Analysis and Reduction of Time Response in Thermally Activated Shape Memory Alloys

This paper aims to study the factors that affect the time response of Shape Memory Alloys (SMA) and establish a method to improve their activation times. In this work, different parameters such as the number, positions and orientation of the perforations on an SMA blade are studied. SMA blades with various designs based on a generated Hadamard matrix are actuated using Joule heating and its corresponding response in terms of force-time derivative is measured. By adapting the shape of the blade to increase heat transfer in high stress areas, this response was improved. The most relevant factor turned out to be the position of the perforations along the blade, followed by their longitudinal number and orientation. The work shows that by selectively removing material, a blade with the same amount of material can generate a threefold force-time derivative response.