MR Fluids

The cheapest viscpsity measures are the one used for paint.

they measure how long it takes a cup with a hole in it to empty.

http://www.google.com/search?hl=en&q=paint+%2Bviscosity+%2Bford

You can make a simple rotary plate viscosimeter from a small motor and a disc that spins in the liquid at a standard RPM. As viscosity get higher the DC current to keep the motor at the standard speed goes up.

You could measure the RPM by counting it with a stopwatch and changing the magnetic field around the rheomagnetic fluid and measure the current drained. If you make the fluid solid, it will stop = infinite viscosity = zero flow.

http://www.google.com/search?hl=en&q=%22rotating+disc%22+%2Bviscometer

these should give you a few ideas.

You can try making a falling ball viscometer, all you need is a long vase or measuring flask, a stop watch and a ball of the right density and size:

http://wise.fau.edu/~blarkin/Viscometer.html

pretty crude, but cheap and easy.

Something more sophisticated that you can buy might be a capillary viscometer:

http://www.cannoninstrument.com/GlassViscometers.htm

Do check out the website of our group for more info on MR fluids and other complex materials:

http://web.mit.edu/nnf/

magnetorheological fluids are usually dark grains of ferrite in a fuid. You can not see through the fluid, but you may be able to hear it hit the bottom with a microphone and thus be able to plot a time of drop chart.

I made a simple (and very cheap!) device once to measure the energy put into a beaker of fluid by a stirring paddle by making a turntable on a precision bearing (air bearing would be ideal) so that it was free to rotate (but did not rotate continuously) upon the vertical shaft of which (turntable) was wound a sewing thread whiich was draped over another bearing (but could have been a frictionless rod in the horizontal plane) and wound around another precision bearing shaft in an orthogonal horizontal plane to which was attached a small steel rod ("pointer": the size of which was chosen to be compatible with what we desired to measure) the end of which was attached to the bearing axle and the other end indicating the torque transferred to the liquid by the angular displacement of the uniformly dense pointer.

When tested against samples with known viscosities, we were able to calibrate the protractor (the way angular displacement was measured) for other viscosities.

The amount of torque transferred and speed of paddle wheel yields power, which may be what you ultimately want to characterize for different magnetorheological fluids.

Please keep in mind that if you choose to use this method to measure viscosity, you will learn much more than something about magnetorheological fluids, the least of which will not be that angular displacement of an eccentric dead weight rotating around a horizontal axis has a non-linear relationship to applied torque.

P. S. Check out electrorheological fluids also . . .

If you want to pursue your studies by using anything I have mentioned above, please let me know.

The real interest of MR fluids is in measuring off-state (no magnetic field) versus on-state (with magnetic field) forces. Depending on how much sample you have, you might be able to rig up something like a capillary rheometer using a plastic syringe, a needle, and some way to measure the force on the piston (maybe a small load cell). You would measure the force needed to push the fluid through the piston at a give rate with no field, then attach a magnet to the needle & repeat the measurement. You'd need some kind of drive motor to keep the rate constant.

If you are near a business or university that works with MR fluids, they may be willing to give you some assistance-- and they might even have a rheometer specially adapted to measure viscosity in a magnetic field. Try a Google search for articles about MR fluids, then Google the authors to see where they are. Good luck!