Dresden 2011 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 13: Fluid Dynamics and Turbulence I

DY 13.9: Talk

Tuesday, March 15, 2011, 12:30–12:45, ZEU 118

Magnetization model for magnetorheological fluids — •Hanna Lagger, Joël Peguiron, Claas Bierwisch, and Michael Moseler — Fraunhofer Institute for Mechanics of Materials 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 dampers, vibration insulators, brakes or clutches. The activation of an external magnetic field causes a fast and dramatic change in the viscosity of the MRF. Chains of magnetized particles are formed within a few milliseconds. The flow properties of the MRF change from liquid to solid.

A magneto-rheological clutch can be built by placing the MRF between the two inner surfaces of the clutch. In the solidified state of the MRF large torque transmission is possible, which makes it interesting for the application in automotive clutches.

In this study, numerical simulations based on the Discrete-Element-Method (DEM) are used to model magneto-rheological fluids.

To accurately treat the magnetic interaction between particles, an appropriate anhysteretic magnetization model for the particles is implemented. DEM-simulations of the MRF with different volume fractions are carried out and the resulting magnetization curves are compared with experimentally measured data. From simulations with different sets of parameters we get useful insights for the optimization of the MRF with regard to high torque transmission.