225 research outputs found

    A Foundation for Analysis of Spherical System Linkages Inspired by Origami and Kinematic Paper Art

    Get PDF
    Origami and its related fields of paper art are known to map to mechanisms, permitting kinematic analysis. Many origami folds have been studied in the context of engineering applications, but a sufficient foundation of principles of the underlying class of mechanism has not been developed. In this work, the mechanisms underlying paper art are identified as “spherical system linkages” and are studied in the context of generic mobility analysis with the goal of establishing a foundation upon which future work can develop.Spherical systems consist of coupled spherical and planar loops, and they motivate a reclassification of mechanisms based on the Chebyshev-GrĂŒbler-Kutzbach framework. Spherical systems are capable of complex, closed-loop motion in 3D space despite the mobility calculation treating the links as constrained to a single 2D surface. This property permits generalization of some multi-loop planar mechanisms, such as the Watt mechanism, to a generalized 3D form with equal mobility. A minimal connectivity graph representation of spherical systems is developed, and generic mobility equations are identified. Spherical system linkages are generalized further into spherical/spatial hybrid mechanisms which may have any combination of spherical, planar, and spatial loops. These are represented and analyzed with a polyhedron model. The connectivity graph is modified for this case and appropriate generic mobility equations are identified and adapted.The generic analyses developed for spherical system linkages are sufficient to inform an exhaustive type synthesis process. Generation of all configurations of a paper art inspired mechanism subject to constraints is discussed, and a case study generates all configurations of a spatial chain using specified link types. This design process is enabled by the developed notation and analyses, which are used to identify, depict, and classify kinematic paper art inspired mechanisms

    Kinetic Solar Skin: A Responsive Folding Technique

    Get PDF
    The paper focuses on optimized movements analysed by means of Origami, the Japanese traditional art of paper folding. The study is a way to achieve different deployable shading systems categorized by a series of parameters that describe the strengths and weaknesses of each tessellation. Through the kinetic behaviour of Origami geometries the research compares simple folding diagrams with the purpose to understand the deployment at global scale and thus the potential of kinetic patterns’ morphology for application in adaptive facades. The possibilities of using a responsive folding technique to develop a kinetic surface that can change its configuration are here examined through the variation of parameters that influence kinematics’ form. Moreover, in order to perform the shape change without any external mechanical devices, the use of Shape Memory Alloy (SMA) actuators has been tested

    A research on a reconfigurable hypar structure for architectural applications

    Get PDF
    Thesis (Master)--Ä°zmir Institute of Technology, Architecture, Ä°zmir, 2013Includes bibliographical references (leaves: 102-108)Text in English; Abstract: Turkish and Englishxii, 108 leavesKinetic design strategy is a way to obtain remarkable applications in architecture. These kinetic designs can offer more advantages compared to conventional ones. Basic knowledge of different disciplines is necessary to generate kinetic designs. In other words, interdisciplinary studies are critical. Therefore, architect's knowledge must be wide-ranging in order to increase novel design approaches and applications. The resulting rich hybrid products increase the potential of the disciplines individually. Research on kinetic structures shows that the majority of kinetic structures are deployable. However, deployable structures can only be transformed from a closed compact configuration to a predetermined expanded form. The motivation of the present dissertation is generating a novel 2 DOF 8R reconfigurable structure which can meet different hyperbolic paraboloid surfaces for architectural applications. In order to obtain this novel structure; the integration between the mechanism science and architecture is essential. The term reconfigurable will be used in the present dissertation to describe deployable structures with various configurations. The novel reconfigurable design utilizes the overconstrained Bennett linkage and the production principals of ruled surfaces. The dissertation begins with a brief summary of deployable structures to show their shortcomings and their lack of form flexibility. Afterward, curved surfaces, basic terms in mechanisms and overconstrained mechanisms were investigated. Finally, a proposed novel mechanism which is inspired from the basic design principles of Bennett linkage and the fundamentals of ruled surfaces are explained with the help of kinematic diagrams and models

    Algorithmic Spatial Form-Finding of Four-Fold Origami Structures Based on Mountain-Valley Assignments

    Get PDF
    AbstractOrigami has attracted tremendous attention in recent years owing to its capability of inspiring and enabling the design and development of reconfigurable structures and mechanisms for applications in various fields such as robotics and biomedical engineering. The vast majority of origami structures are folded starting from an initial two-dimensional crease pattern. However, in general, the planar configuration of such a crease pattern is in a singular state when the origami starts to fold. Such a singular state results in different motion possibilities of rigid or non-rigid folding. Thus, planar origami patterns cannot act as reliable initial configurations for further kinematic or structural analyses. To avoid the singularities of planar states and achieve reliable structural configurations during folding, we introduce a nonlinear prediction–correction method and present a spatial form-finding algorithm for four-fold origami. In this approach, first, initial nodal displacements are predicted based on the mountain-valley assignments of the given origami pattern, which are applied to vertices to form an initial spatial and defective origami model. Subsequently, corrections of nodal displacements are iteratively performed on the defective model until a satisfactory nonplanar configuration is obtained. Numerical experiments demonstrate the performance of the proposed algorithm in the form-finding of both trivial and non-trivial four-fold origami tessellations. The obtained configurations can be effectively utilized for further kinematic and structural analyses. Additionally, it has been verified that corrected and nonplanar configurations are superior to initial configurations in terms of matrix distribution and structural stiffness.</jats:p

    Tailoring stiffness of deployable origami structures

    Get PDF
    Origami has gained popularity in science and engineering because a compactly stowed system can be folded into a transformable 3D structure with increased functionality. Origami can also be reconfigured and programmed to change shape, function, and mechanical properties. In this thesis, we explore origami from structural and stiffness perspectives, and in particular we study how geometry affects origami behavior and characteristics. Understanding origami from a structural standpoint can allow for conceptualizing and designing feasible applications in all scales and disciplines of engineering. We improve, verify, and test a bar and hinge model that can analyze the elastic stiffness, and estimate deformed shapes of origami. The model simulates three distinct behaviors: stretching and shearing of thin sheet panels; bending of the flat panels; and bending along prescribed fold lines. We explore the influence of panel geometry on origami stiffness, and provide a study on fold line stiffness characteristics. The model formulation incorporates material characteristics and provides scalable, and isotopic behavior. It is useful for practical problems such as optimization and parametrization of geometric origami variations. We explore the stiffness of tubular origami structures based on the Miura-ori folding pattern. A unique orientation for zipper coupling of rigidly foldable origami tubes substantially increases stiffness in higher order modes and permits only one flexible motion through which the structure can deploy. Deployment is permitted by localized bending along folds lines, however other deformations are over-constrained and engage the origami sheets in tension and compression. Furthermore, we couple compatible origami tubes into a variety of cellular assemblages that can enhance mechanical characteristics and geometric versatility. Practical applications such as deployable slabs, roofs, and arches are also explored. Finally, we introduce origami tubes with polygonal cross-sections that can reconfigure into numerous geometries. The tubular structures satisfy the mathematical definitions for flat and rigid foldability, meaning that they can fully unfold from a flattened state with deformations occurring only at the fold lines. From a global viewpoint, the tubes do not need to be straight, and can be constructed to follow a non-linear curved line when deployed. From a local viewpoint, their cross-sections and kinematics can be reprogrammed by changing the direction of folding at some folds

    Uncovering the Nonlinear Dynamics of Origami Folding

    Get PDF
    Origami, the ancient art of paper folding, has found lots of different applications in various branches of science, including engineering. However, most of the studies on engineering applications of origami have been limited to static or quasistatic applications. Origami folding, on the other hand, could be a dynamic process. The intricate nonlinear elastic properties of origami structures can lead to interesting dynamic characteristics and applications. Nevertheless, studying the dynamics of folding is still a nascent field. In this dissertation, we try to expand our knowledge of fundamentals of origami folding dynamics. We look at the problem of origami folding dynamics from two different perspectives: 1) How can we utilize folding-induced mechanical properties for dynamic applications? and 2) How can we fold origami structures using dynamic excitations? In order to answer these questions, we conduct three different projects. Regarding the first perspective, we study a unique asymmetric quasi-zero stiffness (QZS) property from the pressurized fluidic origami cellular structure, and examine the feasibility and efficiency of using this nonlinear property for low-frequency vibration isolation. In another project, we analyze the feasibility of utilizing origami folding techniques to create an optimized jumping mechanism. And finally, regarding the second perspective, we examine a rapid and reversible origami folding method by exploiting a combination of resonance excitation, asymmetric multi-stability, and active control. In addition to these studies, Witnessing the rich and nonlinear dynamic characteristics of origami structures, in this dissertation we introduce the idea of using origami structures as physical reservoir computing systems and investigate their potentials in sensing and signal processing tasks without relying on external digital components and signal processing units

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

    Get PDF
    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
    • 

    corecore