Systematic Synthesis of Large Displacement Contact-Aided Monolithic Compliant Mechanisms

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
B. V. S. Nagendra Reddy ◽  
Sujitkumar V. Naik ◽  
Anupam Saxena
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Large Displacement ◽  
Contact Site ◽  
Design Algorithm ◽  
Contact Sites ◽  
Single Piece ◽  
Synthesis Procedure ◽  
Systematic Synthesis ◽  
The Continuum

A single-piece contact-aided compliant mechanism (CCM) deforms to use one or many contact interactions to deliver the prescribed intricate input–output functionality. We present an automated synthesis procedure to design CCMs to trace large, non-smooth paths. Such paths can be traced by rigid-body or partially compliant mechanisms as well but the complexity, bulkiness and the presence of hinges is a disadvantage in terms of increased friction, backlash, need for lubrication, noise, and vibrations. In designing CCMs, both curved frame and two-dimensional finite elements are employed to represent the continuum and simulate the formation of contact sites. A contact site is one that allows relative rotation/sliding of a deforming member with respect to the neighboring one it is in contact with. The proposed design algorithm uses commercial software for large displacement contact analysis. The overall procedure automatically determines the CCM topology, feature shapes and sizes, and therefore the number (e.g., single or multiple) and nature (e.g., stiction or sliding) of contact sites. It systematically favors the continuum designs with lower function values when the synthesis problem is posed using a minimization objective. Synthesis of CCMs is exemplified for path generation applications though the proposed method can be employed for any generic kinematic task.

On a Solution Procedure to Synthesize Non-Smooth Path Generating Compliant Mechanisms With Self Contact

2010 ◽  
Author(s):  
B. V. S. Nagendra Reddy ◽  
Anupam Saxena
Keyword(s):  
Large Deformation ◽  
Elastic Deformation ◽  
Optimum Design ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Solution Procedure ◽  
Motion Generation ◽  
Contact Sites ◽  
Smooth Path ◽  
Single Piece

A contact-aided compliant mechanism (CCM) is a single piece flexible continuum that uses the contact interactions between different portions in addition to the elastic deformation. Our work deals with the design of contact aided compliant mechanisms with initially curved frame elements to trace more complex and non smooth paths. We can achieve these kinematic tasks by using partially compliant mechanisms as well. But the presence of hinges is a disadvantage in terms of increased friction, backlash, need for lubrication, noise and vibrations. In this paper, we propose an automated procedure to obtain the optimum design of large deformation CCMs. Through commercial software, we simulate the formation of pseudo hinges at contact sites that get formed dynamically as the mechanism deforms. By appropriately positioning these pseudo hinges, i.e., by designing a suitable CCM, the aim, in general, is to achieve a variety of function, path and motion generation characteristics via single piece continua.

Two Stage Design of Compliant Mechanisms With Superelastic Compliant Joints

2017 ◽  
Author(s):  
Jovana Jovanova ◽  
Mary Frecker
Keyword(s):  
Analytical Model ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Functionally Graded ◽  
Two Stage ◽  
Stage Design ◽  
Rigid Link ◽  
Starting Point ◽  
Single Piece ◽  
Two Stage Design

The design of compliant mechanisms made of Nickel Titanium (NiTi) Shape Memory Alloys (SMAs) is considered to exploit the superelastic behavior of the material to achieve tailored high flexibility on demand. This paper focuses on two-stage design optimization of compliant mechanisms, as a systematic method for design of the composition of the functionally graded NiTi material within the compliant mechanism devices. The location, as well as geometric and mechanical properties, of zones of high and low flexibility will be selected to maximize mechanical performance. The proposed two-stage optimization procedure combines the optimization of an analytical model of a single-piece functionally graded unit, with a detailed FEA of a continuous compliant mechanism. In the first stage, a rigid-link model is developed to initially approximate the behavior of the compliant mechanism. In the second stage the solution of the rigid-link problem serves as the starting point for a continuous analytical model where the mechanism consists of zones with different material properties and geometry, followed by a detailed FEA of a compliant mechanism with integrated zones of superelasticity. The two-stage optimization is a systematic approach for compliant mechanism design with functional grading of the material to exploit superelastic response in controlled manner. Direct energy deposition, as an additive manufacturing technology, is foreseen to fabricate assemblies with multiple single piece functional graded components. This method could be applied to bio-inspired structures, flapping wings, flexible adaptive structures and origami inspired compliant mechanisms.

Efficient Development of Continuum/Compliant Planar Linkage Mechanisms

2019 ◽  
Author(s):  
Woo Rib Suh ◽  
J. Michael McCarthy ◽  
Edwin A. Peraza Hernandez
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Shape Parameters ◽  
Element Analysis ◽  
Initial Node ◽  
Synthesis Of Mechanisms ◽  
Efficient Alternative ◽  
Computationally Intensive ◽  
The Given ◽  
The Continuum

Abstract This paper presents a method to develop continuum/compliant mechanisms based on planar bar-node linkage precursors. The method takes as inputs the initial node positions and connectivity data of a given bar-node linkage and converts it into a continuum/compliant mechanism having the same targeted motion. The line bars of the given bar-node linkage are thickened into trapezoidal planar members and the nodes are thickened by introducing fillets at each intersection of bars. The thicknesses of the bars and the shape parameters of the fillets in the continuum/compliant linkage are optimized to obtain the same targeted motion of the given bar-node linkage while keeping stresses below a maximum allowable value. Each design generated during the optimization process is evaluated using finite element analysis. The present method allows for the synthesis of mechanisms having the following advantages over conventional bar-node linkages: 1) They do not require complex ball or pin joints; 2) they can be readily 3-D printed and size-scaled, and 3) they can be optimized to decrease stresses below a maximum allowable value. Furthermore, the method uses a relatively small number of optimization variables (thicknesses of the members, shape-parameters of the fillets), making it an efficient alternative to more complex and computationally intensive methods for synthesizing compliant mechanisms such as those incorporating topology optimization.

scholarly journals Design of Large-Displacement Compliant Mechanisms by Topology Optimization Incorporating Modified Additive Hyperelasticity Technique

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Liying Liu ◽  
Jian Xing ◽  
Qingwei Yang ◽  
Yangjun Luo
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Previous Method ◽  
Large Displacement ◽  
Topology Design ◽  
Optimization Process ◽  
Response Analysis ◽  
Modified Technique ◽  
Element Analysis ◽  
Output Displacement

This paper is focused on the topology design of compliant mechanisms undergoing large displacement (over 20% of the structural dimension). Based on the artificial spring model and the geometrically nonlinear finite element analysis, the optimization problem is formulated so as to maximize the output displacement under a given material volume constraint. A modified additive hyperelasticity technique is proposed to circumvent numerical instabilities that occurred in the low-density or intermediate-density elements during the optimization process. Compared to the previous method, the modified technique is very effective and can provide more accurate response analysis for the large-displacement compliant mechanism. The whole optimization process is carried out by the gradient-based mathematical programming method. Numerical examples of a force-inverting mechanism and a microgripping mechanism are presented. The obtained optimal solutions verify the applicability of the proposed numerical techniques and show the necessity of considering large displacement in the design problem.

scholarly journals A Virtual Reality Interface for the Design of Compliant Mechanisms

2009 ◽  
Author(s):  
Utkarsh Seth ◽  
Hai-Jun Su ◽  
Judy M. Vance
Keyword(s):  
Virtual Reality ◽  
Design Process ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Current Method ◽  
Motion Path ◽  
User Centered Design ◽  
Design Algorithm ◽  
Constraint Sets ◽  
User Centered

The objective of this research is to develop an immersive interface and a design algorithm to facilitate the synthesis of compliant mechanisms from a user-centered design perspective. Compliant mechanisms are mechanical devices which produce motion or force through deflection or flexibility of their parts. Using the constraint-based method of design, the design process relies on the designer to identify the appropriate constraint sets to match the desired motion. Currently this approach requires considerable prior knowledge of how non-linear flexible members produce motion. As a result, the design process is based primarily on the designer’s previous experience and intuition. A user-centered methodology is suggested where the interface guides the designer throughout the design process, thus reducing the reliance on intuitive knowledge. This methodology supports constraint-based design methods by linking mathematical models to support compliant mechanism design in an immersive virtual environment. A virtual reality (VR) immersive interface enables the designer to input the intended motion path by simply grabbing and moving the object and letting the system decide which constraint spaces apply. The user-centered paradigm supports an approach that focuses on the designer defining the motion and the system generating the constraint sets, instead of the current method which relies heavily on the designer’s intuition to identify appropriate constraints. The result is an intelligent design framework that will allow a broader group of engineers to design complex compliant mechanisms, giving them new options to draw upon when searching for design solutions to critical problems.

Multi-material topology optimization of large-displacement compliant mechanisms considering material-dependent boundary condition

2021 ◽  
pp. 095440622110361
Author(s):  
Jinqing Zhan ◽  
Yu Sun ◽  
Min Liu ◽  
Benliang Zhu ◽  
Xianmin Zhang
Keyword(s):  
Boundary Condition ◽  
Topology Optimization ◽  
Optimization Problem ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Impedance Matching ◽  
Large Displacement ◽  
Thermal Impedance ◽  
Output Displacement ◽  
Topology Optimization Problem

Multi-material compliant mechanisms design enables potential design possibilities by exploiting the advantages of different materials. To satisfy mechanical/thermal impedance matching requirements, a method for multi-material topology optimization of large-displacement compliant mechanisms considering material-dependent boundary condition is presented in this study. In the optimization model, the element stacking method is employed to describe the material distribution and handle material-dependent boundary condition. The maximization of the output displacement of the compliant mechanism is developed as the objective function and the structural volume of each material is the constraint. Fictitious domain approach is applied to circumvent the numerical instabilities in topology optimization problem with geometrical nonlinearities. The method of moving asymptotes is applied to solve the optimization problem. Several numerical examples are presented to demonstrate the validity of the proposed method. The optimal topologies of the compliant mechanisms obtained by the proposed method can satisfy the specified material-dependent boundary condition.

Modeling of Compliant Mechanisms in MATLAB Simscape

2020 ◽  
Author(s):  
Paul Pena ◽  
Martin Garcia ◽  
Ayse Tekes
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Flexible Systems ◽  
Flexible Links ◽  
Hopping Robot ◽  
Lumped Parameter ◽  
Single Piece ◽  
Modeling Software ◽  
Cad Models ◽  
Tip Position

Abstract This paper presents the informative process of modeling of compliant mechanisms using MATLAB Simscape. Simscape is the modeling environment analyzing both rigid and flexible systems using either the blocks provided in the library or the CAD models imported from modeling software. We present the modeling of four compliant mechanisms: dwell, five bar, translational and hopping mechanisms. Once the cad model of a system is imported into Simscape, the flexible links or flexure segment on each example system is replaced by its equivalent lumped parameter block. Compliant dwell mechanism is comprised of a rail, two pinned-pinned flexible links, slider, rigid crank and a DC motor. The second mechanism is a fully compliant five bar mechanism incorporating large deflecting flexures and actuated by two servo motors. The objective is to control the trajectory of the tip position. Third example models a bio-inspired translational compliant mechanism driven by servo motors and comprised of three sliders connected by single piece designed 2 rigid arm-flexure hinge linkages mimicking the motion of a caterpillar. The last example is the modeling of a compliant hopping robot consisting of two pairs of gears; one pair is attached to the motor and the other pair allows the bottom links to rotate at same angular velocity in opposite directions.

Topological Synthesis of Compliant Mechanisms Using Multi-Criteria Optimization

1997 ◽  
Vol 119 (2) ◽  
pp. 238-245 ◽  
Author(s):  
M. I. Frecker ◽  
G. K. Ananthasuresh ◽  
S. Nishiwaki ◽  
N. Kikuchi ◽  
S. Kota
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Two Dimensional ◽  
Ground Structure ◽  
New Approach ◽  
Input Force ◽  
Single Piece ◽  
Mechanical Devices ◽  
Compliant Mechanism Design ◽  
Topological Synthesis

Compliant mechanisms are mechanical devices that achieve motion via elastic deformation. A new method for topological synthesis of single-piece compliant mechanisms is presented, using a “design for required deflection” approach. A simple beam example is used to illustrate this concept and to provide the motivation for a new multi-criteria approach for compliant mechanism design. This new approach handles motion and loading requirements simultaneously for a given set of input force and output deflection specifications. Both a truss ground structure and a two-dimensional continuum are used in the implementation which is illustrated with design examples.

New horizons in mitochondrial contact site research

2020 ◽  
Vol 401 (6-7) ◽  
pp. 793-809
Author(s):  
Naama Zung ◽  
Maya Schuldiner
Keyword(s):  
Endoplasmic Reticulum ◽  
Molecular Mechanisms ◽  
Contact Site ◽  
New Horizons ◽  
Contact Sites ◽  
Future Goals ◽  
Close Proximity ◽  
Recent Developments ◽  
Site Field ◽  
First Contact

AbstractContact sites, areas where two organelles are held in close proximity through the action of molecular tethers, enable non-vesicular communication between compartments. Mitochondria have been center stage in the contact site field since the discovery of the first contact between mitochondria and the endoplasmic reticulum (ER) over 60 years ago. However, only now, in the last decade, has there been a burst of discoveries regarding contact site biology in general and mitochondrial contacts specifically. The number and types of characterized contacts increased dramatically, new molecular mechanisms enabling contact formation were discovered, additional unexpected functions for contacts were shown, and their roles in cellular and organismal physiology were emphasized. Here, we focus on mitochondria as we highlight the most recent developments, future goals and unresolved questions in the field.

Bistable Compliant Four-Bar Mechanisms With a Single Torsional Spring

2006 ◽  
Author(s):  
Adarsh Mavanthoor ◽  
Ashok Midha
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanism Design ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Stored Energy ◽  
Element Analysis ◽  
Bistable Behavior ◽  
Torsional Spring ◽  
Bistable Mechanism

Significant reduction in cost and time of bistable mechanism design can be achieved by understanding their bistable behavior. This paper presents bistable compliant mechanisms whose pseudo-rigid-body models (PRBM) are four-bar mechanisms with a torsional spring. Stable and unstable equilibrium positions are calculated for such four-bar mechanisms, defining their bistable behavior for all possible permutations of torsional spring locations. Finite Element Analysis (FEA) and simulation is used to illustrate the bistable behavior of a compliant mechanism with a straight compliant member, using stored energy plots. These results, along with the four-bar and the compliant mechanism information, can then be used to design a bistable compliant mechanism to meet specified requirements.

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