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Inspired by Beijing metro rail wheel trucks outside noise prediction theory

Author: LiShuHu
Tutor: LiuGuoWei;LuoBin
School: Central South University
Course: Vehicle Operation Engineering
Keywords: Beijing subway train Wheel-rail excitation Noise BEM Statistical Energy Analysis
CLC: U270.16
Type: Master's thesis
Year: 2007
Downloads: 130
Quote: 0
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Abstract


Metro subway noise characteristics is a measure of an important indicator of the quality of the train car body design, acoustic comfort is necessary to examine the elements. To predict wheel-rail excitation vehicle noise problems, the paper the following aspects in-depth study. Through the body, frame, wheel modeled as multi-body systems, rail processed into discrete intervals by the finite infinitely long sleepers supported Timoshenko beam, the establishment of the first subway car - orbit coupling dynamics model to wheel and rail irregularities as Excitation spectrum of the vibration response of the vehicle is calculated to obtain the two series air spring in contact with the body in three-dimensional space of the vibration loads. The results showed that: track irregularities in vertical and lateral loads caused by excitation amplitude is large, and in the longitudinal load amplitude excitation caused less. A longitudinal positioning system stiffness coefficient greater impact on the smooth, suggested a longitudinal positioning system stiffness is taken as 5MN / m. A lateral positioning stiffness on the train line running stability has little effect on the derailment coefficient greater impact, we recommend a series of lateral positioning stiffness of the bogie shall be taken as 4MN / m. The resonance analyzes of the surface of the head of the vibration displacement car siding as the excitation conditions, evaluate the truck cab, passenger Outdoor sound pressure at different frequencies sound pressure distribution, and calculate the corresponding noise levels. The results show that: the driver outside of the A sound pressure level at 56.6489 ~ 68.3541 dBA change, passengers outdoor A change in sound pressure level at 57.0114 ~ 69.4445dBA. The farther from the body, the smaller the noise, and the basic laws of a linear attenuation. A sound level outside the driver's field of maximum pitch running rails centerline 7.5m, underbody 1.2m, cab side wall 2.6m, its size is 61.5207dBA, when the excitation frequency is 30Hz, the end wall of the cab noise field point The largest contribution to the acoustic contribution factor of 62.2%; when the excitation frequency of 200Hz, the front surface noise contribution to the field point maximum acoustic contribution factor of 87.6% Passengers outdoor sound level A maximum field pitch underbody 1.2m, running rails centerline 7.5m, passenger compartment rear end wall 3.9m, its value 60.91dBA. When the excitation frequency is 30Hz, the end wall of the passenger compartment largest contribution to the field point noise, acoustic contribution factor of 76.9%; when the excitation frequency of 200Hz, the roof plate of the first five largest contribution to the field point noise, acoustic contribution coefficient to 47.19%. Local iron car to 60km / h in speed, the wheel-rail total radiation noise is mainly distributed in the center frequency of 500Hz ~ 4000Hz for a wide range of frequencies; rail radiated noise is mainly distributed in the center frequency of 500 ~ 4000 Hz wide frequency range; wheel radiated noise are mainly distributed in the center frequency of 1250 ~ 4000 Hz in the high-frequency range. From the two terms of contribution to the total noise, rail is the main source of radiation, followed by the wheels. Wheel and rail, rails, wheels overall sound pressure level of radiation was 86dBA, 85dBA, 81dBA. The total radiated sound pressure rail wheels radiation than the total sound pressure level around a large 4dBA, rails, wheels total sound radiation of the radiation pressure on the wheel-rail total contribution of sound pressure were 87.5%, 12.5%. By improving the wheel structure to reduce wheel-rail noise, it is difficult to obtain the desired results. Measures must be taken to reduce the rail surface roughness, to make trucks outside noise is reduced to 80dBA.

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CLC: > Transportation > Rail transport > Vehicle Engineering > General issues > Vehicle theory and experiment > Vehicle noise and to prevent
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