MAE PhD Defense – Russell Mailen

Title: Computational Modeling of Shape Memory Polymer Origami that Responds to Light

(Advisor:  Dr. Mohammed Zikry & Dr. Jan Genzer) 

Abstract

Shape memory polymers (SMPs) transform in response to external stimuli, such as infrared (IR) light. Although SMPs have many applications, this dissertation focuses primarily on their application as actuators in self-folding origami structures. Ink patterned on the surface of the SMP sheet efficiently absorbs thermal energy from the IR light, which produces localized heating. The material shrinks wherever the activation temperature is exceeded. This behavior can produce out-of-plane deformation. The time and temperature dependent response of these SMPs provides unique opportunities for developing complex three-dimensional (3D) structures from initially flat sheets through self-folding origami, but the application of this technique requires predicting accurately the final folded or deformed shape. Computational modeling provides a fundamental understanding of the shape memory behavior and the self-folding process, but current computational models do not couple fully the thermo-mechanical response of the material. These issues are addressed with a nonlinear, 3D, thermo-viscoelastic finite element framework in combination with comparisons to experimental results for self-folding origami structures. This framework is utilized to study systematically various parameters that affect the response of the sheet to an incident IR light source, including the ink pattern, pre-strain conditions, and applied thermal and mechanical loads. The thermal and mechanical solutions are coupled by accounting for both internal, viscous heat generation and time-temperature superposition. A detailed understanding of the shape memory response and the effect of controllable design parameters allows computational modeling to be used as a predictive tool for the design of functional, 3D structures with applications in packaging, bio-inspired devices, and space exploration.

Biography

Russell graduated from the University of Kansas in 2007 with a B.S. in Aerospace Engineering. After graduation, he worked in the aerospace industry at Hawker Beechcraft Corporation and L-3 Communications. In 2012, he graduated from Baylor University with a M.S. in Mechanical Engineering. In 2013, he began his studies for a Ph.D. in Mechanical Engineering at North Carolina State University, where he also earned a Master of Materials Science and Engineering degree. Russell is advised by Dr. Mohammed Zikry in the Department of Mechanical and Aerospace Engineering, and Drs. Jan Genzer and Michael D. Dickey in the Department of Chemical and Biomolecular Engineering. His research interests include computational modeling and the thermo-mechanical behavior of shape memory polymers.