| 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 generally 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 first portion fabricated from a shape memory material and at least one additional portion fabricated from a different shape memory material. An activation device is coupled to the plurality of hook elements, the activation device being operable to selectively provide an activation signal to the plurality of hook elements to change a shape orientation, a yield strength property, a flexural modulus property, or a combination thereof to reduce a shear force and/or a pull-off force of an engaged hook and loop portion. 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 suitable 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. Also disclosed herein are processes for operating the releasable fastener system. |