A Conceptual Design Tool for Synthesis of Spatial Compliant and Shape Morphing Mechanisms

2018 ◽  
Author(s):  
Sreekalyan Patiballa ◽  
Kazuhiro Uchikata ◽  
Ramkumar Komanduri Ranganath ◽  
Girish Krishnan
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Shape Change ◽  
Design Guidelines ◽  
Design Tool ◽  
Three Dimensions ◽  
Shape Morphing ◽  
Compliant Surfaces ◽  
Flow Through ◽  
External Loads

Synthesis of spatial compliant mechanisms for morphing surfaces in three dimensions is challenging as it not only involves meeting the kinematic requirement for spatial shape change, but also providing support against external loads. In three dimensions, there are no existing insightful techniques for synthesis, and the computational approaches are rendered complex. This paper builds on a new insightful technique to synthesize compliant mechanism topologies by visualizing a kinetostatic field of forces that flow through the mechanism geometry. Such a framework when extended to three dimensions, enables a maximally decoupled synthesis framework of shape morphing compliant surfaces, where a primary mechanism meets the shape change requirement, and an auxiliary mechanism provides the required support under external loads. The preliminary design guidelines are implemented using an immersive Virtual Reality based design tool, and verified using finite element simulations for several spatial compliant mechanisms. This design framework is deemed useful for a larger class of shape morphing structures beyond the examples presented in the paper.

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.

Kinematic Synthesis of Planar, Shape-Changing Compliant Mechanisms Using Pseudo-Rigid-Body Models

2012 ◽  
Author(s):  
Kai Zhao ◽  
James P. Schmiedeler ◽  
Andrew P. Murray
Keyword(s):  
Rigid Body ◽  
Shape Matching ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Shape Change ◽  
Flexible Beam ◽  
Beam Model ◽  
Flexible Beams ◽  
Multi Objective Genetic Algorithm ◽  
Optimization Loop

This paper presents a procedure using Pseudo-Rigid-Body Models (PRBMs) to synthesize partially compliant mechanisms capable of approximating a shape change defined by a set of morphing curves in different positions. To generate a single-piece compliant mechanism, flexural pivots and flexible beams are both utilized in the mechanism. New topologies defined by compliant mechanism matrices are enumerated by modifying the components that make up a single degree-of-freedom (DOF) rigid-body mechanism. Because of the introduction of the PRBM for flexural pivots and the simplified PRBM for flexible beams, torsional springs are attached at the characteristic pivots of the 1-DOF rigid-body mechanism in order to generate a corresponding pseudo-rigid-body mechanism. A multi-objective genetic algorithm is employed to find a group of viable compliant mechanisms in the form of candidate pseudo-rigid-body mechanisms that tradeoff minimizing shape matching error with minimizing actuator energy. Since the simplified beam model is not accurate, an optimization loop is established to find the position and shape of the flexible beam using a finite link beam model. The optimal flexible beams together with the pseudo-rigid-body mechanism define the solution mechanism. The procedure is demonstrated with an example in which a partially compliant mechanism approximating two closed-curve profiles is synthesized.

Using Rigid-Body Mechanism Topologies to Design Shape-Changing Compliant Mechanisms

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Kai Zhao ◽  
James P. Schmiedeler
Keyword(s):  
Rigid Body ◽  
Shape Matching ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Shape Change ◽  
Mesh Network ◽  
Adaptive Antenna ◽  
Optimal Size ◽  
Dimensional Synthesis ◽  
Element Analysis

This paper uses rigid-body mechanism topologies to synthesize fully distributed compliant mechanisms that approximate a shape change defined by a set of morphing curves in different positions. For a shape-change problem, a rigid-body mechanism solution is generated first to provide the base topology. This base topology defines a preselected design space for the structural optimization in one of two ways so as to obtain a compliant mechanism solution that is typically superior to the local minimum solutions obtained from searching more expansive design spaces. In the first strategy, the dimensional synthesis directly determines the optimal size and shape of the distributed compliant mechanism having exactly the base topology. In the second strategy, an initial mesh network established from the base topology is used to generate different topologies (in addition to the base), and an improved design domain parameterization scheme ensures that only topologies with well-connected structures are evaluated. The deformation of each generated compliant mechanism is evaluated using geometrically nonlinear finite element analysis (FEA). A two-objective genetic algorithm (GA) is employed to find a group of viable designs that trade off minimizing shape matching error with minimizing maximum stress. The procedure's utility is demonstrated with three practical examples—the first two approximating open-curve profiles of an adaptive antenna and the third approximating closed-curve profiles of a morphing wing.

scholarly journals DAS-2D: a concept design tool for compliant mechanisms

2016 ◽  
Vol 7 (2) ◽  
pp. 135-148 ◽  
Author(s):  
Omer Anil Turkkan ◽  
Hai-Jun Su
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Design Tool ◽  
Concept Design ◽  
Simulation Tools ◽  
Element Simulation ◽  
Mechanism Research ◽  
Analysis And Synthesis ◽  
Engineering Practices

Abstract. Compliant mechanisms utilize the deformation of the elastic members to achieve the desired motion. Currently, design and analysis of compliant mechanisms rely on several commercial dynamics and finite element simulation tools. However, these tools do not implement the most recently developed theories in compliant mechanism research. In this article, we present DAS-2D (Design, Analysis and Synthesis), a conceptual design tool which integrates the recently developed pseudo-rigid-body models and kinetostatic analysis/synthesis theories for compliant mechanisms. Coded in Matlab, the software features a kinematic solver for general rigid-body mechanisms, a kinetostatic solver for compliant mechanisms and a fully interactive graphical user interface. The implementation details of all modules of the program are presented and demonstrated with four different case studies. This tool can be beneficial to classroom teaching as well as engineering practices in design of compliant mechanisms.

Constraint-Based Synthesis of Shape-Morphing Structures in Virtual Reality

2010 ◽  
Author(s):  
Judy M. Vance ◽  
Denis Dorozhkin
Keyword(s):  
Virtual Reality ◽  
Rigid Body ◽  
Method Development ◽  
Compliant Mechanisms ◽  
Design Method ◽  
Shape Change ◽  
The Body ◽  
Motion Path ◽  
Primary Methods ◽  
Shape Morphing

This manuscript outlines a novel approach to the design of compliant shape-morphing structures using constraint-based design method. Development of robust methods for designing shape-morphing structures is the focus of multiple current research projects, since the ability to modify geometric shapes of the individual system components, such as aircraft wings and antenna reflectors, provides the means to affect the performance of the corresponding mechanical systems. Of particular interest is the utilization of compliant mechanisms to achieve the desired adaptive shape change characteristics. Compliant mechanisms, as opposed to the traditional rigid link mechanisms, achieve motion guidance via the compliance and deformation of the mechanism’s members. The goal is to design a single-piece flexible structure capable of morphing a given curve or profile into a target curve or profile while utilizing the minimum number of actuators. The two primary methods prevalent in the design community at this time are the pseudo-rigid body method (PRBM) and the topological synthesis. Unfortunately these methods either tend to suffer from a poor ability to generate potential solutions (being more suitable for the analysis of existing structures) or are susceptible to overly-complex solutions. By utilizing the constraint-based design method (CBDM) we aim to address those shortcomings. The concept of CBDM has generally been confined to the Precision Engineering community and is based on the fundamental premise that all motions of a rigid body are determined by the position and orientation of the constraints (constraint topology) which are placed upon the body. Any mechanism motion path may then be defined by the proper combination of constraints. In order to apply the CBDM concepts to the design and analysis of shape-morphing compliant structures we propose a tiered design method that relies on kinematics, finite element analysis, and optimization. By discretizing the flexible element that comprises the active shape surface at multiple points in both the initial and the target configurations and treating the resulting individual elements as rigid bodies that undergo a planar or general spatial displacement we are able to apply the traditional kinematics theory to rapidly generate sets of potential solutions. The final design is then established via an FEA-augmented optimization sequence. Coupled with a virtual reality interface and a force-feedback device this approach provides the ability to quickly specify and evaluate multiple design problems in order to arrive at the desired solution.

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.

Design of a Reconfigurable, Monolithic Compliant Mechanism for a Six-Axis Nanomanipulator

2004 ◽  
Author(s):  
Martin L. Culpepper ◽  
Soohyung Kim
Keyword(s):  
Natural Frequencies ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Design Tool ◽  
Performance Characteristics ◽  
Mode Shapes ◽  
Dynamic Mode ◽  
High Bandwidth ◽  
Fea Simulation ◽  
Compliant Mechanism Design

In general, compliant mechanisms are single-state devices, meaning there is a one-to-one relationship between the inputs (actuation) and outputs (mechanism motion). This is particularly troublesome in precision mechanisms which offer limited flexibility in performance characteristics for high cost. In this paper we demonstrate a method which was proposed in earlier work (2002) to make a six-axis compliant mechanism with reconfigurable performance characteristics. The mechanism was synthesized using CoMeT, a compliant mechanism design tool, and optimized via FEA simulation. Experimental results show that (1) mechanism transmission ratio can be reconfigured between negative and positive numbers (2) that dynamic mode shapes may be changed and (3) that natural frequencies may be independently reconfigured. A means to handle the competing material requirements of large range and high-bandwidth is briefly presented.

Using Rigid-Body Mechanism Topologies to Design Shape-Changing Compliant Mechanisms

2013 ◽  
Author(s):  
Kai Zhao ◽  
James P. Schmiedeler
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Shape Change ◽  
Adaptive Antenna ◽  
Dimensional Synthesis ◽  
Element Analysis ◽  
Initial Element ◽  
Multi Objective Genetic Algorithm ◽  
Improved Design

This paper uses rigid-body mechanism topologies to synthesize distributed compliant mechanisms that approximate a shape change defined by a set of morphing curves in different positions. A single-actuator compliant mechanism is synthesized from a single degree-of-freedom rigid-body mechanism’s base topology in one of two ways. In one case, the base topology is directly evaluated through dimensional synthesis to determine the compliant mechanism’s optimal dimensions. In the second, the base topology establishes an initial element network for an optimization routine that determines topologies and dimensions simultaneously, and an improved design domain parameterization scheme ensures that only topologies with well-connected structures are evaluated. A multi-objective genetic algorithm is employed to search the design space, and the deformation is evaluated using geometrically nonlinear finite element analysis. The procedure’s utility is demonstrated with two practical examples — one approximating open-curve profiles of an adaptive antenna and the other closed-curve profiles of a morphing wing.

Compliant Mechanism Synthesis Using Degree of Genus and Variable Width Curves

2014 ◽  
Author(s):  
Hong Zhou ◽  
Azher Hussain Naser Mohammed
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Structural Complexity ◽  
Joint Effect ◽  
Synthesis Process ◽  
Mechanism Synthesis ◽  
Shape Morphing ◽  
Optimizing Control ◽  
Material Layout ◽  
Shape And Size

Compliant mechanisms (CMs) utilize elastic deformations for mechanism functions. Their merits primarily come from jointless structures. The structure of a fully CM is a piece of elastic material and is defined by its topology, shape and size. Topology is the overarching material layout of a CM while shape and size are on its structural details, but topology is entangled with shape and size in the synthesis process of a CM because its elastic deformation is from the joint effect of topology, shape and size. Degree of freedom (DOF) and number of links used in rigid mechanism synthesis are not effective to guide the synthesis of CMs since any point of a fully CM can deform and its whole structure forms a single piece. Without effective synthesis guidance, the structural complexity of a synthesized CM can be undesirably high. In this paper, degree of genus (DOG) is introduced for topology guidance of CM synthesis. DOG of a CM is the number of holes and is actively controlled during its synthesis process. With DOG guidance, a synthesized CM will not have overcomplicated topology. Variable width curves (VWCs) are introduced in this paper for shape and size description. Any connection in a CM is defined as a VWC and the entire CM is modeled as a network of VWCs. With VWC description, a synthesized CM will not have unsmooth connection. Under DOG and VWC strategies, CM synthesis is systematized as optimizing control parameters of networks of VWCs. The proposed CM synthesis using DOG and VWC strategies is demonstrated by synthesizing shape morphing compliant mechanisms.

Target Shape Optimization of 3D Compliant Mechanism With Superelastic Joints and Shape Memory Actuation

2019 ◽  
Author(s):  
Jovana Jovanova ◽  
Angela Nastevska ◽  
Mary Frecker
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Shape Change ◽  
Nickel Titanium ◽  
Different Temperatures ◽  
Superelastic Behavior ◽  
Over Time

Abstract The shape memory effect and the superelasticity of nickel titanium (NiTi) alloys are beneficial for design of compliant mechanisms. The superelastic behavior of NiTi can be tailored for optimal flexure design in the compliant mechanism, allowing large deformation and shape change. The shape memory effect can also be utilized to actuate the compliant mechanism flexures enabling programing of the material to take on variety of shapes at different temperatures over time. The compliant mechanism analyzed in this work is inspired from 3D multi leg spider-like locomotion, enabling movement in all directions by triggering different target shapes in time. The control of the material spatial distribution facilitated by additive manufacturing will enable tailored superelastic and shape memory behavior in the flexures of the multifunctional 3D compliant mechanism. Design optimization and analyses as well as overall shape change are explored in this work. Superelastic joints are introduced as flexures to enable segment flexibility. The temperature change is used for actuation taking in consideration different initial strain conditions.

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