Abstract: The design theory of friction double-stage piecewise variable stiffness dual mass flywheel is proposed. Using the given design method, the flexibility with low spring rate of dual mass flywheel at low speed, low torque and low wind-up angle can be realized, and high spring rate and high counter torque at high wind-up angle can also be achieved. The structure and working principle of the proposed friction double-stage piecewise variable stiffness dual mass flywheel is analyzed. The structure for two-stage overload protection is designed, then the mathematical-mechanical model of torque characteristics of friction double-stage piecewise variable stiffness dual mass flywheel is derived, and the test show that the test results of torque characteristics is consistent with the simulation analysis of the constructed model. The affection of spring rate on transmission system’s first and second order resonance speed is researched. The idea that using friction to increase torque and to realize overload protection is introduced into the design of dual mass flywheel, so the design method for high quality dual mass flywheel can be got, the intrinsic nature for vibration damper of double-stage piecewise variable stiffness dual mass flywheel is also revealed.

Key words: Dual mass flywheel, Mechanical vibration, Resonance speed, Torque characteristics, Torsional damper