Numerical Simulation And Optimization Of The Gear Rattle Noise For A Dual-Clutch Transmission

The transmission is an important part of automotive drive line.Vibration and noise of the transmission affect the working performance of a vehicle directly.Rattle noise is one of the main noise of the transmission.Analyzing and optimizing the rattle noise by building the rattle noise predictional model of transmission accurately not only can help us to understrand the mechanism of rattle noise well,but also can reduce the development cost and development cycle of the transmission.The main content and conclusions of the paper are as follows:(1)According to the actual kinematic relations of the transmission and the multi-body system dynamic theory,the dynamic model of a dual-clutch transmission is built in consideration of tooth backlash,time-varying mesh stiffness,nonlinear bearing stiffness,drag torque and velocity fluctuation of the input shaft.The natural frequency and the modal shapes of the transmission housing are obtained after the finite element model of housing is established by using Hypermesh software.Then,the transimission housing is made flexible and a rigid-flexible coupling model of the transmission is built.Engagement forces between non-loaded gears and the vibration accelerations of transmission housing are obtained under the driving condition of the first gear shift.The numerical value is found to agree fairly well with the corresponding experimental results,which demonstrates the effectiveness of the model.(2)The effects of gear backlash,speed fluctuation,the moment of inertia and drag torque on rattle noise are studied.In order to reduce rattle noise,the backlash of non-load gears should be as small as possible.Considering the power transfer efficiency,we should make the drag torque as big as possible.Under the premise of meeting the requirement of strength,the driven gears should be light.Besides,the speed fluctuation can be reduced by decreasing the torque fluctuation.(3)Based on the orthogonal experimental design method,the optimal combination levels and the significant order of factors are obtained by using L16(45)orthogonal arrays.After that,we optimize the rotational inertia and drag torque of the second and the fourth driven gears.The rattle noise is reduced under the driving condition of the first gear shift.The research results show that the rigid-flexible coupling numerical method and orthogonal experimental design can play an important role in the evaluation and optimization of the rattle noise of transmission.Research results of the paper have important value for engineering application.