Topology synthesis of a 3-kink contact-aided compliant switch

2020 ◽  
pp. 1-47
Author(s):  
B V S Nagendra Reddy ◽  
Anupam Saxena
Keyword(s):  
Compliant Mechanisms ◽  
Synthesis Process ◽  
Quadrilateral Elements ◽  
Design Variables ◽  
Rigid Contact ◽  
Contact Surfaces ◽  
Output Characteristics ◽  
Line Elements ◽  
Mechanical Switch ◽  
Synthesis Approach

Abstract A topology synthesis approach to design 2D Contact-aided Compliant Mechanisms (CCMs) to trace output paths with three or more kinks is presented. Synthesis process uses three different types of external, rigid contact surfaces – circular, elliptical and rectangular – which in combination, offer intricate local curvatures that CCMs can benefit from, to deliver desired, complex output characteristics. A network of line elements is employed to generate topologies. A set of circular subregions is laid over this network, and external contact surfaces are generated within each subregion. Both, discrete and continuous design variables are employed – the former set controls the CCM topology, appearance and type of external contact surfaces, whereas the latter set governs shapes and sizes of the CCM constituents, and sizes of contact surfaces. All contact types are permitted with contact modeling made significantly easier through identification of outer and inner loops. Line topologies are fleshed out via a user-defined number of quadrilateral elements along lateral and longitudinal directions. Candidate CCM designs are carefully preprocessed before analysis via a commercial software and evolution using a stochastic search. The process is exemplified via a contact-aided, 3-kink mechanical switch which is thoroughly analysed in presence of friction and wear.

Design of a parallel gripper based on topology synthesis and evolutionary optimization

2021 ◽  
pp. 1-18
Author(s):  
I-Ting Chi ◽  
Teeranoot Chanthasopeephan ◽  
Dung-An Wang
Keyword(s):  
Genetic Algorithm ◽  
Optimal Design ◽  
Design Process ◽  
Compliant Mechanisms ◽  
Synthesis Process ◽  
Dimensional Synthesis ◽  
Multi Objective Genetic Algorithm ◽  
Constraint Model ◽  
Force Displacement ◽  
Synthesis Approach

Abstract A compliant gripper with nearly parallel gripping motion is developed by a topology synthesis and a dimensional synthesis approach. The topology synthesis process can generate linkage type compliant mechanisms. Suitable boundary conditions of the topology synthesis process are selected to achieve the desired functions of the device. The dimensional synthesis is based on an evolutionary optimal design process. In order to meet various design goals, a nondominated multi-objective genetic algorithm is selected for the optimal design process. A kinetostaic model based on the chained beam constraint model is developed for force-displacement analysis of the designs. Efficiency and accuracy of the design approach are proved by experiments. Appropriate linkage types of compliant mechanisms may be discovered by the topology optimization process before moving on to dimensional synthesis to obtain final designs.

Parameterization Strategy for Optimization of Shape Morphing Compliant Mechanisms Using Load Path Representation

2003 ◽  
Author(s):  
Kerr-Jia Lu ◽  
Sridhar Kota
Keyword(s):  
Compliant Mechanisms ◽  
Element Model ◽  
Structural Deformation ◽  
Load Path ◽  
Aircraft Wings ◽  
Shape Morphing ◽  
Design Variables ◽  
Path Representation ◽  
Flexible Antenna ◽  
Synthesis Approach

The distributed compliance and smooth deformation field of compliant mechanisms provide a viable means to achieve shape morphing in many systems, such as flexible antenna reflectors and morphing aircraft wings. We previously developed a systematic synthesis approach to design shape morphing compliant mechanisms using Genetic Algorithm (GA). However, the design variable definition, in fact, allows the generation of invalid designs (disconnected structures) within the GA. In this research, we developed a load path representation to include the structure connectivity information into the design variables, thus improving the GA efficiency. The number of design variables is also independent of the number of elements in the finite element model that is used to solve for the structural deformation. The shape morphing synthesis approach, incorporating this path representation, is demonstrated through two examples, followed by discussions on further refinements.

Topology and Dimensional Synthesis of Compliant Mechanisms Using Discrete Optimization

2005 ◽  
Vol 128 (5) ◽  
pp. 1080-1091 ◽  
Author(s):  
Kerr-Jia Lu ◽  
Sridhar Kota
Keyword(s):  
Discrete Optimization ◽  
Optimization Problem ◽  
Compliant Mechanisms ◽  
Discrete Optimization Problem ◽  
Dimensional Synthesis ◽  
Load Path ◽  
Design Variables ◽  
Gray Areas ◽  
Path Synthesis ◽  
Synthesis Approach

A unified approach to topology and dimensional synthesis of compliant mechanisms is presented in this paper as a discrete optimization problem employing both discrete (topology) and continuous (size) variables. The synthesis scheme features a design parameterization method that treats load paths as discrete design variables to represent various topologies, thereby ensuring structural connectivity among the input, output, and ground supports. The load path synthesis approach overcomes certain design issues, such as “gray areas” and disconnected structures, inherent in previous design schemes. Additionally, multiple gradations of structural resolution and a variety of configurations can be generated without increasing the number of design variables. By treating topology synthesis as a discrete optimization problem, the synthesis approach is incorporated in a genetic algorithm to search for feasible topologies for single-input single-output compliant mechanisms. Two design examples, commonly seen in the compliant mechanisms literature, are included to illustrate the synthesis procedure and to benchmark the performance. The results show that the load path synthesis approach can effectively generate well-connected compliant mechanism designs that are free of gray areas.

Toward a Unified Design Approach for Both Compliant Mechanisms and Rigid-Body Mechanisms: Module Optimization

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Lin Cao ◽  
Allan T. Dolovich ◽  
Arend L. Schwab ◽  
Just L. Herder ◽  
Wenjun (Chris) Zhang
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Optimization Approach ◽  
Structure Model ◽  
Dimensional Synthesis ◽  
Beam Elements ◽  
Compliant Joints ◽  
Design Variables ◽  
Rigid Joints ◽  
Synthesis Approach

Rigid-body mechanisms (RBMs) and compliant mechanisms (CMs) are traditionally treated in significantly different ways. In this paper, we present a synthesis approach that is appropriate for both RBMs and CMs. In this approach, RBMs and CMs are generalized into modularized mechanisms that consist of five basic modules, including compliant links (CLs), rigid links (RLs), pin joints (PJs), compliant joints (CJs), and rigid joints (RJs). The link modules and joint modules are modeled through beam elements and hinge elements, respectively, in a geometrically nonlinear finite-element solver, and subsequently a beam-hinge ground structure model is proposed. Based on this new model, a link and joint determination approach—module optimization—is developed for the type and dimensional synthesis of both RBMs and CMs. In the module optimization approach, the states (both presence or absence and sizes) of joints and links are all design variables, and one may obtain an RBM, a partially CM, or a fully CM for a given mechanical task. Three design examples of path generators are used to demonstrate the effectiveness of the proposed approach to the type and dimensional synthesis of RBMs and CMs.

Synthesis of Path Generating Compliant Mechanisms Using Initially Curved Frame Elements

2006 ◽  
Vol 129 (10) ◽  
pp. 1056-1063 ◽  
Author(s):  
Ashok Kumar Rai ◽  
Anupam Saxena ◽  
Nilesh D. Mankame
Keyword(s):  
Objective Function ◽  
Mechanical Response ◽  
Compliant Mechanisms ◽  
Element Formulation ◽  
Mechanical Responses ◽  
Design Variables ◽  
Lagrangian Finite Element ◽  
Synthesis Procedure ◽  
Synthesis Approach ◽  
Good Agreement

Initially curved frame elements are used in this paper within an optimization-based framework for the systematic synthesis of compliant mechanisms (CMs) that can trace nonlinear paths. These elements exhibit a significantly wider range of mechanical responses to applied loads than the initially straight frame elements, which have been widely used in the past for the synthesis of CMs. As a consequence, fewer elements are required in the design discretization to obtain a CM with a desired mechanical response. The initial slopes at the two nodes of each element are treated as design variables that influence not only the shape of the members in a CM, but also the mechanical response of the latter. Building on our prior work, the proposed synthesis approach uses genetic algorithms with both binary (i.e., 0/1) and continuous design variables in conjunction with a co-rotational total Lagrangian finite element formulation and a Fourier shape descriptors-based objective function. This objective function is chosen for its ability to provide a robust comparison between the actual path traced by a candidate CM design and the desired path. Two synthesis examples are presented to demonstrate the synthesis procedure. The resulting designs are fabricated as is, without any postprocessing, and tested. The fabricated prototypes show good agreement with the design intent.

Topology Optimization of Compliant Mechanisms Using Hybrid Discretization Model

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Hong Zhou
Keyword(s):  
Topology Optimization ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Optimization Procedure ◽  
Optimization Method ◽  
Diagonal Element ◽  
Initial Guess ◽  
Stress Constraint ◽  
Design Variables ◽  
Hybrid Discretization

The hybrid discretization model for topology optimization of compliant mechanisms is introduced in this paper. The design domain is discretized into quadrilateral design cells. Each design cell is further subdivided into triangular analysis cells. This hybrid discretization model allows any two contiguous design cells to be connected by four triangular analysis cells whether they are in the horizontal, vertical, or diagonal direction. Topological anomalies such as checkerboard patterns, diagonal element chains, and de facto hinges are completely eliminated. In the proposed topology optimization method, design variables are all binary, and every analysis cell is either solid or void to prevent the gray cell problem that is usually caused by intermediate material states. Stress constraint is directly imposed on each analysis cell to make the synthesized compliant mechanism safe. Genetic algorithm is used to search the optimum and to avoid the need to choose the initial guess solution and conduct sensitivity analysis. The obtained topology solutions have no point connection, unsmooth boundary, and zigzag member. No post-processing is needed for topology uncertainty caused by point connection or a gray cell. The introduced hybrid discretization model and the proposed topology optimization procedure are illustrated by two classical synthesis examples of compliant mechanisms.

Design of Crashworthy Structures With Controlled Energy Absorption in the Hybrid Cellular Automaton Framework

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Punit Bandi ◽  
James P. Schmiedeler ◽  
Andrés Tovar
Keyword(s):  
Energy Absorption ◽  
Design Space ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Mechanism Synthesis ◽  
Load Paths ◽  
Fully Stressed Design ◽  
Novel Method ◽  
The Given ◽  
Synthesis Approach

This work presents a novel method for designing crashworthy structures with controlled energy absorption based on the use of compliant mechanisms. This method helps in introducing flexibility at desired locations within the structure, which in turn reduces the peak force at the expense of a reasonable increase in intrusion. For this purpose, the given design domain is divided into two subdomains: flexible (FSD) and stiff (SSD) subdomains. The design in the flexible subdomain is governed by the compliant mechanism synthesis approach for which output ports are defined at the interface between the two subdomains. These output ports aid in defining potential load paths and help the user make better use of a given design space. The design in the stiff subdomain is governed by the principle of a fully stressed design for which material is distributed to achieve uniform energy distribution within the design space. Together, FSD and SSD provide for a combination of flexibility and stiffness in the structure, which is desirable for most crash applications.

An Efficient Method for Synthesizing Crank-Rocker Mechanisms for Generating Low Harmonic Curves

2009 ◽  
Author(s):  
Jun Wu ◽  
Q. J. Ge ◽  
Feng Gao
Keyword(s):  
Fourier Series ◽  
Harmonic Analysis ◽  
Efficient Method ◽  
Search Space ◽  
Synthesis Process ◽  
Loop Closure ◽  
Design Variables ◽  
Speed Up ◽  
Analytical Relations

This paper deals with the development of an efficient method for synthesizing crank-rocker mechanisms that are capable of generating perceptually simple and smooth paths that can be approximated by the first and second harmonics of Fourier series. Through the harmonic analysis of the loop closure equations of the crank-rocker mechanism, analytical relations among the nine design variables are identified. This reduces the dimensions of the search space to two and thereby greatly speed up the synthesis process.

The Analysis of a Simplified 2R Pseudo-Rigid-Body Model with Moment Load

2012 ◽  
Vol 224 ◽  
pp. 18-23
Author(s):  
Yun Jiao Zhang ◽  
Guo Wu Wei ◽  
Jian Sheng Dai
Keyword(s):  
Rigid Body ◽  
Objective Function ◽  
Compliant Mechanisms ◽  
Three Dimensional ◽  
Body Model ◽  
Design Variables ◽  
Characteristic Radius ◽  
Rigid Body Model ◽  
Analysis And Synthesis ◽  
Moment Load

Pseudo-rigid-body model (PRBM) method, which simplifies the geometrical nonlinear analysis, has become an important tool for the analysis and synthesis of compliant mechanisms. In this paper, a simplified 2R PRBM with two rigid links and two torsion springs is proposed. The characteristic radius factor and stiffness coefficients are selected as the design variables; in order to be better to simulate the tip point and tip slope, a three-dimensional objective function is formulated to optimize the new pseudo-rigid-body model. It is revealed in this paper that the precision of the tip point simulation can be improved when the coefficient of the tip slope error in the objective function is reduced.

scholarly journals Synthesis method of two translational compliant mechanisms with redundant actuation

2021 ◽  
Vol 12 (2) ◽  
pp. 983-995
Author(s):  
Shihua Li ◽  
Yajie Zhou ◽  
Yanxia Shan ◽  
Shuang Chen ◽  
Jinhan Han
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Compliant Mechanisms ◽  
Synthesis Method ◽  
Synthesis Process ◽  
Parallel Mechanisms ◽  
Synthesis Conditions ◽  
Compliant Parallel Mechanism ◽  
Atlas Method ◽  
Driving Stability

Abstract. In the fields of electronic packaging, micromanipulation, scanning, and two translational (2T) mechanisms are required, especially with high stiffness, for a large workspace, with good driving stability, and other occasions. Redundant actuators are required to improve the performance of the 2T compliant parallel mechanism. The novelty of the work is to propose a new method for the type synthesis of a 2T redundant actuated compliant parallel mechanism based on the freedom and constraint topology (FACT) approach and the atlas approach. The synthesis conditions are given, and the synthesis process is formulated. With this method, new 2T redundant actuated compliant parallel mechanisms are synthesized. Some new mechanisms have been synthesized, which enriches the compliant parallel mechanism configurations. Based on the atlas method, the synthesized mechanism is analyzed. The results verify the correctness and effective of the synthesis method. The method is also suitable for a type of synthesis of redundant actuated compliant parallel mechanisms with 3, 4, 5, and 6 degrees of freedom (DOF), respectively.

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