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DY: Fachverband Dynamik und Statistische Physik

DY 32: Fluid Dynamics

DY 32.2: Vortrag

Freitag, 26. März 2010, 10:30–10:45, H47

Maximizing torque transmission in magneto-rheological clutches — •Hanna Lagger, Claas Bierwisch, and Michael Moseler — Fraunhofer Institut für Werkstoffmechanik IWM, Freiburg, Germany

Typical magneto-rheological fluids (MRF) consist of micron-sized magnetically permeable particles (mostly iron) dispersed in carrier oil. MRF are increasingly being considered in variety of devices such as shock absorbers, vibration insulators, brakes or clutches. The activation of an external magnetic field causes a fast and dramatic change in the apparent viscosity of the MRF contained in the clutch. Chains of magnetized particles are formed between the two inner surfaces of the clutch within a few milliseconds. The flow properties of the MRF change from liquid to solid and, thus, render large torque transmission possible.

In this study, numerical simulations based on the discrete element method (DEM) are used to model magneto-rheological clutches. Magnetic and mechanical interactions among particles and between the particles and the surface of the clutch are implemented.

For different volume fractions of the suspension, we investigate the influence of inter-particle-friction, particle-surface-friction and the external magnetic field on the torque transmission. Mechanisms that may lead to the breaking of the chains of the magnetic particles under high shear stresses are discussed.