Analysis And Control Of Torsional Vibration On Engine Crankshaft System

With the increasingly high demand for NVH performance of engines draws more and more attention. Good performance is an important indicator of the vehicle which can be accepted by the public.Torsional vibration of crankshaft is one of Ihe most important source of excitation.If we can predict the strength of torsional vibration at crankshaft, it is an important way to improve the NVH performance of vehicle.This paper takes 8-cylinder diesel engine as the research object.Firstly,we create the model of crankshaft system with 3D design software Pro/E.According to the actual movement relationship,we complete the assembly.Then establish the multi-body dynamics model at ADAMS and dynamics of the models are simulated using ADAMS.Then create the modal neutral file through ANSYS software and the multi-body dynamics model for the crankshaft assembly including flexible crankshaft is established by importing the file into ADAMS software.Simulation results of rigid body dynamics model and flexible body dynamics model are compared.Conduct dynamics analysis for flexible body dynamics model under the different working conditions and get the simulation analysis results of torsional vibration.According to the simulation results,take measures to reduce the torsional vibration.Through dynamics simulation analysis,the influence law of motion will be found when the system includes flexible crankshaft.Forced torsional vibration of crankshaft system is analysed using the ADAMS software,and dynamic response characteristic of crankshaft system at external excitation is obtained.The torsional vibration amplitude is 0.6 degree under rated conditions.It is beyond the permission value(0.25 degree),so we must take damping measures.According to the results of torsional vibration,a rubber torsional vibration damper must be designed using the conventional design method. Through dynamics simulation analysis with torsional vibration damper,The optimization of damper is brought into effect.Through the research,we can predict the dynamic response characteristic of real crankshaft system.The technology of virtual prototype is convenient to simulate different situations of the crankshaft assembly.