Spatial Concept Synthesis of Compliant Mechanisms Utilizing Non-Linear Eigentwist Characterization

2018 ◽  
Author(s):  
Joep P. A. Nijssen ◽  
Giuseppe Radaelli ◽  
Just L. Herder ◽  
J. B. Ring ◽  
Charles J. Kim
Keyword(s):  
Large Deformation ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Synthesis Method ◽  
Synthesis Methods ◽  
Planar Mechanisms ◽  
Spatial Concept ◽  
Spatial Design ◽  
Kinematic Behavior ◽  
Non Linear

Spatial compliant mechanism are challenging to design owing to their complex spatial kinetic and kinematic behavior. There are many synthesis methods to design compliant mechanisms, but they are often presented for planar mechanisms or have other limitations such as lack of designer input possibilities. In this paper a method based on the compliance ellipsoid is presented to create compliant mechanism topologies for spatial design cases. The result of this synthesis method is a qualitative concept which fundamentally creates the desired kinetic and kinematic profile. This concept can then be further refined using a large deformation eigentwist analysis, presented here. Lastly, these tools are used in a design example to show its potential.

Direct Displacement Synthesis Method for Shape Morphing Skins Using Compliant Mechanisms

2010 ◽  
Author(s):  
Luke A. Berglind ◽  
Joshua D. Summers
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Shape Change ◽  
Synthesis Method ◽  
Bending Stiffness ◽  
Optimization Techniques ◽  
Synthesis Methods ◽  
Specific Load ◽  
Shape Morphing ◽  
Continuum Structure

This paper presents a direct displacement synthesis method for the design of shape morphing skin structures using compliant mechanisms. The objective of this method is to design a skin structure that will deform to a desired final shape when acted on by a specific load. The method utilizes a ground structure geometry which can facilitate variable bending stiffness along the length of the skin using compliant spring members. Synthesis procedures involve the use of direct displacement to determine how the bending stiffness of the skin must vary to produce the desired shape change. The direct displacement synthesis method differs from other compliant mechanism synthesis methods found in literature, such as pseudo-rigid-body and continuum structure optimization, in the approach taken to solve for the unknown variables in the system. By using direct displacement to determine how the structure must respond to a specific load to achieve the desired shape change, the unknown variables within the system can be extracted directly without the use of optimization techniques.

On the Extraction of Kinematic Behavior From Optimal Compliant Topologies With Application to Number Synthesis of Linkages

2001 ◽  
Author(s):  
Anupam Saxena ◽  
G. K. Ananthasuresh
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Optimization Method ◽  
Dimensional Synthesis ◽  
Kinematic Chains ◽  
Design Specifications ◽  
Kinematic Behavior ◽  
Added Benefit ◽  
Number Synthesis ◽  
Elastic Mechanics

Abstract This paper presents a number of systematically designed compliant topologies and discusses how the intrinsic kinematic behavior can be extracted from them. This is then applied to the number synthesis of linkages. Many techniques developed for number synthesis of linkages enumerate numerous possible kinematic chains, but few can select the best configuration among them. A systematic computational approach that can select the best configuration based on kinetostatic design specifications is presented here. This is a serendipitous result that transpired when two well-developed design techniques for compliant mechanisms were combined. A number of examples with non-intuitive design specifications are included to illustrate the new approach to number synthesis. The examples also illustrate that the kinematic behavior is aptly captured in the elastic mechanics-based topology optimization method to compliant mechanism design. Dimensional synthesis is also accomplished in the same procedure, which is an added benefit of this approach.

Large Deformation Behavior of Compliant Mechanisms

2001 ◽  
Author(s):  
Jinyong Joo ◽  
Sridhar Kota ◽  
Noboru Kikuchi
Keyword(s):  
Shape Optimization ◽  
Large Deformation ◽  
Deformation Behavior ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Linear Formulation ◽  
Scaling Effect ◽  
Beam Elements ◽  
Linear And Nonlinear ◽  
Amplification Mechanism

Abstract This paper presents a non-linear formulation for size and shape optimization of compliant mechanisms using tapered beam elements. Designs based on linear and nonlinear formulations are compared using a stroke amplification mechanism example. Also, the scaling effect of the compliant mechanism is investigated.

Classification of Compliant Mechanisms and Determination of the Degrees of Freedom Using the Concepts of Compliance Number and Pseudo-Rigid-Body Model

2019 ◽  
Author(s):  
Pratheek Bagivalu Prasanna ◽  
Ashok Midha ◽  
Sushrut G. Bapat
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Body Model ◽  
Active Compliance ◽  
Kinematic Behavior ◽  
Rigid Body Model

Abstract Understanding the kinematic properties of a compliant mechanism has always proved to be a challenge. A concept of compliance number offered earlier emphasized the development of terminology that aided in its determination. A method to evaluate the elastic degrees of freedom associated with the flexible segments/links of a compliant mechanism using the pseudo-rigid-body model (PRBM) concept is provided. In this process, two distinct classes of compliant mechanisms are developed involving: (i) Active Compliance and (ii) Passive Compliance. Furthermore, these also aid in a better characterization of the kinematic behavior of a compliant mechanism. A more lucid interpretation of the significance of compliance number is provided. Applications of this method to both active and passive compliant mechanisms are exemplified. Finally, an experimental procedure that aids in visualizing the degrees of freedom as calculated is presented.

scholarly journals Design of compliant mechanism-based variable camber morphing wing with nonlinear large deformation

2019 ◽  
Vol 16 (6) ◽  
pp. 172988141988674 ◽  
Author(s):  
Yaqing Zhang ◽  
Wenjie Ge ◽  
Ziang Zhang ◽  
Xiaojuan Mo ◽  
Yonghong Zhang
Keyword(s):  
Large Deformation ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Flight Performance ◽  
Morphing Wing ◽  
Structure Topology ◽  
Trailing Edges ◽  
Morphing Wings

The morphing wing with large deformation can benefit its flight performance a lot in different conditions. In this study, a variable camber morphing wing with compliant leading and trailing edges is designed by large-displacement compliant mechanisms. The compliant mechanisms are carried out by a hyperelastic structure topology optimization, based on a nonlinear meshless method. A laminated leading-edge skin is designed to fit the curvature changing phenomenon of the leading edge during deformation. A morphing wing demonstrator was manufactured to testify its deformation capability. Comparing to other variable camber morphing wings, the proposal can realize larger deflection of leading and trailing edges. The designed morphing wing shows great improvement in aerodynamic performance and enough strength to resist aerodynamic and structural loadings.

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.

Multiple-Segment-Pseudo-Rigid-Body Model Concept in Compliant Mechanism Design and Analysis

2000 ◽  
Author(s):  
Gregory A. Mettlach ◽  
Ashok Midha
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Synthesis Methods ◽  
Model Concept ◽  
Displacement Boundary ◽  
Body Model ◽  
Rigid Body Model ◽  
Analysis And Synthesis ◽  
Beam Type

Abstract The concept of a pseudo-rigid-body model for a flexible member proven very instrumental in the design and analysis of compliant mechanisms. It provides a means by which a compliant mechanism may be modeled as an equivalent pseudo-rigid-body mechanism. This makes it possible for compliant mechanisms to be analyzed and designed using a wealth of existing methods for rigid-body mechanisms. Oftentimes, however, it is not possible to model a compliant member with a typical pseudo-rigid-body model. This may be due to a force or displacement boundary condition applied to a compliant member at a point other than the beam end. For situations such as these, a planar, multiple-segment pseudo-rigid-body model concept is introduced which allows arbitrary beam type compliant members, regardless of geometry, loading, or boundary conditions, to be modeled as an assemblage of rigid members with torsional springs at characteristic pivots. This methodology enables existing analysis and synthesis methods to be applied in the design of complex compliant mechanisms.

Geometric Synthesis of Spatial Compliant Mechanisms Using Three-Dimensional Wide Curves

2008 ◽  
Author(s):  
Hong Zhou ◽  
Kwun-Lon Ting
Keyword(s):  
Cross Sections ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Synthesis Method ◽  
Three Dimensional ◽  
Programming Algorithm ◽  
Variable Cross ◽  
Finite Element Procedure ◽  
And Performance ◽  
Selection Of

A three-dimensional wide curve is a spatial curve with variable cross sections. This paper introduces a geometric synthesis method for spatial compliant mechanisms by using three-dimensional wide curves. In this paper, every connection in a spatial compliant mechanism is represented by a three-dimensional wide curve and the whole spatial compliant mechanism is modeled as a set of connected three-dimensional wide curves. The geometric synthesis of a spatial compliant mechanism is considered as the generation and optimal selection of control parameters of the corresponding three-dimensional parametric wide curves. The deformation and performance of spatial compliant mechanisms are evaluated by the isoparametric degenerate-continuum nonlinear finite element procedure. The problem-dependent objectives are optimized and the practical constraints are imposed during the optimization process. The optimization problem is solved by the MATLAB constrained nonlinear programming algorithm. The effectiveness of the proposed geometric procedures is verified by the demonstrated examples.

Large Deformation Analysis and Experiments With Double Parallelogram Compliant Mechanisms

2018 ◽  
Author(s):  
Abhijit A. Tanksale ◽  
Prasanna S. Gandhi
Keyword(s):  
Large Deformation ◽  
High Precision ◽  
Large Deformations ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Vertical Plane ◽  
Coupled Analysis ◽  
Deformation Analysis ◽  
Flexible Beams ◽  
Straight Line

Compliant mechanisms are highly preferred in applications demanding motion with high precision. These mechanisms provide friction-less, backlash-free precise motion obtained through deformation of flexible members. The double parallelogram compliant mechanism (DPCM) is one the most important compliant mechanisms to obtain highly precise straight-line motion. DPCM when operated in horizontal plane yield high precision straight-line motion (even with large deformations) useful in several engineering applications. However, constraints such as space, dead loads, etc. may demand DPCMs to be used in the vertical plane. For DPCMs operating in a vertical plane, the axial load due to gravity causes tension and compression in flexible beams which get coupled to bending under large deformations. This ultimately affects the parasitic error of straight-line motion. This paper presents a coupled analysis, along with experimental validation, of DPCM operating in vertical plane considering gravity effects with large deformation.

Optimal Synthesis of Compliant Mechanisms to Satisfy Kinematic and Structural Requirements: Preliminary Results

1996 ◽  
Author(s):  
Mary I. Frecker ◽  
Noboru Kikuchi ◽  
Sridhar Kota
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Synthesis Method ◽  
Design Procedure ◽  
Problem Formulation ◽  
Mechanism Synthesis ◽  
Ground Structure ◽  
Design Problems ◽  
Structural Requirements ◽  
External Loads

Abstract Compliant mechanism synthesis is an automated design procedure which allows the designer to systematically generate the optimal structural form for a particular set of loading and motion requirements. The synthesis method presented here solves a particular class of design problems, where the compliant mechanism is required to be both flexible to meet motion requirements, and stiff to withstand external loads. A two-part problem formulation is proposed using mutual and strain energies, whereby the conflicting design objectives of required flexibility and stiffness are handled via multi-criteria optimization. The resulting compliant mechanism topologies satisfy both kinematic and structural requirements. The problem formulation is implemented using a truss ground structure and SLP algorithm. Several design examples are presented to illustrate this method.

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