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The rapid development of automotive technology has promoted the application of higher efficiency engines, while also putting higher requirements on the control of crankshaft torsional vibration. The traditional clutch driven disc torsional vibration damper can no longer meet the current new vibration and noise reduction requirements. Under these circumstances adopting dual mass flywheel (DMF) could be an efficient measure to reduce powertrain torsional fluctuations. For the sake of studying the torsional characteristics of DMF, a dual mass flywheel with circumstance arc spring (DMF-CS) is taken as the research subject. Firstly, According to lumped mass model, a multi-degree of freedom torsional vibration model of DMF-CS is established, which takes the mutual conversion of dry friction and viscous friction into consideration. Then, the overall and partial torsion characteristics of dual mass flywheel are obtained through numerical analysis.

The nonlinear characteristics impact of multi-staged stiffness clutch damper on the vehicle creeping is investigated by using the lumped-parameter modeling method as a certain mass-production passenger sedan is taken as the research subject. Firstly, a quasi-transient engine model of an inline four-cylinder and four-stroke engine, based on measured data of cylinder gas pressure versus crankshaft angle, is derived. Effective output torque is acquired and as the input excitation to the driveline system. Secondly, a 12-DOF (Degree of Freedom) nonlinear and branched powertrain system and vehicle longitudinal dynamics model is established. The differential mechanism characteristics and dynamic tire property based on the LuGre tire model are considered. Then, for a traditional two-staged stiffness clutch damper in consideration of hysteresis characteristics, vehicle powertrain system responses in both the time and frequency domain are obtained.