Analysis And Experimental Study On Noise And Vibration Of Rear Drive Axle For A Commercial Vehicle

In modern society,cars not only bring great convenience to people,but also have a serious impact on the ecological environment.At the same time,consumers’ functional requirements for cars are also constantly improving,and some singlefunction vehicles are also difficult to meet the market demand.As a result,the multipurpose vehicle,MPV;has emerged.As a member of the world of heavy-duty vehicles,MPV has to meet the requirements of mobility,load-carrying capacity and comfort,etc.The front engined and rear drive structure has become the first choice for many commercial vehicles.The rear drive axle is an important part of the power transmission system of the commercial vehicle,and its vibration and noise will directly affect the comfort of the commercial vehicle.In this paper,the vibration and noise of the rear drive axle of a commercial vehicle are simulated and tested by finite element method.The main reducer system and the differential system are the core components of the drive axle assembly.When the car goes straight,the differential planetary gear doesn’t work,and the hypoid gear pair of the main reducer is one of the main excitation sources of the vibration and noise of the rear drive axle.The vibration of the hypoid gear often induces the vibration of the parts connected with the hypoid gear,which affects the working performance of the whole machine.With the increase of the speed and loading of hypoid gears,the noise of the gears is more prominent than that of other sound sources.Therefore,the research on the vibration and noise reduction of the rear drive axle of a commercial vehicle is mainly focused on hypoid gears in this paper.At present,there are still some problems in the construction of hypoid gear finite element model,such as the application of boundary conditions.In the finite element contact analysis of hypoid gear,the analysis results are difficult to verify for the reason that only gear pair or single gear are considered and artificial boundary conditions are added to simulate the real gear.The loads in the meshing process of hypoid gears are distributed in the meshing region.Defining the moment directly on the node does not represent the true working load of the gear.In this paper,the discrete data points of the tooth surface of the hypoid gear obtained by numerical calculation are reconstructed by the method of NURBS surface reconstruction.Other parts of the drive axle except gear are scanned point by point by three-dimensional imaging technology and Tritop function.The coordinate system of rear axle assembly is established,the 3D model of rear axle assembly is reconstructed by CATIA V5,and the assembly design is carried out.The finite element model of the whole drive axle is established by using HYPERMESH software.The simulation modal analysis of the rear axle assembly is carried out,and the inherent characteristics of the rear axle assembly are studied.The modal test of the rear axle assembly is carried out by using the LMS_Test._lab software and the feasibility of digital simulation is verified by the hammering method.Then ANSYS software is used to directly apply rotational speed to the input end of the drive axle assembly,and the torque is applied at the two ends of the drive axle hub to simulate the real working state of the hypoid gear of the main reducer of the drive axle.The dynamic characteristics of gear and rear axle assembly are analyzed,and the change of gear stress is analyzed,and the vibration response of the shell surface at different rotational speeds is obtained.The feasibility of all simulation work of the rear axle is verified by the bench test of the drive axle assembly,and the vibration and noise level of the rear axle assembly of a commercial vehicle is tested.Finally,an appropriate value is obtained by using MATLAB/Simulink software and ControlDesk software based on hypoid gear coincidence degree.Based on the traditional design of hypoid gears,the optimal mathematical model of hypoid gears is established,and the parameters of hypoid gears on the rear axle of a commercial vehicle are optimized.Thus,gear noise and gear meshing excitation can be minimized under the same condition of machining accuracy and assembly accuracy,which is finally verified by the overall simulation method.