Shape Memory Alloys and Some Explorations of Aerospace Applications

David Wang Auditorium, 3rd floor Dalia Maydan Bldg.
Dr. Yong Liu

Dr. Yong Liu, School of Mechanical and Aerospace Engineering,
Nanyang Technological University, Singapore

Since the discovery of NiTi Shape Memory Alloy (SMA) about 50 years ago,
scientists and engineers have made tremendous efforts to apply it to solve real
engineering problems. Over the last two decades significant progresses have been
made in the understanding of SMAs, in the development of laboratory prototypes
incorporated with SMA actuators, and in the implementation of SMA actuators in real
engineering structures. Especially in recent years, SMAs have received strong
attention for solving some challenging problems in aerospace engineering. These
include vibration control, noise reduction, fracture mitigation, shape morphing, selfhealth-monitoring, deployable structures etc. SMAs possess three major properties,
i.e., shape memory effect, super-elasticity and high damping capacity. In order to
effectively use SMAs, understanding these properties and influential factors are of
ultimate importance.

This seminar will begin with the properties of SMA and their major influential factors,
followed by examples to illustrate how to effectively use SMAs in applications.
Particular attention will be paid to the processing-microstructure-property relation
and transformation hysteresis which is one of the most important properties for
aerospace applications. Several laboratory prototypes will be demonstrated and
explained including SMA actuated morphing wing mechanisms for UAV, SMA
actuated flapping wing and telescopic wing mechanisms, SMA actuated mechanisms
for deployment of satellite antenna and solar panel. Finally, new opportunities in
additive manufacturing of smart structures (recently called 4D printing) will be
discussed. Some results on 3D printing of SMAs and Shape Memory Polymers
(SMPs) will be presented. Several design principles will be explained together with
demonstration of laboratory prototypes. Future direction of SMAs will also be
discussed. The content of this seminar will be mainly based on the results obtained in
my research group in the past and recent years.