Numerical And Experimental Investigations On The Vibration Of A Transmission Housing

Gear transmission mechanism with advantages of compact design, high efficiency, and steady transmission ratio is one of the most important part of powertrain, which has been widely applied in vehicle, ship, construction machinery and other mechanical fields. During the gear transmission process, the transmission housing will vibrate due to the effects of the timevarying mesh stiffness and the dynamic bearing load. If the excited frequency is equal to or close to the natural frequency of the transmission housing, it will cause the housing to resonate, which will affect the vehicle NVH performance. It is becoming more and more important to estimate the dynamic characteristics and the vibration level of the transmission housing because people’s requirements on driving comfort become higher.In this paper, a transmission is selected as the research object. Based on the multi-body system dynamic theory and the LMS Virtual Lab software, the dynamic model of a gear transmission system was built to obtain the internal excitation. Then the natural vibration characteristics of the transmission housing were obtained after the transmission housing finite element model was built. Finally, based on the dynamic simulation and the modal analysis, the vibration response of the transmission housing was studied and compared with the experiment. The main contents of the paper are as follows:(1) Based on the multi-body system dynamic theory, the dynamic model of a gear transmission system was built in consideration of the effects of the time-varying mesh stiffness, the tooth backlash, the non-linear bearing stiffness and the speed variation. Then, the dynamic meshing forces of gears and the dynamic forces of housing bearing seats were calculated.(2) The natural frequency and the modal shapes of the transmission housing were obtained after the housing finite element model was built and the modal was analyzed by using the Lanczos method. Then, using the modal superposition method, the dynamic response of the housing was calculated to acquire the vibration of nodes on the housing surface.(3)To verify the accuracy of simulation results, the vibration test platform of transmission was built. The results show that when a constant torque is applied, the vibration acceleration amplitude of the housing surface increases along with the rise of the rotating speed, which agrees well with the experimental outcome within a reasonable error range.A good agreement between numerical and experimental results shows that the model can reasonably simulate the real vibration state of the transmission, which has important references for the design and the vibration and noise reduction of the transmission.