Differentiating Bending From Folding in Origami Engineering Using Active Materials

Abstract

Origami engineering — the use of origami principles in engineering applications — provides numerous opportunities to revolutionize the way we design, manufacture, assemble, and package products and devices. By combining origami principles with active materials, we can create reconfigurable products and devices that can fold and unfold on demand. In origami, the folded medium is paper, yet many engineering applications require materials with finite thickness to provide the necessary strength and stiffness to achieve the desired functionality. In such applications, it is important to distinguish between bending and folding so that we understand the differences in material behavior when actuated. In this paper, we propose definitions for bending and folding for materials used in engineering applications. The literature is reviewed in detail to provide context and support for the proposed definitions, and examples from our own research with active materials, specifically, magneto-active elastomers (MAE) and dielectric elastomers (DE), are used to illustrate the subtle, yet important, differences between bending and folding in materials with finite thickness.

“2D or not 2D”: Shape-programming polymer sheets

“…Several recent publications discuss the difference between bending and folding in shape programming materials. [1][2][3][4][5] Simply stated, folding involves localized deformation whereas bending is global.…”

Origami tubes assembled into stiff, yet reconfigurable structures and metamaterials

“…The model is made scalable and incorporates thickness (t = 0.01), Young's modulus (E = 10 6 ), Poisson's ratio (ν = 1=4), and density (ρ = 1) of the material (32). A parameter, R FP = 1=10, relates fold line bending to panel bending stiffness and can vary greatly, depending on the materials, the fabrication technique, and the actuation process (33)(34)(35)(36). Using a sensitivity analysis in SI Text, section S3 and Fig.…”

Composite Reinforcement Architectures: A Review of Field-Assisted Additive Manufacturing for Polymers

“…4D printed structures, soft robots and actuators and other biomimetic shape morphing systems could also take advantage of field-assisted AM for control [13,[89][90][91]. Other promising research has shown improved mechanical properties such as strength, stiffness, fracture toughness, and damping in composites with the inclusion of non-structural functions in the form of electrical and/or thermal conductivity, sensing and actuation, energy harvesting/storage, self-healing capability, electromagnetic interference (EMI) shielding, recyclability and biodegradability, in order to produce a multifunctional composite structure [136][137][138][139][140][141]. Another important application of polymer composites where electrical conductivity is required is in aircraft structures, where non-conducting structures may be damaged by lightning strikes.…”