A SMA wire in the un-stretched condition is then given an initial strain of εo (to preload the wire) at room temperature (RT). Its ends are then rigidly fixed. What force is developed in the wire?

Answer: tensional force

Explanation:

Tension force on a material occurs when two equal forces act on a material in an opposite direction away from the ends of the material.

Pre-tensing a wire material increases its load bearing capacity and reduces its flexure.