A Pseudo Rigid Body Model of a Single Vertex Compliant-Facet Origami Mechanism (SV-COFOM)

2016 ◽  
Author(s):  
Jelle Rommers ◽  
Giuseppe Radaelli ◽  
Just Herder
Keyword(s):  
Rigid Body ◽  
Computational Cost ◽  
Element Model ◽  
Design Tool ◽  
Single Vertex ◽  
Starting Point ◽  
Rigid Body Model ◽  
Cost Efficient ◽  
The Moment ◽  
Planar Fabrication

Recently, there has been an increased interest in origami art from a mechanism design perspective. The deployable nature and the planar fabrication method inherent to origami provide potential for space and cost efficient mechanisms. In this paper, a novel type of origami mechanisms is proposed in which the compliance of the facets is used to incorporate spring behavior: Compliant Facet Origami Mechanisms (COFOMs). A simple model that computes the moment characteristic of a Single Vertex COFOM has been proposed, using a semi-spatial version of the Pseudo-Rigid Body (PRB) theory to model bending of the facets. The performance of this PRB model has been evaluated numerically and experimentally, and showed performance comparable to a Finite Element model with 122 elements. The PRB model is a potential starting point for a design tool which would provide an intuitive way of designing this type of mechanisms including their spring behavior, with very low computational cost.

Pseudo-Rigid-Body Modeling of a Single Vertex Compliant-Facet Origami Mechanism

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
Jelle Rommers ◽  
Giuseppe Radaelli ◽  
Just L. Herder
Keyword(s):  
Rigid Body ◽  
Computational Cost ◽  
Design Tool ◽  
Single Vertex ◽  
Starting Point ◽  
Cost Efficient ◽  
The Moment ◽  
Planar Fabrication ◽  
Efficient Mechanisms ◽  
Low Computational Cost

Recently, there has been an increased interest in origami art from a mechanism design perspective. The deployable nature and the planar fabrication method inherent to origami provide potential for space and cost-efficient mechanisms. In this paper, a novel type of origami mechanisms is proposed in which the compliance of the facets is used to incorporate the spring behavior: compliant facet origami mechanisms (COFOMs). A simple model that computes the moment characteristic of a single vertex COFOM has been proposed, using a semispatial version of the pseudo-rigid-body (PRB) theory to model bending of the facets. The PRB model has been evaluated numerically and experimentally, showing good performance. The PRB model is a potential starting point for a design tool which would provide an intuitive way of designing this type of mechanisms including their spring behavior, with very low computational cost.

Synthesis Methods in Compliant Mechanisms: An Overview

2009 ◽  
Author(s):  
Juan A. Gallego ◽  
Just Herder
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Design Methods ◽  
Synthesis Methods ◽  
Starting Point ◽  
Rigid Body Model ◽  
Wide Perspective ◽  
Conceptual Overview ◽  
Compliant Mechanism Design

Compliant mechanisms are rapidly gaining importance, yet their design remains challenging. A great variety of methods are being developed as it is reported in a growing stream of publications. However, so far no review of this body of literature is available. This paper provides a comprehensive and conceptual overview of the main notions behind the most relevant design methods for compliant mechanisms. Rigid-Body-Replacement methods including the Pseudo-Rigid-Body model and the FACT approach are covered, as well as Building Block approaches. In addition an introduction and explanation on Topology Optimization and Shape Optimization is provided, including their most common parameterizations and formulations. This work aims to serve as an introduction into compliant mechanism design methods and as a reference work for more experienced scholars and professionals. It is intended to be a starting point for the exploration of the literature, as well as a guide to specific papers about a particular design problem one may have. For this reason, the paper presents the methods in a wide perspective, emphasizing the conceptual ideas behind every method and refers to literature for details and advanced features.

A Design Tool for a Single Vertex Compliant-Facet Origami Mechanism Including Torsional Hinge Lines

2017 ◽  
Vol 9 (6) ◽  
Author(s):  
Jelle Rommers ◽  
Giuseppe Radaelli ◽  
Just L. Herder
Keyword(s):  
Mean Squared Error ◽  
Design Tool ◽  
Torsional Stiffness ◽  
Moment Curve ◽  
Single Vertex ◽  
Squared Error ◽  
Design Variables ◽  
The Moment ◽  
And Robotics ◽  
Constant Moment

Principles from origami art are applied in the design of mechanisms and robotics increasingly frequent. A large part of the application driven research of these origami-like mechanisms focuses on devices where the creases (hinge lines) are actuated and the facets are constructed as stiff elements. In this paper, a design tool is proposed in which hinge lines with torsional stiffness and flexible facets are used to design passive, instead of active mechanisms. The design tool is an extension of a model of a single vertex compliant facet origami mechanism (SV-COFOM) and is used to approximate a desired moment curve by optimizing the design variables of the mechanism. Three example designs are presented: a constant moment joint (CMJ), a gravity compensating joint (GCJ) and a zero moment joint (ZMJ). The CMJ design has been evaluated experimentally, resulting in a root-mean-squared error (RMSE) of 6.4 × 10−2 N·m on a constant moment value of 0.39 N·m. This indicates that the design tool is suitable for a course estimation of the moment curve of the SV-COFOM in early stages of a design process.

Coupled-Field Analysis of the Compliant Slider Mechanism with Rectangle Flexure Hinges Based on ANSYS

2011 ◽  
Vol 189-193 ◽  
pp. 1897-1900
Author(s):  
Lei Duan ◽  
Li Fang Qiu ◽  
Hai Shan Weng ◽  
Zhi Yong Xie
Keyword(s):  
Finite Element ◽  
Rigid Body ◽  
Element Model ◽  
Field Analysis ◽  
Flexure Hinges ◽  
Body Model ◽  
Coupled Field ◽  
Rigid Body Model ◽  
Relationship Of ◽  
The Relationship

The compliant slider mechanism with rectangle flexure hinges was designed, and its pseudo-rigid-body model was built. The theoretical value of the relationship between force and displacement was given after analysis; the electrostatic-structural-coupled field finite element model of this mechanism was also built and analyzed by ANSYS, and the simulation value of the relationship between voltage and displacement was obtained; According to the relationship of voltage and force, the theoretical value was compared with the simulation value. The result indicates that the model is valid and the analysis is correct.

scholarly journals Influence of External Factors on Airborne Missile’s Horizontal Backward Launching

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xiao Pan ◽  
Yi Jiang ◽  
Dong Hu ◽  
Huihui Guan
Keyword(s):  
Finite Element ◽  
Rigid Body ◽  
Pitch Angle ◽  
Random Vibration ◽  
Element Model ◽  
Body Model ◽  
Ejection Force ◽  
Ejection Process ◽  
Rigid Body Model ◽  
The Finite Element Model

This paper studies the influence of different external disturbance factors on the horizontal backward separation of airborne missiles on large transport aircraft. The method of comparison with experiment was adopted to verify the accuracy of the finite element model during the ejection process. By comparing the finite element model, it was confirmed that the all rigid body model and partly rigid body model are inaccurate in calculating the pitch angle and pitch velocity of the missile separation. Finally, the influences of ejection force, random vibration, and missile loading position on the ejection process are analyzed. The analysis found that the ejection force and the sliding distance will increase the vibration of the launching platform, therefore increase the separation pitch angle and the pitch velocity of the missile, but the influence of random vibration on platform is much greater than the other two factors, and it will also introduce randomness into the movement of the missile.

Moment-Dependent Pseudo-Rigid-Body Models for Straight Beams

2010 ◽  
Author(s):  
Diego A. Espinosa ◽  
Craig P. Lusk
Keyword(s):  
Rigid Body ◽  
Rational Function ◽  
Statistical Significance ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Beam Model ◽  
Characteristic Radius ◽  
Rigid Body Model ◽  
The Moment ◽  
Key Parameter

This paper introduces a parametric beam model for describing the kinematics and elastic properties of ortho-planar compliant beams subject to specific buckling loads. This model uses an approach similar to the Pseudo-Rigid-Body Model but differs that in a key parameter, the characteristic radius factor, is not a constant, but a rational function of the moment. The rational function coefficients are determined by least squares, along with the statistical significance of the coefficients. Results are calculated for straight beams for two cases: a vertical displacement and a horizontal displacement.

An Energy Approach to a 2DOF Compliant Parallel Mechanism With Self-Guiding Statically-Balanced Straight-Line Behavior

2010 ◽  
Author(s):  
Emile J. Rosenberg ◽  
Giuseppe Radaelli ◽  
Just L. Herder
Keyword(s):  
Structural Design ◽  
Compliant Mechanisms ◽  
Element Model ◽  
Energy Approach ◽  
Straight Line ◽  
Synthesis Tool ◽  
Rigid Body Model ◽  
Physical Prototype ◽  
Manufacturing Techniques ◽  
Cost Efficient

This paper presents a novel straight-line self-guiding statically-balanced mechanism which reflects on the advantages of lumped compliant mechanisms. The forthcoming structural design is conceived with an energy approach for static balancing of mechanisms. In this paper the application and effectiveness of the energy approach as a synthesis tool is validated. Moreover the paper demonstrates the translation from pseudo-rigid body model to lumped compliance in statically-balanced mechanisms. A physical prototype and a finite-element model served to evaluate the conceptual design. Manufacturing techniques are suggested for rapid, light-weight and cost-efficient prototyping. The presented self-guiding mechanism is statically-balanced along its straight-line range of motion while showing stable behavior in other directions.

L’absence chez Michel Butor. L’Emploi du temps et Degrés

2012 ◽  
pp. 66-80
Author(s):  
Michał Mrozowicki
Keyword(s):  
Human Memory ◽  
Point Of View ◽  
Narrative Discourse ◽  
The Novel ◽  
Michel Butor ◽  
Starting Point ◽  
One Year ◽  
The Moment ◽  
Narrative Mode ◽  
The City

Michel Butor, born in 1926, one of the leaders of the French New Novel movement, has written only four novels between 1954 and 1960. The most famous of them is La Modification (Second thoughts), published in 1957. The author of the paper analyzes two other Butor’s novels: L’Emploi du temps (Passing time) – 1956, and Degrés (Degrees) – 1960. The theme of absence is crucial in both of them. In the former, the novel, presented as the diary of Jacques Revel, a young Frenchman spending a year in Bleston (a fictitious English city vaguely similar to Manchester), describes the narrator’s struggle to survive in a double – spatial and temporal – labyrinth. The first of them, formed by Bleston’s streets, squares and parks, is symbolized by the City plan. During his one year sojourn in the city, using its plan, Revel learns patiently how to move in its different districts, and in its strange labyrinth – strange because devoid any centre – that at the end stops annoying him. The other, the temporal one, symbolized by the diary itself, the labyrinth of the human memory, discovered by the narrator rather lately, somewhere in the middle of the year passed in Bleston, becomes, by contrast, more and more dense and complex, which is reflected by an increasinly complex narration used to describe the past. However, at the moment Revel is leaving the city, he is still unable to recall and to describe the events of the 29th of February 1952. This gap, this absence, symbolizes his defeat as the narrator, and, in the same time, the human memory’s limits. In Degrees temporal and spatial structures are also very important. This time round, however, the problems of the narration itself, become predominant. Considered from this point of view, the novel announces Gerard Genette’s work Narrative Discourse and his theoretical discussion of two narratological categories: narrative voice and narrative mode. Having transgressed his narrative competences, Pierre Vernier, the narrator of the first and the second parts of the novel, who, taking as a starting point, a complete account of one hour at school, tries to describe the whole world and various aspects of the human civilization for the benefit of his nephew, Pierre Eller, must fail and disappear, as the narrator, from the third part, which is narrated by another narrator, less audacious and more credible.

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