Research

Our group focuses on studying the mechanics of folded thin-sheet structures at various scales. We study modeling techniques, fabrication methods, and unique mechanical behaviors of such structures. Here is a list of ongoing projects:

Ongoing Projects

(1) Functional Small Scale Actuators with Origami Inspired Structures

The small scale actuator project is funded by DARPA. In this project, our group is studying the potential of including origami inspired assemblages in the design of various MEMS (micro-electro-mechanical system) devices. The initial goal is to fabricate the folding device using combined PZT / Active Polymer system to complex assembling of intricate 3D structures. In this project, we have worked on developing simulation platforms for origami inspired micro-robots and fabrication techniques for bring these robots into reality. (More details on this project)

(2) Behavior of Curved-Crease Origami Structures

Curved-crease origami is a generalization of origami where the lines no longer need to be straight. By folding thin sheets about curved creases, three-dimensional shapes appear, and the sheets between creases form beautiful curved surfaces. This type of origami is understudied, but new ideas are emerging every day. Origami, in general, has three features that make it useful to structural engineers: (1) origami uses thin sheets which are lightweight and save material, (2) origami starts from flat sheets which can be easily stacked and shipped to construction sites, and (3) origami folds into three-dimensional shapes that can be exceptionally stronger than the flat sheets. Curved-crease origami adds several advantages to straight-crease origami. These advantages include: (1) the curved surfaces of curved-crease origami are aesthetically pleasing, (2) the curved surfaces give thin sheets much more stiffness than flat panels, (3) the curved surfaces have the potential for thermal or acoustic control, (4) curved creases offer more design freedom because the lines do not have to be straight, and (5) many more uses that researchers are discovering right now. (More details on this project)

 

(3) Using Tunable Origami for Active Energy Absorption

Energy absorption devices are widely used to mitigate damage from collisions and impact loads. Due to the inherent uncertainty of possible impact characteristics, passive energy absorbers with fixed mechanical properties are not capable of serving in different application scenarios. Therefore, origami-inspired structures, which possess the ability to reconfigure and deploy, are a qualified candidate for a novel active design. In this work, we apply the constrained zipper-coupled Miura-ori tubes (deployable and stiff after locking) as the basis to a tubular energy absorber. Numerical and experimental (static and dynamic) studies are performed to quantify the response of these novel structures. This work shows that the reconfigurable origami could change their stiffness and the total amount of energy they absorb. These behaviors are suitable for creating systems with on-demand properties that adapt to different impact scenarios. (More details on this project)

 

(4) Bistable Behavior of Oirigami Hypar

This project explores the mechanical behavior of the origami hyperbolic paraboloid (hypar). The hypar is created from a flat and developable sheet, however, when folded, it forms a bistable three dimensional structure resembling a hyperbolic paraboloid with non-zero Gaussian curvature. We have used experiments to evaluate the global and local behaviors of the structure, which are unique from other bistable origami systems. For the system to reconfigure between the two stable states, each crease first unfolds and then refolds into the new stable geometry. Our work shows that this bistable transition is also affected by stretching of the thin sheet, local buckling in the system, and nonlinear behaviors in the material. We have reinforced our understanding of the hypar behavior by establishing an analytical model that can simulate the kinematics, the buckling, and the force–displacement behavior of the structure. In addition to uncovering the mechanics of the hypar, we have also motivated the future adoption of these systems into functional and practical applications. Because hypars can be created from thin developable sheets, they are suitable for efficient manufacturing through flat patterning and self-assembly. The project has also explored topics for future extension and introduces hypar chains, where multiple hypars are connected in series to achieve multistability. (More details on this project)

 


Previous Projects:

(1) Origami inspired tubular structures

 

Prof. E.T. Filipov’s previous research on folded structures focuses on mechanics of origami tubular structures. This works studies the mechanics behind a stiff yet reconfigurable Zipper tube structure and demonstrates wide application potential of this structure. The work also proposed a polytube structure that can reconfigure and alter between different stable state. Finally, this work improves the bar and hinge simulation framework to study the behaviors of origami structures. (More details on this project)