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.
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.