Optimal design of an MR device

This paper presents a formulation for the optimal design of MR dampers. MR materials are suspensions of magnetically soft particles in a hydraulic medium. The application of intense magnetic flux to these materials gives rise to a fibrated microstructure which, when sheared, resists flow with yielding and viscous mechanisms. The yield stress is controllable by the magnetic field and is completely and immediately reversible when the field is removed. Controllable MR dampers utilizing MR materials entails a magnetic circuit consisting of a coil and low-permeability magnetic material to contain and guides the magnetic field. The electrical behavior of MR devices depends on many parameters including the nonlinear magnetic permeability of the constituent components of the device, including the MR fluid, and the characteristics of the magnetic coil. Because of the large number of variables involved in the magnetic circuit design, good electrical properties (low power requirement and short inductive time constants) may be achieved via an optimization process. This paper illustrates this process with numerical and experimental examples. The MR device that was built and tested achieved performance (force level, dynamic range, power consumption) that were within ten percent of the targeted specifications.

Duke Scholars

Author Henri P. Gavin Civil and Environmental Engineering