Characterization and Modeling of Elastomeric Joints in Miniature Compliant Mechanisms

2012 ◽  
Author(s):  
Dana E. Vogtmann ◽  
Satyandra K. Gupta ◽  
Sarah Bergbreiter
Keyword(s):  
Analytical Model ◽  
Compliant Mechanisms ◽  
Analytical Models ◽  
Accurate Analysis ◽  
Element Analysis ◽  
Torsional Spring ◽  
Tension Tests ◽  
In Series ◽  
Linear Spring ◽  
Analysis Models

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. The modeling portion is achieved using finite element analysis (FEA). Also presented is a 2-dimensional pseudo rigid body (PRB) analytical model for these hinges. Characterization was carried out in the form of several experimental bending tests and tension tests on representative hinges in 5 different configurations. The results of these experiments were then compared to the same tests modeled using FEA. We have represented the experimental results using FEA to within 12% error. This allows the use of FEA to model more complicated mechanisms’ behavior with some assurance of accuracy. Based on these tests and FEA models, a simplified 2-dimensional PRB analytical model was developed, consisting of a torsional spring, a linear spring, and another torsional spring in series. These analytical models enable us explore large design spaces efficiently. The accuracy of this model for geometries without corner effects has been verified to within 3% error when compared to FEA models in bending, and 17% in tension.

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.

Development of a generalized analytical model for tubular braided-architecture composites

2017 ◽  
Vol 51 (28) ◽  
pp. 3861-3875 ◽  
Author(s):  
Garrett W Melenka ◽  
Jason P Carey
Keyword(s):  
Elastic Properties ◽  
Analytical Model ◽  
Volume Averaging ◽  
Analytical Models ◽  
Braided Composites ◽  
Element Analysis ◽  
Shear Moduli ◽  
Braided Structure ◽  
Braiding Angle ◽  
Analysis Models

Tubular braided composites are manufactured using a Maypole braiding machine which interlaces yarns in order to manufacture a braided structure. Braids can be produced in Diamond (1/1), Regular (2/2) and Hercules (3/3) patterns. In addition, axial yarns can be included in order to produce triaxial braid structures. Several analytical and finite element analysis models have been developed in order to predict the elastic properties of braided composites. Despite the fact that many models exist for braided composites, a comprehensive model has not been presented that can capture the variety of braiding patterns which can be manufactured using the braiding process. In this study, a new analytical model has been developed that can describe the elastic properties of Diamond, Regular and Hercules braids. The proposed analytical model uses a volume averaging stiffness method in order to account for yarn undulations and the orientation of braid yarns within the braid structure. The model presented here has been compared with the existing FEA and analytical models and has also been validated experimentally. Experimental validation comprised tensile and torsional tests in order to predict the longitudinal and shear moduli for both Diamond and Regular braid geometries. The experimental and proposed model results highlight the effect of braiding pattern and braiding angle on the mechanical properties.

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.

Updating of Non-Conservative Systems Using Inverse Methods

1997 ◽  
Author(s):  
Ladislav Starek ◽  
Milos Musil ◽  
Daniel J. Inman
Keyword(s):  
Analytical Model ◽  
Degrees Of Freedom ◽  
Ad Hoc ◽  
Natural Frequencies ◽  
Eigenvalue Problems ◽  
Model Updating ◽  
Analytical Models ◽  
Mode Shapes ◽  
Element Analysis ◽  
Modal Data

Abstract Several incompatibilities exist between analytical models and experimentally obtained data for many systems. In particular finite element analysis (FEA) modeling often produces analytical modal data that does not agree with measured modal data from experimental modal analysis (EMA). These two methods account for the majority of activity in vibration modeling used in industry. The existence of these discrepancies has spanned the discipline of model updating as summarized in the review articles by Inman (1990), Imregun (1991), and Friswell (1995). In this situation the analytical model is characterized by a large number of degrees of freedom (and hence modes), ad hoc damping mechanisms and real eigenvectors (mode shapes). The FEM model produces a mass, damping and stiffness matrix which is numerically solved for modal data consisting of natural frequencies, mode shapes and damping ratios. Common practice is to compare this analytically generated modal data with natural frequencies, mode shapes and damping ratios obtained from EMA. The EMA data is characterized by a small number of modes, incomplete and complex mode shapes and non proportional damping. It is very common in practice for this experimentally obtained modal data to be in minor disagreement with the analytically derived modal data. The point of view taken is that the analytical model is in error and must be refined or corrected based on experimented data. The approach proposed here is to use the results of inverse eigenvalue problems to develop methods for model updating for damped systems. The inverse problem has been addressed by Lancaster and Maroulas (1987), Starek and Inman (1992,1993,1994,1997) and is summarized for undamped systems in the text by Gladwell (1986). There are many sophisticated model updating methods available. The purpose of this paper is to introduce using inverse eigenvalues calculated as a possible approach to solving the model updating problem. The approach is new and as such many of the practical and important issues of noise, incomplete data, etc. are not yet resolved. Hence, the method introduced here is only useful for low order lumped parameter models of the type used for machines rather than structures. In particular, it will be assumed that the entries and geometry of the lumped components is also known.

Modeling and Design of an Optically Powered Microactuator for a Microfluidic Dispenser

2005 ◽  
Vol 127 (4) ◽  
pp. 825-836 ◽  
Author(s):  
Mandar Deshpande ◽  
Laxman Saggere
Keyword(s):  
Solar Cell ◽  
Analytical Model ◽  
Potential Application ◽  
Analytical Models ◽  
Element Analysis ◽  
Input And Output ◽  
Flow Through ◽  
Liquid Chemical ◽  
Key Dimensions ◽  
Piezoelectric Unimorph

This paper presents systematic modeling and design of an optically powered piezoelectric microactuator for driving a microfluidic dispenser that could find a potential application in a retinal prosthesis. The first part of the paper treats a microactuator system comprised of a micron-scale piezoelectric unimorph integrated with a miniaturized solid-state solar cell. The microactuator design is tailored for driving a microfluidic dispenser to dispense a stored liquid chemical through its micron-sized outlet ports at a rate of about 1pl∕s when the integrated solar cell is irradiated by light at a power density of 3W∕m2, corresponding to the requirements of the potential application. The microactuator system design is accomplished by first obtaining analytical models for the solar cell characteristic behavior and the microactuator displacements and then combining them to obtain the key dimensions of the microactuator through a design optimization. An analysis of the performance characteristics of the microactuator and a finite element analysis validating the analytical model for the microactuator’s displacements and the peak stresses under the operating loads are presented. The latter part of the paper presents a design of a microfluidic dispenser utilizing the optically powered microactuator and satisfying the desired input/output requirements. An analytical model integrating various energy domains involved in the system, viz. opto-electrical, piezoelectric, mechanical and hydraulic, is derived for the liquid flow through the dispenser’s micron-sized outlet ports. Finally, the energetic feasibility of the microactuator design obtained for the specified input and output criteria is also discussed.

scholarly journals Output decoupling property of planar flexure-based compliant mechanisms with symmetric configuration

2016 ◽  
Vol 7 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Y. S. Du ◽  
T. M. Li ◽  
Y. Jiang ◽  
J. L. Zhang
Keyword(s):  
Analytical Model ◽  
Compliant Mechanisms ◽  
Element Analysis ◽  
Modeling Methods ◽  
Stiffness Modeling ◽  
Symmetric Configuration ◽  
Parallel Structures ◽  
The Matrix ◽  
Micro Motion ◽  
Good Agreement

Abstract. This paper presents the output decoupling property of planar flexure-based compliant mechanisms with symmetric configuration. Compliance/stiffness modeling methods for flexure serial structures and flexure parallel structures are first derived according to the matrix method. Analytical model of mechanisms with symmetric configuration is then developed to analyze the output decoupling property. The proposed analytical model shows that mechanisms are output decoupled when they are symmetry about two perpendicular axes or when they are composed of either three or an even number of identical fundamental forms distributed evenly around the center. Finally, output compliances of RRR and 4-RRR compliant micro-motion stages are derived from the analytical model and finite element analysis (FEA). The comparisons indicate that the results obtained from the proposed analytical model are in good agreement with those derived from FEA, which validates the proposed analytical model.

Deployable Euler Spiral Connectors

2021 ◽  
pp. 1-17
Author(s):  
Collin Ynchausti ◽  
Nathan Brown ◽  
Spencer P Magleby ◽  
Anton E. Bowden ◽  
Larry L Howell
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Compliant Mechanisms ◽  
Element Analysis ◽  
Spinal Implant ◽  
In Series ◽  
Euler Spiral ◽  
Analytic Models

Abstract Deployable Euler Spiral Connectors (DESCs) are introduced as compliant deployable flexures that can span gaps between segments in a mechanism and then lay flat when under strain in a stowed position. This paper presents models of Euler spiral beams combined in series and parallel that can be used to design compact compliant mechanisms. Constraints on the design of DESCs are also presented. Analytic models were compared to finite element analysis and experimental data. A spinal implant and a linear ratcheting system are presented as illustrative applications of DESCs.

Simplified Thermo-Elasto-Plastic Analysis Models for Determination of Global and Local Stresses in Coke Drums

2013 ◽  
Author(s):  
Yanxiang Zhang ◽  
Zihui Xia
Keyword(s):  
Shell Element ◽  
Pressure Vessels ◽  
Analytical Models ◽  
Analysis Tool ◽  
Uniform Temperature ◽  
Element Analysis ◽  
Local Stresses ◽  
Petroleum Refineries ◽  
Analysis Models ◽  
Global And Local

Coke drums are major pressure vessels used in petroleum refineries. In this paper, two simplified analytical models based on thermo-elasto-plastic constitutive theory have been developed to evaluate global and local stresses in coke drums during their operation cycles. The first model considers the temperature and internal pressure cycle experienced by a drum shell element consisting of clad and base steels. The second model is an axisymmetric circular cladding plate model experiencing a non-uniform temperature distribution history. The latter model considers the effects of severe local non-uniform temperature distributions produced by the hot/cold spots appearing randomly in coke drums during the water quenching stage. The predicted results by the simplified models are in agreement with the results obtained from much complicated and time-consuming finite element analysis (FEA) models for the coke drums. Corresponding software packages for application of the two simplified analysis models (SAM) have also been developed. The developed SAM and software could be a more convenient analysis tool for coke drum designers and engineers in comparison to the use of FEA software package.

Stiffness Design of Circular-Axis Hinge, Self-Similar Mechanism With Large Out-of-Plane Motion

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
N. Lobontiu ◽  
T. Gress ◽  
M. Gh. Munteanu ◽  
B. Ilic
Keyword(s):  
Analytical Model ◽  
Compliant Mechanisms ◽  
Experimental Testing ◽  
Plane Motion ◽  
Element Simulation ◽  
Stiffness Design ◽  
Out Of Plane ◽  
In Series ◽  
Generic Architecture ◽  
Self Similar

This research proposes the self-similarity design concept of flexible mechanisms by studying the out-of-plane, piston motion of a compliant device. Self-similar compliant mechanisms can be formed by connecting flexible units of scaled-down, identical geometry in series and/or parallel. We study a folded-architecture, compact mechanism class formed of multiple flexible, circular, and concentric segments that are serially connected. The device is capable of producing large displacements by summing the small deformations of its units. A simple analytical model is derived, which predicts the mechanism piston compliance/stiffness in terms of configuration, geometry, and material parameters. Experimental testing of a prototype and finite element simulation of various designs confirm the validity of the mathematical model. Several particular designs resulting from the generic architecture are further characterized based on the analytical model to highlight the mechanism stiffness performance and the way it scales with its defining parameters and unit stiffness.

Effect of Ply Stacking Sequence on Structural Response of Symmetric Composite Laminates

2014 ◽  
Author(s):  
Mosfequr Rahman ◽  
Saheem Absar ◽  
F. N. U. Aktaruzzaman ◽  
Abdur Rahman ◽  
N. M. Awlad Hossain
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Analytical Model ◽  
Composite Laminates ◽  
Structural Response ◽  
Laminated Composite ◽  
Analytical Models ◽  
Orthotropic Materials ◽  
Stacking Sequence ◽  
Element Analysis

In this work, the effect of ply stacking sequence on the structural response of multi-ply unidirectional fiber-reinforced composite laminates was evaluated using finite element analysis. The objective of this study was to develop a computational model to analyze the stress response of individual plies in a composite laminate for a given stacking sequence. A laminated composite plate structure under tensile loading was modeled in ANSYS. Stress profiles of the individual plies were obtained for each lamina. An Epoxy matrix with both unidirectional Graphite and Kevlar fibers was considered for the model. Three dimensional sectioned shell elements (SHELL181) were used for meshing the model. Several sets of stacking sequences were implemented, symmetrical to the mid-plane of the laminate. Symmetric stacking configurations of 6 layers stacked in ply angles of [0/45/-45]s, [0/60/-60]s, [0/45/90]s, and an 8-layered arrangement of [0/45/60/90]s were modeled for the analysis. The layer thickness was maintained at 0.1 mm. The results were compared against an analytical model based on the generalized Hooke’s law for orthotropic materials and classical laminate theory. A numerical formulation of the analytical model was implemented in MATLAB to evaluate the constitutive equations for each lamina. The stress distributions obtained using finite element analysis have shown good agreement with the analytical models in some of the cases.

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