Session: SYMP 1-2: Shape Memory Polymers

Paper Number: 140423

140423 - Mechanical Properties of Self-Folding Polymer Miura Ori 

Large space structures enable the next generation of space exploration, but launching these large structures to orbit is challenging and expensive. This has been mitigated to a small degree by using folding or telescoping metal-based structures, but these approaches add weight and complexity with motors and other actuators. Origami presents a promising solution through its ability to form complex shapes from thin, flexible, lightweight sheets with limited added complexity. Herein, we investigate the feasibility of using self-folding Miura Ori in space environments for generating pre-defined geometries. Miura Ori is a form of origami that uses a repeated parallelogram unit cell fold pattern to form quasi-smooth two-dimensional (2D) or three-dimensional (3D) surfaces. A drawback to Miura Ori is that folding the tessellations manually is difficult and time-consuming. However, we have demonstrated the use of Shape Memory Polymers (SMPs) and localized heating to autonomously activate and control folding of thin sheets in a process called self-folding origami. For this, we use sheets of clear pre-strained polystyrene (Grafix® shrink film) as the SMP. We pattern sheets of SMPs on the top and bottom surface using a CNC machine  that has been modified to hold a marker. The CNC machine allows us to align fold patterns on both sides of the SMP sheet and obtain bi-directional folding. After patterning the sheet, we pre-heat the material close to the glass transition temperature (Tg) with a hot plate and expose the sample to infrared (IR) lights. The IR light is absorbed by the black ink, which creates gradients in temperature and shrinking to induce self-folding. The folded sheets have a much higher stiffness around the area of the fold. To better understand the use of SMP Miura Ori for forming large space structures, we aim to understand the mechanical properties of self-folded Miura Ori. We will determine the dependence of the final strength and stiffness of the shape on the unit cell size and shape, hinge line thickness, preheating temperature, and the time to fold the sample. In addition, this will allow us to investigate how well the sample folds as the geometry is scaled up and down. For each folded sample, we measure the mechanical properties using tension, compression, and bending tests. This research will allow us to advance the Technology Readiness Levels of SMPs set for self-folding Miura Ori for space applications, opening the gateway to forming more complex, lightweight space structures where the form is inherent to the function of the payload or space vehicle (i.e., telescopes, drag devices, solar arrays).

Presenting Author: Russell Mailen Auburn University

Presenting Author Biography: Russell Mailen is an assistant professor in the Department of Aerospace Engineering at Auburn University. He holds a B.S. in Aerospace Engineering (Kansas), a M.S. in Mechanical Engineering (Baylor), a Master of Materials Science and Engineering (MMSE North Carolina State University) and a Ph.D. in Mechanical Engineering (North Carolina State University). His research group at Auburn University, the Polymer Mechanics Research Laboratory, focuses on self-folding origami, mechanical metamaterials, and the characterization of smart and multifunctional materials.

Authors:

Cameron Cohen
Russell Mailen