Internal combustion engines produce a fluctuating torque due to discrete combustion events, as well as inertial actions of the reciprocating masses. In standard operating conditions, the resulting torsional oscillations of the crankshaft are transferred to the gearbox, leading to a number of comfort problems. Dual mass flywheels (DMF) may be a solution to reduce torsional oscillations. They consist of a primary mass connected to the engine, a secondary mass connected to the transmission shaft and two or more sets of arc springs placed between the two rotary inertias. Friction between the primary mass and the arc springs ensure an additional source of damping when the arc springs are not loaded. This paper presents a discussion of the 3D nonlinear dynamic effects introduced in the driveline by an automotive DMF. A model for the DMF is developed and included into a multi-body model of the vehicle powertrain to assess the effect of its main parameters on the driveline behaviour (e.g. modes of vibration, radial forces). The DMF is modelled by primary and secondary masses and the arc springs between them. Centrifugal effects and redirection forces acting on the springs as well as nonlinear contact forces due to stoppers and flanges bounding spring motion are accounted for. Moreover, friction occurring in seals and friction resulting from the spring radial forces are included. Contact forces between primary and secondary masses of DMF with arc springs are modelled with a penalty approach and a contact detection algorithm. The developed 3D MB model has been compared with experimental data to assess its capability to reproduce DMF dynamics. A good correlation was found between numerical and experimental data during torsion tests at standstill and small displacement cycles at different angular speeds. Complex frictional phenomena like arc spring stiffening and hysteresis cycle shrinking with increasing angular speed are correctly captured, furthermore radial forces exchanged between DMF stages and transmission shafts can be evaluated thanks to a full 3D model.

Nonlinear Dynamic Effects Induced by an Automotive Dual-Mass Flywheel

G. Quattromani;E. Sabbioni;F. Cheli;
2017-01-01

Abstract

Internal combustion engines produce a fluctuating torque due to discrete combustion events, as well as inertial actions of the reciprocating masses. In standard operating conditions, the resulting torsional oscillations of the crankshaft are transferred to the gearbox, leading to a number of comfort problems. Dual mass flywheels (DMF) may be a solution to reduce torsional oscillations. They consist of a primary mass connected to the engine, a secondary mass connected to the transmission shaft and two or more sets of arc springs placed between the two rotary inertias. Friction between the primary mass and the arc springs ensure an additional source of damping when the arc springs are not loaded. This paper presents a discussion of the 3D nonlinear dynamic effects introduced in the driveline by an automotive DMF. A model for the DMF is developed and included into a multi-body model of the vehicle powertrain to assess the effect of its main parameters on the driveline behaviour (e.g. modes of vibration, radial forces). The DMF is modelled by primary and secondary masses and the arc springs between them. Centrifugal effects and redirection forces acting on the springs as well as nonlinear contact forces due to stoppers and flanges bounding spring motion are accounted for. Moreover, friction occurring in seals and friction resulting from the spring radial forces are included. Contact forces between primary and secondary masses of DMF with arc springs are modelled with a penalty approach and a contact detection algorithm. The developed 3D MB model has been compared with experimental data to assess its capability to reproduce DMF dynamics. A good correlation was found between numerical and experimental data during torsion tests at standstill and small displacement cycles at different angular speeds. Complex frictional phenomena like arc spring stiffening and hysteresis cycle shrinking with increasing angular speed are correctly captured, furthermore radial forces exchanged between DMF stages and transmission shafts can be evaluated thanks to a full 3D model.
NAFEMS World Congress 2017 Summary of Proceedings
978-1-910643-37-2
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1063144
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