Shape memory-based multifunctional structural actuator panels

A multifunctional panel concept is presented in which a lightweight, structural sandwich panel is able to undergo a reversible change in shape upon application of a localized thermal stimulus. The shape change is effected by metallic (or polymeric) shape memory (SM) face sheet elements, which exploit a "one-way" SM effect only. Unlike other designs, no external or bias forces are required to complete the full cycle of shape change. This is accomplished by a core design which, when one of the two face sheets is activated and thus undergoes a length change, forces the opposite (inactive) face sheet to martensitically deform in tension. By alternately heating one face sheet and then the other, to transform the martensitic structure to austenite, the sandwich beam or panel is able to perform fully reversible cyclic shape changes. Heating can be accomplished electrically or by other means. The performance of the sandwich panel, in terms of required thermal power, actuation frequency, peak load bearing capacity, stiffness, and weight, can be optimized by proper selection of face sheet material and its thickness, the overall core thickness, core member thickness and length, and the design of the joint connecting core members and face sheet.