Reducing Noise Of Tractor-trailer Cab Based On Finite Element Method

The NVH(noise vibration and harshness) characteristic of automobile is a key comprehensive index to measure the performance of automobile.What feeling it gives to the driver is the most direct.So the vibration and noise of automobile is becoming the focus of the people’s attention.Since the last century,people have been concerned about the NVH of automotive.But with the continuous improvement of automotive technology and level.So semi trailer tractor with high noise in the car becomes a hot research topic in the current research.The research object of this paper is a new design of semi trailer tractor.In this paper, we research and analysis of low frequency noise in vehicle cab by the finite element method and experiment and then improve the structure of the cab.In order to study an effective noise reduction scheme.First,the cab structure’s simplify model of semi trailer tractor is established according to the actual structure of semi trailer tractor.Through the mesh division to establishing the finite element model, the finite element model of acoustic,and the acoustic solid coupled finite element model and then to finite analysis element.The law of the frequency variation of the acoustic characteristic of the cab panel is summarized.We test the sound pressure level at the driver’s right ear and the vibration acceleration of the cab suspension, rear wall, ceiling.Then,the load of the cab suspension is calculated indirectly by using the singular value decomposition method according to the test results and load it into the finite element model of the acoustic solid coupled finite element model.We get the sound pressure and level of sound pressure of the driver’s right ear by dynamic response analysis.It is proved that the validity of the cab model in this paper by combining the experimental results and the finite element analysis.Last,we optimize the shape of the cab rear wall and ceiling which has the poor stiffness and great influence on the peak value of sound pressure with the aim of reducing noise.After optimization, the peak of sound pressure level is obviously decreased.Again to optimize the cab by the design method of orthogonal test according to the acoustic characteristics analysis.The main objectives of the optimization are the cab floor,front wall and the front windshield.Finally, an optimalscheme is obtained.And this scheme reduces the sound pressure level effectively at the driver’s right ear.