Study On Vibration And Noise Damping Technigue Of Large Bus Body

With the continuous progress of science and technology, and the increasing of requirement for comfort, the characteristics NVH(Noise, Vibration, Harshness)of a large bus has become an important judge for their overall performance. Therefore, it has become a research focus to large automobile manufacturer how to effectively reduce vibration and noise of large bus.During bus running, the thin plate structure of bus body can easily produce vibration and radiated noise to bus interior under interaction of bus tires, power systems and engine. It is a very good method conducive to vibration and noise reduction by laying viscoelastic damping material on bus body, so many car designers use the method. Numerical simulation method is used to analysis the BY6128 type bus of Guangdong Yunshan Company. Bus body sound-solid coupling system and vibration-acoustic characteristics thin walled damping composite structure are studied in this paper.It has established a relatively BY6128 bus body finite element model on CATIA and Hypermesh platform, and analyzed the vehicle body frame structure chamber cavity mode by using the finite element method on Nastran and VirtualLAB. In order to describe the bus room acoustics accurately, boundary element method for sound field of car room and the contribution of body segments are used in this paper, then find out the car noise sound pressure peak corresponds to the vibration frequency of the premises and the peak under the noise sources section. Complex structure damping modeling method of evaluation has been studied in order to accurately describe the structure of the vibration and noise damping characteristics, and effect of geometry parameters and material to structure damping performance is calculated base on modal strain energy algorithm in this paper. Take thin-walled of bus body as example, indirect boundary element method is used to compare added before and after damping layer thin body acoustic radiation sensitivity.Damping composite structure optimized design is used to get the goal of bus body vibration-noise reductive and lightweight body design. Damping composite structure parameters under corresponding constraints are solved base on sound radiation, modal frequencies and loss factors characteristics of damping composite structures model using MATLAB code. It has achieved good results after damping vibration and noise reduction on the bus body.