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Article
Publication date: 1 April 1986

A. Benallal

Complex constitutive equations including non‐linear kinematic as well as isotropic hardening rules are introduced in the framework of the finite element method to analyse…

Abstract

Complex constitutive equations including non‐linear kinematic as well as isotropic hardening rules are introduced in the framework of the finite element method to analyse the behaviour of structures in quasi‐static elasto‐viscoplasticity under cyclic loadings. An implicit time marching process is developed together with a substructuring technique and the corresponding numerical details are underlined. Practical examples are treated to demonstrate the capabilities of the proposed finite element code.

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Engineering Computations, vol. 3 no. 4
Type: Research Article
ISSN: 0264-4401

Article
Publication date: 1 March 1991

Y.W. KWON

An analysis model has been developed for the elasto‐viscoplastic analysis of continuous fibre‐reinforced composite structures. Elastic deformation of fibre and…

Abstract

An analysis model has been developed for the elasto‐viscoplastic analysis of continuous fibre‐reinforced composite structures. Elastic deformation of fibre and elasto‐viscoplastic deformation of matrix are considered in the analysis model because the yield strength of matrix is, in general, substantially lower than that of fibre. A finite element formulation is derived for the proposed analysis model. If matrix is assumed homogeneous and isotropic, the von Mises yield criterion is used for viscoplastic yielding. As numerical examples, a parametric study has been performed for elasto‐viscoplastic analysis of unidirectional composite plates subjected to inplane loads.

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Engineering Computations, vol. 8 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 February 1985

D.R.J. Owen and Guo Qiang Liu

An elasto‐viscoplastic analysis of anisotropic plates and shells is undertaken by means of the finite element displacement method. A thick shell formulation accounting for…

Abstract

An elasto‐viscoplastic analysis of anisotropic plates and shells is undertaken by means of the finite element displacement method. A thick shell formulation accounting for shear deformation is considered and a layered approach is adopted in order to model property changes through the shell thickness. In order to avoid ‘locking’ behaviour as the shell thickness is reduced, the nine‐node Lagrangian and heterosis elements are introduced into the present model. Viscoplastic yielding is based on the Huber—Mises criterion extended by Hill for anisotropic materials. Time integration of the strain rate equations is accomplished by both explicit and implicit algorithms and special consideration is given to the evaluation of the viscoplastic strain increment for anisotropic situations. The computer code developed is demonstrated by application to a range of numerical examples.

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

Article
Publication date: 1 June 2003

B. Bouhafs, K. Woznica and P. Klosowski

In this paper, the problem of the elasto‐viscoplastic dynamic and thermal behaviour of geometrically non‐linear plates and shells is studied under the assumption of small…

Abstract

In this paper, the problem of the elasto‐viscoplastic dynamic and thermal behaviour of geometrically non‐linear plates and shells is studied under the assumption of small strains and large rotations. The first‐order shear deformation shell theory and the Chaboche constitutive viscoplastic model taking the temperature fields into account are used for computations. An effective procedure using the central difference method of solving the equations of motion is applied. The trapezoidal method is used to integrate the constitutive viscoplastic law. A nine node isoparametric shell element has been utilised for the finite element algorithm. Finally, some examples are presented and compared with the results obtained by moderate rotation theory.

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Engineering Computations, vol. 20 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 November 1996

C. Kropik and H.A. Mang

Contains a report on three‐dimensional finite element (FE) analyses of deformations and stresses resulting from the excavation of shallow underground railway tunnels…

Abstract

Contains a report on three‐dimensional finite element (FE) analyses of deformations and stresses resulting from the excavation of shallow underground railway tunnels. Multisurface elasto‐viscoplastic material models are employed for consideration of the mechanical behaviour of the soil and the shotcrete shell supporting the excavation. Both are formulated within the framework of closest point projection algorithms. For soil a cap model is used, consisting of a curved failure surface, a tension cut‐off and an elliptical cap. The latter allows consideration of the evolution of plastic strains even for the limiting case of a purely volumetric stress state. The movement of the cap is governed by a hardening law, describing the relation between the hydrostatic pressure and void ratio. The shotcrete model is a rotating crack model, taking ageing of the maturing concrete into account. It consists of a strain‐hardening Drucker‐Prager cone and three Rankine (crack) surfaces. Demonstrates the usefulness of the cap model to predict the mechanical behaviour of the soil by means of tests on remoulded, saturated clay. The model parameters of the clayey silt of Vienna, where the analysed tunnel is located, are fit to standard test results. The parameters of the shotcrete model are fit to test results published in the literature. Compares the analysis of a single‐track tunnel with the results of field measurements from sliding micrometers. Furthermore, the stresses in the shotcrete lining are examined. In view of the inhomogeneity of the material and of unavoidable deficiencies of the measurements it is fair to say that the mechanical effects resulting from the excavation of tunnels are modelled reasonably well.

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Engineering Computations, vol. 13 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 March 1988

A. Benallal and D. Marquis

An elasto‐viscoplastic constitutive model valid under general complex cyclic loadings is proposed to describe the multiaxial behaviour of engineering metallic materials…

Abstract

An elasto‐viscoplastic constitutive model valid under general complex cyclic loadings is proposed to describe the multiaxial behaviour of engineering metallic materials. Its numerical implementation in the framework of the finite element method is underlined. Its application to the prediction of some various tests is compared to the experimental responses.

Details

Engineering Computations, vol. 5 no. 3
Type: Research Article
ISSN: 0264-4401

Article
Publication date: 1 January 1988

J.L. Chenot

The constitutive equations for the deformation of elastoplastic, viscoplastic or compressible materials are presented for the small strain approximation and for the large…

Abstract

The constitutive equations for the deformation of elastoplastic, viscoplastic or compressible materials are presented for the small strain approximation and for the large strain theory of Hill. A velocity approach is proposed for time discretization, which leads to a second order approximation for small strain, and an incrementally objective second order approximation for large deformation processes. Two other quasi second order formulations are discussed. The finite element space discretization is outlined and the solution procedure is described.

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Engineering Computations, vol. 5 no. 1
Type: Research Article
ISSN: 0264-4401

Article
Publication date: 1 June 1992

Y.W. KWON

A formulation has been developed for thermo‐elastoviscoplastic finite element analyses of continuous fibre‐reinforced composite plates subject to bending loading using a…

Abstract

A formulation has been developed for thermo‐elastoviscoplastic finite element analyses of continuous fibre‐reinforced composite plates subject to bending loading using a generalized continuum mechanics approach. Such an approach is used to model the non‐homogeneity in a composite, which is constituted by fibres embedded in a matrix material. The present formulation computes the respective stresses occurring in each constituent so that the respective yield criterion and flow rule of each constituent may be used if there is a material yielding in any constituent. Thermo‐elastic deformation of fibre and thermo‐elastoviscoplastic deformation of matrix are considered in the present study because the yield strength of fibre is substantially higher than that of matrix in many cases. Both constituents are assumed to be isotropic so that the von‐Mises yield criterion may be used for viscoplastic yielding of matrix. As numerical examples, a parametric study is performed for thermo‐elastoviscoplastic deformations of laminated composite plates subject to thermal bending loads.

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Engineering Computations, vol. 9 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 August 1997

Zeljana Nikolic and Ante Mihanovic

Presents a non‐linear numerical model for the computations of post‐tensioned plane structures. Generally curved prestressing tendons and reinforcing bars are embedded into…

1020

Abstract

Presents a non‐linear numerical model for the computations of post‐tensioned plane structures. Generally curved prestressing tendons and reinforcing bars are embedded into the concrete and they are modelled independently of the concrete mesh using one‐dimensional curvilinear elements. Among the losses which influence the decrease in the prestress force, it is possible to compute the losses caused by friction between tendons and the concrete, the losses which result from the concrete deformation and the losses in the anchorage zone. The computation for post‐tensioned structures is organized in phases: the phase preceding prestressing (Phase I), the prestressing phase (Phase II) and the phase following prestressing (Phase III). The load is applied incrementally until failure. The model is tested on a number of examples.

Details

Engineering Computations, vol. 14 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 January 1988

M.B. Reed

The aim of the model is to represent the main features of soft or brittle rock strata, using a small number of physically‐meaningful material parameters. The yield surface…

Abstract

The aim of the model is to represent the main features of soft or brittle rock strata, using a small number of physically‐meaningful material parameters. The yield surface is based on either the Mohr—Coulomb or Hoek—Brown criterion, and a simple small‐dilation flow rule allows the implicit algorithm of elasto‐viscoplasticity to be used. Elastic—brittle plastic behaviour is modelled, resulting in stress discontinuities across the interface between intact and failed rock. The effects of lamination and jointing are taken into account. Results are presented for a tunnelling problem with axial symmetry.

Details

Engineering Computations, vol. 5 no. 1
Type: Research Article
ISSN: 0264-4401

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