Zero Torque Compliant Mechanisms Employing Pre-buckled Beams

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Pietro Bilancia ◽  
Samuel P. Smith ◽  
Giovanni Berselli ◽  
Spencer P. Magleby ◽  
Larry L. Howell
Keyword(s):  
Analytical Approach ◽  
Compliant Mechanisms ◽  
Negative Stiffness ◽  
Rotational Degree ◽  
Annular Domain ◽  
Archimedean Spiral ◽  
Element Analysis ◽  
Buckled Beams ◽  
Physical Prototype ◽  
Spiral Beam

Abstract The concept of a statically balanced mechanism with a single rotational degree-of-freedom is presented. The proposed device achieves static balancing by combining positive stiffness elements and negative stiffness elements within an annular domain. Two designs are discussed. The first is composed of an Archimedean spiral and two pinned-pinned pre-buckled beams. The overall mechanism is modeled via an analytical approach and the element dimensions are optimized. The optimal configuration is then tested through finite element analysis (FEA). A second approach replaces the spiral beam with elastic custom-shaped spline beams. A FEA optimization is performed to determine the shape and size of such spline beams. The behavior of the negators is used as reference for the optimization so as to achieve a complete balancing. A physical prototype of each configuration is machined and tested. The comparison between predicted and acquired data confirmed the efficacy of the design methods.

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.

Dämpfungsschlitze in Kreissägeblättern*/Parametric FE analysis to identify the mode of action of damping slots in circular saw blades

2015 ◽  
Vol 105 (01-02) ◽  
pp. 41-46
Author(s):  
C. Birenbaum ◽  
U. Heisel ◽  
S. Weiland
Keyword(s):  
Finite Element Analysis ◽  
Thermal Expansion ◽  
Analytical Approach ◽  
Simulation Models ◽  
Fe Analysis ◽  
Element Analysis ◽  
Annular Plates ◽  
Circular Saw ◽  
Characteristic Modes ◽  
The Relationship

In Kreissägeblättern werden zur Verminderung von Schwingungen und zum Ausgleich thermischer Dehnungen sogenannte Dehnungs- und Dämpfungsschlitze eingebracht. Die Wirkungsweise der Schlitze auf die dynamischen Eigenschaften besteht einerseits in der Dämpfungswirkung sowie andererseits in der Modifikation der Schwingungseigenformen. Um Wirkmechanismen und Optimierungsmöglichkeiten zu identifizieren, werden in den hier vorgestellten Untersuchungen mithilfe der Finiten-Elemente-Methode (FEM) Analysen von Kreisscheiben mit einfachen Schlitzkonfigurationen durchgeführt. Hierdurch sollen Zusammenhänge einzelner Schlitzparameter mit den statischen und dynamischen Eigenschaften von Kreissägeblättern aufgezeigt werden. Zur Validierung des entwickelten Simulationsmodells dienen analytische Berechnungen.   To reduce vibrations and adjust for thermal expansion, so-called damping slots and expansion slots are applied to circular saw blades. The slots affect the dynamic behavior of the saw blades by damping the vibration and altering the characteristic modes and frequencies. An FE(Finite Element) analysis of annular plates with simple arrangements of damping and expansion slots is performed to identify the mechanisms and improvement opportunities. This allows determining the relationship between slot parameters and the static and dynamic qualities of circular saw blades. The developed simulation models are validated using an analytical approach.

Comparison of Numerical Methods for Determining Torsion Stiffness of Automotive Chassis

2011 ◽  
Author(s):  
Steven Tebby ◽  
Ebrahim Esmailzadeh ◽  
Ahmad Barari
Keyword(s):  
Finite Element Analysis ◽  
Analytical Approach ◽  
Torsional Stiffness ◽  
Design Stage ◽  
Element Analysis ◽  
Detailed Design ◽  
Vertical Displacements ◽  
Comparison Of The Results ◽  
Torsion Stiffness

The torsion stiffness of an automotive chassis can be determined using an analytical approach based purely on geometry, using an experimental method, or alternatively by employing a Finite Element Analysis (FEA) process. These three methods are suitable at different design stages and combined together could prove to be practical methods of determining the torsion stiffness of a chassis. This paper describes and compares two distinct FEA processes to determine the torsion stiffness of an automotive chassis during the detailed design stage. The first process iteratively applies forces to the model and records displacements, while the second process gradually applies vertical displacements in place of force to determine the torsional stiffness threshold. Each method is explained and supported with a case study to provide a basis of comparison of the results.

Modeling Large Spatial Deflections of Slender Bisymmetric Beams in Compliant Mechanisms Using Chained Spatial-Beam Constraint Model

2016 ◽  
Vol 8 (4) ◽  
Author(s):  
Guimin Chen ◽  
Ruiyu Bai
Keyword(s):  
Finite Element Analysis ◽  
Compliant Mechanisms ◽  
Research Community ◽  
Nonlinear Finite Element ◽  
Nonlinear Constraint ◽  
Element Analysis ◽  
Flexible Beams ◽  
Spatial Beams ◽  
Spatial Beam ◽  
Constraint Model

Modeling large spatial deflections of flexible beams has been one of the most challenging problems in the research community of compliant mechanisms. This work presents a method called chained spatial-beam constraint model (CSBCM) for modeling large spatial deflections of flexible bisymmetric beams in compliant mechanisms. CSBCM is based on the spatial-beam constraint model (SBCM), which was developed for the purpose of accurately predicting the nonlinear constraint characteristics of bisymmetric spatial beams in their intermediate deflection range. CSBCM deals with large spatial deflections by dividing a spatial beam into several elements, modeling each element with SBCM, and then assembling the deflected elements using the transformation defined by Tait–Bryan angles to form the whole deflection. It is demonstrated that CSBCM is capable of solving various large spatial deflection problems either the tip loads are known or the tip deflections are known. The examples show that CSBCM can accurately predict large spatial deflections of flexible beams, as compared to the available nonlinear finite element analysis (FEA) results obtained by ansys. The results also demonstrated the unique capabilities of CSBCM to solve large spatial deflection problems that are outside the range of ansys.

Analytical and Experimental Investigation on Sound Transmission of Double Thin Plates with Magnetic Negative Stiffness

2018 ◽  
Vol 10 (05) ◽  
pp. 1850054 ◽  
Author(s):  
Akintoye Olumide Oyelade ◽  
Yi Chen ◽  
Ruojun Zhang ◽  
Gengkai Hu
Keyword(s):  
Finite Element ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Interaction Force ◽  
Negative Stiffness ◽  
Thin Plates ◽  
Acoustic Metamaterials ◽  
Element Analysis ◽  
Theoretical Formulation ◽  
Wave Condition

Transmission loss of acoustic metamaterials (AM) made of double thin plates with magnetic (negative) stiffness was analyzed using theory, finite element analysis and experimental techniques. The theoretical formulation was done using a rectangular duct below the first cut off frequency, the model is then validated against finite element method and experiment. Two cubic magnets were used, their interaction force and the resulted magnetic stiffness were calculated. The sound transmission loss (STL) of the structure is calculated for plane wave condition, the addition of magnetic mass shifts STL peaks to the lower frequency compared to a structure without mass. The slight increase in STL for small negative stiffness in experiment is not enough to cancel the effect of air compressibility. However, a significant enhancement could be expected if negative stiffness can be made large enough in the double thin plates. The developed AM can be employed as a prospective sound engineering control at low frequency.

Design, analysis and test of a novel cylinder-driven mode applied to microgripper

2021 ◽  
pp. 1-14
Author(s):  
Xiaodong Chen ◽  
ZM Xie ◽  
Huifeng Tan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Compliant Mechanisms ◽  
Research Field ◽  
Driving Pressure ◽  
Maximum Output ◽  
Element Analysis ◽  
Output Displacement ◽  
Micro Parts ◽  
The Relationship

Abstract How to enlarge the output displacement is a key issue in the research field of microgrippers. It is difficult to further enlarge the output displacement for the traditional displacement transmission mechanism (DTM). In this research, a two-stage amplification cylinder-driven DTM based on the compliant mechanisms is designed to realize the displacement output expansion. The opening and closing of the clamping jaws is driven by the air cylinder to enlarge the output displacement of the microgripper. According to the analysis of statics model of the mechanism, the relationship between the output displacement of the microgripper and the driving pressure of the cylinder is established. The magnification of the microgripper is obtained using a dynamic model. Moreover, based on the finite element analysis, the mechanical structure parameters are optimized. The microgripper was fabricated by utilizing wire electro discharge machining (WEDM) technique, and then a series of experiments were carried out to obtain the relationship between the displacement and the driving pressure. It is found that the maximum output displacement measured is 1190.4μm under the pressure of 0-0.6 Mpa, corresponding to the magnification of 47.63. Compared with the results of finite element analysis and theoretical calculation, the test results have a discrepancy of 2.39% and 6.62%, respectively. The microgripper has successfully grasped a variety of micro-parts with irregular shapes, and parallel grasping can be achieved, demonstrating the potential application of this design in the field of micromanipulation.

Effect of Matching Buckling Loads on Post-Buckling Behavior in Compliant Mechanisms

2021 ◽  
Author(s):  
A. Numić ◽  
T. W. A. Blad ◽  
F. van Keulen
Keyword(s):  
Compliant Mechanisms ◽  
Relative Length ◽  
Optimal Designs ◽  
Element Analysis ◽  
Buckling Loads ◽  
Actuation Force ◽  
Stepped Beam ◽  
Buckling Behavior ◽  
Post Buckling ◽  
Novel Method

Abstract In this paper, a novel method for stiffness compensation in compliant mechanisms is investigated. This method involves tuning the ratio between the first two critical buckling loads. To this end, the relative length and width of flexures in two architectures, a stepped beam and parallel guidance, are adjusted. Using finite element analysis, it is shown that by maximizing this ratio, the actuation force for transversal deflection in post-buckling is reduced. These results were validated experimentally by identifying the optimal designs in a given space and capturing the force-deflection characteristics of these mechanisms.

Modeling and Experimental Validation of Actuating a Bistable Buckled Beam Via Moment Input

2015 ◽  
Vol 82 (5) ◽  
Author(s):  
Jonathon Cleary ◽  
Hai-Jun Su
Keyword(s):  
Theoretical Model ◽  
Experimental Test ◽  
Experimental Validation ◽  
Stable Equilibrium ◽  
Compliant Mechanisms ◽  
Computational Tool ◽  
Specific Mechanism ◽  
Test Setup ◽  
Buckled Beams ◽  
Buckled Beam

Bistable mechanisms have two stable equilibrium positions separated by a higher energy unstable equilibrium position. They are well suited for microswitches, microrelays, and many other macro- and micro-applications. This paper discusses a bistable buckled beam actuated by a moment input. A theoretical model is developed for predicting the necessary input moment. A novel experimental test setup was created for experimental verification of the model. The results show that the theoretical model is able to predict the maximum necessary input moment within 2.53%. This theoretical model provides a guideline to design bistable compliant mechanisms and actuators. It is also a computational tool to size the dimensions of buckled beams for actuating a specific mechanism.

Integrated Design of Compliant Mechanisms and Embedded Rotary Actuators and Bending Actuators for Motion Generation

2016 ◽  
Author(s):  
Lin Cao ◽  
Wenjun (Chris) Zhang
Keyword(s):  
Compliant Mechanisms ◽  
Optimization Technique ◽  
Integrated Design ◽  
Simultaneous Optimization ◽  
Motion Generation ◽  
Element Analysis ◽  
Integrated Design Approach ◽  
3D Printed ◽  
Checking Scheme ◽  
Actuator Placement

This paper presents an integrated design approach, a new topology optimization technique, to simultaneously synthesizing the optimal structural topologies of compliant mechanisms (CMs) and actuator placement — bending actuators and rotary actuators — for motion generation. The approach has the following salient features: (1) the use of bending actuators and rotary actuators as the actuation of CMs, (2) the simultaneous optimization of the CM and the location and orientation of the actuator that is embedded in the CM, (3) the guiding of a flexible link from an initial configuration to a series of desired configurations (including precision positions, orientations, and shapes), and (4) a new connectivity checking scheme to check whether the regions of interest in a design candidate are well connected. A program was employed for the geometrically nonlinear finite element analysis of large-displacement CMs driven by either bending actuators or rotary actuators. Two design examples were presented to demonstrate the proposed approach. The design results were 3D printed, and they all achieved desired shape changes when actuated.

Characterization and Modeling of Elastomeric Joints in Miniature Compliant Mechanisms

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Dana E. Vogtmann ◽  
Satyandra K. Gupta ◽  
Sarah Bergbreiter
Keyword(s):  
Analytical Model ◽  
Compliant Mechanisms ◽  
Analytical Models ◽  
Accurate Analysis ◽  
Element Analysis ◽  
Fea Model ◽  
Torsional Spring ◽  
Tension Tests ◽  
In Series ◽  
Efficient Exploration

Accurate analysis models are critical for effectively utilizing elastomeric joints in miniature compliant mechanisms. This paper presents work toward the characterization and modeling of miniature elastomeric hinges. Characterization was carried out in the form of several experimental bending tests and tension tests on representative hinges in five different configurations. The modeling portion is achieved using a planar pseudo rigid body (PRB) analytical model for these hinges. A simplified planar 3-spring PRB analytical model was developed, consisting of a torsional spring, an axial spring, and another torsional spring in series. These analytical models enable the efficient exploration of large design spaces. The analytical model has been verified to within an accuracy of 3% error in pure bending, and 7% in pure tension, when compared to finite element analysis (FEA) models. Using this analytical model, a complete mechanism—a robotic leg consisting of four rigid links and four compliant hinges—has been analyzed and compared to a corresponding FEA model and a fabricated mechanism.

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