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The rheological properties of novel MR fluids are characterized using a parallel plate MR shear rheometer. In these MR fluids the surface of iron particles is coated with a polymer. The rheological properties are measured and compared at various magnetic field strengths, shear rates and strain amplitudes. It has been shown that these MR fluids exhibit stable and desirable rheological properties such as, low viscosity and high yield stress.

The on-state yield stress is the primary design parameter for an MR actuator. We have evaluated several methods for measuring yield stress on a number of MR fluids of varying composition using a commercial parallel plate magnetic rheometer. The data obtained by these methods is evaluated for reproducibility and sensitivity to sample size variation and is compared against data obtained with a concentric cylinder magnetic rheometer and literature results. Based on these evaluations and comparisons, we selected two tests for further evaluation.

In this paper, the vibration and damping of a hollow sandwich box column containing a viscoelastic layer (VEL) or an electrorheological (ER) or magnetorheological (MR) fluid core with a constraining layer are analyzed and a comparison of performance is made. The hollow sandwich box column comprises two skin plates and a VEL/ER/MR fluid core layer. The finite element method is used to study the vibration and damping behaviors of the column. The natural frequencies and modal loss factors are obtained by solving the complex eigenvalue problem. The modal dampings and natural frequencies of the column are calculated for various electric as well as magnetic fields and their performance is compared with that of the viscoelastic core layer for the clamped-free boundary condition. Effects of core thickness, electric voltage and magnetic field on the vibration behavior of the sandwich box column are investigated.

In order to create efficient legged robots it is needed to care about energy consumption. During motion, energy is used in two different ways: positive energy to generate movement, and negative energy to brake movement. The use of passive components to dissipate the energy by friction could be a possible solution to avoid braking with active elements. This paper deals with the problem of determining experimentally the benefits of damping the knee by absorbing negative energy in MRF dampers, against actively braking using the actuators.