Analysis Of Torsional Vibration For The Powertrain Of A Tracked Vehicle

With the continuous development of China’s economic and military, the use ofhigh-power diesel engine is increasing, thus making the structure vibration andinterior noise control has become one of the key problems of research on modernvehicles’ development. The torsional vibration is a great cause of a vehicle’spowertrain structural vibration. When the excitation frequency of the engineis equalor close to the natural frequency of a vehicle’s powertrain system, a shaft systemresonance will occur, thus results in system dynamic load increased dramatically, andthen makes the shafting parts overloaded, eventually causes serious influence to thetransmission parts’ strength and service life. In this paper, the following work hadbeen finished in order to analyze the torsional vibration of a trucked vehicle’spowertrain:Based on the structure characteristic of the tracked vehicle powertrain system, a9-DOF lumped mass model was established according to the dynamic modelprinciples and discussed the main parameters of the model.Analyzed the free vibration characteristic based on the torsional vibration model.Calculated the inherent frequency and vibration mode of the powertrain system, thusobtained the characteristic of the powertrain by comparing the vibration modes underdifferent mechanical gears. By using the information of the natural frequency analysis,pointed out the potential resonance speed of engine under regular usage anddangerous spot of the powertrain.On basis of the theory of resonance, explained the excitation torque of the engine,and rebuilt the periodic torque of engine by using empirical formula method.Analyzed the forced vibration characteristics of the powertrain in computer simulation,in this way got access to the alternating torque information of each lumpedmassontime domain and frequency domain. In order to verify the correctness of thetheoretical analysis, observed the response of the powertrain system under differentengine speed and different harmonic order.In order to study the main factors which were influencing the torsional vibrationperformance of the powertrain, judged each parameter by two criteria as following:the ability to change the resonance frequency and the ability to change the resonanceamplitude.Made several changes to the damping coefficient of elastic coupling, the rigidity of the rotary inertia of engine flywheel and the clutch modification, analyzedtheir ability of alternating the torsional vibration performance of the powertrain, inthis way, put forward a solution of vibration reduction and avoidance.