Validation and optimization of a compact push-pull rubber actuator energized by an outer coil of shape memory wire

The authors have formerly published the analytical model and finite element validation of a push-pull actuator made by winding a thin shape memory wire on a solid rubber cylinder. The cylinder provides elastic backup for the wire upon cooling down and transforms its circumferential contraction into a magnified axial elongation upon heating up. Building on that study, this paper accomplishes three tasks: (1) build prototype actuators and perform simple tests to validate the theory; (2) develop simple procedures for the optimal design of the actuator starting from high-level engineering specifications; (3) envision how the present concept could be improved by replacing the rubber block with a compliant lattice-like or shell-like scaffold with designed properties to further enhance the axial stroke.