Abstract: The restrained shape memory alloy (SMA) wires, as actuators, are winded and pasted on the outside surfaces of a thin wall tube at angle of a degree with respect to the tube axis. Upon beating the wires, the martensitic residual strain will be restored, the large recovery forces are induced so that the tube will induce deformation. A mechanic model of a thin tube pasted with an actuator (SMA wires), is presented, the mixed deformations of compression and torsion of the tube are analyzed and the relation between the angle of twist of the tube and temperature in a temperature cycle is given. The theoretical predictions are validated with static experiments.

Key words: Actuator, Shape memory alloy, Smart structure, Thin walled tube