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.

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

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Anirudh Krishnakumar ◽  
Krishnan Suresh
Keyword(s):  
Topology Optimization ◽  
Numerical Experiments ◽  
Control Parameter ◽  
Compliant Mechanisms ◽  
Volume Fraction ◽  
Compliant Mechanism ◽  
Target Volume ◽  
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 exhibits numerous desirable properties including: (1) the mechanisms are hinge-free; (2) mechanisms with different geometric and mechanical advantages (GA and MA) can be generated by varying a single control parameter; (3) a target volume fraction need not be 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. The proposed method and implementation are illustrated through numerical experiments in 2D and 3D.

scholarly journals Compliant Mechanism Road Bicycle Brake: A Rigid-Body Replacement Case Study

2011 ◽  
Author(s):  
Brian M. Olsen ◽  
Larry L. Howell ◽  
Spencer P. Magleby
Keyword(s):  
Rigid Body ◽  
High Performance ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Element Analysis ◽  
Low Weight ◽  
Rigid Body Model ◽  
Compliant Mechanism Design

This paper demonstrates rigid-body replacement synthesis in the design a mechanism with known design objectives. The design of high-performance bicycle brakes is complicated by a variety of competing design objectives, including increased performance and low weight. But this challenge also provides a good case study to demonstrate the design of compliant mechanisms to replace traditional rigid-link mechanisms. This paper briefly reviews current road brake designs, demonstrates the use of rigid-body replacement synthesis to design a compliant mechanism, and illustrates the combination of compliant mechanism design tools. The resulting concept was generated from the modified dual-pivot brake design and is a partially compliant mechanism where one pin has the dual role of a joint and a mounting pin. The pseudo-rigid-body model, finite element analysis, and optimization algorithms are used to generate design dimensions, and designs are considered for both titanium and E-glass flexures. The resulting design has the potential of reducing the part count and overall weight while maintaining a performance similar to the benchmark.

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.

An Evolutionary Soft-Add Topology Optimization Method for Synthesis of Compliant Mechanisms With Maximum Output Displacement

2017 ◽  
Vol 9 (5) ◽  
Author(s):  
Chih-Hsing Liu ◽  
Guo-Feng Huang ◽  
Ta-Lun Chen
Keyword(s):  
Topology Optimization ◽  
Compliant Mechanisms ◽  
Volume Fraction ◽  
Compliant Mechanism ◽  
Optimization Method ◽  
Computational Time ◽  
Maximum Output ◽  
Spring Stiffness ◽  
Output Displacement ◽  
Topology Optimization Method

This paper presents an evolutionary soft-add topology optimization method for synthesis of compliant mechanisms. Unlike the traditional hard-kill or soft-kill approaches, a soft-add scheme is proposed in this study where the elements are equivalent to be numerically added into the analysis domain through the proposed approach. The objective function in this study is to maximize the output displacement of the analyzed compliant mechanism. Three numerical examples are provided to demonstrate the effectiveness of the proposed method. The results show that the optimal topologies of the analyzed compliant mechanisms are in good agreement with previous studies. In addition, the computational time can be greatly reduced by using the proposed soft-add method in the analysis cases. As the target volume fraction in topology optimization for the analyzed compliant mechanism is usually below 30% of the design domain, the traditional methods which remove unnecessary elements from 100% turn into inefficient. The effect of spring stiffness on the optimized topology has also been investigated. It shows that higher stiffness values of the springs can obtain a clearer layout and minimize the one-node hinge problem for two-dimensional cases. The effect of spring stiffness is not significant for the three-dimensional case.

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.

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