Experiments on shape memory alloy actuator and practical applicability considerations

This paper describes the design and the experimental work on a force-generating Shape Memory Alloy (SMA) actuator concept.The objective of the work was to test the applicability of the actuator concept for semi-active vibration control.The actuator was designed for bolt-force adjustment in structural joints.The SMA material applied was standard commercial NiTinol alloy.Two different actuator designs were constructed and tested: a smaller air-heated design, and a larger water-heated design.The actuator's ability to generate a force as a function of the bolt pre-tension was studied in the experiments.The magnitude of the forces generated was from 1 kN to 70 kN.In terms of design and control, non-linear behavior of the actuator was considered a challenge.From the industrial application point of view, the long-term behavior and the price of the material were considered the greatest challenges.Ability to generate large forces relatively quickly was seen as a promising opportunity.Furthermore, both actuator constructions were relatively simple and consisted of a small number of components.