Thanks, meves, and welcome to this forum. Interesing link. Now, can I complain?
Magneto-rheological materials are used in F1. I post and post and post and nobody reads... Is this a clue?
I know, I know, Carlos, you do.
Good, as I can use all the
old posts and save some time (or waste some of yours...
)
This is the Sachs magneto-rheological damp adsorber used by Ferrari since 2003:
Sachs explanation about MR dampers
Abstract by FIAT scientists
They work in a different manner of the ones I know. This is how they look on the inside (this drawing is sort of a joke, pleeeze).
A rotational damper works by turning the vanes to push the fluid through a set of valves, as "clearly" shown in the right part of the picture. Of course, the resistance you get when you turn the vanes inside the tube depicted depends on how viscous is (how sticky) the fluid inside.
There are several fluids that have diferent "rheological properties" (viscosity) when the conditions change. The first that comes to my mind is ketchup: if you slowly apply forces to ketchup, it has high viscosity; on the other hand, if you apply the force quickly, its viscosity lessens (that's why you hit the bottom of the bottle to "release" it)
If you put magnets inside the damper, you can alter the "stickiness" of a magnetic fluid. This is called "magnetorheology" (viscosity altered by magnetism). The best I could quickly find is this linear mono-chamber damper (the fourth option I gave in the old post mentioned).
The light blue squares are the magnets and the lines on top of them are the "magnetic restricted zone", where the fluid becomes sticky:
PDF
Finally, I found here that the damping variation caused by permanent magnets is not too far from the one you get with active, electromagnetic ones:
http://web.me.unr.edu/ciml/11.pdf.
You can see that the force with "magnets-only" (gray lower line), even if lower than when electrically excited (pink upper line) it is still sizeable,
which means the thingies work without clasifying as active suspension:
BTW, the invention is old: 1940, by Jacob Rainbow, an american.
I wonder if these devices, together with what we've wrote about a new theory of tyres (I've posted about it a hundred times, search the forum for "Bo Persson"), that explains the many different damping modes you get from rubber and finally (the theory hadn't changed since the 18th century) give a rational explanation to friction, are behind Ferrari's dominance.
