Actuator

摘要

An actuator ( 12 ) is disclosed for example for controlling gas flow in a gas turbine engine. The actuator ( 12 ) comprises a first portion ( 14 ) having shape memory properties, and a second portion ( 16 ) formed of substantially the same material as the first portion and having reduced shape memory properties relative to the first portion. The first portion ( 14 ) is movable from a first position to a second position at a temperature above the phase transition temperature of the shape memory material of the first portion ( 14 ). The second portion ( 16 ) is arranged to urge the first portion ( 14 ) from the second position to the first position at a temperature below the phase transition temperature of the shape memory material.