Research On The Dynamic Characteristics And Optimization Of Automotive Powertrain Mounting System

Automotive powertrain is one of the most important excitation of vehicle vibration, and the mounting system is an important part to isolate the vibration between the powertrain and the frame.Optimization design of powertrain mount system reasonably can isolate vibration effectively.This paper focused on a national car powertrain mounting system, and studied on model, evaluation and optimization. First of all, inertia parameter of system is identified by modal testing. We got the position of mass center and the inertial parameters by the mass line of FRF, which had a good consistency with CATIA, and built the model by Lagrange Function. Secondly, evaluating the design project by test and calculation. Vibration isolation rate is calculated to evaluate the vibration isolation performance and vibration isolation rate by testing the vibration of mounting system at different working conditions, the result is that the front mount and the gearbox mount show a bad performance at low speed, 0% load and 100% load condition; then we calculated the location of torque roll axis and model decoupling rate, and evaluated the design project of mounts by natural frequency, energy decoupling principle and torque roll axis principle in MATLAB. The results show that the natural frequency is reasonable, but the decoupling rate in the main direction is 76.36% and 50.68% which is unsatisfactory. Finally, with the sensitive coefficient of each parameter and torque roll axis principle, ADAMS is used to optimize the stiffness and the location of the mount by multi-objective optimization. And with the parameters obtained by optimization design the decoupling rate of main direction rose to 98.87% and 92.37%, the other directions are all more than 90%.Then the exciting force of Powertrain is calculated and is compared with original one to verify the optimization result.The results of this paper indicated that, modal testing is an accurate way to identify the inertial parameter of powertrain; Torque roll axis principle and energy decoupling principle provided references for evaluation and design of the mounting system.