Measurements of Dielectric Properties for Intense Heating Applications

MRS Proceedings ◽

10.1557/proc-430-231 ◽

1996 ◽

Vol 430 ◽

Cited By ~ 1

Author(s):

J. M. Borrego ◽

K. A. Connor ◽

J. Braunstein

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Dielectric Properties ◽

Wave Structure ◽

Analytical Models ◽

Dielectric Measurements ◽

Element Analysis ◽

Measurement Apparatus

AbstractDielectric measurements for frequencies in the tens of gigahertz are discussed. Interpretation of measurements obtained for mixtures are presented based on some simple analytical models and finite-element analysis of the wave structure in the measurement apparatus.

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A 2-legged XY parallel flexure motion stage with minimised parasitic rotation

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406214526865 ◽

2014 ◽

Vol 228 (17) ◽

pp. 3156-3169 ◽

Cited By ~ 8

Author(s):

Guangbo Hao

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Parallel Manipulator ◽

Parallel Manipulators ◽

Design Approach ◽

Analytical Models ◽

Geometrical Parameters ◽

Element Analysis ◽

Motion Range ◽

Cross Axis

XY compliant parallel manipulators (aka XY parallel flexure motion stages) have been used as diverse applications such as atomic force microscope scanners due to their proved advantages such as eliminated backlash, reduced friction, reduced number of parts and monolithic configuration. This paper presents an innovative stiffness centre based approach to design a decoupled 2-legged XY compliant parallel manipulator in order to better minimise the inherent parasitic rotation and have a more compact configuration. This innovative design approach makes all of the stiffness centres, associated with the passive prismatic (P) modules, overlap at a point that all of the applied input forces can go through. A monolithic compact and decoupled XY compliant parallel manipulator with minimised parasitic rotation is then proposed using the proposed design approach based on a 2-PP kinematically decoupled translational parallel manipulator. Its load–displacement and motion range equations are derived, and geometrical parameters are determined for a specified motion range. Finite element analysis comparisons are also implemented to verify the analytical models with analysis of the performance characteristics including primary stiffness, cross-axis coupling, parasitic rotation, input and output motion difference and actuator nonisolation effect. Compared with the existing XY compliant parallel manipulators obtained using 4-legged mirror-symmetric constraint arrangement, the proposed XY compliant parallel manipulators based on stiffness centre approach mainly benefits from fewer legs resulting in reduced size, simpler modelling as well as smaller lost motion. Compared with existing 2-legged designs with the conventional arrangement, the present design has smaller parasitic rotation, which has been proved from the finite element analysis results.

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Biomechanical effects of Skeletally anchored Class III elastics on the maxillofacial complex: a 3D finite element analysis

Progress in Orthodontics ◽

10.1186/s40510-021-00375-3 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Priyank Rai ◽

Dhiraj Garg ◽

Tulika Tripathi ◽

Anup Kanase ◽

Gayatri Ganesh

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Analytical Models ◽

Class Iii ◽

Maxillary Expansion ◽

Element Analysis ◽

3D Finite Element ◽

3D Finite Element Analysis ◽

Skeletal Class ◽

Computed Tomography Images

Abstract Background Although, the outcomes and changes in the maxillofacial complex after the application of intraoral bone anchored Class III elastics, have been reported by multiple clinical studies, there was no finite element study to assess and evaluate the stress pattern and displacement on maxillomandibular complex with bimaxillary anchorage. The present study aims to evaluate the biomechanical effects on maxillomandibular complex of Skeletally anchored Class III elastics with varying angulations using the 3D finite element analysis. Methodology Two 3-dimensional analytical models were developed using the Mimics 8.11 (Materialise: Leuven, Belgium) and ANSYS software Version 12.1 (ANSYS Inc, Canonsburg, PA, USA) from sequential computed tomography images taken from a Skeletal Class III subject. The models were meshed into 465,091 tetrahedral elements and 101,247 nodes. Intraoral mechanics for skeletally anchored maxillary protraction (I-SAMP) were applied on two models i.e. A and B (without and with maxillary expansion respectively) between miniplates on maxilla and mandible on both right and left sides with three different angulations of forces—10°, 20° and 30°). Results Although the craniomaxillary complex in both the models (A and B) displaced forward while demonstrating rotations in opposite directions, the displacements and rotations decreased gradually with the increase of the angle of load application from 10° to 30°. The mandible rotated clockwise in both the simulations, but the displacement of mandibular surface landmarks was higher in Simulation A. However, the antero-inferior displacement of the glenoid fossa was higher in Simulation B than in A. Conclusion Significant displacement of maxillofacial sutures and structures was witnessed with I-SAMP with maxillary expansion and Class III elastics for correction of Skeletal Class III with maxillary retrognathism. Thus, I-SAMP with maxillary expansion is a desired protocol for treatment of maxillary retrognathism. However, the prescribed angulation of the Class III elastics should be as low as possible to maximise the desired effects.

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Wrinkling of a stiff thin film bonded to a pre-strained, compliant substrate with finite thickness

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2016.0339 ◽

2016 ◽

Vol 472 (2192) ◽

pp. 20160339 ◽

Cited By ~ 16

Author(s):

Yinji Ma ◽

Yeguang Xue ◽

Kyung-In Jang ◽

Xue Feng ◽

John A. Rogers ◽

...

Keyword(s):

Thin Film ◽

Finite Element Analysis ◽

Finite Element ◽

Finite Thickness ◽

Analytical Models ◽

Thickness Effect ◽

Element Analysis ◽

Compliant Substrate ◽

Tensile Stiffness ◽

The Finite Element Analysis

A stiff thin film bonded to a pre-strained, compliant substrate wrinkles into a sinusoidal form upon release of the pre-strain. Many analytical models developed for the critical pre-strain for wrinkling assume that the substrate is semi-infinite. This critical pre-strain is actually much smaller than that for a substrate with finite thickness (Ma Y et al. 2016 Adv. Funct. Mater. ( doi:10.1002/adfm.201600713 )). An analytical solution of the critical pre-strain for a system of a stiff film bonded to a pre-strained, finite-thickness, compliant substrate is obtained, and it agrees well with the finite-element analysis. The finite-thickness effect is significant when the substrate tensile stiffness cannot overwhelm the film tensile stiffness.

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ANALYSIS OF ANALYTICAL MODELS AND THE DEPENDENCES REALIZED BY THEM FOR DEFINITION OF MECHANICAL CHARACTERISTICS OF COMPOSITE FILLERS

Municipal economy of cities ◽

10.33042/2522-1809-2021-1-161-8-18 ◽

2021 ◽

Vol 1 (161) ◽

pp. 8-18

Author(s):

A. Kondratiev

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Elastic Modulus ◽

Information Technologies ◽

Mechanical Characteristics ◽

Sandwich Structures ◽

Accuracy Assessment ◽

Analytical Models ◽

Element Analysis ◽

Shear Moduli

The analysis of the accuracy of analytical models and the mechanical properties they implement is carried out for various types of composite aggregates of sandwich structures. The accuracy assessment of approximate analytical dependencies of the mechanical characteristics of the composite honeycomb core is given. The applicability of analytical dependencies at the initial stages of the design of cellular structures is established. The accuracy of the results of a numerical experiment is noted. This is due to the approximate nature of standard test methods. Both for the elastic modulus and for the shear moduli, their values obtained on the basis of information technologies of finite element analysis exceed their corresponding values determined by analytical dependencies. This excess over the corresponding analytical values for the shear moduli is close to a constant value for various reinforcement angles and does not exceed 1.14. For the elastic modulus of the first kind, the excess varies from 1.03 to 1.8 for various angles of cell reinforcement. The analytical dependences of the reduced mechanical characteristics of the tubular aggregate are obtained. The idea of the method for determining the mechanical characteristics of a tubular filler is to fulfill the requirement of equality of the relative axial and shear deformations of a conventional continuous type element and a real one, selected within one tube, taking into account only its material. The conclusion is drawn that the mechanical characteristics of the tubular aggregate, determined by the analytical model, to different degrees differ from the corresponding characteristics obtained on the basis of information technology of finite element analysis. Moreover, the difference in the elastic moduli of the first kind is much smaller than in the shear moduli. The reasons for these discrepancies are analyzed. It is justified and recommended to use constant correction factors for the analytical values of the reduced mechanical characteristics of the tubular aggregate, allowing their further use in the calculation of plate and shell sandwich structures.

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

Volume 10: Micro- and Nano-Systems Engineering and Packaging ◽

10.1115/imece2014-37217 ◽

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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Three-dimensional Finite-element Analysis of Conductivity and Dielectric Attenuation in Arbitrary Slow-wave Structure of Traveling-wave Tubes

JOURNAL OF ELECTRONICS INFORMATION TECHNOLOGY ◽

10.3724/sp.j.1146.2011.01332 ◽

2013 ◽

Vol 34 (8) ◽

pp. 2028-2032

Author(s):

Li Xu ◽

Zhong-hai Yang ◽

Jian-qing Li ◽

Bin Li

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Traveling Wave ◽

Three Dimensional ◽

Wave Structure ◽

Slow Wave Structure ◽

Element Analysis ◽

Dimensional Finite Element ◽

Traveling Wave Tubes ◽

Three Dimensional Finite Element

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Analytical Models for Seabed Interaction Effects on Steel Catenary Riser in Touchdown Zone

Volume 4B: Pipeline and Riser Technology ◽

10.1115/omae2013-11421 ◽

2013 ◽

Cited By ~ 2

Author(s):

Kosar Rezazadeh ◽

Yong Bai ◽

Jiwei Tang ◽

Liang Zhang

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

System Performance ◽

Analytical Models ◽

System Response ◽

Complex Nature ◽

Element Analysis ◽

Steel Catenary Riser ◽

Steel Catenary Risers ◽

Seabed Interaction

The complex nature of seabed interaction with steel catenary risers (SCR) in touch down zone (TDZ) of SCRs makes serious difficulties for engineering design industry. Design must ensure that the curvature remains well within elastic limits, and that fatigue damage remains acceptable during the life. Analytical methods, despite it is limited in the accuracy because of idealizations of the system response, it offers a first step in assessing the system performance. The paper compares the results of different seabed interaction models with those from finite element analysis to evaluate the accuracy and consistency of solutions for initial design assumptions and fatigue assessment.

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Design of a cutting head for a crosscutting machine

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406216661367 ◽

2016 ◽

Vol 231 (1) ◽

pp. 5-17 ◽

Cited By ~ 1

Author(s):

D Croccolo ◽

M De Agostinis ◽

S Fini

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Structural Analysis ◽

Dynamic Behavior ◽

Analytical Model ◽

Analytical Models ◽

Rectangular Section ◽

Element Analysis ◽

Cutting Head ◽

Numerical Finite Element

The present paper deals with the structural analysis and the re-design of a cutting head for an automatic crosscutting machine. The machine is already marketed, and can process rectangular section wooden slats. The principal goal of this work is to develop a new mechanism capable of enhancing the productivity of the machine by around 80%. The work has been carried out by means of both numerical finite element analysis tools and analytical models. In fact, a secondary aim of the research is to define an analytical model which can capture the dynamic behavior of the device: this tool will be helpful to the design engineer in order to save costs associated with the development of future head designs.

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