Magnetorheological fluids

University of Alberta. Educational Software for Micromachines and Related Technologies. Available online. URL http //www. cs.ualberta.ca/ database/MEMS/sma mems/index2.html. Accessed May 28,2009. Research groups at the University of Alberta in Canada constructed this Web resource, which discusses a variety of smart materials, including shape-memory alloys, piezoelectric materials, and electrorheological and magnetorheological fluids. 

National Aeronautics and Space Administration—Ames Education Division Smart Materials. Available online. URL http //virtualskies.arc. nasa.gov/research/youDecide/smartMaterials.html. Accessed May 28, 2009. As part of an educational activity in which students plan an aviation research project, this Web site provides links to pages discussing piezoelectric materials, electrorheological and magnetorheological fluids, shape-memory alloys, and magnetostrictive materials. 

Scientists now understand the basic principles that determine the behavior of electrorheological and magnetorheological fluids. They believe that the imposition of an external electrical or magnetic held polarizes the particles suspended in the fluid. In the case of an... 

Rheological fluids are generally a dispersion composed of a base fluid (usually a type of oil) and particles. These particles can be either polymer in electrorheological fluids (ERF) or iron based in magnetorheological fluids (MRF). If a field is applied, the so-called particle chains are built and the fluid changes its viscosity to the point of becoming a viscoelastic solid (see Fig. 11). 

Yang G (2001) Large-scale magnetorheological fluid damper for vibration mitigation modeling, testing and control. Ph.D. Dissertation. University of Notre Dame, Notre Dame, IN, 2001... 

M.T. Ldpez-Lopez, G. Vertelov, G. Bossis, P. Kuzhir, JDG, Duran New magnetorheological fluids based on magnetic fibers, /. Mater. Chem., 2007, 17, 3839. 

G.T. Ngatu, N.M. Wereley, J.O. Karli, R.C. Bell, Dimorphic magnetorheological fluids, exploiting partial substitution of microspheres by nanowires. Smart Mater. Struct., 2008,17,045022. 

J. de Vicente, J.P. Segovia-Gutierrez, E. Andablo-Reyes, F. Vereda, R. Hidalgo-Alvarez, Dynamic rheology of sphere- and rod-based magnetorheological fluids,/. Chem. Phys., 2009, 131, 194902. 

Materials that allow an intelligent or smart structure to adapt to its environment are known as actuators. These materials have the ability to change the shape, stiffness, position, natural frequency, damping, friction, fluid flow rate, and other mechanical characteristics of adaptronic structures in response to changes in temperature, electric field, or magnetic field. The most common actuator materials are shape memory alloys, piezoelectric materials, mag-netostrictive materials, electrorheological fluids, and magnetorheological fluids [2]. Actuators with these materials will be described in detail in Sects. 6.2 to 6.6 therefore you will find only a brief overview below. 

Magnetorheological fluid production levels in 2005 are of the order of hundreds of metric tons per year (or tens of thousands of liters) such that commercial applications on several automotive platforms are supported. A factor of ten or more increase in volume over the next decade is anticipated. It is estimated that there are presently more than one hundred thousand MR dampers, shock absorbers, brakes and clutches in use worldwide. This number is expected to rise into the millions as more automotive platforms adopt smart MR fluid suspensions and clutch systems. 

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