Shape Memory Alloys (SMA) have proven to be a lightweight, low cost alternative to conventional
actuators for a number of commercial applications. Future applications will require a more complex shape
changes and a detailed understanding of the performance of more complex SMA actuators is required. The
purpose of this study is to validate engineering models and design practices for SMA beams of various
configurations for future applications. Until now, SMA actuators have been fabricated into relatively
simple beam shapes. Boeing is now fabricating beams with more complicated geometries in order to
determine their strength and shape memory characteristics. These more complicated shapes will allow for
lighter and more compact SMA actuators as well as provide more complex shape control. Some of the
geometries evaluated include vertical and horizontal I-beams, sine wave and linear wave beams, a truss,
and a beam perforated with circular holes along the length.
A total of six beams were tested; each was a complex shape made from 57% Nickel by weight with the
remainder composed of Titanium (57NiTi). Each sample was put through a number of characterization
tests. These include a 3-point bend tests to determine force/displacement properties, and thermal cycling
under a range of isobaric loads to determine actuator properties. Experimental results were then compared
to modeled results. Test results for one representative beam were used to calibrate a 3-D constitutive
model implemented in an finite element framework. It is shown that the calibrated analysis tool is accurate
in predicting the response of the other beams. Finally, the actuation work capabilities of the beams are
compared using a second round of finite element anaylysis.
Synthetic Jet Actuators have been the topic of extensive study in the aerospace industry because of their ability to actively control flow over aerodynamic surfaces without discrete control surfaces such as a flap. One challenge has been to develop a low frequency, lightweight actuator that can provide large displacements. This study will discuss the modeling, design, manufacture, and testing of a bimorph piezo-composite actuator that will provide such displacements at low frequencies. The design employs two opposing benders that provide a piston-type motion. The initial goals of this study were to achieve 30 m/s out of the slot while maintaining the mechanical resonant frequency of the system at about 100 Hz.