A Material Selection and Design Method for Multi-Constraint Compliant Mechanisms

2016 ◽  
Author(s):  
John Sessions ◽  
Nathan Pehrson ◽  
Kyler Tolman ◽  
Jonathan Erickson ◽  
David Fullwood ◽  
...  
Keyword(s):  
Performance Metrics ◽  
Compliant Mechanisms ◽  
Material Selection ◽  
Compliant Mechanism ◽  
Design Method ◽  
Solar Array ◽  
Multiple Constraints ◽  
Systematic Method ◽  
Electrically Conductive ◽  
Compliant Mechanism Design

One of the challenges often encountered in compliant mechanism design is managing material selection given the need to meet multiple constraints. Many methods have been offered previously to systematically facilitate that decision process. However, these methods struggle to incorporate a systematic method for material selection in multi-functional compliant mechanisms. This work seeks to address this gap by generically implementing a new Ashby-based material selection and design method for compliant mechanisms with multi constraint design criteria. To help demonstrate the method, the design of an electrically conductive lamina emergent torsion (LET) joint used for a back-packable solar array is explored. The methodology described here can be used to create other compliant mechanism performance metrics to address the design of specific compliant mechanisms.

Piezoelectric Actuator Performance Metrics and Relation to Compliant Mechanism Design

2001 ◽  
Author(s):  
Hima Maddisetty ◽  
Mary Frecker
Keyword(s):  
Topology Optimization ◽  
Performance Metrics ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Mechanical Efficiency ◽  
High Energy ◽  
High Energy Density ◽  
High Bandwidth ◽  
Compliant Mechanism Design ◽  
Actuator Performance

Abstract Piezoceramic actuators have gained widespread use due to their desirable qualities of high force, high bandwidth, and high energy density. Compliant mechanisms can be designed for maximum stroke amplification of piezoceramic actuators using topology optimization. In this paper, the mechanical efficiency and other performance metrics of such compliant mechanism/actuator systems are studied. Various definitions of efficiency and other performance metrics of actuators with amplification mechanisms from the literature are reviewed. These metrics are then applied to two compliant mechanism example problems and the effect of the stiffness of the external load is investigated.

A Well-Behaved Revolute Flexure Joint for Compliant Mechanism Design

1999 ◽  
Vol 121 (3) ◽  
pp. 424-429 ◽  
Author(s):  
M. Goldfarb ◽  
J. E. Speich
Keyword(s):  
Mechanism Design ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Bending Properties ◽  
Thin Beam ◽  
Primary Mechanism ◽  
Joint Characteristics ◽  
Flexure Joints ◽  
Compliant Mechanism Design ◽  
Torsional Properties

This paper describes the design of a unique revolute flexure joint, called a split-tube flexure, that enables (lumped compliance) compliant mechanism design with a considerably larger range-of-motion than a conventional thin beam flexure, and additionally provides significantly better multi-axis revolute joint characteristics. Conventional flexure joints utilize bending as the primary mechanism of deformation. In contrast, the split-tube flexure joint incorporates torsion as the primary mode of deformation, and contrasts the torsional properties of a thin-walled open-section member with the bending properties of that member to obtain desirable joint behavior. The development of this joint enables the development of compliant mechanisms that are quite compliant along kinematic axes, extremely stiff along structural axes, and are capable of kinematically well-behaved large motions.

Utilizing a Classification Scheme to Facilitate Rigid-Body Replacement for Compliant Mechanism Design

2010 ◽  
Author(s):  
Brian M. Olsen ◽  
Yanal Issac ◽  
Larry L. Howell ◽  
Spencer P. Magleby
Keyword(s):  
Rigid Body ◽  
Mechanism Design ◽  
Classification Scheme ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
The Other ◽  
Design Approach ◽  
Compliant Mechanism Design

The knowledge related to the synthesis and analysis of compliant mechanisms continues to grow and mature. Building on this growth, a classification scheme has been established to categorize compliant elements and mechanisms in a manner that engineers can incorporate compliance into their designs. This paper demonstrates a design approach engineers can use to convert an existing rigid-body mechanism into a compliant mechanism by using an established classification scheme. This approach proposes two possible techniques that use rigid-body replacement synthesis in conjunction with a compliant mechanism classification scheme. One technique replaces rigid-body elements with a respective compliant element. The other technique replaces a complex rigid-body mechanism by decomposing the mechanism into simpler functions and then replacing a respective rigid-body mechanism with a compliant mechanism that has a similar functionality.

Hybrid Compliant Mechanism Design Using a Mixed Mesh of Flexure Hinge Elements and Beam Elements Through Topology Optimization

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Lin Cao ◽  
Allan T. Dolovich ◽  
Wenjun (Chris) Zhang
Keyword(s):  
Topology Optimization ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Optimization Technique ◽  
Flexure Hinge ◽  
Beam Elements ◽  
Flexure Hinges ◽  
New Type ◽  
Meshing Scheme ◽  
Compliant Mechanism Design

This paper proposes a topology optimization framework to design compliant mechanisms with a mixed mesh of both beams and flexure hinges for the design domain. Further, a new type of finite element, i.e., super flexure hinge element, was developed to model flexure hinges. Then, an investigation into the effects of the location and size of a flexure hinge in a compliant lever explains why the point-flexure problem often occurs in the resulting design via topology optimization. Two design examples were presented to verify the proposed technique. The effects of link widths and hinge radii were also investigated. The results demonstrated that the proposed meshing scheme and topology optimization technique facilitate the rational decision on the locations and sizes of beams and flexure hinges in compliant mechanisms.

Shape Optimization Framework for the Path of the Primary Compliance Vector in Compliant Mechanisms

2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Hylke Kooistra ◽  
Charles J. Kim ◽  
Werner W. P. J. van de Sande ◽  
Just L. Herder
Keyword(s):  
Mechanism Design ◽  
Deformation Mechanism ◽  
General Framework ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Optimization Framework ◽  
Kinematic Behavior ◽  
Curve Representation ◽  
Compliant Mechanism Design ◽  
Load Perturbations

Abstract The primary compliance vector (PCV) captures the dominant kinematic behavior of a compliant mechanism. Its trajectory describes large deformation mechanism behavior and can be integrated in an optimization objective in detailed compliant mechanism design. This paper presents a general framework for the optimization of the PCV path, the mechanism trajectory of lowest energy, using a unified stiffness characterization and piecewise curve representation. We present a meaningful objective formulation for the PCV path that evaluates path shape, location, orientation, and length independently and apply the framework to two design examples. The framework is useful for design of planar and shell compliant mechanisms that traverse a specified mechanism trajectory and that are insensitive to load perturbations.

A Compliant Mechanism Design Methodology for Coupled and Uncoupled Systems, and Governing Free Choice Selection Considerations

2004 ◽  
Author(s):  
Ashok Midha ◽  
Yuvaraj Annamalai ◽  
Sharath K. Kolachalam
Keyword(s):  
Rigid Body ◽  
Design Methodology ◽  
Free Choice ◽  
Compliant Mechanisms ◽  
State Of The Art ◽  
Compliant Mechanism ◽  
Mechanism Synthesis ◽  
Strongly Coupled ◽  
Revolute Joints ◽  
Compliant Mechanism Design

Compliant mechanisms are defined as mechanisms that gain some, or all of their mobility from the flexibility of their members. Suitable use of pseudo-rigid-body models for compliant segments, and relying on the state-of-the-art knowledge of rigid-body mechanism synthesis types, greatly simplifies the design of compliant mechanisms. Assuming a pseudo-rigid-body four-bar mechanism, with one to four torsional springs located at the revolute joints to represent mechanism compliance, a simple, heuristic approach is provided to develop various compliant mechanism types. The synthesis with compliance method is used for three, four and five precision positions, with consideration of one to four torsional springs, to systematically develop design tables for standard mechanism synthesis types. These tables appropriately reflect the mechanism compliance by specification of either energy or torque. Examples are presented to demonstrate the use of weakly or strongly coupled sets of kinematic and energy/torque equations, as well as different compliant mechanism types in obtaining solutions.

A Two-Stage Design Method for Compliant Mechanisms Having Specified Non-Linear Output Paths

2006 ◽  
Author(s):  
Masakazu Kobayashi ◽  
Hiroshi Yamakawa ◽  
Shinji Nishiwaki ◽  
Kazuhiro Izui ◽  
Masataka Yoshimura
Keyword(s):  
Topology Optimization ◽  
Shape Optimization ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Design Method ◽  
Two Stage ◽  
Traditional Methods ◽  
Stage Design ◽  
Second Stage ◽  
Additional Constraints

Compliant mechanisms generated by traditional topology optimization methods have linear output response, and it is difficult for traditional methods to implement mechanisms having non-linear output responses, such as nonlinear deformation or path. To design a compliant mechanism having a specified nonlinear output path, a two-stage design method based on topology and shape optimization is constructed here. In the first stage, topology optimization generates an initial and conceptual compliant mechanism based on ordinary design conditions, with “additional” constraints that are used to control the output path at the second stage. In the second stage, an initial model for the shape optimization is created, based on the result of the topology optimization, and the additional constraints are replaced by spring elements. The shape optimization is then executed, to generate a detailed shape of the compliant mechanism having the desired output path. In this stage, parameters that represent the outer shape of the compliant mechanism and the properties of spring elements are used as design variables in the shape optimization. In addition to configuration of the specified output path, executing the shape optimization after the topology optimization also makes it possible to consider the stress concentration and large displacement effects. This is an advantage offered by the proposed method, since it is difficult for traditional methods to consider these aspects, due to inherent limitations of topology optimization.

Characteristic Deflection Domain for Various Compliant Segment Types, and its Importance in Compliant Mechanism Synthesis and Analysis

2014 ◽  
Author(s):  
Ashok Midha ◽  
Sushrut G. Bapat
Keyword(s):  
Boundary Conditions ◽  
Mechanism Design ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Solution Process ◽  
Displacement Boundary ◽  
Fundamental Understanding ◽  
Rigid Body Model ◽  
Compliant Mechanism Design ◽  
Insight Into

Compliant mechanism design inherently requires certain specified displacement boundary conditions to be satisfied. Obtaining realistic solutions for such problem types often becomes a challenge as the number of displacement boundary condition specifications increases. Typically, related failures are attributed to the numerical nature of the solution process. Little attention has been given to the fundamental understanding of the deformation behavior of flexible continuum with respect to its limits of mobility or reach. This paper strives to provide an insight into this aspect of compliant mechanism design. To assist a designer with the specification of realistic and achievable requirements, the concept of characteristic deflection domain has been proposed in the past. This paper systematically develops the characteristic deflection domain for a variety of compliant segment types. The pseudo-rigid-body model (PRBM) representation is utilized for determining the lower and upper boundaries of the deflection domain. The paper further investigates the mobility characteristics of compliant mechanisms comprised of multiple segment types. Case studies are presented that help exemplify the use of the characteristic deflection domain plots. The results suggest that the number, type, and orientation of the compliant segments have a significant effect on the mobility of compliant mechanisms. Thus, care must be exercised by the designer when specifying free-choices/boundary conditions in compliant mechanisms synthesis and analysis.

Hinge-Free Compliant Mechanism Design via the Topological Level-Set

2013 ◽  
Author(s):  
Krishnan Suresh
Keyword(s):  
Numerical Experiments ◽  
High Performance ◽  
Compliant Mechanisms ◽  
Volume Fraction ◽  
Compliant Mechanism ◽  
Target Volume ◽  
Iterative Solvers ◽  
Stiffness Matrices ◽  
2D And 3D ◽  
Compliant Mechanism Design

The objective of this paper is to introduce and demonstrate a new method for the topology optimization of compliant mechanisms. The proposed method relies on exploiting the topological derivative, and it exhibits numerous desirable properties including: (1) the mechanisms are hinge-free, (2) mechanisms with different geometric and mechanical advantages can be generated by varying a single control parameter, (3) a target volume fraction need not specified; instead numerous designs, of decreasing volume fractions, are generated in a single optimization run, and (4) the underlying finite element stiffness matrices are well-conditioned, permitting the use of high-performance iterative solvers. The proposed method and implementation are illustrated through numerical experiments in 2D and 3D.

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.

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