Design of a Compliant Hinge Based on Closed Form Pressure Balancing

2020 ◽  
Author(s):  
Robin F. P. Gomes ◽  
Joep P. A. Nijssen ◽  
Ron A. J. van Ostayen
Keyword(s):  
Closed Form ◽  
Elastic Deformation ◽  
Compliant Mechanisms ◽  
State Of The Art ◽  
3D Analysis ◽  
Stiffness Ratio ◽  
Rotational Stiffness ◽  
Fluid Medium ◽  
Form Pressure ◽  
Rotation Stiffness

Abstract Compliant mechanisms consist of a monolithic body and obtain motion through elastic deformation. Multiple compliant flexure designs are known but their translational to rotation stiffness ratio is often limited. This work introduces a novel compliant hinge design with increased stiffness ratio compared to the state of the art compliant hinges. The hinge functions by having an encapsulated fluid medium that contributes to high normal stiffness, but doesn’t influence the rotational stiffness. A 2D design model is presented that shows the effect of the geometry on the stiffness ratio performance. Subsequently, a computational 3D analysis is performed and the resulting design is realized as a demonstrator. The performance is compared to conventional compliant hinges based on the stiffness ratio. This shows an increase of at least a factor 30 on the stiffness ratio.

Parametric Deflection Approximations for End-Loaded, Large-Deflection Beams in Compliant Mechanisms

1995 ◽  
Vol 117 (1) ◽  
pp. 156-165 ◽  
Author(s):  
L. L. Howell ◽  
A. Midha
Keyword(s):  
Closed Form ◽  
Large Deflection ◽  
Numerical Solutions ◽  
Compliant Mechanisms ◽  
Elliptic Integral ◽  
Cantilever Beams ◽  
Simple Method ◽  
Body Angle ◽  
Analysis And Design ◽  
Integral Solutions

Geometric nonlinearities often complicate the analysis of systems containing large-deflection members. The time and resources required to develop closed-form or numerical solutions have inspired the development of a simple method of approximating the deflection path of end-loaded, large-deflection cantilever beams. The path coordinates are parameterized in a single parameter called the pseudo-rigid-body angle. The approximations are accurate to within 0.5 percent of the closed-form elliptic integral solutions. A physical model is associated with the method, and may be used to simplify complex problems. The method proves to be particularly useful in the analysis and design of compliant mechanisms.

scholarly journals A Theoretically Derived Probability Distribution of Scour

2018 ◽  
Author(s):  
Salvatore Manfreda ◽  
Oscar Link ◽  
Alonso Pizarro
Keyword(s):  
Probability Distribution ◽  
Closed Form ◽  
State Of The Art ◽  
Mathematical Formulation ◽  
Gumbel Distribution ◽  
The State ◽  
Bridge Scour ◽  
Flood Peak ◽  
Hydraulic Conditions ◽  
Model Extension

Based on recent contributions regarding the treatment of unsteady hydraulic conditions into the state-of-the-art of scour literature, the theoretically derived probability distribution of bridge scour is introduced. The model is derived assuming a rectangular hydrograph shape with a given duration, and random flood peak following a Gumbel distribution. A model extension for a more complex flood event is also presented, assuming a synthetic exponential hydrograph shape. The mathematical formulation can be extended to any flood-peak probability distribution. The aim of the manuscript is to move forward the current approaches adopted for the bridge design coupling hydrological, hydraulic, and erosional models in a mathematical closed form.

Evaluating Compliant Hinge Geometries for Origami-Inspired Mechanisms

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Isaac L. Delimont ◽  
Spencer P. Magleby ◽  
Larry L. Howell
Keyword(s):  
Closed Form ◽  
Design Space ◽  
Compliant Mechanisms ◽  
Large Deflections ◽  
Center Of Rotation ◽  
Closed Form Solutions ◽  
Potential Development ◽  
Design Guide

Origami-inspired design is an emerging field capable of producing compact and efficient designs. Compliant hinges are proposed as a way to replicate the folding motion of paper when using nonpaper materials. Compliant hinges function as surrogate folds and can be defined as localized reduction of stiffness. The purpose of this paper is to organize and evaluate selected surrogate folds for use in compliant mechanisms. These surrogate folds are characterized based on the desired motion as well as motions typically considered parasitic. Additionally, the surrogate folds' ability to rotate through large deflections and their stability of center of rotation are evaluated. Existing surrogate folds are reviewed and closed-form solutions presented. A diagram intended as a straightforward design guide is presented. Areas for potential development in the surrogate fold design space are noted.

scholarly journals Micro-scale Realization of Compliant Mechanisms: Manufacturing Processes and Constituent Materials—A Review

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Minchang Wang ◽  
Daohan Ge ◽  
Liqiang Zhang ◽  
Just L. Herder
Keyword(s):  
3D Printing ◽  
Compliant Mechanisms ◽  
State Of The Art ◽  
Manufacturing Processes ◽  
Mems Devices ◽  
Process Selection ◽  
Micro Scale ◽  
Great Progress ◽  
Different Types ◽  
Made In

AbstractCompliant micromechanisms (CMMs) acquire mobility from the deflection of elastic members and have been proven to be robust by millions of silicon MEMS devices. However, the limited deflection of silicon impedes the realization of more sophisticated CMMs, which often require larger deflections. Recently, some novel manufacturing processes have emerged but are not well known by the community. In this paper, the realization of CMMs is reviewed, aiming to provide help to mechanical designers to quickly find the proper realization method for their CMM designs. To this end, the literature surveyed was classified and statistically analyzed, and representative processes were summarized individually to reflect the state of the art of CMM manufacturing. Furthermore, the features of each process were collected into tables to facilitate the reference of readers, and the guidelines for process selection were discussed. The review results indicate that, even though the silicon process remains dominant, great progress has been made in the development of polymer-related and composite-related processes, such as micromolding, SU-8 process, laser ablation, 3D printing, and the CNT frameworking. These processes result in constituent materials with a lower Young’s modulus and larger maximum allowable strain than silicon, and therefore allow larger deflection. The geometrical capabilities (e.g., aspect ratio) of the realization methods should also be considered, because different types of CMMs have different requirements. We conclude that the SU-8 process, 3D printing, and carbon nanotube frameworking will play more important roles in the future owing to their excellent comprehensive capabilities.

scholarly journals Kinetostatic and Dynamic Modeling of Flexure-Based Compliant Mechanisms: A Survey

2020 ◽  
Vol 72 (3) ◽  
Author(s):  
Mingxiang Ling ◽  
Larry L. Howell ◽  
Junyi Cao ◽  
Guimin Chen
Keyword(s):  
Dynamic Modeling ◽  
Compliant Mechanisms ◽  
State Of The Art ◽  
Large Deflections ◽  
Mechanical Behaviors ◽  
Precision Engineering ◽  
Open Problems ◽  
Modeling Methods ◽  
Dynamic Analyses ◽  
Future Challenges

Abstract Flexure-based compliant mechanisms are becoming increasingly promising in precision engineering, robotics, and other applications due to the excellent advantages of no friction, no backlash, no wear, and minimal requirement of assembly. Because compliant mechanisms have inherent coupling of kinematic-mechanical behaviors with large deflections and/or complex serial-parallel configurations, the kinetostatic and dynamic analyses are challenging in comparison to their rigid-body counterparts. To address these challenges, a variety of techniques have been reported in a growing stream of publications. This paper surveys and compares the conceptual ideas, key advances, and applicable scopes, and open problems of the state-of-the-art kinetostatic and dynamic modeling methods for compliant mechanisms in terms of small and large deflections. Future challenges are discussed and new opportunities for extended study are highlighted as well. The presented review provides a guide on how to select suitable modeling approaches for those engaged in the field of compliant mechanisms.

A Compliant Mechanism Design Methodology for Coupled and Uncoupled Systems, and Governing Free Choice Selection Considerations

2004 ◽  
Author(s):  
Ashok Midha ◽  
Yuvaraj Annamalai ◽  
Sharath K. Kolachalam
Keyword(s):  
Rigid Body ◽  
Design Methodology ◽  
Free Choice ◽  
Compliant Mechanisms ◽  
State Of The Art ◽  
Compliant Mechanism ◽  
Mechanism Synthesis ◽  
Strongly Coupled ◽  
Revolute Joints ◽  
Compliant Mechanism Design

Compliant mechanisms are defined as mechanisms that gain some, or all of their mobility from the flexibility of their members. Suitable use of pseudo-rigid-body models for compliant segments, and relying on the state-of-the-art knowledge of rigid-body mechanism synthesis types, greatly simplifies the design of compliant mechanisms. Assuming a pseudo-rigid-body four-bar mechanism, with one to four torsional springs located at the revolute joints to represent mechanism compliance, a simple, heuristic approach is provided to develop various compliant mechanism types. The synthesis with compliance method is used for three, four and five precision positions, with consideration of one to four torsional springs, to systematically develop design tables for standard mechanism synthesis types. These tables appropriately reflect the mechanism compliance by specification of either energy or torque. Examples are presented to demonstrate the use of weakly or strongly coupled sets of kinematic and energy/torque equations, as well as different compliant mechanism types in obtaining solutions.

Buckling of a Rectangular Frame Revisited

1987 ◽  
Vol 54 (3) ◽  
pp. 617-622
Author(s):  
P. Seide
Keyword(s):  
Limit Load ◽  
Bending Stiffness ◽  
Stiffness Ratio ◽  
Stiffness Parameter ◽  
Rotational Stiffness ◽  
Height Ratio ◽  
Rectangular Frame ◽  
Uniform Beam ◽  
Symmetrical Deformation ◽  
Deformation Limit

An investigation of the buckling under uniform beam load of a rectangular frame with columns restrained by linear rotational springs indicates that for certain ranges of bending stiffness ratio, length-height ratio, and support rotational stiffness parameter, the antisymmetrical bifurcation mode of buckling does not exist and buckling occurs at a symmetrical deformation limit load. The ranges of parameters for which this phenomenon may be important are studied.

Evaluating Compliant Hinge Geometries for Origami-Inspired Mechanisms

2014 ◽  
Author(s):  
Isaac L. Delimont ◽  
Spencer P. Magleby ◽  
Larry L. Howell
Keyword(s):  
Closed Form ◽  
Design Space ◽  
Compliant Mechanisms ◽  
Large Deflections ◽  
Center Of Rotation ◽  
Closed Form Solutions ◽  
Potential Development ◽  
Design Guide

Origami-inspired design is an emerging field capable of producing compact and efficient designs. Compliant hinges are proposed as a way to replicate the folding motion of paper when using non-paper materials. Compliant hinges function as surrogate folds and can be defined as localized reduction of stiffness. The purpose of this paper is to organize and evaluate selected surrogate folds for use in compliant mechanisms. These surrogate folds are characterized based on the desired motion as well as motions typically considered parasitic. Additionally the surrogate folds’ ability to rotate through large deflections and their stability of center of rotation are evaluated. Existing surrogate folds are reviewed and closed-form solutions presented. A diagram intended as a straightforward design guide is presented. Areas for potential development in the surrogate fold design space are noted.

Dynamically Loaded Finite Length Journal Bearings: Analytical Method of Solution

1999 ◽  
Vol 121 (4) ◽  
pp. 844-852 ◽  
Author(s):  
H. Hirani ◽  
K. Athre ◽  
S. Biswas
Keyword(s):  
Pressure Distribution ◽  
Closed Form ◽  
Analytical Method ◽  
Journal Bearings ◽  
Positive Pressure ◽  
Maximum Pressure ◽  
Pressure Curve ◽  
Connecting Rod ◽  
Dynamically Loaded ◽  
Form Pressure

A closed-form pressure distribution, using a combination of short- and long-bearing approximations, is proposed for dynamically loaded journal bearings. The angles for start and finish of positive pressure curve are determined employing simple analytical equations. The mobility method, based on the suggested pressure distribution is easy to use, predicts results of acceptable accuracy and the execution time is comparable to that required for the short bearing approximation. This paper also provides a conceptually simple analytical method for evaluating angular location of the instantaneous maximum pressure using proposed closed form pressure distribution. Simple algebraic equations are derived to obtain the instantaneous maximum pressure in dynamically loaded bearings directly, without involving any iteration. To illustrate the validity of present study, a connecting rod big end bearing and two crankshaft main bearings are analyzed. The mobility components, minimum film thickness and maximum pressure are plotted over a load cycle and compared with established analytical and curve fit methods. The results are also compared with those obtained using finite element method.

scholarly journals Regional Registration of Whole Slide Image Stacks Containing Major Histological Artifacts

2020 ◽  
Author(s):  
Mahsa Paknezhad ◽  
Sheng Yang Michael Loh ◽  
Yukti Choudhury ◽  
Valerie Koh Cui Koh ◽  
Timothy Tay Kwang Yong ◽  
...  
Keyword(s):  
Patch Size ◽  
State Of The Art ◽  
The State ◽  
3D Analysis ◽  
Image Stack ◽  
Tissue Volume ◽  
Multi Scale ◽  
Registration Algorithm ◽  
Regional Registration ◽  
Whole Slide Images

Abstract Background: High resolution 2D whole slide imaging provides rich information about the tissue structure. This information can be a lot richer if these 2D images can be stacked into a 3D tissue volume. A 3D analysis, however, requires accurate reconstruction of the tissue volume from the 2D image stack. This task is not trivial due to the distortions such as tissue tearing, folding and missing at each slide. Performing registration for the whole tissue slices may be adversely affected by distorted tissue regions. Consequently, regional registration is found to be more effective. In this paper, we propose a new approach to an accurate and robust registration of regions of interest for whole slide images. We introduce the idea of multi-scale attention for registration. Results: Using mean similarity index as the metric, the proposed algorithm (mean +- std: 0.84 +- 0.11) followed by a fine registration algorithm (0.86 +- 0.08) outperformed the state-of-the-art linear whole tissue registration algorithm (0.74 +- 0.19) and the regional version of this algorithm (0.81 +- 0.15). The proposed algorithm also outperforms the state-of-the-art nonlinear registration algorithm (original: 0.82 +- 0.12, regional: 0.77 +- 0.22) for whole slide images and a recently proposed patch-based registration algorithm (patch size 256: 0.79 +- 0.16 , patch size 512: 0.77 +- 0.16) for medical images. Conclusion: Using multi-scale attention mechanism leads to a more robust and accurate solution to the problem of regional registration of whole slide images corrupted in some parts by major histological artifacts in the imaged tissue.

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