performance of the interior ornaments can be improved by adding the vibration damping cushion and the damping adhesive. Those measures can weaken the noise transmitted into the train during the running process of the rolling stock. For the metro rolling stock running in the tunnel, the double-layer vacuum glass windows should be adopted in order to prevent the noise from being transmitted to the carriage through the window glass on two sides of the rolling stock.