| Title |
Stress Localization and Excess Recovery in a Shape Memory Alloy |
| Authors |
지광구(K . K . Jee); 한준현(J . H . Han); 미서군(X . K . Mi); 신명철(M . C . Shin) |
| Abstract |
Temperature response is tested for a Ni-Ti shape memory spring with prestrain or a constant load. An apparatus for measuring variation in deflection of the spring with temperature and DSC are employed to evaluate the characteristics. Localized elastic stress, accumulating on thermo-mechanical cycling, give rise to excess recovery, i.e., continuance of shape change at temperatures well above Af. The accumulation of even apparently elastic stress concentration can initiate dislocation slip, causing a SMA spring to lose its precision. Thus it is strongly advised that SMA thermo-actuator be cycled until no further permanent is induced, before its parameters are evaluated for designing. |