Focus: To understand the actuation fatigue mechanisms and fracture properties of SMAs.
Actuation fatigue tests are performed to determine the expected life of an SMA actuator.
A constant load is applied to the specimen and the temperature is cycled. Trends are established for the fatigue life as a function of the applied load and the cooling method. Microstructural evaluation is preformed to identify failure mechanisms to aide in future alloy development.
Finite element calculations are carried out to determine the mechanical fields
near the crack tip and to examine the toughness enhancement associated with trans- formation dissipation in the wake of an advancing crack.