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Article
Publication date: 5 October 2015

Shi Zhang, Yun Zhang, Zhigao Huang, Huamin Zhou and Jianhui Li

– The purpose of this paper is to study the inter-element coupling effect of membrane and plate components between two adjacent shells occurring on the common boundary.

Abstract

Purpose

The purpose of this paper is to study the inter-element coupling effect of membrane and plate components between two adjacent shells occurring on the common boundary.

Design/methodology/approach

In this paper, three triangular flat shells developed by combining an excellent membrane element (OPT) with three outstanding plate bending elements (DKT, RDKTM and DST-BK), respectively, are used to study this phenomenon. Benchmark tests are implemented to evaluate the performance of three selected plate elements and the formulated flat shells.

Findings

The inter-element coupling effect of membrane and plate components belonging, respectively, to two adjacent shells deteriorate the performance of shells. Therefore, a shell’s performance cannot be guaranteed certainly by the superimposed membrane and plate behaviors.

Practical implications

The “order matching” criterion is proposed to explain this phenomenon and it is concluded that the flat shell that follows this criterion explicitly may alleviate or even overcome the inter-element coupling effect.

Originality/value

Previous studies mainly focus on formulation of high-performance membrane and plate elements. However, the inter-element coupling effect of membrane and plate components between two adjacent shells occurring on the common boundary, has attracted less attention. Thorough benchmark tests for three flat shells are implemented to investigate the phenomenon. The results shows that the inter-element coupling effect deteriorates the performance of shells. And the “order matching” criterion is proposed to explain this phenomenon and it is concluded that the flat shell that follows this criterion explicitly may alleviate or even overcome the inter-element coupling effect.

Details

Engineering Computations, vol. 32 no. 7
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 25 January 2021

Preeti Pannu and Devendra Kumar Sharma

This paper aims to design a most demanding low profile and compact ultra-wide band (UWB) antenna system for various wireless applications. The performance (in terms of…

Abstract

Purpose

This paper aims to design a most demanding low profile and compact ultra-wide band (UWB) antenna system for various wireless applications. The performance (in terms of data rate) of UWB system is improved by using multiple-input-multiple-output (MIMO) technology with it. Owing to the overlap of other existing licensed bands with that of UWB, electromagnetic signals can interfere. So, notched band UWB MIMO antenna system reported here which is highly compact, bandwidth efficient, superior data rate and high inter-element isolation comparatively to other reported designs.

Design/methodology/approach

A 49 × 49 × 1.6 mm3 quad-port UWB MIMO antenna with specific bandwidth elimination property is designed. The proposed planar MIMO configuration comprises unique four identical “Cordate-shaped” monopole radiators fed by 2.3-mm thick microstrip-lines. The radiators are located right-angled to each other to enhance inter-element isolation. Further, a different approach of slitted-substrate is applied to minimize the overall size and mutual coupling of the MIMO antenna, as a substitute of decoupling and matching structures. The defected ground structure is used to obtain −10 dB impedance bandwidth in entire UWB band, without compromising with the lower cut-off frequency response. Further, to eliminate the undesired resonant band (WLAN at 5.5 GHz) from UWB, a rounded split ring resonator is introduced in monopole patch.

Findings

In the entire operating band of 2.8 to 11 GHz, isolation among elements is more than 24 dB, envelope correlation coefficient less than 0.002, diversity gain greater than 9.99 dB and TARC less than −7 dB are obtained at all 4-ports.

Research limitations/implications

The measured parameters of the fabricated prototype antenna on FR4 substrate are found in good agreement with the simulated results. The small variation in software results and hardware results are observed due to hardware design limitations.

Practical implications

The proposed design may be used for any wireless application following in the range of UWB.

Originality/value

It can be shown from graphs of measured parameters of the fabricated prototype antenna. They found to be in good agreement with the simulated results.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 1 February 2003

M.G. Cottrell, J. Yu, Z.J. Wei and D.R.J. Owen

In recent years, developments in the field of lightweight armour have been of primary importance to the defence industry. This necessity has led to many organisations…

Abstract

In recent years, developments in the field of lightweight armour have been of primary importance to the defence industry. This necessity has led to many organisations adopting composite armours comprising both the traditional heavy armours and new lighter weight ceramic armours. The numerical modelling of metal based armour systems has been well documented over the years using purely continuum based methods; and also the modelling of brittle systems using discrete element methods, therefore it is the objective of this paper to demonstrate how a coupled finite and discrete element approach, can be used in the further understanding of the quantitative response of ceramic systems when subjected to dynamic loadings using a combination of adaptive continuum techniques and discrete element methods. For the class of problems encountered within the defence industry, numerical modelling has suffered from one principal weakness; for many applications the associated deformed finite element mesh can no longer provide an accurate description of the deformed material, whether this is due to large ductile deformation, or for the case of brittle materials, degradation into multiple bodies. Subsequently, two very different approaches have been developed to combat such deficiencies, namely the use of adaptive remeshing for the ductile type materials and a discrete fracture insertion scheme for the modelling of material degradation. Therefore, one of the primary objectives of this paper is to present examples demonstrating the potential benefits of explicitly coupling adaptive remeshing methods to the technique of discrete fracture insertion in order to provide an adaptive discontinuous solution strategy, which is computationally robust and efficient.

Details

Engineering Computations, vol. 20 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 11 October 2011

Rabe Alsafadie, Mohammed Hjiaj, Hugues Somja and Jean‐Marc Battini

The purpose of this paper is to present eight local elasto‐plastic beam element formulations incorporated into the corotational framework for two‐noded three‐dimensional…

Abstract

Purpose

The purpose of this paper is to present eight local elasto‐plastic beam element formulations incorporated into the corotational framework for two‐noded three‐dimensional beams. These formulations capture the warping torsional effects of open cross‐sections and are suitable for the analysis of the nonlinear buckling and post‐buckling of thin‐walled frames with generic cross‐sections. The paper highlights the similarities and discrepancies between the different local element formulations. The primary goal of this study is to compare all the local element formulations in terms of accuracy, efficiency and CPU‐running time.

Design/methodology/approach

The definition of the corotational framework for a two‐noded three‐dimensional beam element is presented, based upon the works of Battini .The definitions of the local element kinematics and displacements shape functions are developed based on both Timoshenko and Bernoulli assumptions, and considering low‐order as well as higher‐order terms in the second‐order approximation of the Green‐Lagrange strains. Element forces interpolations and generalized stress resultant vectors are then presented for both mixed‐based Timoshenko and Bernoulli formulations. Subsequently, the local internal force vector and tangent stiffness matrix are derived using the principle of virtual work for displacement‐based elements and the two‐field Hellinger‐Reissner assumed stress variational principle for mixed‐based formulations, respectively. A full comparison and assessment of the different local element models are performed by means of several numerical examples.

Findings

In this study, it is shown that the higher order elements are more accurate than the low‐order ones, and that the use of the higher order mixed‐based Bernoulli element seems to require the least number of FEs to accurately model the structural behavior, and therefore allows some reduction of the CPU time compared to the other converged solutions; where a larger number of elements are needed to efficiently discretize the structure.

Originality/value

The paper reports computation times for each model in order to assess their relative efficiency. The effect of the numbers of Gauss points along the element length and within the cross‐section are also investigated.

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Article
Publication date: 1 March 1997

Pinhas Z. Bar‐Yoseph and Eduard Moses

Deals with the formulation and application of temporal and spatial spectral element approximations for the solution of convection‐diffusion problems. Proposes a new…

Abstract

Deals with the formulation and application of temporal and spatial spectral element approximations for the solution of convection‐diffusion problems. Proposes a new high‐order splitting space‐time spectral element method which exploits space‐time discontinuous Galerkin for the first hyperbolic substep and space continuous‐time discontinuous Galerkin for the second parabolic substep. Analyses this method and presents its characteristics in terms of accuracy and stability. Also investigates a subcycling technique, in which several hyperbolic substeps are taken for each parabolic substep; a technique which enables fast, cost‐effective time integration with little loss of accuracy. Demonstrates, by a numerical comparison with other coupled and splitting space‐time spectral element methods, that the proposed method exhibits significant improvements in accuracy, stability and computational efficiency, which suggests that this method is a potential alternative to existing schemes. Describes several areas for future research.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 7 no. 2/3
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 January 1985

R. de Borst and P. Nauta

A new model for handling non‐orthogonal cracks within the smeared crack concept is described. It is based on a decomposition of the total strain increment into a concrete…

Abstract

A new model for handling non‐orthogonal cracks within the smeared crack concept is described. It is based on a decomposition of the total strain increment into a concrete and into a crack strain increment. This decomposition also permits a proper combination of crack formation with other non‐linear phenomena such as plasticity and creep and with thermal effects and shrinkage. Relations are elaborated with some other crack models that are currently used for the analysis of concrete structures. The model is applied to some problems involving shear failures of reinforced concrete structures such as a moderately deep beam and an axisymmetric slab. The latter example is also of interest in that it confirms statements that ‘reduced integration’ is not reliable for problems involving crack formation and in that it supports the assertion that identifying numerical divergence with structural failure may be highly misleading.

Details

Engineering Computations, vol. 2 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 29 July 2019

Djamel Boutagouga

This paper aims to describe the formulation of a displacement-based triangular membrane finite element with true drilling rotational degree of freedom (DOF).

Abstract

Purpose

This paper aims to describe the formulation of a displacement-based triangular membrane finite element with true drilling rotational degree of freedom (DOF).

Design/methodology/approach

The presented formulation incorporates the true drilling rotation provided by continuum mechanics into the displacement field by way of using the polynomial interpolation. Unlike the linked interpolation, that uses a geometric transformation between displacement and vertex rotations, in this work, the interpolation of the displacement field in terms of nodal drilling rotations is obtained following an unusual approach that does not imply any presumed geometric transformation.

Findings

New relationship linking the mid-side normal displacement to corner node drilling rotations is derived. The resulting new element with true drilling rotation is compatible and does not include any problem-dependent parameter that may influence the results. The spurious zero-energy mode is stabilized in a careful way that preserves the true drilling rotational degrees of freedom (DOFs).

Originality/value

Several works dealing with membrane elements with vertex rotational DOFs have been published with improved convergence rate, however, owing to the need for incorporating rotations in the finite element meshes involving solids, shells and beam elements, having finite elements with true drilling rotational DOFs is more appreciated.

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Article
Publication date: 5 September 2016

Manikandan Alagarsamy, Uma Maheswari Sangareswaran and P. Dhanaraj

The purpose of this paper is to discuss and analyze a microstrip feed equilateral triangular microstrip array antenna (ETMPAA) that is proposed for S band (3 GHz) applications.

Abstract

Purpose

The purpose of this paper is to discuss and analyze a microstrip feed equilateral triangular microstrip array antenna (ETMPAA) that is proposed for S band (3 GHz) applications.

Design/methodology/approach

The ETMPAA comprises three equilateral triangular patches with equal distance. The size of the antenna is 49.4 mm (0.0494 m)×18.4 mm (0.184 m). The proposed antenna has been designed by etching triangular shape structure on glass epoxy substrate (FR4).

Findings

The simulated result shows that ETMPAA has the impedance bandwidth of 900 MHz and the bandwidth can be achieved by controlling the gap between the patch antennas. The antenna is fed by microstrip feeding technique. Design of an antenna using advanced design system (ADS), based on finite element methods (FEM) has been used to analyze and optimize the antenna. Based on the measurement results an antenna proposed with maximum efficiency and maximum gain.

Originality/value

This paper fulfils an identified need to study a microstrip feed ETMPAA is proposed for S band (3 GHz) applications.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 35 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 February 1995

A. Munjiza, D.R.J. Owen and N. Bicanic

This paper discusses the issues involved in the development of combined finite/discrete element methods; both from a fundamental theoretical viewpoint and some related…

Abstract

This paper discusses the issues involved in the development of combined finite/discrete element methods; both from a fundamental theoretical viewpoint and some related algorithmic considerations essential for the efficient numerical solution of large scale industrial problems. The finite element representation of the solid region is combined with progressive fracturing, which leads to the formation of discrete elements, which may be composed of one or more deformable finite elements. The applicability of the approach is demonstrated by the solution of a range of examples relevant to various industrial sections.

Details

Engineering Computations, vol. 12 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 27 May 2014

V. Rajesh and Ali J. Chamkha

The purpose of this paper is to consider unsteady free convection flow of a dissipative fluid past an exponentially accelerated infinite vertical porous plate in the…

Abstract

Purpose

The purpose of this paper is to consider unsteady free convection flow of a dissipative fluid past an exponentially accelerated infinite vertical porous plate in the presence of Newtonian heating and mass diffusion.

Design/methodology/approach

The problem is governed by coupled non-linear partial differential equations with appropriate boundary conditions. A Galerkin finite element numerical solution is developed to solve the resulting well-posed two-point boundary value problem. It is a powerful, stable technique which provides excellent convergence and versatility in accommodating coupled systems of ordinary and partial differential equations.

Findings

It is found that the skin friction coefficient increases with increases in either of the Eckert number, thermal Grashof number, mass Grashof number or time whereas it decreases with increases in either of the suction parameter, Schmidt number or the acceleration parameter for both air and water. The skin friction coefficient is also found to decrease with increases in the values of the Prandtl number. In addition, it is found that the rate of heat transfer increases with an increase in the suction parameter and decreases with an increase in the Eckert number for both air and water. Lastly, it is found that the rate of heat transfer increases with increasing values of the Prandtl number and decreases with increasing time for all values of the Prandtl number.

Research limitations/implications

The present study has considered only Newtonian fluids. Future studies will address non-Newtonian liquids.

Practical implications

A very useful source of information for researchers on the subject of free convective flow over the surface when the rate of heat transfer from the surface is proportional to the local surface temperature.

Originality/value

This paper is relatively original and illustrates the effects of viscous dissipation on free convective flow past an exponentially accelerated infinite vertical porous plate with Newtonian heating and mass diffusion.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 24 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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