🚀 go-pugleaf

>In article <BxxsAw.Kq7@aplcenmp.apl.jhu.edu> doherty@aplcenmp.apl.jhu.edu  
(Kevin
> Doherty) writes:
>>esm40@cd.amdahl.com (Ed McGettigan) writes:
>>
>>>Does anyone know of any materials/liquids that harden when you apply
>>>a voltage/current to them and revert when you turn it off?
>>
>>  Think there's a whole family of such materials-called (I believe)
>>electrorheologic materials.

>That's true but.....
>>
>>  The ones I've heard of tend to be used in magnetic clutches and the
>>like.  They consist of thick oils loaded with powdered steel-under the
>>influence of a magnetic field the material 'solidifies' (the powder
>>consolidates).  The stuff would likely behave the same if you ran a
>>current thru it (because of the resulting magnetic field).  No problem
>>that it's an insulator-one variety of this stuff uses mercury as a
>>matrix.
>
>What you are refering to here is more likely ferrofluids.
>Electrorheological fluids use electric fields instead of magnetic fields
>and the particles are suspended in a dielectric fluid and are themselves
>dielectrics.  The idea is that the particles become polarized upon
>application of the electric field and form long chains.  These chains
>cause a substantial increase in the viscosity of the fluid.  For a good
>all round review of the field of electrorheological fluids check out:
>
>M. Block and J.P. Kelly, "Electro-rheology review article", J. Phys. D:
>Appl Phys. vol 21, Dec 14, 1988, p. 1661-1677.
>
>Hope this helps,
>
>Kent Goeking
>Creare Inc.
>kwg@creare.com
>
>


Hi everyone,

I looked in several  Physics Journals in order to obtain some 
articles about this ferrofluids,
or  materials that harden/soften with applied magnetic field.
Unfortunately I did nut sucesseed.

I would greatly appreciate any references or pointer.

M. BOUZIT   
mbouzit@robo.jussieu.fr
Robotics Lab of Paris
Universite Piere et Marie Currie
FRANCE