LE coupon based technology

SMYLE involved mathematical modelling, design, fabrication and testing of a Shape Memory Alloy coupon undergoing actuated controlled deformation. It was envisaged that two different SM actuating principles were pursued. In the first approach, the actuator was embedded in the coupon in the form of an active layer, whereas in the second approach the use of the so-called compliant mechanisms was investigated with the SMA wires as actuating elements. Work was carried out as follows: Determination of single-cycle/multi-cycle loading conditions which involve the thermal-mechanical and electrical aspects, with emphasis on hysteresis, as well as determination of experimental conditions, i.e. surface uniform- & non-uniform actuation type of loading; prediction of specimen's surface response by means of simple analytic methods.

Uniform as well non-uniform surfaces of the same SMA specimen were pursued. Testing included the deformation to the desired shapes repeatedly and measured reproducibility and attainment of desired shape. The effect of temperature was also evaluated by completing several actuation cycles at temperatures near the SMA transformation temperature. Commercially available SMA was used and an initial characterisation phase is foreseen. The aim was to have the material behaviour under static and dynamic conditions up to failure. It was foreseen that, for every actuating principle, the most promising concepts were bench-tested to evaluate characteristics and highlight challenges. Up to four concepts were tested in this context. Eventual modification of numerical model and structural correction of the SMA specimen in case of unsatisfactory experimental outcome was carried out. Finally, a functional SMA specimen and recommendations for future work were delivered.