| dc.description.abstract | Large monolithic shape memory alloy (SMA) actuators are currently limited to applications
with low cyclic actuation frequency due to their high thermal masses coupled with low heat transfer
rates. Liquid gallium-indium eutectic is a room-temperature liquid metal that can be used as a
multifunctional heat transfer fluid. Integrated into an additively manufactured NiTi SMA actuator,
liquid metal can cool an actuator via forced fluid convection through interior channels and then
use those same channels to inductively heat the SMA, if electrically isolated and configured into
induction-favorable geometries. Computational models suggest that such actuators can demonstrate
an increased actuation frequency of 400%, compared to traditional cycling of large SMAs.
In this work, a cantilever SMA beam actuator is additively manufactured with an embedded
planar induction geometry for a latterly applied liquid metal channel. This actuator is deformed,
actuated, and found to have an increased cooling rate of 40% compared to free convection. A variety
of topics related to the integration of liquid metal and SMAs are also investigated including: the
surface roughness of additively manufactured internal structures and its mitigation via electropolishing
techniques, liquid metal-induced corrosion, and polymer coatings for electrical isolation
of the liquid metal adhered to a high-temperature, highly strained SMA. It is also concluded that
lower laser energy density during additive manufacturing leads to reduced surface roughness, liquid
metal does not induce corrosion on NiTi alloys until temperatures between 400◦C and 600◦C,
and Xylan© acts as a sufficient coating for the electrical insulation of SMAs. | en |
