Flexible actuator based on shape memory alloy sheet

• Main Authors: TORRES-JARA EDUARDO R, RUS DANIELA
• Format: Patent
• Language: English
• Published: 27.05.2014
• Subjects: BLASTING; COMBUSTION ENGINES; ENGINE PLANTS IN GENERAL; HEATING; HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINEPLANTS; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS; LIGHTING; MACHINES OR ENGINES IN GENERAL; MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENTTYPE, e.g. STEAM ENGINES; MECHANICAL ENGINEERING; NOT OTHERWISE PROVIDED FOR; STEAM ENGINES; USE OF WASTE HEAT OF COMBUSTION ENGINES; WEAPONS

A flexible unit-cell actuator includes a shape memory alloy sheet having a fold between adjacent legs in one state and a heat source that upon activation concentrates heating of the shape memory alloy sheet at the fold relative to the legs to change the fold between one state and another state. The heat source may include resistive heating due to an electric current passing through the shape memory alloy sheet. The fold typically includes a reduced cross-sectional area and may include slits to increase electrical resistance at the fold relative to the adjacent legs. An actuator array includes a plurality of flexible unit-cell actuators formed in a sheet, each unit-cell actuator mechanically coupled to at least one other unit-cell actuator at a coupling region. Plural unit-cell actuators may be mechanically coupled in series, in parallel, or both, may be electrically connected in series, and may move along a defined curve or surface. A linear or curvilinear actuator includes a guide, a plurality of bearings or support elements slidable along the guide, and an array of actuators coupled between adjacent bearings and circumferentially about the bearings. An actuator includes a plurality of segments fanning from a hinge and shape memory alloy actuators coupled between adjacent segments to cause the segments to fan in an out about the hinge.