Accurate Stiffness Modeling Method for Flexure Hinges with a Complex Contour Curve

2019 ◽  
Vol 11 ◽  
Author(s):  
Jinliang Gong ◽  
Yanfei Zhang ◽  
Kazi Mostafa ◽  
Xiang Li
Keyword(s):  
Virtual Work ◽  
First Integral ◽  
Flexure Hinge ◽  
Global Coordinate System ◽  
Flexure Hinges ◽  
Complex Contour ◽  
Stiffness Matrices ◽  
Comparison Results ◽  
Integral Element ◽  
The Right

The transfer matrix of a flexure hinge was derived on the basis of balance equations and the virtual work principle with consideration of axial, shear, and bending deformations. The element stiffness matrix of a flexure hinge was obtained from the relationship between the transfer and stiffness matrices. In this manner, the unified formula of element stiffness of a general flexure hinge was established. By using this method, rigidity models of parabolic, corner-filled, and the right circular flexure hinge have been deduced. By taking the right circular flexure hinge as an example, the result obtained using this method were compared with those of methods provided in other studies and the finite element results. The comparison results revealed that the proposed method increases the rigidity accuracy because the effect of the uneven distribution coefficient of shear stress was considered. The stiffness error was within 10%, which demonstrates the validity of this method. In contrast to the other methods, the proposed method can be applied by determining the first integral element stiffness of a common flexible hinge. Moreover, the proposed method provides better commonality, flexibility, and ease of programming. In particular, it is much easier for the flexure hinges with a complex contour curve. Transitivity can be used to calculate the rigidity after the flexure hinge has been divided into subunits, thus making it unnecessary to convert to the global coordinate system.

Corner-Filleted Flexure Hinges

2000 ◽  
Vol 123 (3) ◽  
pp. 346-352 ◽  
Author(s):  
Nicolae Lobontiu ◽  
Jeffrey S. N. Paine ◽  
Ephrahim Garcia ◽  
Michael Goldfarb
Keyword(s):  
Finite Element ◽  
Closed Form ◽  
Finite Element Simulation ◽  
Analytical Approach ◽  
Flexure Hinge ◽  
Closed Form Solutions ◽  
Flexure Hinges ◽  
Element Simulation ◽  
Model Predictions ◽  
The Right

The paper presents an analytical approach to corner-filleted flexure hinges. Closed- form solutions are derived for the in-plane compliance factors. It is demonstrated that the corner-filleted flexure hinge spans a domain delimited by the simple beam and the right circular flexure hinge. A comparison that is made with the right circular flexure hinges indicates that the corner-filleted flexures are more bending-compliant and induce lower stresses but are less precise in rotation. The finite element simulation and experimental results confirmed the model predictions.

Design of Circular Cross-Section Corner-Filleted Flexure Hinges for Three-Dimensional Compliant Mechanisms

2002 ◽  
Vol 124 (3) ◽  
pp. 479-484 ◽  
Author(s):  
Nicolae Lobontiu ◽  
Jeffrey S. N. Paine
Keyword(s):  
Cross Section ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Axial Loading ◽  
Flexure Hinge ◽  
Flexure Hinges ◽  
Element Simulation ◽  
The Right

The paper introduces the circular cross-section corner-filleted flexure hinges as connectors in three-dimensional compliant mechanism applications. Compliance factors are derived analytically for bending, axial loading and torsion. A circular cross-section corner-filleted flexure hinge belongs to a domain delimited by the cylinder (no fillet) and the right circular cross-section flexure hinge (maximum fillet radius). The analytical model predictions are confirmed by finite element simulation and experimental measurements. The circular cross-section corner-filleted flexure hinges are characterized in terms of their compliance, precision of rotation and stress levels.

Modeling of a Symmetric Five-Bar Displacement Amplification Compliant Mechanism Using Energy Methods

2015 ◽  
Author(s):  
Moataz M. Elsisy ◽  
Yasser Anis ◽  
Mustafa Arafa ◽  
Chahinaz Saleh
Keyword(s):  
Vibration Amplitude ◽  
Energy Harvester ◽  
Compliant Mechanism ◽  
Mechanical Vibration ◽  
Element Model ◽  
Design Parameters ◽  
Flexure Hinge ◽  
Energy Methods ◽  
Flexure Hinges ◽  
The Right

We present a symmetric five-bar compliant mechanism for the displacement amplification of mechanical vibration. When the proposed mechanism is connected to an energy harvester, amplification of the input excitation vibration amplitude leads to an increase in the harvested power. Displacements in the compliant mechanism are caused by deflections in its flexure hinges. The flexure hinges we use are either of the right-circular, or the corner-filleted types. The mechanism is analyzed using energy methods. The displacement amplification was verified analytically and numerically using a finite element model. Through our model we present relations governing the displacement amplification in terms of the design parameters, such as the geometry of the mechanism, the flexure hinges dimensions, in addition to the load caused by the harvester. The effects of the flexure hinge dimensions on displacement amplification, are also presented.

Combined Compliance Method of the Variable Cross Section Flexure Hinge and its Verification

2015 ◽  
Vol 798 ◽  
pp. 85-91
Author(s):  
Qing Ling Liu ◽  
Xing Xin Wang
Keyword(s):  
Cross Section ◽  
Variable Cross Section ◽  
Flexure Hinge ◽  
Variable Cross ◽  
Structure Characteristics ◽  
Compliant Structure ◽  
Flexure Hinges ◽  
Different Types ◽  
Characteristics Analysis ◽  
The Right

Flexure hinge is the most basic compliant structure, the compliance is one of the important performance parameter. The structure characteristics is analysed and the new method used for calculating the compliance is performed in this paper. Based on the structure characteristics analysis of the right circle, corner filleted and elliptical flexure hinge (symmetric and non-symmetric), half flexure hinges are analysed and the compliance formulas are given by selecting the reasonable integral variable. The combined compliance formulas of 12 kinds flexure hinge (simple, hybrid (symmetric,non-symmetric)) are obtained by half different types of flexure hinge being combined. The right circular flexure hinge, right circular elliptical hybrid flexure hinge and non-symmetric elliptical flexure hinge are selected and their compliance are calculated with the formulas in this paper and in literatures, which results indiceted the validity and correctness of the combined compliance method.

Investigating judge as a new figure in the Kyrgyz Republic criminal procedure

2020 ◽  
Vol 2020 (3) ◽  
pp. 140-147
Author(s):  
Sof'ya Shestakova ◽  
Uulzhan Imanalieva
Keyword(s):  
Criminal Procedure ◽  
Comparative Perspective ◽  
Kyrgyz Republic ◽  
Trial Procedure ◽  
Judicial Control ◽  
Legal Model ◽  
Integral Element ◽  
The Right ◽  
Conceptual Foundations ◽  
Former Soviet Republics

The article iis devoted to the research of the institution of investigative judge introduced into the criminal procedure of the Kyrgyz Republic in 2019. The authors analyze the conceptual foundations of this institution, its procedural significance, as well as the legal model under Kyrgyz legislation in its comparative perspective with the legislation of Germany and some former Soviet republics. Two main achievements: the organizational and functional isolation of an investigating judge during the criminal procedure and granting them the power of deposition are seen by the authors as advantages of the Kyrgyz model of the institution of an investigative judge. The former is aimed at guaranteeing the objectivity, impartiality and neutrality of the judge considering the case on the merits, who is discharged judicial control in pre-trial procedure nowadays. The latter is aimed at implementing for the prosecution and defense the right to be equal parties of procedural opportunities to participate in evidence as an integral element of the adversarial principle.

An Empirically Determined Design Guideline for Rectangular Cross Section Nitinol Flexure Hinges With the Focus on Flexibility-Strength Trade-Off

2018 ◽  
Author(s):  
S. Coemert ◽  
M. Olmeda ◽  
J. Fuckner ◽  
C. Rehekampff ◽  
S. V. Brecht ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Cross Section ◽  
Electrical Discharge Machining ◽  
Rectangular Cross Section ◽  
Flexure Hinge ◽  
Element Analysis ◽  
Design Guideline ◽  
Trade Off ◽  
Flexure Hinges ◽  
Compliance Modeling

In our group, we are developing flexure hinge based manipulators made of nitinol for minimally invasive surgery. On the one hand, sufficient flexibility is required from flexure hinges to be able to cover the surgical workspace. On the other hand, the bending amount of the flexure hinges has to be limited below the yielding point to ensure a safe operation. As a result of these considerations, it has to be questioned how much bending angle a nitinol flexure hinge with given geometric dimensions can provide without being subject to plastic deformation. Due to the nonlinearities resulting from large deflections and the material itself, the applicability of the suggested approaches in the literature regarding compliance modeling of flexure hinges is doubtful. Therefore, a series of experiments was conducted in order to characterize the rectangular cross section nitinol flexure hinges regarding the flexibility-strength trade-off. The nitinol flexure hinge samples were fabricated by wire electrical discharge machining in varying thicknesses while keeping the length constant and in varying lengths while keeping the thickness constant. The samples were loaded and unloaded incrementally until deflections beyond visible plastic deformation occured. Each pose in loaded and unloaded states was recorded by means of a digital microscope. The deflection angles yielding to permanent set values corresponding to 0.1% strain were measured and considered as elastic limit. A quasilinear correlation between maximum elastic deflection angle and length-to-thickness ratio was identified. Based on this correlation, a minimal model was determined to be a limit for a secure design. The proposed guideline was verified by additional measurements with additional samples of random dimensions and finite element analysis.

Dynamics of a compliant mechanism based on flexure hinges

2005 ◽  
Vol 219 (2) ◽  
pp. 225-235 ◽  
Author(s):  
K-B Choi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Compliant Mechanism ◽  
Equation Of Motion ◽  
Rigid Bodies ◽  
Flexure Hinge ◽  
Flexure Hinges ◽  
Better Than ◽  
Element Method

This paper presents a novel equation of motion for flexure hinge-based mechanisms. The conventional equation of motion presented in previous work does not adequately describe the behaviours of rigid bodies for the following reasons: firstly, rotational directions for a transformed stiffness lack consistency at the two ends of a flexure hinge; secondly, the length of the flexure hinge is not considered in the equation. The equation of motion proposed in this study solves these problems. Modal analyses are carried out using the proposed equation of motion, the conventional equation of motion found in previous work, and a finite element method. The results show that the proposed equation of motion describes the behaviours of the rigid bodies better than the conventional equation of motion does.

Compliances Calculation and Performance Analysis of the Novel Half Hybrid Flexure Hinge

2013 ◽  
Vol 303-306 ◽  
pp. 1714-1720 ◽  
Author(s):  
Qing Ling Liu
Keyword(s):  
Finite Element ◽  
Performance Analysis ◽  
Theoretical Calculations ◽  
Finite Element Simulations ◽  
Flexure Hinge ◽  
The Novel ◽  
Compact Structure ◽  
And Performance ◽  
The Right ◽  
Better Than

A novel flexure hinge named right circular corner filleted half hybrid flexure hinge was advanced. Based on the Castigliano second theorem, the compliance formulas of the novel flexure hinge were formulated. The theoretical calculations and the finite element simulations were performed simultaneously, the similar results were obtained which indicated the correctness of the compliance formulas. The influence of the geometric parameters of the novel flexure hinge on its performance was analysed. Compared with right circular corner filleted double hybrid flexure hinge, the compliance and sensitivity to the load of the novel half hybrid flexure hinge were better than that of the right circular corner filleted double hybrid flexure hinge. All of the above analysis results indicated the novel flexure hinge are more suitable for application in the compact structure and large displacement.

Displacement Amplification Using a Compliant Mechanism for Vibration Energy Harvesting

2015 ◽  
Author(s):  
Moataz Elsisy ◽  
Yasser Anis ◽  
Mustafa Arafa ◽  
Chahinaz Saleh
Keyword(s):  
Energy Harvester ◽  
Compliant Mechanism ◽  
Mechanical Vibration ◽  
Element Model ◽  
Design Parameters ◽  
Vibration Energy ◽  
Vibration Energy Harvesting ◽  
Flexure Hinges ◽  
Rigid Body Model ◽  
The Right

In this paper, we introduce a symmetric five-bar compliant mechanism for the displacement amplification of mechanical vibration. When the proposed mechanism is connected to an energy harvester, input excitation vibrations to the mechanism are amplified, which leads to an increase in harvested power. The mechanism is composed of both rigid links and flexure hinges, which enable deflection. The flexure hinges we use are either of the right-circular, or the corner-filleted types. The mechanism is analyzed using a pseudo-rigid-body-model, where flexure hinges are substituted with rotational springs. We developed an analytical model of the displacement amplification, which was validated both experimentally and numerically using a finite element model. Our model reveals that the displacement amplification is a function in design parameters, such as the geometry of the mechanism, the flexure hinges stiffness, in addition to the load caused by the harvester. The effects of the flexure hinge dimensions on the flexure hinges stiffness, and thus on displacement amplification were investigated. Preliminary experiments indicate the success of our proposed mechanism in amplifying small excitation harmonic inputs and generation of power.

Hybrid Compliant Mechanism Design Using a Mixed Mesh of Flexure Hinge Elements and Beam Elements Through Topology Optimization

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Lin Cao ◽  
Allan T. Dolovich ◽  
Wenjun (Chris) Zhang
Keyword(s):  
Topology Optimization ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Optimization Technique ◽  
Flexure Hinge ◽  
Beam Elements ◽  
Flexure Hinges ◽  
New Type ◽  
Meshing Scheme ◽  
Compliant Mechanism Design

This paper proposes a topology optimization framework to design compliant mechanisms with a mixed mesh of both beams and flexure hinges for the design domain. Further, a new type of finite element, i.e., super flexure hinge element, was developed to model flexure hinges. Then, an investigation into the effects of the location and size of a flexure hinge in a compliant lever explains why the point-flexure problem often occurs in the resulting design via topology optimization. Two design examples were presented to verify the proposed technique. The effects of link widths and hinge radii were also investigated. The results demonstrated that the proposed meshing scheme and topology optimization technique facilitate the rational decision on the locations and sizes of beams and flexure hinges in compliant mechanisms.

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