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Article
Publication date: 8 July 2019

Qing Xie, Yucai Hu, Yexin Zhou and Wanshui Han

Poor bending response is a major shortcoming of lower-order elements due to excessive representation of shear stress/strain field. Advanced finite element (FE…

Abstract

Purpose

Poor bending response is a major shortcoming of lower-order elements due to excessive representation of shear stress/strain field. Advanced finite element (FE) formulations for classical elasticity enhance the bending response by either nullifying or filtering some of the symmetric shear stress/strain modes. Nevertheless, the stress/strain field in Cosserat elasticity is asymmetric; consequently any attempt to nullify or filter the anti-symmetric shear stress/strain modes may lead to failure in the constant couple-stress patch test where the anti-symmetric shear stress/strain field is linear. This paper aims at enhancing the bending response of lower-order elements for Cosserat elasticity problems.

Design/methodology/approach

A four-node quadrilateral and an eight-node hexahedron are formulated by hybrid-stress approach. The symmetric stress is assumed as those of Pian and Sumihara and Pian and Tong. The anti-symmetric stress components are first assumed to be completely linear in order to pass the constant couple-stress patch test. The linear modes are then constrained with respect to the prescribed body-couple via the equilibrium conditions.

Findings

Numerical tests show that the hybrid elements can strictly pass the constant couple-stress patch test and are markedly more accurate than the conventional elements as well as the incompatible elements for bending problems in Cosserat elasticity.

Originality/value

This paper proposes a hybrid FE formulation to improve the bending response of four-node quadrilateral and eight-node hexahedral elements for Cosserat elasticity problems without compromising the constant couple-stress patch test.

Details

Engineering Computations, vol. 36 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 9 January 2007

Jianzhong Lin, Shanliang Zhang and James A. Olson

This paper seeks to explore the fiber orientation distribution and rheological properties of turbulent fiber suspensions flowing through a contraction.

Abstract

Purpose

This paper seeks to explore the fiber orientation distribution and rheological properties of turbulent fiber suspensions flowing through a contraction.

Design/methodology/approach

The Reynolds averaged Navier‐Stokes equation was solved with the Reynolds stress model to get the mean fluid velocity and the turbulent kinetic energy in the turbulent flow of a contraction with rectangular cross‐section. The turbulent velocity fluctuations were represented as a Fourier series with random coefficients. Then the slender‐body theory was used to predict the fiber orientation distribution, orientation tensor, additional shear stress and first normal stress difference of suspensions in the flow.

Findings

It is found that the longer fibers tend to align the streamline easily. Increased contraction ratio results in higher fiber alignment in the direction of flow. The fibers are weakly and strongly aligned in the direction of flow in the region near the inlet and the exit, respectively. Fibers are significantly more aligned in the plane of the contraction than in the xz plane. Contraction ratio and fiber length were shown to strongly and weakly affect the distributions of additional shear stress and first normal stress difference.

Originality/value

It is the first time that the fiber orientation distribution and rheological properties of turbulent fiber suspensions flowing through a contraction have been computed numerically. The computational approach and results are valuable to the design and operation of contraction used in the industrial processes.

Details

Engineering Computations, vol. 24 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 16 September 2013

Jaw-Ren Lin, Rong-Fang Lu, Li-Ming Chu and Chi-Ren Hung

– The purpose of this paper is to investigate the effects of non-Newtonian rheology on the dynamic characteristics of a secant-shaped couple-stress lubricated slider bearing.

Abstract

Purpose

The purpose of this paper is to investigate the effects of non-Newtonian rheology on the dynamic characteristics of a secant-shaped couple-stress lubricated slider bearing.

Design/methodology/approach

By applying the linear dynamic theory to the film force equation, a closed-form solution of the stiffness and damping coefficients is obtained for the secant-shaped bearing taking into account the non-Newtonian effects of Stokes couple stress fluids.

Findings

Comparing with the secant-shaped Newtonian-lubricant bearing, the effects of non-Newtonian couple stresses provide an apparent improvement in the dynamic stiffness and damping characteristics, especially for the secant-shaped slider bearing operating at lower squeezing-film heights and with larger non-Newtonian couple stress parameters.

Originality/value

Comparing with those of the inclined plane-shaped non-Newtonian slider bearings, better dynamic stiffness and damping performances are provided for the secant-shaped non-Newtonian slider bearing designed at larger values of the shoulder parameters. The advantages of secant-shaped slider-bearing types provide engineers useful information in bearing selection and engineering application.

Details

Industrial Lubrication and Tribology, vol. 65 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 5 May 2015

Lan Song, Yang Zhao , Yaoming Zhou and Haifei Xiang

The purpose of this paper is to analyze and figure out the temperature field and thermal stress field with the calculation model of thermal insulation material and…

Abstract

Purpose

The purpose of this paper is to analyze and figure out the temperature field and thermal stress field with the calculation model of thermal insulation material and composite material.

Design/methodology/approach

The paper adopted the three-dimensional finite element algorithm.

Findings

The simulated results showed great shearing strength between the chipset and the printed circuit board. The position of chip exerts great influence on the distribution of temperature field and thermal stress field of circuit board. The reasonable distribution of chip will effectively reduce the temperature extremum and stress extremum of circuit board.

Originality/value

The paper analyzes and presents a discussion of the problems relating to the density of electronic packaging. The analysis process and the method of the paper provide essential help in resolving electronic device heat problems.

Details

Circuit World, vol. 41 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

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Article
Publication date: 10 July 2007

Shantanu C. Prabhune and Ramesh Talreja

To provide a basis for making assessment of the safety of adhesively bonded joints after they have been de‐painted by a dry abrasive method or a wet chemical method.

Abstract

Purpose

To provide a basis for making assessment of the safety of adhesively bonded joints after they have been de‐painted by a dry abrasive method or a wet chemical method.

Design/methodology/approach

Stress analysis by a finite element method has been conducted for metal/composite and composite/composite joints in a single lap configuration. The effects of degradation of composite and adhesive, separately or combined, on the stresses in the adhesive layer bonding the two components are studied. Effects of wet and dry conditions of de‐painting are included in the study. It is assumed that in the composite these conditions affect only the laminae close to the surface from which the paint coating is removed.

Findings

The locations and values of the maximum peel and shear stresses in the adhesive are determined for both joints under different assumed conditions of degradation caused by de‐painting.

Research limitations/implications

Experimental data indicating the extent of surface damage caused by de‐painting is not available.

Originality/value

Extensive literature study did not show any investigation of composite surface damage and adhesive property degradation on integrity of adhesively bonded joints. Results reported here will be of use in assessing effects of de‐painting on the structural performance of adhesively bonded joints.

Details

Aircraft Engineering and Aerospace Technology, vol. 79 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 13 October 2020

Shalini M. Patil, C.V. Vinay and Dinesh P.A.

The purpose of this paper is to study the amalgamated consequences of nonNewtonian fluid and permeability for nonporous journal spinning with constant tangential velocity…

Abstract

Purpose

The purpose of this paper is to study the amalgamated consequences of nonNewtonian fluid and permeability for nonporous journal spinning with constant tangential velocity inside a rough porous bearing.

Design/methodology/approach

The flow is assumed to have developed under low Reynolds number, and the flow is governed by reduced Navier–Stokes equations. Based on Stokes theory for couple-stress fluid, a closed form of nonNewtonian Reynolds equation is obtained. Finite difference based multigrid method is adopted to study the various parameters of journal bearings.

Findings

It is found that bearing attributes such as pressure distribution and weight carrying capacity are commanding for nonNewtonian couple-stress fluid compared to the classical Newtonian case.

Originality/value

The multigrid method for the Reynolds equation is used, which accelerates the convergence rate of the solution and is independent of the grid size. The effects of couple-stress fluid promote the enhanced pressure distribution in the fluid. Both increased weight bearing capacity and delayed squeezing time reduce the skin-friction and hence take longer time to come in contact with each other.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2020-0051/

Details

Industrial Lubrication and Tribology, vol. 73 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 6 January 2021

Naeem Ullah, Sohail Nadeem, Luthais McCash, Anber Saleem and Alibek Issakhov

This paper aims to focus on the natural convective flow analysis of micropolar nanofluid fluid in a rectangular vertical container. A heated source is placed in the lower…

Abstract

Purpose

This paper aims to focus on the natural convective flow analysis of micropolar nanofluid fluid in a rectangular vertical container. A heated source is placed in the lower wall to generate the internal flow. In further assumptions, the left/right wall are kept cool, while the upper and lower remaining portions are insulated. Free convection prevails in the regime because of thermal difference in-between the lower warmer and upper colder region.

Design/methodology/approach

The physical setup owns mathematical framework in-terms of non-linear partial differential equations. For the solution purpose of the differential system, finite volume method is adopted. The interesting features of the flow along with thermal transportation involve both translational and rotational movement of fluid particles.

Findings

Performing the simulations towards flow controlling variables the outputs are put together in contour maps and line graphs. It is indicated that the variations in flow profile mass concentration and temperature field augments at higher Rayleigh parameter because of stronger buoyancy effects. Higher viscosity coefficient implies decrease in flow and thermal transportation. Further, the average heat transfer rate also grows by increasing both the Rayleigh parameter and heated source length.

Originality/value

To the best of the authors’ knowledge, no such study has been addressed yet. Further, the results are validated by comparing with previously published work.

Details

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

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Article
Publication date: 8 January 2020

Yanni Bouras and Zora Vrcelj

Concrete arch structures are commonly constructed for various civil engineering applications. Despite their frequent use, there is a lack of research on the response and…

Abstract

Purpose

Concrete arch structures are commonly constructed for various civil engineering applications. Despite their frequent use, there is a lack of research on the response and performance of concrete arches when subjected to fire loading. Hence, this paper aims to investigate the response and in-plane failure modes of shallow circular concrete arches subjected to mechanical and fire loading.

Design/methodology/approach

This study is conducted through the development of a three-dimensional finite element (FE) model in ANSYS. The FE model is verified by comparison to a non-discretisation numerical model derived herein and the reduced modulus buckling theory, both used for the non-linear inelastic analysis of shallow concrete arches subjected to uniformly distributed radial loading and uniform temperature field. Both anti-symmetric and symmetric buckling modes are examined, with analysis of the former requiring geometric imperfection obtained by an eigenvalue buckling analysis.

Findings

The FE results show that anti-symmetric bifurcation buckling is the dominant failure mode in shallow concrete arches under mechanical and fire loading. Additionally, parametric studies are presented which illustrate the influence of various parameters on fire resistance time.

Originality/value

Fire response of concrete arches has not been reported in the open literature. The authors have previously investigated the stability of shallow concrete arches subjected to mechanical and uniform thermal loading. It was found that temperature greatly reduced the buckling loads of concrete arches. However, this study was limited to the simplifying assumptions made which include elastic material behaviour and uniform temperature loading. The present study provides a realistic insight into the fire response and stability of shallow concrete arches. The findings herein may be adopted in the fire design of shallow concrete arches.

Details

Journal of Structural Fire Engineering, vol. 11 no. 1
Type: Research Article
ISSN: 2040-2317

Keywords

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Article
Publication date: 1 April 2008

Rajneesh Kumar and B.S. Hundal

The propagation of circular crested waves in a fluid saturated incompressible porous plate is analyzed. The frequency equations, for symmetric and anti‐symmetric waves…

Abstract

The propagation of circular crested waves in a fluid saturated incompressible porous plate is analyzed. The frequency equations, for symmetric and anti‐symmetric waves, connecting the phase velocity with wave number are derived. At short wave length limits the frequency equations for symmetric and antisymmetric waves in a stress free plate reduce to Rayleigh type surface wave frequency equation and the finite thickness plate appears as a semi‐infinite medium. The results at various steps are compared with the corresponding results of classical theory and finally the variations of phase velocity, attenuation coefficient with wave number and displacements amplitudes with distance from the boundary of the plate is presented graphically and discussed.

Details

Multidiscipline Modeling in Materials and Structures, vol. 4 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

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Article
Publication date: 12 February 2018

Rajendran Selvamani

This study aims to construct a mathematical model to study the dispersion analysis of magneto-electro elastic plate of arbitrary cross sections immersed in fluid by using…

Abstract

Purpose

This study aims to construct a mathematical model to study the dispersion analysis of magneto-electro elastic plate of arbitrary cross sections immersed in fluid by using the Fourier expansion collocation method (FECM).

Design/methodology/approach

The analytical formulation of the problem is designed and developed using three-dimensional linear elasticity theories. As the inner and outer boundaries of the arbitrary cross-sectional plate are irregular, the frequency equations are obtained from the arbitrary cross-sectional boundary conditions by using FECM. The roots of the frequency equation are obtained using the secant method, which is applicable for complex solutions.

Findings

The computed physical quantities such as radial stress, hoop strain, non-dimensional frequency, magnetic potential and electric potential are plotted in the form of dispersion curves, and their characteristics are discussed. To study the convergence, the non-dimensional wave numbers of longitudinal modes of arbitrary (elliptic and cardioid) cross-sectional plates are obtained using FECM and finite element method and are presented in a tabular form. This result can be applied for optimum design of composite plates with arbitrary cross sections.

Originality/value

This paper contributes the analytical model for the role of arbitrary cross-sectional boundary conditions and impact of fluid loading on the dispersion analysis of magneto-electro elastic plate. From the graphical patterns of the structure, the effects of stress, strain, magnetic, electric potential and the surrounding fluid on the various considered wave characteristics are more significant and dominant in the cardioid cross sections. Also, the aspect ratio (a/b) and the geometry parameters of elliptic and cardioids cross sections are significant to the industry or other fields that require more flexibility in design of materials with arbitrary cross sections.

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