Nonlinear analysis of torsional vibrations of dual mass flywheel in a three-cylinder engine

Torsional vibration of the power transmission system is one of the main factors which affects ride comfort and fatigue of the driveline components. These vibrations are caused by periodic changes in the gas pressure and inertial forces. To reduce these vibrations, dual mass flywheels (DMF) are used in some vehicles. DMFs are usually modelled as two disks connected with linear springs. However large rotation angle in DMFs can invalidate linear assumption. In this research, torsional vibration of a three-cylinder engine with nonlinear DMF is investigated and an analytical solution is obtained for the governing nonlinear equations of torsional vibrations under real engine torsional excitation for the first time. It should be noted that in the previous works, the torsional vibration equations of the DMF had been solved numerically. Analytical solution helps to study the effect of design parameters of DMF more easily. It is shown that the analytical and numerical solutions are well matched in steady-state conditions. Finally, a parametric study is performed and the effects of design parameters on the oscillation amplitude of the engine speed and flywheel output speed are presented.