Browse Publications Technical Papers 2019-01-1556
2019-06-05

Investigation and Improvement of a Bouncing Torsional Vibration in Automotive Dual Mass Flywheel by Combination of Testing and 1D CAE Modeling Approach 2019-01-1556

Dual Mass Flywheel (DMF) is a well-known isolation system for vehicle drivetrain. There are two typical elastic energy storage systems for DMF i.e., long travel arc springs and in-series spring units including two or more springs and sliding shoes connected in series. DMF has a complex nonlinear characteristic such as torque-dependent torsional stiffness and rotational speed-dependent hysteresis friction due to its dependency of centrifugal force applied on components and radial force of springs. Because of this complexity, Subharmonic Vibration (SHV) may occur under a certain circumstance, such as under a light-load and high rotational conditions. In general, SHV frequency is 1/2 or 1/3 of combustion frequency of engine, and it may cause human discomfort. Therefore, it is important to design DMF robust against such nonlinear vibration. In this paper, in order to reduce the occurrence of SHV and to show a more robust design indicator, SHV causing mechanism is researched by test and 1D CAE modeling. In detail, DMF interior behavior in high-speed rotation is clear with high-speed cinematography on test bench, and high-resolution relative torsional angle of DMF is obtained by evaluating the actual vehicle with a conventional four-cylinder gasoline engine, equipped with in-series spring unit type DMF. As a result, there is a possibility that “Bouncing” Torsional Vibration (BTV) is being occurred when spring shoe and secondary-side driven flange are in contact to each other, and being a trigger of SHV excitation. 1D CAE model developed with consideration of the obtained mechanism is verified due to the fact that substantially the same BTV and SHV occur between test and simulation result. According to 1D CAE, highly-sensitive parameters and clue for reducing SHV can be found with sensitivity analysis for physical parameters of DMF. And the effect of those parameters are confirmed with the vehicle test.

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