Fasteners with conforming sleeves
View Patent ↗A sleeve interference fastener including a conformable sleeve, wherein the conformable sleeve is comprised of at least one first material having a hardness of X, and a pin member, wherein the pin member is comprised of at least one second material having a hardness of Y, wherein X is sufficiently less than Y so that, in an installed position of an interference fit, at least a portion of the at least one first material of the conformable sleeve conforms to a contour of an inner surface of a hole of a composite structure so as to create a continuous electrical contact at an interface between the inner surface of the hole of the composite structure and the conformable sleeve.
1. A sleeve interference fastener adapted to be installed in a hole of a composite structure comprising:
a.) a conformable sleeve having a head at one end and a tubular portion, wherein the tubular portion is comprised of an inner base layer and an outer coating layer, wherein the tubular portion has an inner diameter and an outer diameter, wherein the outer diameter of the tubular portion is less than an inner diameter of the hole of the composite structure, wherein the inner base layer is comprised of at least one first material having a hardness of X, and wherein the outer coating layer is comprised of at least one second material having a hardness of Y;
b.) a pin member, wherein the pin member has at least a pin head at one end, a locking portion at an opposite end of the pin head, and a shank portion therein between, wherein the shank portion, located below the pin head, has a diameter greater than the inner diameter of the tubular portion of the conformable sleeve, and wherein the pin member is comprised of at least one third material having a hardness of Z;
c.) wherein X is sufficiently less than Y and wherein Z is equal to or higher than X so that, in an installed position, at least a portion of the outer coating layer of the tubular portion conforms to a contour of an inner surface of the hole so as to create a continuous electrical contact at an interface between the inner surface of the hole of the composite structure and the conformable sleeve; and
d) wherein, upon a pressure from the shank portion of the pin member, the conformable sleeve is adapted to expand radially over the inner surface of the hole to form an interference fit between the outer diameter of the sleeve and the hole of the composite structure so as to provide the installed position.
2. The sleeve interference fastener of claim 1 , wherein the outer layer is a fixed solid coating.
3. The sleeve interference fastener of claim 2 , wherein the fixed solid coating comprises i) at least one organic material and ii) at least one conductive filler material.
4. The sleeve interference fastener of claim 2 , wherein the fixed solid coating comprises a metal material.
5. The sleeve interference fastener of claim 4 , wherein the metal material comprises one or more metal elements selected from a group consisting of silver, aluminum, gold, and nickel.
6. The sleeve interference fastener of claim 1 , wherein X is less than 100 HRB on Rockwell B scale.
7. The sleeve interference fastener of claim 1 , wherein the inner surface of the hole has a sealant when the fastener is in the installed position.
8. The sleeve interference fastener of claim 1 , wherein, to facilitate a movement of the pin member through the conformable sleeve, the fastener further comprises a lubricant.
9. The sleeve interference fastener of claim 8 , wherein the lubricant comprises a conductive solid film material.
10. The sleeve interference fastener of claim 9 , wherein the conductive solid film material comprises carbon nano-tubes at a concentration between 0.05 to 30 percent of a total weight of the conductive solid film material.