On the Nomenclature and Classification of Compliant Mechanisms: The Components of Mechanisms

1992 ◽  
Author(s):  
Ashok Midha ◽  
Tony W. Norton ◽  
Larry L. Howell
Keyword(s):  
Rigid Body ◽  
Current Literature ◽  
Compliant Mechanisms ◽  
Efficient Design ◽  
Concerted Effort ◽  
Research Activity ◽  
The Past ◽  
Systematic Development ◽  
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. Compliant mechanisms are desirable since they require fewer parts, and have less wear, noise, and backlash than their rigid-body counterpart mechanisms. The field of compliant mechanisms is important, and is expected to continue to grow as materials with superior properties are developed. Inasmuch as evolution of efficient design techniques is viewed as essential research activity, a parallel, systematic development of appropriate vocabulary (nomenclature, classification, etc.) is of primary importance. This paper proposes standard nomenclature for the components of compliant mechanisms and discusses the relevant issues involved in this process. Definitions for components, such as “links” and “joints,” remove ambiguity that has been associated with these terms in the past. A concerted effort is made to be consistent with current literature on both rigid-body mechanisms and compliant mechanisms whenever possible.

On the Nomenclature, Classification, and Abstractions of Compliant Mechanisms

1994 ◽  
Vol 116 (1) ◽  
pp. 270-279 ◽  
Author(s):  
A. Midha ◽  
T. W. Norton ◽  
L. L. Howell
Keyword(s):  
Rigid Body ◽  
Current Literature ◽  
Compliant Mechanisms ◽  
Efficient Design ◽  
Concerted Effort ◽  
Research Activity ◽  
Levels Of Abstraction ◽  
Standard Nomenclature ◽  
The Past ◽  
Systematic Development

Compliant mechanisms, unlike rigid-body mechanisms, gain some or all of their mobility from the flexibility of their members. Complaint mechanisms are desirable since they require fewer parts, and have less wear, noise, and backlash than their rigid-body counterpart mechanisms. The field of compliant mechanisms is expected to continue to grow as materials with superior properties are developed. Inasmuch as evolution of efficient design techniques is viewed as an essential research activity, a parallel, systematic development of appropriate vocabulary (nomenclature, classification, etc.) is of primary importance. This paper proposes a standard nomenclature for the components of compliant mechanisms and discusses the relevant issues involved in this process. Definitions for components, such as “links” and “joints,” remove ambiguity that has been associated with these terms in the past. Names and diagrams are discussed, and are shown to be similar because they represent “abstractions” of the same mechanisms. The concept of “levels of abstraction” is introduced, and common levels of abstraction are identified. A concerted effort is made to be consistent with current literature on both rigid-body mechanisms and compliant mechanisms whenever possible.

On the Nomenclature and Classification of Compliant Mechanisms: Abstractions of Mechanisms and Mechanism Synthesis Problems

1992 ◽  
Author(s):  
Ashok Midha ◽  
Tony W. Norton ◽  
Larry L. Howell
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Mechanism Synthesis ◽  
Levels Of Abstraction ◽  
Significant Growth ◽  
Important Field ◽  
The Common ◽  
Body Joints

Abstract A compliant mechanism is one which gains all or part of its mobility from the relative flexibility of its members rather than from rigid-body joints only. Compliant mechanisms offer clear advantages, such as need for fewer parts, less wear, noise and backlash due to clearances, when compared to rigid-body mechanisms performing similar functions. This important field is expected to undergo significant growth as materials with superior properties are developed. In the development of compliant mechanisms, the establishment of nomenclature and classification is of primary importance. This paper discusses common representations, i.e. names and diagrams, for a compliant mechanism. Names and diagrams will be shown to be similar because they represent “abstractions” of the same mechanism. The concept of “levels of abstraction” is introduced, and common levels of abstraction are identified. The relevance of this concept to the naming of mechanisms is shown by applying it to both rigid-body and compliant mechanism examples. Nomenclature is proposed for several of the common levels of abstraction, and issues involved in naming mechanisms are discussed. Finally, a discussion of synthesis types is presented, as are the advantages, disadvantages, and issues involved in the synthesis of a compliant mechanism.

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.

How to Choose From a Synthesized Set of Path-Generating Mechanisms

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
Sujitkumar V. Naik ◽  
Anupam Saxena ◽  
Ashok Kumar Rai ◽  
B. V. S. Nagendra Reddy
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Decision Matrix ◽  
Analytic Hierarchy ◽  
Qualitative And Quantitative ◽  
Design Alternatives ◽  
Compact Design ◽  
Body Joints ◽  
Design Simplicity ◽  
Hierarchy Process

Partially compliant mechanisms inherit the attributes of fully compliant and rigid-body linkages and offer simpler, compact design alternatives to accomplish complex kinematic tasks such as tracing large nonsmooth paths. This paper describes qualitative and quantitative criteria that can be employed to select the linkage configuration. The proposed criteria are categorized as general or specific. General criteria pertain to often-used kinematic attributes whereas specific criteria address the application at hand. The veracity and viability of each mechanism are evaluated with respect to compactness, design simplicity, static and dynamic failure, number of rigid-body joints, relative ease of fabrication, and other relevant criteria. Three decision-making techniques, namely, Pugh decision matrix, analytic hierarchy process, and a variant of the Pugh decision matrix are used to perform the evaluation. An example of a displacement-delimited gripper with a prescribed large nonsmooth path is used to illustrate linkage selection.

A Review on Compliant Joints and Rigid-Body Constant Velocity Universal Joints Toward the Design of Compliant Homokinetic Couplings

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
D. Farhadi Machekposhti ◽  
N. Tolou ◽  
J. L. Herder
Keyword(s):  
Rigid Body ◽  
Constant Velocity ◽  
Compliant Mechanisms ◽  
Material Selection ◽  
Analytical Data ◽  
Graph Representations ◽  
Common Basis ◽  
Compliant Joints ◽  
Body Joints ◽  
Universal Joints

This paper presents for the first time a literature survey toward the design of compliant homokinetic couplings. The rigid-linkage-based constant velocity universal joints (CV joints) available from literature were studied, classified, their graph representations were presented, and their mechanical efficiencies compared. Similarly, literature is reviewed for different kinds of compliant joints suitable to replace instead of rigid-body joints in rigid-body CV joints. The compliant joints are compared based on analytical data. To provide a common basis for comparison, consistent flexure scales and material selection are used. It was found that existing compliant universal joints are nonconstant in velocity and designed based on rigid-body Hooke's universal joint. It was also discovered that no compliant equivalent exists for cylindrical, planar, spherical fork, and spherical parallelogram quadrilateral joints. We have demonstrated these compliant joints can be designed by combining existing compliant joints. The universal joints found in this survey are rigid-body non-CV joints, rigid-body CV joints, or compliant non-CV joints. A compliant homokinetic coupling is expected to combine the advantages of compliant mechanisms and constant velocity couplings for many applications where maintenance or cleanliness is important, for instance in medical devices and precision instruments.

On the Classification of Compliant Mechanisms and Synthesis of Compliant Single-Strip Mechanisms

2011 ◽  
Author(s):  
Ashok Midha ◽  
Sharath K. Kolachalam ◽  
Yuvaraj Annamalai
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Basic Mechanism ◽  
Governing Equations ◽  
Mechanism Synthesis ◽  
Synthesis Techniques ◽  
Single Strip

Compliant mechanisms, unlike rigid-body mechanisms, are devices that derive some or all of their mobility due to the deformation of their flexible members. The knowledge of existing rigid-body mechanism synthesis techniques is very useful in designing compliant mechanisms. In rigid-body mechanisms, a four-bar is treated as the basic mechanism that can transfer motion, force or energy. In this paper, a compliant single-strip continuum is introduced as the basic compliant mechanism that can transfer motion, force or energy. A classification of compliant mechanisms is presented herein. A methodology for compliant single-strip mechanism synthesis for energy, force or torque specifications is developed in this research as our second objective. The synthesis types, the governing equations, and the variables involved are enumerated.

A Method for the Design of Compliant Mechanisms With Small-Length Flexural Pivots

1994 ◽  
Vol 116 (1) ◽  
pp. 280-290 ◽  
Author(s):  
L. L. Howell ◽  
A. Midha
Keyword(s):  
Rigid Body ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Trial And Error ◽  
Flexible Link ◽  
Body Model ◽  
Input And Output ◽  
Rigid Body Model ◽  
Element Type ◽  
Body Joints

Compliant or flexible-link mechanisms gain some or all of their motion from the relative flexibility of their joints rather than from rigid-body joints only. Unlike rigid-body mechanisms, energy is not conserved between the input and output ports of compliant mechanisms because of energy storage in the flexible members. This effect and the nonlinearities introduced by large deflections complicate the analysis of such mechanisms. The design of compliant mechanisms in industry is currently accomplished by expensive trial and error methods. This paper introduces a method to aid in the design of a class of compliant mechanisms wherein the flexible sections (flexural pivots) are small in length compared to the relatively rigid sections. The method includes a definition and use of a pseudo-rigid-body model, and the use of a large-deflection finite element type algorithm. An example is used to illustrate the design technique described.

A Compliance Number Concept for Compliant Mechanisms, and Type Synthesis

1987 ◽  
Vol 109 (3) ◽  
pp. 348-355 ◽  
Author(s):  
I. Her ◽  
A. Midha
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Compliant Mechanisms ◽  
Type Synthesis ◽  
Number Concept ◽  
Fundamental Level ◽  
The Past ◽  
Convenient Approach ◽  
Kinematic Properties

While much has been contributed to techniques for enumerating and identifying rigid-body mechanisms in the past decades, proportionally little has been accomplished in this regard in compliant mechanisms design. This paper deals primarily with identification and discussion of important kinematic properties of compliant mechanisms. To facilitate these appropriate terminology is developed at the very fundamental level. The conventional degrees-of-freedom concept for a rigid-body chain is briefly reviewed. It is then used to help define a compliance number (or degrees-of-compliance) concept for characterizing compliant mechanisms. Finally, a systematic and convenient approach is presented, enabling the type synthesis of this class of mechanisms.

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

1996 ◽  
Vol 118 (1) ◽  
pp. 126-131 ◽  
Author(s):  
L. L. Howell ◽  
A. Midha ◽  
T. W. Norton
Keyword(s):  
Rigid Body ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Spring Stiffness ◽  
Model Concept ◽  
Analysis And Design ◽  
Body Model ◽  
Rigid Body Model ◽  
Body Joints

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. 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.

Second international scientific conference «Present fundamental problems of vegetation classification» (Yalta, 15–20 September 2019)

2019 ◽  
pp. 135-142
Author(s):  
K. V. Ivanova ◽  
A. M. Lapina ◽  
V. V. Neshataev
Keyword(s):  
Plant Communities ◽  
National Archive ◽  
Botanical Garden ◽  
Vegetation Classification ◽  
Scientific Conference ◽  
Scientific Journals ◽  
Time Dynamics ◽  
The Past ◽  
Research Organizations

The 2nd international scientific conference «Fundamental problems of vegetation classification» took place at the Nikitskiy Botanical Garden (Yalta, Republic of Crimea, Russia) on 15–20 September 2019. There were 56 participants from 33 cities and 43 research organizations in Russia. The conference was mostly focused on reviewing the success in classification of the vegetation done by Russian scientists in the past three years. The reports covered various topics such as classification, description of new syntaxonomical units, geobotanical mapping for different territories and types of vegetation, studies of space-time dynamics of plant communities. The final discussion on the last day covered problems yet to be solved: establishment of the Russian Prodromus and the National archive of vegetation, complications of higher education in the profile of geobotany, and the issue of the data leakage to foreign scientific journals. In conclusion, it was announced that the 3rd conference in Nikitskiy Botanical Garden will be held in 2022.

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