Design of a Dielectric Elastomer Cylindrical Actuator With Quasi-Constant Available Thrust: Modeling Procedure and Experimental Validation

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Giovanni Berselli ◽  
Giovanni Scirè Mammano ◽  
Eugenio Dragoni
Keyword(s):  
Experimental Validation ◽  
Large Deflection ◽  
Analytical Procedure ◽  
Compliant Mechanisms ◽  
Elastic Beam ◽  
Dielectric Elastomer ◽  
Fe Analysis ◽  
Buckled Beam ◽  
Slender Beams ◽  
Novel Design

A novel design for a dielectric elastomer (DE) actuator is presented. The actuator is obtained by coupling a cylindrical DE film with a series of slender beams axially loaded beyond their buckling limit. Similar to previous published solutions, where different actuator geometries were coupled with compliant mechanisms of various topologies, the elastic beams are designed so as to provide a suitable compensating force that allows obtaining a quasi-constant available thrust along the entire actuator stroke. Whilst the elastic beam are sized on the basis of an analytical procedure, the overall system performance is evaluated by means of multiphysics finite element (FE) analysis, accounting for the large deflection of the buckled-beam springs (BBSs) and for the DE material hyperelasticity. Numerical and experimental results are finally provided, which demonstrate the prediction capabilities of the proposed modeling method and confirm that well-behaved cylindrical actuators can be conceived and produced.

Design and Modeling of a Dielectric Elastomer Cylindrical Actuator With Quasi-Constant Available Thrust

2013 ◽  
Author(s):  
Giovanni Berselli ◽  
Giovanni Scirè Mammano ◽  
Eugenio Dragoni
Keyword(s):  
Finite Element Analysis ◽  
System Performance ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Dielectric Elastomer ◽  
Constant Force ◽  
Element Analysis ◽  
Buckled Beam ◽  
Slender Beams ◽  
Novel Design

A novel design for a Dielectric Elastomer (DE) actuator is presented. The actuator is obtained by coupling a cylindrical DE film with a series of slender beams axially loaded beyond their buckling limit. Similarly to previous published solutions, where different actuator geometries were coupled with compliant mechanisms of various topologies, the elastic beams are designed so as to provide a suitable compensating force that allows obtaining a quasi-constant available thrust along the entire actuator stroke. The overall system performance are subsequently evaluated by means finite element analysis, accounting for the large deflection of the buckled-beam springs and for the DE material hyperelasticity. Final results confirm that compact and better behaved constant force cylindrical actuators can be obtained, which potentially outperform similar devices in terms of achievable stroke.

Modeling and Experimental Validation of Actuating a Bistable Buckled Beam Via Moment Input

2015 ◽  
Vol 82 (5) ◽  
Author(s):  
Jonathon Cleary ◽  
Hai-Jun Su
Keyword(s):  
Theoretical Model ◽  
Experimental Test ◽  
Experimental Validation ◽  
Stable Equilibrium ◽  
Compliant Mechanisms ◽  
Computational Tool ◽  
Specific Mechanism ◽  
Test Setup ◽  
Buckled Beams ◽  
Buckled Beam

Bistable mechanisms have two stable equilibrium positions separated by a higher energy unstable equilibrium position. They are well suited for microswitches, microrelays, and many other macro- and micro-applications. This paper discusses a bistable buckled beam actuated by a moment input. A theoretical model is developed for predicting the necessary input moment. A novel experimental test setup was created for experimental verification of the model. The results show that the theoretical model is able to predict the maximum necessary input moment within 2.53%. This theoretical model provides a guideline to design bistable compliant mechanisms and actuators. It is also a computational tool to size the dimensions of buckled beams for actuating a specific mechanism.

A Methodology for Compliant Mechanisms Design: Part I — Introduction and Large-Deflection Analysis

1992 ◽  
Author(s):  
A. Midha ◽  
I. Her ◽  
B. A. Salamon
Keyword(s):  
Large Deflection ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Companion Paper ◽  
Computational Techniques ◽  
Shooting Methods ◽  
Mechanism Synthesis ◽  
Calculation Algorithm ◽  
Deflection Analysis ◽  
Kinematic Properties

Abstract A broader research proposal seeks to systematically combine large-deflection mechanics of flexible elements with important kinematic considerations, in yielding compliant mechanisms which perform useful tasks. Specifically, the proposed design methodology will address the following needs: development of the necessary nomenclature, classification and definitions, and identification of the kinematic properties; categorization of mechanism synthesis types, both structurally as well as by function; development of efficient computational techniques for design; consideration of materials; and application and validation. Contained herein, in particular, is an introduction to the state-of-the-art in compliant mechanisms, and the development of an accurate chain calculation algorithm for use in the analysis of a large-deflection, cantilevered elastica. Shooting methods, which permit specification of additional boundary conditions on the elastica, as well as compliant mechanism examples are presented in a companion paper.

Evaluation of Equivalent Spring Stiffness for Use in a Pseudo-Rigid-Body Model of Large-Deflection Compliant Mechanisms

1994 ◽  
Author(s):  
Larry L. Howell ◽  
Ashok Midha
Keyword(s):  
Rigid Body ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Spring Stiffness ◽  
Model Concept ◽  
Analysis And Design ◽  
Body Model ◽  
Rigid Body Model ◽  
Body Joints

Abstract Compliant mechanisms gain some or all of their mobility from the flexibility of their members rather than from rigid-body joints only. More efficient and usable analysis and design techniques are needed before the advantages of compliant mechanisms can be fully utilized. In an earlier work, a pseudo-rigid-body model concept, corresponding to an end-loaded geometrically nonlinear, large-deflection beam, was developed to help fulfill this need. In this paper, the pseudo-rigid-body equivalent spring stiffness is investigated and new modeling equations are proposed. The result is a simplified method of modeling the force/deflection relationships of large-deflection members in compliant mechanisms. Flexible segments which maintain a constant end angle are discussed, and an example mechanism is analyzed. The resulting models are valuable in the visualization of the motion of large-deflection systems, as well as the quick and efficient evaluation and optimization of compliant mechanism designs.

Parametric Deflection Approximations for Initially Curved, Large-Deflection Beams in Compliant Mechanisms

1996 ◽  
Author(s):  
Larry L. Howell ◽  
Ashok Midha
Keyword(s):  
Rigid Body ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Curved Beam ◽  
Analysis And Design ◽  
Body Model ◽  
Rigid Body Model ◽  
Fundamental Type ◽  
Applied Forces ◽  
Flexible Member

Abstract The analysis of systems containing highly flexible members is made difficult by the nonlineararities caused by large deflections of the flexible members. The analysis and design of many such systems may be simplified by using pseudo-rigid-body approximations in modeling the flexible members. The pseudo-rigid-body model represents flexible members as rigid links, joined at pin joints with torsional springs. Appropriate values for link lengths and torsional spring stiffnesses are determined such that the deflection path and force-deflection relationships are modeled accurately. Pseudo-rigid-body approximations have been developed for initially straight beams with externally applied forces at the beam end. This work develops approximations for another fundamental type of flexible member, the initially curved beam with applied force at the beam end. This type of flexible member is commonly used in compliant mechanisms. An example of the use of the resulting pseudo-rigid-body approximations in compliant mechanisms is included.

Parametric Deflection Approximations for End-Loaded, Large-Deflection Beams in Compliant Mechanisms

1995 ◽  
Vol 117 (1) ◽  
pp. 156-165 ◽  
Author(s):  
L. L. Howell ◽  
A. Midha
Keyword(s):  
Closed Form ◽  
Large Deflection ◽  
Numerical Solutions ◽  
Compliant Mechanisms ◽  
Elliptic Integral ◽  
Cantilever Beams ◽  
Simple Method ◽  
Body Angle ◽  
Analysis And Design ◽  
Integral Solutions

Geometric nonlinearities often complicate the analysis of systems containing large-deflection members. The time and resources required to develop closed-form or numerical solutions have inspired the development of a simple method of approximating the deflection path of end-loaded, large-deflection cantilever beams. The path coordinates are parameterized in a single parameter called the pseudo-rigid-body angle. The approximations are accurate to within 0.5 percent of the closed-form elliptic integral solutions. A physical model is associated with the method, and may be used to simplify complex problems. The method proves to be particularly useful in the analysis and design of compliant mechanisms.

scholarly journals Design of Compliant Joints for Large Scale Structures

2020 ◽  
Author(s):  
Angela Nastevska ◽  
Jovana Jovanova ◽  
Mary Frecker
Keyword(s):  
Large Scale ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Small Scale ◽  
Nonlinear Bending ◽  
Large Scale Structures ◽  
Compliant Joints ◽  
Scale Structures ◽  
High Level ◽  
Novel Design

Abstract Large scale structures can benefit from the design of compliant joints that can provide flexibility and adaptability. A high level of deformation is achieved locally with the design of flexures in compliant mechanisms. Additionally, by introducing contact-aided compliant mechanisms, nonlinear bending stiffness is achieved to make the joints flexible in one direction and stiff in the opposite one. All these concepts have been explored in small scale engineering design, but they have not been applied to large scale structures. In this paper the design of a large scale compliant mechanism is proposed for novel design of a foldable shipping container. The superelasticity of nickel titanium is shown to be beneficial in designing the joints of the compliant mechanism.

scholarly journals A Seminalytical Approach to Large Deflections in Compliant Beams under Point Load

2009 ◽  
Vol 2009 ◽  
pp. 1-13 ◽  
Author(s):  
N. Tolou ◽  
J. L. Herder
Keyword(s):  
Cantilever Beam ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Geometrical Nonlinearity ◽  
Adomian Decomposition Method ◽  
Analytical Form ◽  
Point Load ◽  
Large Deflections ◽  
Adomian Decomposition

The deflection of compliant mechanism (CM) which involves geometrical nonlinearity due to large deflection of members continues to be an interesting problem in mechanical systems. This paper deals with an analytical investigation of large deflections in compliant mechanisms. The main objective is to propose a convenient method of solution for the large deflection problem in CMs in order to overcome the difficulty and inaccuracy of conventional methods, as well as for the purpose of mathematical modeling and optimization. For simplicity, an element is considered which is a cantilever beam out of linear elastic material under vertical end point load. This can further be used as a building block in more complex compliant mechanisms. First, the governing equation has been obtained for the cantilever beam; subsequently, the Adomian decomposition method (ADM) has been utilized to obtain a semianalytical solution. The vertical and horizontal displacements of a cantilever beam can conveniently be obtained in an explicit analytical form. In addition, variations of the parameters that affect the characteristics of the deflection have been examined. The results reveal that the proposed procedure is very accurate, efficient, and convenient for cantilever beams, and can probably be applied to a large class of practical problems for the purpose of analysis and optimization.

Design of Planar Large-Deflection Compliant Mechanisms With Decoupled Multi-Input-Output Using Topology Optimization

2019 ◽  
Vol 11 (3) ◽  
Author(s):  
Benliang Zhu ◽  
Qi Chen ◽  
Hai Li ◽  
Hongchuan Zhang ◽  
Xianmin Zhang
Keyword(s):  
Topology Optimization ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Geometrical Nonlinearity ◽  
Method Comparison ◽  
Output Coupling ◽  
Large Displacements ◽  
Interpolation Scheme ◽  
Input Output ◽  
Output Behavior

This paper presents a method for topology optimization of large-deflection compliant mechanisms with multiple inputs and outputs by considering the coupling issue. First, the objectives of the design problem are posed by modeling the output loads using several springs to enable control of the input–output behavior. Second, a scheme is proposed to obtain a completely decoupled mechanism. Both input coupling and output coupling are considered. Third, with the implementation of an energy interpolation scheme to stabilize the numerical simulations, the geometrical nonlinearity is considered to appropriately capture the large displacements of compliant mechanisms. Finally, several numerical examples are presented to demonstrate the validity of the proposed method. Comparison studies with the obtained results without considering the coupling issues are also presented.

scholarly journals An Artificial Vibrissa-Like Sensor for Detection of Flows

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3892
Author(s):  
Moritz Scharff ◽  
Philipp Schorr ◽  
Tatiana Becker ◽  
Christian Resagk ◽  
Jorge H. Alencastre Miranda ◽  
...  
Keyword(s):  
Compressible Flow ◽  
Surface Texture ◽  
Large Deflection ◽  
Sensory System ◽  
Flow Characteristics ◽  
Elastic Beam ◽  
Sensory Systems ◽  
Tactile Sensors ◽  
Complex Receptor ◽  
Simulation And Experiment

In nature, there are several examples of sophisticated sensory systems to sense flows, e.g., the vibrissae of mammals. Seals can detect the flow of their prey, and rats are able to perceive the flow of surrounding air. The vibrissae are arranged around muzzle of an animal. A vibrissa consists of two major components: a shaft (infector) and a follicle–sinus complex (receptor), whereby the base of the shaft is supported by the follicle-sinus complex. The vibrissa shaft collects and transmits stimuli, e.g., flows, while the follicle-sinus complex transduces them for further processing. Beside detecting flows, the animals can also recognize the size of an object or determine the surface texture. Here, the combination of these functionalities in a single sensory system serves as paragon for artificial tactile sensors. The detection of flows becomes important regarding the measurement of flow characteristics, e.g., velocity, as well as the influence of the sensor during the scanning of objects. These aspects are closely related to each other, but, how can the characteristics of flow be represented by the signals at the base of a vibrissa shaft or by an artificial vibrissa-like sensor respectively? In this work, the structure of a natural vibrissa shaft is simplified to a slender, cylindrical/tapered elastic beam. The model is analyzed in simulation and experiment in order to identify the necessary observables to evaluate flows based on the quasi-static large deflection of the sensor shaft inside a steady, non-uniform, laminar, in-compressible flow.

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