A novel active material for controllable, high work density applications was designed, fabricated, analyzed, and tested. This active material uses a lens-shaped element to implement simple shear motion with gas pressure actuation. The lens element is a bladder-filled Kevlar fabric embedded in a polyurethane matrix. The polyurethane’s hyperelastic material parameters were found by experiment and estimated by numerical analysis. The Ogden material constant set found shows good agreement within the shear actuator’s working range. A fabricated, single-element shear actuator reached 34.2% free shear strain when pressurized to 1.03 MPa. A unitary shear actuator was modeled as were single-acting and dual-acting shear actuator arrays so that solitary and multi-cell behaviors were estimated. Actuator work performance and power from nonlinear finite element analysis found conventional work density is 0.2289 MJ/m3 and 0.2482 MJ/m3, for the singleacting and double-acting shear actuator, respectively. Scientific work densities are 0.0758 MJ/m3 and 0.0375 MJ/m3, for single-acting and double-acting shear actuators, respectively. Calculation shows the volumetric power for a single-acting shear actuator is 0.4578 MW/m3 and 0.4964 MW/m3 for the double-acting shear actuator. Finally, a nastic actuator is applied to twist a generic structural beam. The nasticmaterial actuated structure has an advantage over conventional actuator systems. Work per unit volume for nastic materials is 2280~8471% higher than conventional, discrete actuators that use electric motors. When compared by work per unit mass, this nastic actuator is 2592~13900% better than conventional actuator because nastic actuator is made from lighter materials and it distributes the actuation throughout the structure, which eliminates connecting components. The nastic actuator’s volumetric power is 2217~8602% higher than conventional actuators. Finally, the nastic actuator is 2656~14269% higher than conventional actuators for power per unit mass.

This thesis endeavors to develop a new locking method for a twisted morphing wing spar. The conventional wing has to have hinges and a discontinuous surface. These cause air separation that decreases aerodynamic performance. Unlike this old concept, the new airfoil comprises a square cross section spar into the wing blade. Twisting the spar changes the airfoil?s angle of attack to control lifting and thrust force without a discontinuous surface. A nastic actuator generates shear stress for twisting the spar. A thermoplastic polymer locks the twisted shape. Applying heat and solidifying the polymer makes the beam lock into the twisted position even after removing the shear stress. This concept was evaluated by computer simulation and an experiment with a prototype construction. The analysis with 5m long spar shows that +450Pa shear stress generated +2 degrees twist and maximum 1.49MN/m spring constant at the spar tip. This spring constant helps a designer select the locking material, Ultem. The analysis proves that the Ultem film?s shear spring constant is high enough to hold the aluminum spar?s spring back. Physical experiment conditions might differ from computer simulation because environmental limitations might be present. The prototype spar has to be less than 300mm long to fit in an electric oven. Tension made the beam twist and baked it with locking material. When the polymer softened, the beam was taken from the oven and cooled. The solidified locking material held the spar at twisted status. The observation shows no detectable spring back after removing tension. Analytic solution also presents no spring back in twisting the prototype section spar. The FEA of the section spar verifies the physical experiment results. As a normal polymer, the Ultem shows stress relaxation. The load drop affects deceasing elastic modulus. Subsequently, the Ultem is able to lock the twisted spar even after the relaxation.