Magnetorheological fluid damper

1. A magnetorheological damper, the damper comprising:

a cylindrically shaped housing;

a magnetorheological fluid disposed in the cylindrically shaped housing;

a piston assembly disposed within the cylindrically shaped housing in sliding engagement with the cylindrically shaped housing defining a first chamber and a second chamber, wherein the piston assembly comprises a plurality of cylindrically shaped fluid passageways extending from the first chamber to the second chamber, and at least one electromagnet, wherein the cylindrically shaped fluid passageways are formed from a plurality of annular plates stackedly arranged, wherein each one of the plurality of annular plates comprise a plurality of circular openings that when aligned with the other ones of the plurality of annular plates form the cylindrically shaped fluid passageways; and

a power supply in electrical communication with the at least one electromagnet.

2. The magnetorheological damper of claim 1 , wherein the plurality of cylindrically shaped fluid passageways defines a cross sectional area of the piston assembly of at least about 30 to about 70 percent.

3. The magnetorheological damper of claim 1 , wherein the cylindrically shaped fluid passageway has a diameter that increases from the first chamber to the second chamber.

4. The magnetorheological damper of claim 1 , wherein the cylindrically shaped fluid passageway has a diameter that decreases from the first chamber to the second chamber.

5. The magnetorheological damper of claim 1 , further comprising a third chamber defined by a second floating piston and an end of the housing, wherein the third chamber is filled with an inert gas.

6. A magnetorheological damper, the damper comprising:

a cylindrically shaped housing;

a magnetorheological fluid disposed in the cylindrically shaped housing;

a piston assembly disposed within the cylindrically shaped housing in sliding engagement with the cylindrically shaped housing defining a first chamber and a second chamber, wherein the piston assembly comprises an open cell porous media comprising a plurality of fluid passageways in fluid communication with a plurality of opening in a top surface and in a bottom surface of the piston assembly, and at least one electromagnet centrally disposed in the piston assembly; and

a power supply in electrical communication with the at least one electromagnet.

7. The magnetorheological damper of claim 6 , wherein the fluid passageways have circular or polygon shaped cross sectional openings.

8. The magnetorheological damper of claim 6 , wherein the open cell porous media comprises a plurality of stackedly arranged sheets, wherein each sheet of the plurality of stackedly arranged sheets is a rigid lattice network of nonmetallic material having hexagonally shaped openings.

9. The magnetorheological damper of claim 6 , wherein the fluid passageways formed in the open cell porous media have a cross sectional area of about 30 to about 70 percent.

10. The magnetorheological damper of claim 6 , wherein the open cell porous media comprises a rigid foam comprising a plurality of irregularly shaped fluid passageways extending from the first chamber to the second chamber.

11. The magnetorheological damper of claim 6 , wherein the fluid passageways have different size and/or shaped openings.

12. The magnetorheological damper of claim 6 , further comprising a third chamber defined by a floating piston and an end of the housing, wherein the third chamber is filled with an inert gas.