In recent years, a demand for compact, lightweight, solid-state actuation systems has emerged, driven in part by the needs of the aeronautics industry. However, most actuation systems used in turbomachinery require not only elevated temperature but high-force capability. As a result, shape memory alloy (SMA) based systems have worked their way to the forefront of a short list of viable options to meet such a technological challenge. Most of the effort centered on shape memory systems to date has involved binary NiTi alloys but the working temperatures required in many aeronautics applications dictate significantly higher transformation temperatures than the binary systems can provide. Hence, a high temperature shape memory alloy (HTSMA) based on NiTiPdPt, having a transformation temperature near 300 o C, was developed. Various thermo-mechanical processing schemes were utilized to further improve the dimensional stability of the alloy and it was later extruded/drawn into wire form to be more compatible with envisioned applications. Mechanical testing on the finished wire form showed reasonable work output capability with excellent dimensional stability. Subsequently, the wire form of the alloy was incorporated into a benchtop system, which was shown to provide the necessary stroke requirements of ~0.125 inches for the targeted surge-control application. Cycle times for the actuator were limited to ~4 seconds due to control and cooling constraints but this cycle time was determined to be adequate for the surge control application targeted as the primary requirement was initial actuation of a surge control rod, which could be completed in approximately one second.

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Shape Memory Effect (SME) TiNi torque tubes were fabricated, tested and installed to supply 2500 in.lbs and 500 in.lbs of torque for inboard and outboard sections, respectively, of the DARPA smart wing wind tunnel model . Structural connections to the tubes were designed so that the entire assembly would fit within the interior of the wing, whose maximum dimensions of depth ranged from 1.125" to 0.375", depending on the position along the wing span. The torque tubes themselves were made by gun drilling a TiNi ingot and ElectroSpark Discharge Machining (EDM ) to the required dimensions, which were calculated from a simple model described in a previous paper. The torque tubes were placed into the wing and twist deflections were measured. Deflections on the wing were measured at 1.3°, which provided a significant increase (-8%) in the wing rolling moment. IntroductionThe Shape Memory Effect (SME) is due to a first order martensitic phase transformation from a low modulus martensitic phase to a high modulus austenitic phase. Relevant phase transformation temperatures are denoted as Mf (Martensitic finish temperature) below which the material is fully

To verify the predicted benefits of the smart wing concept, two 1 6% scale wind tunnel models, one conventional and the other incorporating smart wing design features, were designed, fabricated and twice tested at NASA Langley's 16ft Transonic Dynamic Tunnel, in two series oftests, conducted in May 1996 and June 1998, respectively. A key objective of the Smart Wing Phase 1 program was not only to construct wind tunnel models that could be used to validate the predicted benefits of using smart materials, but also to identif' and reduce the risks involved in eventually integrating smart materials into an actual flight vehicle. Among the challenges encountered in developing the wind tunnel model were the attachment ofthe shape memory alloy (SMA) control surfaces to the wing box, integration of the SMA torque tube in the wing structure, installation of the instrumentation, and development of fail safe control mechanisms to protect the model and the tunnel in the event offailure ofthe smart systems.In this paper, design and fabrication details of the two Smart Wing Phase 1 wind tunnel models are presented. Among the topics covered are 1) model design requirements, model design and static testing ; 2) manufacturing techniques with particular emphasis on the improvements in the design and fabrication of the SMA control surfaces from the first to the second test; 3) system integration; and 4) post-test analysis and planned improvements. Lessons learned from the Phase 1 effort are discussed along with plans for the Smart Wing Phase 2 program.