Composite article having adjustable surface morphology and methods of making and using
Disclosed are composite articles having adjustable surface morphologies, methods of making the composite articles, and methods of using the composite articles. The composite articles generally include an active layer comprising a shape memory material configured to undergo a change in property upon receipt of an activation signal, a bias layer configured to provide a mechanism for the composite article to return to a first shape from a second shape, and an activation device for providing the activation signal to the shape memory material.
1 . A composite article having an adjustable surface morphology, comprising:
an active layer comprising a shape memory material configured to undergo a change in a property upon receipt of an activation signal;
a bias layer configured to provide a mechanism for the composite article to return to a first shape from a second shape; and
an activation device for providing the activation signal to the shape memory material.
2 . The composite article of claim 1 , wherein the change in the property of the shape memory material is effective to transform the composite article from the first shape to the second shape.
3 . The composite article of claim 1 , wherein the shape memory material is a shape memory alloy, ferromagnetic shape memory alloy, a shape memory polymer, or a combination comprising at least one of the foregoing shape memory materials.
4 . The composite article of claim 1 , wherein the bias layer comprises a metal, a ceramic, a composite, or a combination comprising at least one of the foregoing, such that the bias layer has a greater elastic modulus and strength than the active layer.
5 . The composite article of claim 1 , further comprising a friction-producing element deposited on a shape changing surface of the composite article.
6 . The composite article of claim 1 , wherein the adjustable surface morphology of the composite article is effective to control a friction force between the composite article and a surface of an other body in contact therewith.
7 . The composite article of claim 6 , wherein the other body is a second composite article having an adjustable surface morphology.
8 . The composite article of claim 1 , wherein the composite article comprises at least a portion of a clutch, a brake, a bearing, a traction drive, a mechanical seat, a tire, a device that controls fluid flow over or between surfaces, or a clamp.
9 . The composite article of claim 1 , wherein the activation signal is a thermal activation signal.
10 . A method for making a composite article having an adjustable surface morphology, the method comprising:
forming a recessed portion in an active layer with an indenter, wherein the active layer comprises a shape memory material configured to undergo a change in a property upon receipt of an activation signal; and
forming a bias layer over at least a portion of the recessed portion of the active layer, wherein forming the recessed portion and forming the bias layer are accomplished absent the activation signal.
11 . The method of claim 10 , further comprising depositing a friction-producing element on at least a portion of a shape-changing surface of the composite article.
12 . The method of claim 10 , wherein depositing the friction-producing element is accomplished absent the activation signal.
13 . The method of claim 10 , wherein forming the recessed portion is accomplished by pressing a die onto the active layer, compression rolling the active layer, ballistically contacting the active layer with projectiles, or chemical etching.
14 . The method of claim 10 , wherein the recessed portion has a substantially hemispherical shape.
15 . A method for using a composite article having an adjustable surface morphology, the method comprising:
activating a shape memory material of an active layer of the composite article with an activation device; and
changing a shape of a surface of the composite article from a first shape to a second shape, wherein the surface of the composite article comprises a bias layer deposited thereon to restore the shape of the surface of the composite article to the first shape.
16 . The method of claim 15 , further comprising restoring the composite article to the first shape from the second shape.
17 . The method of claim 16 , wherein a measured dimensional distortion between the first shape before the activating and the first shape after the restoring is less than about 1.0%.
18 . The method of claim 16 , further comprising:
controlling a friction force between the shape-changing surface of the composite article and a surface of an other body in contact therewith by adjusting the shape-changing surface of the composite article from the first or second shape to the other of the first or second shape while maintaining contact between the shape-changing surface of the composite article and the surface of the other body.
19 . The method of claim 18 , wherein the other body is a second composite article having an adjustable surface morphology.
20 . The method of claim 15 , wherein the composite article comprises at least a portion of a clutch, a brake, a bearing, a traction drive, a mechanical seal, a tire, a device that controls fluid flow over or between surfaces, or a clamp.