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Experimental Analysis of Tiba Gearbox and Provide a Solution to Reduce NVH

Falahati Marvast, Amin | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51613 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saadat Foumani, Mahmud
  7. Abstract:
  8. For over a hundred years, vehicles have entered the human environment and influenced it. One of the most important effects that vehicles have on their surroundings and humans is their acoustic noise. The gearbox is one of the important components of the vehicle's transmission chain, in which the gears interact with each other and cause to create noise and vibration. These vibrations are transmitted through the bearings to the gearbox casing and then transferred to other parts of the vehicle via gearbox supports. Many researchers have studied the factors of NVH production in gearboxes and used methods such as gear profile modification and optimization of shaft and casing to reduce NVH. This project is a part of an industrial project entitled "Reducing NVH of TIBA X200 gearbox". For this purpose, the finite element model of the gearbox casing was prepared in Abaqus, and then dynamic equations of gearbox components were solved in AVL_Excite_Powerunit software, which resulted in casing vibrations. Then, by using AVL_Excite_Acoustics software, gearbox noise was achived from the gearbox casing vibrations. In the parallel process, vibration tests were performed on gearbox and the simulation results were compared with the results of the test and then verified. By ensuring that the results of the simulation were reliable, the defects and abnormal noise and vibrational factors in gearbox were identified. The simulation results indicated that by applying the Engine vibration on gearbox input, noise and vibration of gearbox at 1st and 2nd gear sets increased sharply. In order to reduce the noise and vibration in these gear sets, the influence of different parameters was investigated. Finally, by optimizing the shafts of geabox and adding ribs on gearbox case, the amount of noise and vibrations decreased. The amount of this reduction in 1st gear set was 3 dBA, and in 2nd gear set ,it was 6.7 dBA. By applying these modifications, the noise in the other gear sets remained almost unchanged. Also, the casing vibrations, which are cause of noise creation, also decreased. This decrease was at the highest point of 1st gear set up to 6g and in 2nd gear set up to 13g
  9. Keywords:
  10. Gearbox Noise ; Vibration ; Vehicle Noise-Vibration-Harshness (NVH) Reduction ; Gearbox Simulation ; Tiba Vehicle ; Noise Reduction

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