Architected Origami Materials: How Folding Creates Sophisticated Mechanical Properties

Origami, the ancient Japanese art of paper folding, is not only an inspiring technique to create sophisticated shapes, but also a surprisingly powerful method to induce nonlinear mechanical properties. Over the last decade, advances in crease design, mechanics modeling, and scalable fabrication have fostered the rapid emergence of architected origami materials. These materials typically consist of folded origami sheets or modules with intricate 3D geometries, and feature many unique and desirable material properties like auxetics, tunable nonlinear stiffness, multistability, and impact absorption. Rich designs in origami offer great freedom to design the performance of such origami materials, and folding offers a unique opportunity to efficiently fabricate these materials at vastly different sizes. Here, recent studies on the different aspects of origami materialsâ geometric design, mechanics analysis, achieved properties, and fabrication techniquesâ are highlighted and the challenges ahead discussed. The synergies between these different aspects will continue to mature and flourish this promising field.Origami, the ancient art of paper folding, has become a framework of designing and constructing architected materials. These materials consist of folded sheets or modules with intricate geometries, and feature many unique and desirable mechanical properties. Recent progress in architected origami materials is highlighted, especially the foldingâ induced mechanics, and the challenges ahead are discussed.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147779/1/adma201805282_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147779/2/adma201805282.pd

Rigid Foldability of Generalized Triangle Twist Origami Pattern and Its Derived 6R Linkages

Rigid origami is a restrictive form of origami that permits continuous motion between folded and unfolded states along the predetermined creases without stretching or bending of the facets. It has great potential in engineering applications, such as foldable structures that consist of rigid materials. The rigid foldability is an important characteristic of an origami pattern, which is determined by both the geometrical parameters and the mountain-valley crease (M-V) assignments. In this paper, we present a systematic method to analyze the rigid foldability and motion of the generalized triangle twist origami pattern using the kinematic equivalence between the rigid origami and the spherical linkages. All schemes of M-V assignment are derived based on the flat-foldable conditions among which rigidly foldable ones are identified. Moreover, a new type of overconstrained 6R linkage and a variation of doubly collapsible octahedral Bricard are developed by applying kirigami technique to the rigidly foldable pattern without changing its degree-of-freedom. The proposed method opens up a new way to generate spatial overconstrained linkages from the network of spherical linkages. It can be readily extended to other types of origami patterns

Developing Design and Analysis Framework for Hybrid Mechanical-Digital Control of Soft Robots: from Mechanics-Based Motion Sequencing to Physical Reservoir Computing

The recent advances in the field of soft robotics have made autonomous soft robots working in unstructured dynamic environments a close reality. These soft robots can potentially collaborate with humans without causing any harm, they can handle fragile objects safely, perform delicate surgeries inside body, etc. In our research we focus on origami based compliant mechanisms, that can be used as soft robotic skeleton. Origami mechanisms are inherently compliant, lightweight, compact, and possess unique mechanical properties such as– multi-stability, nonlinear dynamics, etc. Researchers have shown that multi-stable mechanisms have applications in motion-sequencing applications. Additionally, the nonlinear dynamic properties of origami and other soft, compliant mechanisms are shown to be useful for ‘morphological computation’ in which the body of the robot itself takes part in performing complex computations required for its control. In our research we demonstrate the motion-sequencing capability of multi-stable mechanisms through the example of bistable Kresling origami robot that is capable of peristaltic locomotion. Through careful theoretical analysis and thorough experiments, we show that we can harness multistability embedded in the origami robotic skeleton for generating actuation cycle of a peristaltic-like locomotion gait. The salient feature of this compliant robot is that we need only a single linear actuator to control the total length of the robot, and the snap-through actions generated during this motion autonomously change the individual segment lengths that lead to earthworm-like peristaltic locomotion gait. In effect, the motion-sequencing is hard-coded or embedded in the origami robot skeleton. This approach is expected to reduce the control requirement drastically as the robotic skeleton itself takes part in performing low-level control tasks. The soft robots that work in dynamic environments should be able to sense their surrounding and adapt their behavior autonomously to perform given tasks successfully. Thus, hard-coding a certain behavior as in motion-sequencing is not a viable option anymore. This led us to explore Physical Reservoir Computing (PRC), a computational framework that uses a physical body with nonlinear properties as a ‘dynamic reservoir’ for performing complex computations. The compliant robot ‘trained’ using this framework should be able to sense its surroundings and respond to them autonomously via an extensive network of sensor-actuator network embedded in robotic skeleton. We show for the first time through extensive numerical analysis that origami mechanisms can work as physical reservoirs. We also successfully demonstrate the emulation task using a Miura-ori based reservoir. The results of this work will pave the way for intelligently designed origami-based robots with embodied intelligence. These next generation of soft robots will be able to coordinate and modulate their activities autonomously such as switching locomotion gait and resisting external disturbances while navigating through unstructured environments

Designing Origami-Adapted Deployable Modules for Soft Continuum Arms

© Springer Nature Switzerland AG 2019. Origami has several attractive attributes including deployability and portability which have been extensively adapted in designs of robotic devices. Drawing inspiration from foldable origami structures, this paper presents an engineering design process for fast making deployable modules of soft continuum arms. The process is illustrated with an example which adapts a modified accordion fold pattern to a lightweight deployable module. Kinematic models of the four-sided Accordion fold pattern is explored in terms of mechanism theory. Taking account of both the kinematic model and the materials selection, a 2D flat sheet model of the four-sided Accordion fold pattern is obtained for 3D printing. Following the design process, the deployable module is then fabricated by laminating 3D printed origami skeleton and flexible thermoplastic polyurethane (TPU) coated fabric. Preliminary tests of the prototype shown that the folding motion are enabled mainly by the flexible fabric between the gaps of thick panels of the origami skeleton and matches the kinematic analysis. The proposed approach has advantages of quick scaling dimensions, cost effective and fast fabricating thus allowing adaptive design according to specific demands of various tasks

Mechanics Modeling of Non-rigid Origami: From Qualitative to Quantitative Accuracy

Origami, the ancient art of paper folding, has recently evolved into a design and fabrication framework for various engineering systems at vastly different scales: from large-scale deployable airframes to mesoscale biomedical devices to small-scale DNA machines. The increasingly diverse applications of origami require a better understanding of the fundamental mechanics and dynamics induced by folding. Therefore, formulating a high-fidelity simulation model for origami is crucial, especially when large amplitude deformation/rotation exists during folding. The currently available origami simulation models can be categorized into three branches: rigid-facet models, bar-hinge models, and finite element models. The first branch of models assumes that the origami facets are rigid panels and creases behaving like hinges. It is a powerful tool for kinematics analysis without unnecessary complexities. On the other hand, the bar-hinge models have become widely used for simulating nonrigid-foldable origamis. The basic idea of these models is to place stretchable bar elements along the creases and across facet diagonals, discretizing the continuous origami into a pin-jointed truss frame system. Therefore, one can analyze facet deformations, including in-plane shearing, out-of-plane bending, and twisting. Moreover, more complex crease deformations can also be captured by adding appropriate components to the bar-hinge models. Because of their simplicity and modeling capability, the bar-hinge models have been utilized with many successes in analyzing the global deformation of non-rigid origami and uncovering its mechanical principles. However, one can only achieve qualitatively accurate predictions of the bar-hinge models compared to the physical experiments, especially when complex deformation exists during origami folding. The third branch, finite element models, does not impose explicit simplification on the facet deformation using shell elements. It can accurately analyze the deformation modes of origami structures; however, their disadvantages are also evident. On the one hand, it requires a time-consuming cycle for both modeling and computing, including pre-processing and post-processing. On the other hand, the traditional shell element might experience convergence issues when large and dynamic rotations occur, as commonly observed in origami systems. This thesis investigates the mechanics modeling of non-rigid origami and proposes a new dynamic model based on Absolute Nodal Coordinate Formulation (ANCF hereafter). Firstly, we discuss the accuracy of the widely used bar-hinge model through a case study on the multi-stability behavior in a non-rigid stacked Miura-origami structure. The model successfully investigates the underpinning principles of the multi-stability behavior in non-rigid origami and finds the existence of asymmetric energy barriers for extension and compression by tailoring its crease stiffness and facet bending stiffness. This interesting phenomenon can be exploited to create a mechanical diode. Experiment results confirm the existence of asymmetric multi-stability; however, the model\u27s prediction is only qualitatively verified due to its assumption of discrete lattices. In the next part, we develop a new origami mechanics model based on ANCF, a powerful modeling tool for the nonlinear dynamic simulation of multibody systems with large rotation and deformation. The new model treats origami as ANCF thin plate elements rotating around compliant creases, and the so-called torsional spring damper connectors are developed and utilized to simulate crease folding. Finally, its modeling accuracy is experimentally validated through two case studies, including motion analysis of simple fold mechanism and dynamic deployment of Miura-ori structures. The new origami simulation model can be used to quantitatively predict the dynamic responses of non-rigid origami with complex deformations. It can help deepen our knowledge of folding-induced mechanics and dynamics and broaden the application of origami in science and engineering

Explicit kinematic equations for degree-4 rigid origami vertices, Euclidean and non-Euclidean

We derive algebraic equations for the folding angle relationships in completely general degree-4 rigid-foldable origami vertices, including both Euclidean (developable) and non-Euclidean cases. These equations in turn lead to elegant equations for the general developable degree-4 case. We compare our equations to previous results in the literature and provide two examples of how the equations can be used: in analyzing a family of square twist pouches with discrete configuration spaces, and for proving that a folding table design made with hyperbolic vertices has a single folding mode

From Folds to Structures, a Review

International audienceStarting from simple notions of paper folding, a review of current challenges regarding folds and structures is presented. A special focus is dedicated to folded tessellations which are raising interest from the scientific community. Finally, the different mechanical modeling of folded structures are investigated. This reveals efficient applications of folding concepts in the design of structures

Rigid-foldable cylindrical origami with tunable mechanical behaviors

Rigid-foldable origami shows significant promise in advanced engineering applications including deployable structures, aerospace engineering, and robotics. It undergoes deformation solely at the creases during the folding process while maintaining rigidity throughout all facets. However, most types of cylindrical origami, such as Kresling origami, water-bomb origami, and twisted tower origami, lack rigid-foldability. Although shape transformation can be achieved through elastic folding, their limited rigid foldability constrains their engineering applications. To address this limitation, we proposed a type of cylindrical origami inspired by Kresling origami, named foldable prism origami (FP-ori), in this paper. FP-ori possesses not only rigid-foldability but also several tunable properties, including flat-foldability, self-locking, and bistability. The geometric properties of FP-ori were analyzed and the relationship between different parameters and tunable mechanical behaviors were verified through finite element method simulations, as well as experiments using paper models. Furthermore, we proposed stacked structures composed of multiple cubic FP-ori units, the rotation directions of which could be controlled through the combination arrangement. And drawing inspiration from kirigami, a negative Poisson’s ratio tessellation structure was created. These results indicated that FP-ori has substantial potential for broad application in engineering fields