Analysis And Test Study Of Vibration And Noise For A Medium Bus Drive Axle

With the rapid development of vehicle industry, the car has become an important meansof transportation and influent the basic life of thousands of people. In recent years, theydon’t only focus on the traditional automobile performance, suchas power performance, fueleconomy and safety, but also the vehicle ride comfort. The main goal of vehicle ride comfortresearch is to reduce the interior vibration and noise and improve the interior environment.As an important part of driveline, the vibration and noise of drive axle have great influenceon the vehicle ride comfort. This paper mainly concludes the finite element dynamicsimulation and test research of the drive axle.The core components of the drive axle assembly are the main reduction gear system anddifferential system. The main reduction gear meshing impact is the basic reason of drive axlevibration and noise. The meshing impact transfers the bearings of drive gear and differentialto the axle housing, of which the surface will vibrate and then radiate noise. Therefore, thereduction of vibration and noise of drive axle mainly focus on the main reduction gears. Thispaper mainly discusses vibration and noise of the medium bus running straightly on citycondition and high-way condition. The differential doesn’t work when driving on straightroad and has little effect on the vibration and noise of the assembly. Generally grasp the coreof the problem, study the main factors and neglect some secondary factors in modeling.Therefore establish a simplified model containing main reduction gear, bearings, half shaftsand housing.Firstly build the3-D model of the drive axle assembly, then clean up the geometry,mesh and check quality in HYPERMESH. At last this meshing data is imported intoABAQUS, in which the material definition and boundary condition definition are completed.Use the finite element model (FEM) to simulate vibration characteristic of drive axle working under the two conditions above, and then analyze the meshing print, the contactstress distribution and the surface vibration of the housing. Meanwhile the naturalfrequencies and the corresponding mode shapes of the axle housing are calculated in case ofresonance.Secondly, extract time domain data of the outer surface of the bearings which connectsthe main reduction gears and the housing. Through the FFT, transform it into frequencydomain data which will be used as the excitation data in axle housing vibration and noiseanalysis. Choose some frequencies which may lead to large vibration of the housing，including the natural frequencies. At natural frequencies, small excitation may cause largevibration. Calculate the radiation noise level and noise energy distribution at differentfrequencies in noise analysis software SYSNOISE. The main location for radiation noiseenergy is the focus of noise reduction for drive axle.Finally verify the validity of the simplified FEM through bench test. The vibration andnoise spectrum analysis is done under the two conditions and find the primary sources ofdrive axle vibration and noise. Based on the main factors, two measures of noise reductionare proposed and the effect of improvement is verified through bench test.