Global ETD Search

1	The Application of Origami to the Design of Lamina Emergent Mechanisms (LEMs) with Extensions to Collapsible, Compliant and Flat-Folding Mechanisms Greenberg, Holly 30 April 2012 (has links) (PDF) Lamina emergent mechanisms (LEMs) are a subset of compliant mechanisms which are fabricated from planar materials; use compliance, or flexibility of the material, to transfer energy; and have motion that emerges out of the fabrication plane. LEMs provide potential design advantages by reducing the number of parts, reducing cost, reducing weight, improving recyclability, increasing precision, and eliminating assembly, to name a few. However, there are inherent design and modeling challenges including complexities in large, non-linear deflections, singularities that exist when leaving the planar state, and the coupling of material properties and geometry in predicting mechanism behavior. This thesis examines the planar and spherical LEMs and their relation to origami. Origami, the art of paper folding, is used to better understand spherical LEMs and flat-folding mechanisms in general. All single-layer planar four-bar LEMs are given with their respective layouts. These are all change-point pinned mechanisms (i.e. no slider cranks). Graph representations are used to show the similarities between action origami and mechanisms. Origami principles of flat-folding are shown to be analogous to principles of mechanisms including rules for assembly and motion. origami compliant mechanism lamina emergent mechanism Mechanical Engineering
2	Evaluation and Development of Actuators for Lamina Emergent Mechanisms with Emphasis on Flat Solenoids Black, Justin Durant 24 April 2012 (has links) (PDF) Lamina emergent mechanisms (LEMs) can provide a way to meet the demand for more compact and inexpensive mechanisms. Previous research has developed LEM designs and identified applications for them, but many applications would benefit from suitable actuation techniques. This thesis presents the design considerations and a variety of applicable methods for internal and external LEM actuation in the macro scale. Integrated LEM actuator possibilities have been identified, each with its advantages and disadvantages depending on the application. Shape memory alloys are especially compatible with LEMs. Traditional actuators have also been discussed as a way of actuating a LEM from the outside for cases in which space constraints allow it. The feasibility of new internal actuators using basic actuation principles, especially flat solenoids, has been explored. The magnetic field distribution along the axis of a high-aspect-ratio solenoid has been derived. Analytical and experimental results show that the output force of a high-aspect-ratio solenoid is suitable for LEMs. A pseudo-solenoid conceptual prototype was manufactured and evaluated, revealing challenges for which solutions have been recommended. Justin Black lamina emergent mechanism compliant mechanism flat integrated actuator actuation solenoid pseudo-coil Mechanical Engineering
3	Compliant Joints Suitable for Use as Surrogate Folds Delimont, Isaac L. 25 August 2014 (has links) (PDF) Origami-inspired design is an emerging field capable of producing compact and efficient designs. The object of a surrogate fold is to provide a fold-like motion in a non-paper material without undergoing yielding. Compliant mechanisms provide a means to achieve these objectives as large deflections are achieved. The purpose of this thesis is to present a summary of existing compliant joints suitable for use as surrogate folds. In doing so, motions are characterized which no existing compliant joint provides. A series of compliant joints is proposed which provides many of these motions. The possibility of patterning compliant joints to form an array is discussed. Arrays capable of producing interesting motions are noted. compliant mechanisms origami-inspired design surrogate folds flexible hinge monolithic hinge lamina emergent mechanism Mechanical Engineering
4	Fundamental Components for Lamina Emergent Mechanisms Jacobsen, Joseph O. 22 February 2008 (has links) (PDF) This thesis introduces lamina emergent mechanisms (LEMs) and presents components that can be used as building blocks to create LEMs capable of more complex motion. As the name suggests, lamina emergent mechanisms are fabricated out of planar materials (the lamina) but their motion is out of that plane (emergent). Lamina emergent mechanisms can provide benefits that include reduced manufacturing costs and minimal volume when in the planar state. The compact initial state of LEMs is beneficial in reducing shipping costs, especially in volume critical applications. LEMs also exhibit the potential benefits of compliant mechanisms, namely increased precision, reduced weight, reduced wear, and part count reduction. The LEM components presented in this thesis include flexible segments, fundamental mechanisms, and a new complaint joint, the lamina emergent torsional (LET) Joint. The flexible segments are developed through changes in geometry, boundary/loading conditions, and material. The fundamental mechanisms presented have motion similar to planar change-point four-bar and six-bar mechanisms, and spherical change-point mechanisms. The LET Joint is presented as a compliant joint suited for applications where large angular rotation is desired, but high off-axis stiffness is not as critical. The joint is introduced and the equations necessary for determining the force-deflection characteristics and stress are presented. Since the LET Joint can be fabricated from a single planar layer, it is well suited for macro and micro applications. Illustrative examples of the LET Joint are provided with devices fabricated from materials as diverse as steel, polypropylene, and polycrystalline silicon. compliant mechanism lamina emergent mechanism torsional hinge lamina emergent torsional (LET) joint planar fabrication ortho-planar mechanism Mechanical Engineering
5	Design Principles and Preliminary Actuation Approaches for Novel Multiple-Layer Lamina Emergent Mechanisms Gollnick, Paul Shumway 13 October 2010 (has links) (PDF) Multiple-layer Lamina Emergent Mechanisms (MLEMs) are mechanisms made from multiple sheets (lamina) of material with motion that emerges out of the fabrication plane. This study has shown that understanding how layers are used in existing products and in nature provides insight into how MLEMs can also use layers to achieve certain tasks. The multi-layered nature of MLEMs and the interactions between these layers are what enhance the capabilities of MLEMs and allow them to better meet design objectives. Layer separation is one objective for which MLEMs are well-suited. Layer separation can have a variety of applications and there are a number of different ways to design a MLEM to achieve this objective. Single-layer LEM and MLEM designs could greatly benefit from suitable actuation techniques; those that are consistent with the advantages of these mechanisms and could be incorporated into their design. This work presents shape memory alloys, piezoelectrics and dielectric elastomers as suitable ways of actuating LEMs and MLEMs. A number of novel MLEMs are presented throughout this thesis. Paul Gollnick multi-layer multiple-layer lamina emergent mechanism lamina emergent mechanism LEM MLEM actuation layer separation Mechanical Engineering
6	Achieving Complex Motion with Fundamental Components for Lamina Emergent Mechanisms Winder, Brian Geoffrey 01 March 2008 (has links) (PDF) Designing mechanical products in a competitive environment can present unique challenges, and designers constantly search for innovative ways to increase efficiency. One way to save space and reduce cost is to use ortho-planar compliant mechanisms which can be made from sheets of material, or lamina emergent mechanisms (LEMs). This thesis presents principles which can be used for designing LEMs. Pop-up paper mechanisms use topologies similar to LEMs, so it is advantageous to study their kinematics. This thesis outlines the use of planar and spherical kinematics to model commonly used pop-up paper mechanisms. A survey of common joint types is given, as well as an overview of common monolithic and layered mechanisms. In addition, it is shown that more complex mechanisms may be created by combining simple mechanisms in various ways. The principles presented are applied to the creation of new pop-up joints and mechanisms, which also may be used for lamina emergent mechanisms. Models of the paper mechanisms presented in Chapter 2 of the thesis are found in the appendix, and the reader is encouraged to print, cut out and assemble them. One challenge associated with spherical and spatial LEM design is creating joints with the desired motion characteristics, especially where complex spatial mechanism topologies are required. Hence, in addition to a study of paper mechanisms, some important considerations for designing joints for LEMs are presented. A technique commonly used in robotics, using serial chains of revolute and prismatic joints to approximate the motion of complex joints, is presented for use in LEMs. Important considerations such as linkage configuration and mechanism prototyping are also discussed. Another challenge in designing LEMs is creating multi-stable mechanisms with the ability to have coplanar links. A method is presented for offsetting the joint axes of a spatial compliant mechanism to introduce multi-stability. A new bistable spatial compliant linkage that uses that technique is introduced. In the interest of facilitating LEM design, the final chapter of this thesis presents a preliminary design method. While similar to traditional methods, this method includes considerations for translating the mechanism topology into a suitable configuration for use with planar layers of material. paper mechanism pop-up popup pop up mechanism linkage paper engineering paper crafts origami kinematics spatial mechanism planar mechanism bistable multi-stable spherical mechanism ortho-planar compliant PRBM pseudo-rigid-body model Lamina Emergent Mechanism LEM sheet goods planar layer complex joint elemental joint spatial joint degrees of freedom mechanism modeling mechanism design serial joint chain parallel series fundamental components complex motion revolute prismatic spherical cylindric universal half planar RSSR RCCC RSRC RTRT Altmann Bricard Bennett Goldberg 6R 4R joint axis angular offset paper joint V-fold circular arch figure-8 single slit double slit tube strap arch knee mechanism 45 degree fold solid shape floating layer tent Mechanical Engineering

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