Planar Flexible Hinges With Curvilinear-Axis Segments for Mechanisms of In-Plane and Out-of-Plane Operation

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Nicolae Lobontiu
Keyword(s):  
Compliant Mechanisms ◽  
Design Procedure ◽  
Small Displacement ◽  
Constant Thickness ◽  
Compliance Matrix ◽  
Element Simulation ◽  
Specific Performance ◽  
Out Of Plane ◽  
Compliance Model ◽  
Circular Axis

The new design class and related analytic compliance-matrix model of planar flexible hinges with curvilinear longitudinal axes is presented here. The proposed approach enhances and generalizes the existing design and modeling variants dedicated to straight-axis and circular-axis hinge configurations. In-plane and out-of-plane small-displacement compliances are derived for standalone curvilinear-axis hinges as well as for hinges that are formed by serially connecting several curvilinear- and straight-axis segments. The general algorithm is further utilized to derive the compliance model of symmetric hinges, which utilizes a reduced number of compliances defining half the hinge. To illustrate the modeling/design procedure, a new flexible hinge is introduced and studied whose half portion comprises a constant-thickness parabolic-axis segment and a straight-axis segment of elliptically varying thickness. The resulting analytical compliances are validated by finite element simulation (FEA). Two compliant mechanisms that incorporate the new hinge design are studied in terms of specific performance qualifiers.

In-Plane Compliances of Planar Flexure Hinges With Serially Connected Straight- and Circular-Axis Segments

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Nicolae Lobontiu
Keyword(s):  
Small Displacement ◽  
Variable Cross ◽  
Motion Direction ◽  
Compliance Matrix ◽  
Cross Sectional ◽  
Flexure Hinges ◽  
Element Simulation ◽  
Compliance Matrices ◽  
Planar Motion Stage ◽  
Circular Axis

The paper introduces a new category of planar flexure hinges that are formed by serially connecting variable cross-sectional segments of straight longitudinal axes with segments of circular longitudinal axes. The small-displacement compliance analytical model is derived for a general hinge configuration using a matrix approach that sums the transformed local-frame compliance matrices of individual component segments. The particular class of antisymmetric flexure hinges is studied using the general model and the corresponding global-frame compliance matrix is calculated as a linear combination of compliances defining the half-hinge configuration. A serpentine (folded) flexure hinge is introduced to illustrate the generic antisymmetric design and model. Finite element simulation is used to validate the analytic compliances of this particular configuration and the compliance sensitivity to geometric parameters variation is further analyzed. The translation stiffnesses of a planar-motion stage with two identical serpentine hinges are calculated based on hinge compliances. The optimum hinge design is subsequently identified, which realizes minimum-resistance motion along the stage axial motion direction.

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.

Design of Single-Input-Single-Output Compliant Mechanisms for Practical Applications Using Selection Maps

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Sudarshan Hegde ◽  
G. K. Ananthasuresh
Keyword(s):  
Compliant Mechanisms ◽  
Material Selection ◽  
Design Procedure ◽  
Single Input Single Output ◽  
Practical Applications ◽  
Beam Elements ◽  
Single Output ◽  
Out Of Plane ◽  
Single Input ◽  
Interactive Map

We present an interactive map-based technique for designing single-input-single-output compliant mechanisms that meet the requirements of practical applications. Our map juxtaposes user-specifications with the attributes of real compliant mechanisms stored in a database so that not only the practical feasibility of the specifications can be discerned quickly but also modifications can be done interactively to the existing compliant mechanisms. The practical utility of the method presented here exceeds that of shape and size optimizations because it accounts for manufacturing considerations, stress limits, and material selection. The premise for the method is the spring-leverage (SL) model, which characterizes the kinematic and elastostatic behavior of compliant mechanisms with only three SL constants. The user-specifications are met interactively using the beam-based 2D models of compliant mechanisms by changing their attributes such as: (i) overall size in two planar orthogonal directions, separately and together, (ii) uniform resizing of the in-plane widths of all the beam elements, (iii) uniform resizing of the out-of-plane thicknesses of the beam elements, and (iv) the material. We present a design software program with a graphical user interface for interactive design. A case-study that describes the design procedure in detail is also presented while additional case-studies are posted on a website.

Analysis of Parasitic Motion in Compliant Mechanisms Using Eigenwrenches and Eigentwists

2018 ◽  
Author(s):  
Werner W. P. J. van de Sande ◽  
Just L. Herder
Keyword(s):  
Compliant Mechanisms ◽  
Screw Theory ◽  
Compliant Mechanism ◽  
Degree Of Freedom ◽  
Compliance Matrix ◽  
Parasitic Motion ◽  
Actual Degree ◽  
Motion Metrics ◽  
Mechanism Kinematic ◽  
Kinematic Information

Parasitic motion is undesired in precision mechanisms, it causes unwanted kinematics. These erroneous motions are especially apparent in compliant mechanisms. Usually an analysis of parasitic motion is only valid for one type of mechanism. Kinematic information is imbedded in the compliance matrix of any mechanism; an eigenscrew decomposition expresses this kinematic information as screws. It uses screw theory to identify the lines along which a force yields a parallel translation and a rotation yields a parallel moment. These lines are called eigenwrenches and eigentwists. Any other load on the compliant mechanism will lead to parasitic motion. This article introduces two parasitic motion metrics using eigenscrew decomposition: the parasitic resultant from an applied screw and the deviation of an actual degree of freedom from a desired degree of freedom. These metrics are applicable to all compliant mechanism and allow comparison between two compliant mechanisms. These metrics are applied to some common compliant mechanisms as an example.

Out-of-Plane Design Procedure for Confined Masonry Walls

2016 ◽  
Vol 142 (2) ◽  
pp. 04015126 ◽  
Author(s):  
Joel Moreno-Herrera ◽  
Jorge Varela-Rivera ◽  
Luis Fernandez-Baqueiro
Keyword(s):  
Design Procedure ◽  
Masonry Walls ◽  
Confined Masonry ◽  
Out Of Plane

Failure of GRP Pipe Bends Under Out-of-Plane Flexure with and Without Pressure

1993 ◽  
Vol 207 (2) ◽  
pp. 133-141
Author(s):  
R Kitching ◽  
P Myler
Keyword(s):  
Internal Pressure ◽  
Polyester Resin ◽  
Design Procedure ◽  
Out Of Plane ◽  
Failure Loads ◽  
Smooth Pipe ◽  
Plane Bending ◽  
Chopped Strand Mat ◽  
Plane Flexure

Tests to failure have been carried out on six smooth pipe bends constructed by hand lay-up from polyester resin and glass in the form of chopped strand mat. The failure loads under out-of-plane bending only are compared with those where this type of loading is combined with internal pressure. The results are discussed in relation to the design procedure adopted in BS 7159: 1989.

Assembly variation analysis of compliant mechanisms by combining direct linearization method and Lagrange’s equations

2019 ◽  
Vol 39 (4) ◽  
pp. 740-751 ◽  
Author(s):  
Zhihua Niu ◽  
Zhimin Li ◽  
Sun Jin ◽  
Tao Liu
Keyword(s):  
Compliant Mechanisms ◽  
Linearization Method ◽  
Application Area ◽  
Variation Analysis ◽  
Content Type ◽  
Compliant Joints ◽  
Lagrange’S Equations ◽  
Element Simulation ◽  
Direct Linearization ◽  
Lagrange's Equations

Purpose This paper aims to carry out assembly variation analysis for mechanisms with compliant joints by considering deformations induced by manufactured deviations. Such an analysis procedure extends the application area of direct linearization method (DLM) to compliant mechanisms and also illustrates the dimensional interaction within multi-loop compliant structures. Design/methodology/approach By applying DLM to both geometrical equations and Lagrange’s equations of the second kind, an analytical deviation modeling method for mechanisms with compliant joints are proposed and further used for statistical assembly variation analysis. The precision of this method is verified by comparing it with finite element simulation and traditional DLM. Findings A new modeling method is proposed to represent kinematic relationships between joint deformations and parts/components deviations. Based on a case evaluation, the computational efficiency is improved greatly while the modeling accuracy is maintained at more than 94% rate comparing with the benchmark finite element simulation. Originality/value The Equilibrium Equations of Incremental Forces derived from Lagrange’s equations are proposed to quantitatively represent the relationships between manufactured deviations and assembly deformations. The present method extends the application area of DLM to compliant structures, such as automobile suspension systems and some Micro-Electro-Mechanical-Systems.

Forming limit diagrams by including the M–K model in finite element simulation considering the effect of bending

2016 ◽  
Vol 232 (8) ◽  
pp. 625-636 ◽  
Author(s):  
Mostafa Habibi ◽  
Ramin Hashemi ◽  
Ahmad Ghazanfari ◽  
Reza Naghdabadi ◽  
Ahmad Assempour
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Metal Forming ◽  
Forming Limit Diagram ◽  
Element Model ◽  
Forming Limit ◽  
Finite Element Models ◽  
Element Simulation ◽  
Simple Tension ◽  
Out Of Plane

Forming limit diagram is often used as a criterion to predict necking initiation in sheet metal forming processes. In this study, the forming limit diagram was obtained through the inclusion of the Marciniak–Kaczynski model in the Nakazima out-of-plane test finite element model and also a flat model. The effect of bending on the forming limit diagram was investigated numerically and experimentally. Data required for this simulation were determined through a simple tension test in three directions. After comparing the results of the flat and Nakazima finite element models with the experimental results, the forming limit diagram computed by the Nakazima finite element model was more convenient with less than 10% at the lower level of the experimental forming limit diagram.

Simulation and Optimization of Flexible Hooke Hinge

2012 ◽  
Vol 201-202 ◽  
pp. 574-577 ◽  
Author(s):  
Wei Sun
Keyword(s):  
Degrees Of Freedom ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Rotation Angle ◽  
Basic Unit ◽  
Excellent Performance ◽  
Simulation And Optimization ◽  
Element Simulation ◽  
New Type ◽  
Perpendicular Axis

Flexible Flexible hinge is a typical flexible element in compliant mechanisms. Hooke hinge is a combination of the two revolute whose axis through the same point. It allows the two components have relative rotation of two degrees of freedom along the perpendicular axis. The distributed multi-reeds and large-deflection flexible Hooke hinge with the curve reed as the basic unit is analysed by finite element simulation, and is optimized in Multi-objective. The Hooke hinge after optimization lines with the basic rotation characteristics of Hooke hinge. It can provide the larger two-dimensional rotating schedule.It’s unilateral rotation angle can up to ±11.9 °, and the center drift and input coupling of rotation is small. So this flexible Hooke hinge is a new type of large deformation flexible Hook hinge which have excellent performance.

Sign in / Sign up

Export Citation Format

Share Document