Releasable fastener system

Abstract

A releasable fastener system comprises a loop portion and a hook portion. The loop portion includes a support and a loop material disposed on one side thereof. The hook portion includes a support and a plurality of closely spaced upstanding hook elements extending from one side thereof, wherein the plurality of hook elements comprises a fiber and a shape memory alloy coating deposited onto the fiber, and wherein the fiber and the shape memory alloy coating comprises a non-axisymmetric coating or deposition of the shape memory alloy about a portion of the fiber. When the hook portion and loop portion are pressed together they interlock to form a releasable engagement. The resulting joint created by the engagement is relatively resistant to shear and pull forces and weak in peel strength forces. Introducing a thermal activation signal to the plurality of hook elements causes a change in shape orientation, flexural modulus property, or a combination thereof that is effectively reduces the shear and/or pull off forces in the releasable engagement. In this manner, disengagement of the releasable fastener system provides separation of the hook portion from the loop portion under controlled conditions.