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Lockheed Martin Corporation

Brian J Maclean

Joseph H Armstrong

Mohan S Misra

William J Arbegast

Bernard F Carpenter

A pliant, controllable contour control surface comprising a first flexible facesheet formed to a first initial contour of the control surface, and a second flexible facesheet formed to a second initial contour of the control surface. The first and second facesheets each have a set of prestrained shape memory alloy tendons embedded therein, extending from a leading edge to a trailing edge of the control surface. Each set of the shape memory alloy tendons is separately connected to a controlled source of electrical current such that tendons of the first and second flexible facesheets can be selectively heated in an antagonistic, slack-free relationship, to bring about a desired modification of the configuration of the control surface. A computer based control system is utilized for maintaining a constant temperature of the antagonists to establish conditions conducive to the stress induced transformation from austenite to martensite, accomplished by causing constant current to flow through the antagonists. Proportional/integral (PI) control is utilized in connection with the opposing shape memory tendons.

Adaptive control surface using antagonistic shape memory alloy tendons

A fastener having an elongated shank formed of a shape memory alloy, a head at the upper end of the shank, and an annular segment at the lower end of said shank having a deformed cross-sectional shape suitable for insertion into an opening extending through adjacent workpieces. The annular segment has a frusto-conical trained shape that is larger than this opening. The annular segment radially flares from the deformed shape to an approximation of the trained shape when heated above a critical transformation temperature, thereby securing the fastener in place with respect to the workpieces. Alternatively, a sleeve made of a different material (e.g. aluminum) extending over a portion or the entire length of the fastener can be added for improved deformational characteristics, by providing the same frusto-conical shape through axial contraction of the shank.

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Daniel, WY, United States of America

Brian J Maclean