Apparatus with active material surface in contact with rheological fluid and method of enhancing performance thereof
First Claim
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1. An apparatus, comprising:
- a rheological fluid characterized by an increase in yield stress under an applied field;
a mechanical assembly configured to provide the field and including an active material component forming a surface in contact with the rheological fluid;
wherein the surface is characterized by a first surface geometry when the active material component is not activated and by a second surface geometry when the active material component is activated;
wherein one of said first and second surface geometries is rougher than the other surface geometry; and
wherein activation of the active material component is configured to be controllable such that the rougher surface geometry is in contact with the rheological fluid when the field is applied and the other of the surface geometries is in contact with the rheological fluid when the field is removed.
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Abstract
An apparatus is provided having an active material forming a surface thereof in contact with a rheological fluid. The active material is controllable to vary a surface geometry thereof between a rough or nonsmooth surface geometry to increase drag, and achieve an increase in stress transmitted through the fluid, when a field is applied, while allowing a smooth surface geometry and an associated reduction in stress transmitted through the fluid when the field is removed. A method of enhancing performance of an apparatus that includes a rheological fluid is also provided.
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Citations
16 Claims
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1. An apparatus, comprising:
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a rheological fluid characterized by an increase in yield stress under an applied field; a mechanical assembly configured to provide the field and including an active material component forming a surface in contact with the rheological fluid;
wherein the surface is characterized by a first surface geometry when the active material component is not activated and by a second surface geometry when the active material component is activated;
wherein one of said first and second surface geometries is rougher than the other surface geometry; and
wherein activation of the active material component is configured to be controllable such that the rougher surface geometry is in contact with the rheological fluid when the field is applied and the other of the surface geometries is in contact with the rheological fluid when the field is removed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 15)
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10. A torque-transmitting device comprising:
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first and second concentric members configured for relative rotation and having a plurality of surfaces defining an annular cavity therebetween; a magnetorheological fluid disposed in the annular cavity;
wherein the magnetorheological fluid is magnetizable to couple the first and second concentric members to transmit torque therebetween;an active material component covering and fixed on at least one of the surfaces and having an active surface in contact with the magnetorheological fluid;
wherein the active surface is characterized by a first surface geometry when not activated and a second surface geometry when activated and remains covering and fixed on said at least one of the surfaces both when activated and when not activated;
wherein the first surface geometry is smoother than the second surface geometry to minimize drag on the magnetorheological fluid when the magnetorheological fluid is not magnetized; and
wherein the second surface geometry increases the drag on the magnetorheological fluid when the magnetorheological fluid is magnetized. - View Dependent Claims (11, 16)
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12. A method of enhancing performance of an apparatus that includes a rheological fluid, comprising:
activating an active material component while the active material component is in contact with the rheological fluid to thereby cause one of an increase or a decrease in surface roughness of the active material component by causing protrusions and depressions that are relatively aligned on a surface of the active material component to form grooves and valleys, and thereby causing a corresponding increase or decrease in stress transferred through the rheological fluid in contact therewith. - View Dependent Claims (13, 14)
Specification