Research On Prediction And Optimization Of Transmission Shell Vibration And Noise Based On Transmission Error Excitation

As the core components of automobile drive system,transmission performance has an effect on automobile fuel economy and power,but also affects the automobile comfort.In recent years,with the speed development of automobile NVH(Noise & Vibration &Harshness)technology,engine NVH,body NVH,road noise and wind noise have been well controlled.However,the NVH issue of transmission has become increasingly prominent,and it has attracted the attention of engineers.At present,the research on transmission NVH performance mainly uses a variety of test methods,which generally reduces the vibration and noise of transmission by improving the machining precision and the tooth surface modification method.High machining accuracy and tooth surface modification will not only increase the manufacturing cost,but also the effect is not great,so it is important to explore the engineering application from the transmission shell to achieve the transmission of vibration and noise control.In this paper,a manual five-speed transmission was taken as the research object,and its gear transmission system model,the finite element model and the boundary element model of its shell were established,and its vibration and noise characteristics under the transmission error excitation were analyzed,and constrained damping was applied to its shell to reduce vibration and noise.The main contents are as follows:?With the help of Romax Designer software,the gear transmission system model was established according to the design parameters and microscopic parameters.The gear transmission error of each condition was analyzed and the bearing dynamic forces under condition with the maximum transmission error were calculated.Research condition is that speed is 3500 r/min and input torque is 40% of the rated torque.?The finite element model of the transmission shell was established,and the modal analysis and the vibration response analysis under the dynamic forces of the bearings were carried out.The natural frequency and mode of the shell were obtained by modal analysis that could be used to verify the accuracy of the finite element model.The vibration velocity color maps of the shell and the vibration velocity spectrums of test points were obtained by the vibration response analysis.?The boundary element model of the transmission shell was established,and the noise radiation of the transmission was calculated by modal acoustic transfer vector(MATV)method.The sound power level,the sound pressure level and the sound pressure level distribution of the transmission shell were analyzed.?The modal participation factor and the modal acoustics contribution were analyzed to determine the modal order to be optimized.The modal strain energy distribution was analyzed,and the transmission shell was subjected to local constrained damping according to the modal strain energy distribution.After analyzing the vibration characteristics and acoustic radiation characteristics of the shell,the vibration and noise were obviously reduced after damping optimization and the effect of the second solution is better.