Affiliations: [a] Korea Advanced Institute of Science and Technology,
Daejeon 305-701, Korea. Tel.: +82 42 869 3717; E-mail:
[email protected]
Abstract: Recently, morphing concepts for UAV or MAV have been significant
issues in aerospace engineering. Morphing wing concept, a biomimetic technology
in aerospace engineering, has been realized by various methods including
changes of wing's cross-section, plan form, and spar position. This paper
investigates a morphing wing with variable camber using SMA actuators. The test
model is a symmetric wing structure composed of two tapered graphite/epoxy
composite plates and a steel body. Shape memory alloy (SMA) is attracting much
attention as actuators for controlling the shape of structures because of high
recovery force and large deformation. Four pairs of the SMA wire actuators are
attached on the bottom surfaces of the wings in the chord-wise direction. SMA
actuators produce enough deformation to cause significant improvement the
static and dynamic characteristics of the wing model. Lift and drag forces,
most important static aerodynamic characteristics, were measured at various
angles of attack. Lift of the wing was increased without increasing drag forces
when electric current was applied to the SMA actuators. Dynamic vibration
signals were measured by FBG sensor at the root of the wing. The FBG sensor was
successfully applied to the monitoring of the aeroelastic unstable phenomena at
various angles of attack. At flutter speed, limit cycle oscillation with
constant frequency occurred. It was also observed that the vibration energy is
concentrated on the flutter mode and increased with the increase of the airflow
speed. The effects of the angle of attack on aeroelastic characteristics of the
wing were investigated. The amplitude of the limit cycle oscillation was
significantly reduced at the flutter velocity when SMA actuators were
activated.
