A Large Range Spatial Linear Guide With Torsion Reinforcement Structures

2018 ◽  
Author(s):  
J. Rommers ◽  
M. Naves ◽  
D. M. Brouwer ◽  
J. L. Herder
Keyword(s):  
Range Of Motion ◽  
Large Range ◽  
Small Range ◽  
The Novel ◽  
Precision Engineering ◽  
Linear Guide ◽  
Leaf Springs

Flexure mechanisms are popular in the precision engineering field due to their highly repeatable behavior. However, implementations are limited to small range of motion applications. In this paper, a spatial linear guide with a range comparable to the size of its footprint is presented. The design is based on two novel ‘Triflex’ elements in which torsion reinforcement structures are used to decrease build volume and increase guiding stiffness. The mechanism is compared to a common linear guide consisting of six folded leaf springs, after optimizing both designs. The novel linear guide shows better guiding stiffness performance, while occupying a smaller and less obstructive build volume.

A Non-Prismatic Beam Element for the Optimization of Flexure Mechanisms

2020 ◽  
Author(s):  
Koen Dwarshuis ◽  
Ronald Aarts ◽  
Marcel Ellenbroek ◽  
Dannis Brouwer
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Range Of Motion ◽  
Beam Element ◽  
Precision Engineering ◽  
Element Analysis ◽  
Leaf Springs ◽  
Prismatic Beam ◽  
The Common ◽  
Flexure Joints

Abstract Flexure joints are rapidly gaining ground in precision engineering because of their predictable behavior. However the range of motion of flexure joints is limited due to loss of support stiffness in deformed configurations. Most of the common flexure joints consist of prismatic leaf springs. This paper presents a simple non-prismatic beam formulation that can be used for the efficient modelling of non-prismatic leaf springs. The resulting stiffness and stress computed by the non-prismatic beam element are compared to the results of a finite element analysis. The paper shows that the support stiffness of two typical flexure joints can be increased up to a factor of 1.9 by using non-prismatic instead of prismatic leaf springs.

Novel XY Compliant Parallel Manipulators for Large Displacement Translation With Enhanced Stiffness

2010 ◽  
Author(s):  
Guangbo Hao ◽  
Xianwen Kong
Keyword(s):  
Range Of Motion ◽  
Building Block ◽  
Parallel Manipulator ◽  
Large Range ◽  
Parallel Manipulators ◽  
Large Displacement ◽  
Analytical Models ◽  
The Novel ◽  
Out Of Plane ◽  
Error Motion

A novel XY compliant parallel manipulator (CPM) and a spatial double three-beam module both with distributed compliance are first proposed for large range of translation. Then, an improved XY CPM is proposed by combining the above XY CPM and a spatial double three-beam module in parallel. The normalized analytical models are further presented for the novel XY CPM, double three-beam module and improved XY CPM. It is shown that the improved XY CPM has the following merits: (1) large range of motion, constrained parasitic error motion, output-decoupling, maximal actuation isolation and minimal lost motion; and (2) large out-of-plane stiffness and no friction with base. The improved XY CPM may also be used as a building block to construct new spatial CPMs.

A flexure-based linear guide with torsion reinforcement structures

2021 ◽  
pp. 1-12
Author(s):  
Jelle Rommers ◽  
Mark Naves ◽  
Dannis Brouwer ◽  
Just L. Herder
Keyword(s):  
Mean Absolute Error ◽  
Theoretical Models ◽  
Absolute Error ◽  
Linear Guide ◽  
Leaf Springs ◽  
Motion Range ◽  
Volume Stress

Abstract In this work, a flexure-based (compliant) linear guide with a motion range comparable to its footprint is presented. The design consists of two folded leaf springs on which torsion reinforcement structures are added. Due to these structures, only two folded leaf springs are needed instead of a minimum of five as in pre-existing designs. The new design is compared to such a pre-existing design, after optimizing both on a support stiffness metric. The new design scores over twice as high on the support stiffness metric, while occupying a smaller (−33%) and a less obstructive build volume. Stress, build volume and manufacturing limitations are taken into account. Additionally, a variation on the new design using three torsion reinforced folded leaf springs is presented and optimized. This design occupies a build volume similar to the pre-existing design, but scores four times higher on the support stiffness metric. A prototype of the new design is built and its parasitic eigenfrequencies are measured, validating the theoretical models (Normalized Mean Absolute Error of 4.3%).

scholarly journals Characterizing and modeling of low twist yarn mechanics

2019 ◽  
Vol 14 ◽  
pp. 155892501986694
Author(s):  
Benjamin K O Cheung ◽  
Jason P Carey
Keyword(s):  
Linear Regression ◽  
Standard Error ◽  
Prediction Models ◽  
Large Range ◽  
Short Fiber ◽  
Regenerated Cellulose ◽  
Small Range ◽  
Longitudinal Stiffness ◽  
Simple Linear Relationship ◽  
Multifilament Yarns

Twist in yarns can be used for handling or testing purposes, but it is not necessary when using continuous multifilament yarns as compared to the spinning required for a short fiber yarn. Small amounts of twist have shown to increase the strength of the yarn while decreasing the longitudinal stiffness. Previous models, including Gegauff’s cos2 θ model and Rao and Farris’ model, are compared and discussed. A para-aramid (Kevlar 49) and a regenerated cellulose (BioMid) yarn are tested at various levels of twist to compare with these models. Twist is manually applied, and the samples are tested under continuous rate of extension to determine chord modulus, breaking tenacity, and elongation and break. The results are then fit to existing prediction models using a minimization of the standard error of the regression. Finally, a linear regression is also applied to the data to contrast the fit compared to traditional models. It was found that while the Gegauff model and the Rao and Farris model may capture the overall trend and decrease in longitudinal stiffness over a large range of twist, the small range over which twist can practically be used is not well represented by these models and is better represented by a simple linear relationship.

Serial Casting of the Ankle and Knee in a Child With Vascular Anomaly of the Calf Musculature: A Case Report

2019 ◽  
Author(s):  
Colleen Peyton
Keyword(s):  
Lower Extremity ◽  
Range Of Motion ◽  
Vascular Anomaly ◽  
The Novel ◽  
Case Description ◽  
Limited Evidence ◽  
Posterior Compartment ◽  
Serial Casting ◽  
Toe Walking ◽  
Gait Impairments

Abstract Background and Purpose Contracture and toe-walking in children due to vascular anomaly of the calf musculature is rarely described and there is limited evidence regarding treatment. The purpose of this case is to describe the novel use of serial casting, combining the knee and ankle, to reduce contracture in a child with hemangioma of the calf. Case Description An 11-year-old girl received 12 casts of the ankle and knee, followed by custom orthotics, to address chronic contracture and gait impairments caused by a vascular anomaly in the posterior compartment of the lower extremity. Outcomes After casting, the patient had fully restored knee range of motion and improved ankle range of motion by 45 degrees. She received custom orthotics and maintained her range of motion four months after casting. Discussion Serial casting of the knee and ankle may be a useful alternative to surgical lengthenings in patients with chronic contractures caused by vascular anomalies of the lower extremity.

Passively Driven Redundant Spherical Joint With Very Large Range of Motion

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
Louis-Thomas Schreiber ◽  
Clément Gosselin
Keyword(s):  
Range Of Motion ◽  
Tilt Angle ◽  
Active Component ◽  
Large Range ◽  
Kinematic Model ◽  
Static Model ◽  
Spherical Joint ◽  
Torsional Spring

This paper presents a novel passive redundant spherical joint with a very large range of motion. A kinematic model is first developed in order to provide a framework for the analysis. The principle of the redundant joint is then introduced. The proposed joint does not require any active component since the redundancy is passively handled using springs. A static model of the joint is developed in order to clearly demonstrate how all singularities or jamming configurations can be avoided. Two possible arrangements are presented, one using linear springs and one using a torsional spring. Finally, experimental prototypes are demonstrated that can attain a range of tilt angle of ±150 deg.

Synthesis of Fluorinated and Trifluoromethyl-Substituted Alkenes through the Modified Julia Olefination: An Update

Synthesis ◽  
2015 ◽  
Vol 47 (11) ◽  
pp. 1534-1546 ◽  
Author(s):  
Emmanuel Pfund ◽  
Thierry Lequeux ◽  
David Gueyrard
Keyword(s):  
Large Range ◽  
Short Review ◽  
The Novel ◽  
Smiles Rearrangement ◽  
Julia Olefination

The modified Julia olefination is now a powerful tool for the synthesis of a large range of functionalized alkenes. This short review covers the last five years and provides an overview of the synthesis of mono-, difluoro-, and trifluoromethyl-substituted alkenes via the modified Julia olefination focusing on the novel scope of this reaction.1 Introduction2 Monofluoroalkenes2.1 Disubstituted α- and β-Monofluoroalkenes2.2 Bis(trifluoromethyl)phenyl Sulfones2.3 Conjugated Monofluoroalkenes2.4 Intramolecular Julia Olefination2.5 Smiles Rearrangement from Fluorinated Keto Sulfones2.6 Fluoroallylamines2.7 Fluorinated exo-Glycals2.8 Monofluoroalkenes with an α-Stereocenter at the Allylic Position3 1,1-Difluoroalkenes4 Trifluoromethyl-Substituted Alkenes5 Conclusion

Poetics of novel of A.N. Varlamov the “Soul my Paul”

2018 ◽  
Vol 7 (6) ◽  
pp. 57-64
Author(s):  
В. Серафимова ◽  
V. Serafimova
Keyword(s):  
Large Range ◽  
The Novel ◽  
The Past

The article deals with the composition of the new Chapter of the novel "my soul Paul", which consists of five parts, divided into chapters, and explores a large range of problems. Compositional clarity gives the novel intertwining storylines, United through the theme, the theme of the past, its relationship with the present and future, the theme of memory, the concept Of man-Creator, capable of self-improvement. The novel presents interesting examples of solving communicative problems, creating communicative situations.

A 3-DOF Translational Compliant Parallel Manipulator Based on Flexure Motion

2009 ◽  
Author(s):  
Guangbo Hao ◽  
Xianwen Kong
Keyword(s):  
Range Of Motion ◽  
Parallel Manipulator ◽  
Large Range ◽  
Parallel Manipulators ◽  
Mathematic Modeling ◽  
Ultra Precision ◽  
Cross Axis ◽  
Force Displacement

This paper presents a novel class of 3-DOF translational compliant parallel manipulators (CPMs) based on flexure motion. The analytic mathematic modeling of CPMs is first developed. The analysis of CPMs is then implemented. It is shown that the proposed CPMs have many characteristics such as large range of motion, negligible cross-axis coupling, actuator complete isolation, and no loss motion and no rotational yaw. The inverse relationships of force-displacement of the 3-DOF CPM are further derived to calculate the input forces required for generating a specified path. In addition, the 3-DOF CPM can also be turned into a 2-DOF CPM. This work lays the foundation for the development of new spatial CPMs based on flexure motions for applications such as ultra precision manipulation.

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