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Article
Publication date: 1 April 1991

PHILIPPE HRYCAJ, SERGE CESCOTTO and J. OUDIN

Inside the finite element framework of LAGAMINE code, the contact conditions are introduced with specific two‐node interface elements and four‐node quadrangular elements or…

Abstract

Inside the finite element framework of LAGAMINE code, the contact conditions are introduced with specific two‐node interface elements and four‐node quadrangular elements or four‐node one point quadrature elements. A non‐associated flow rule is involved for sliding unilateral contact modelling. Two methods of penalty factor computations in the penalty contact algorithms are presented. These methods are then used for contact modelling of two isothermal examples: axisymmetric tube expansion and asymmetric slab bending, the material bulk constitutive equation being isotropic and elasto‐plastic.

Details

Engineering Computations, vol. 8 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 3 August 2015

Johan Clausen, Lars Damkilde and Lars Vabbersgaard Andersen

The purpose of this paper is to present several methods on how to deal with yield surface discontinuities. The explicit formulations, first presented by Koiter (1953), result in…

376

Abstract

Purpose

The purpose of this paper is to present several methods on how to deal with yield surface discontinuities. The explicit formulations, first presented by Koiter (1953), result in multisingular constitutive matrices which can cause numerical problems in elasto-plastic finite element calculations. These problems, however, are not documented in previous literature. In this paper an amendment to the Koiter formulation of the constitutive matrices for stress points located on discontinuities is proposed.

Design/methodology/approach

First, a review of existing methods of handling yield surface discontinuities is given. Examples of the numerical problems of the methods are presented. Next, an augmentation of the existing methods is proposed and its robustness is demonstrated through footing bearing capacity calculations that are usually considered “hard”.

Findings

Previous studies documented in the literature all present “easy” calculation examples, e.g. low friction angles and few elements. The amendments presented in this paper result in robust elasto-plastic computations, making the solution of “hard” problems possible without introducing approximations in the yield surfaces. Examples of “hard” problems are highly frictional soils and/or three-dimensional geometries.

Originality/value

The proposed method makes finite element calculations using yield criteria with corners and apices, e.g. Mohr-Coulomb and Hoek-Brown, much more robust and stable.

Details

Engineering Computations, vol. 32 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 January 2013

N.N.S. Yapage and D.S. Liyanapathirana

Several constitutive models are available in the literature to describe the mechanical behaviour of cement stabilized soils. However, difficulties in implementing such models…

Abstract

Purpose

Several constitutive models are available in the literature to describe the mechanical behaviour of cement stabilized soils. However, difficulties in implementing such models within commercial finite element programs have hindered their application to solve related boundary value problems. Therefore, the aim of this study is to implement a constitutive model, which has the capability to simulate cement stabilized soil behaviour, into the finite element program ABAQUS through the user material subroutine UMAT.

Design/methodology/approach

After a detailed review of existing constitutive models for cement stabilized soils, a model based on the elasto‐plastic theory and the extended critical state concept with an associated flow rule is selected for the finite element implementation. A semi‐implicit integration method (cutting plane algorithm) with a continuum elasto‐plastic modulus and path dependent stress prediction strategy has been used in the implementation. The performance of the new finite element formulation of the constitutive model is verified by simulating triaxial test data using the finite element program with the new implementation and predictions from constitutive equations as well as experimental data.

Findings

The paper provides the implementation procedure of the constitutive model into ABAQUS but this method is useful for the implementation of any other constitutive model into ABAQUS or any other finite element program. Simulated results for the volumetric deformation of cement stabilized soils show that the cement stabilized soils do not obey the associated flow rule at high confining pressures. The parametric study shows that the influence of cementation increases the brittle nature and the bearing capacity of treated clay. In addition the results show that proposed finite element implementation has the ability to illustrate key features of the cement stabilized clay.

Originality/value

This paper presents an implementation of an elasto‐plastic constitutive model, based on the extended critical state concept, for cement stabilized soils into a finite element programme, which has been identified as an important and challenging topic in computational geomechanics. This implementation is useful in solving boundary value problems in geomechanics involving cement stabilized soils, incorporating key characteristics of these soils.

Details

Engineering Computations, vol. 30 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 15 November 2011

Xi Chen and Yong‐Gang Cheng

The initial stiffness method has been extensively adopted for elasto‐plastic finite element analysis. The main problem associated with the initial stiffness method, however, is…

Abstract

Purpose

The initial stiffness method has been extensively adopted for elasto‐plastic finite element analysis. The main problem associated with the initial stiffness method, however, is its slow convergence, even when it is used in conjunction with acceleration techniques. The Newton‐Raphson method has a rapid convergence rate, but its implementation resorts to non‐symmetric linear solvers, and hence the memory requirement may be high. The purpose of this paper is to develop more advanced solution techniques which may overcome the above problems associated with the initial stiffness method and the Newton‐Raphson method.

Design/methodology/approach

In this work, the accelerated symmetric stiffness matrix methods, which cover the accelerated initial stiffness methods as special cases, are proposed for non‐associated plasticity. Within the computational framework for the accelerated symmetric stiffness matrix techniques, some symmetric stiffness matrix candidates are investigated and evaluated.

Findings

Numerical results indicate that for the accelerated symmetric stiffness methods, the elasto‐plastic constitutive matrix, which is constructed by mapping the yield surface of the equivalent material to the plastic potential surface, appears to be appealing. Even when combined with the Krylov iterative solver using a loose convergence criterion, they may still provide good nonlinear convergence rates.

Originality/value

Compared to the work by Sloan et al., the novelty of this study is that a symmetric stiffness matrix is proposed to be used in conjunction with acceleration schemes and it is shown to be more appealing; it is assembled from the elasto‐plastic constitutive matrix by mapping the yield surface of the equivalent material to the plastic potential surface. The advantage of combining the proposed accelerated symmetric stiffness techniques with the Krylov subspace iterative methods for large‐scale applications is also emphasized.

Article
Publication date: 1 May 2002

Sven Klinkel and Sanjay Govindjee

In this paper an interface is derived between arbitrary three‐dimensional material laws and finite elements which include special stress conditions. The mechanical models of beams…

1427

Abstract

In this paper an interface is derived between arbitrary three‐dimensional material laws and finite elements which include special stress conditions. The mechanical models of beams and shells are usually based upon zero‐stress conditions. This requires a material law respecting the stress condition for each finite element formulation. Complicated materials, e.g. finite strain models are often described in the 3D‐continuum. Considering the zero‐stress condition requires a reformulation of these material laws, which is often complicated. The subject of this paper is to incorporate physically non‐linear 3D‐material laws in beam and shell elements. To this effect a local algorithm will be developed to condense an arbitrary 3D‐material law with respect to the zero‐stress condition. The algorithm satisfies the stress condition at each integration point on the element level.

Details

Engineering Computations, vol. 19 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 2 March 2012

Rosario Borrelli, Umberto Mercurio and Simona Alguadich

The purpose of this paper is to improve knowledge of the water impact phenomenon from both the experimental and numerical points of view.

Abstract

Purpose

The purpose of this paper is to improve knowledge of the water impact phenomenon from both the experimental and numerical points of view.

Design/methodology/approach

A drop test campaign on water was carried out on semi‐cylindrical steel structures. Therefore, an experimental database for validation purpose was generated. Subsequently, a finite element model was developed in LS‐DYNA in order to reproduce the tests. The behaviour of water was modeled by using the smoothed particle hydrodynamics (SPH) methods. Numerical simulations were compared to experimental data and the influence of some numerical parameters on the simulations was investigated.

Findings

The FE model was found to be able to reproduce the tests, at least in terms of acceleration peak and distribution of plastic deformation. Acceptable prediction was also found for the pressure peak in soft areas.

Research limitations/implications

In case of low velocity impact, the water model was found to be too rigid and the acceleration peaks were over‐predicted by the simulations. Further investigations are needed to adjust the water model in order to obtain better results also in the case of low velocity impact.

Originality/value

The experimental database could be very useful to the crashworthiness community to validate their numerical models. Moreover, the present paper provides guidelines to modelling the water impact correctly.

Article
Publication date: 1 April 1994

A. Huerta and F. Casadei

The arbitrary Lagrangian—Eulerian (ALE)formulation, which is already well established in the hydrodynamics andfluid‐structure interaction fields, is extended to materials

Abstract

The arbitrary Lagrangian—Eulerian (ALE) formulation, which is already well established in the hydrodynamics and fluid‐structure interaction fields, is extended to materials with memory, namely, non‐ linear path‐dependent materials. Previous attempts to treat non‐ linear solid mechanics with the ALE description have, in common, the implicit interpolation technique employed. Obviously, this implies a numerical burden which may be uneconomical and may induce to give up this formulation, particularly in fast‐transient dynamics where explicit algorithms are usually employed. Here, several applications are presented to show that if adequate stress updating techniques are implemented, the ALE formulation could be much more competitive than classical Lagrangian computations when large deformations are present. Moreover, if the ALE technique is interpreted as a simple interpolation enrichment, adequate—in opposition to distorted or locally coarse—meshes are employed. Notice also that impossible computations (or at least very involved numerically) with a Lagrangian code are easily implementable in an ALE analysis. Finally, it is important to observe that the numerical examples shown range from a purely academic test to real engineering simulations. They show the effective applicability of this formulation to non‐linear solid mechanics and, in particular, to impact, coining or forming analysis.

Article
Publication date: 26 August 2021

Yuran Jin, Robert Campbell, Jinhuan Tang, Huisheng Ji, Danrong Song and Xiaoqin Liu

Global economic growth provides new opportunities for the development of clothing enterprises, but at the same time, the rapid growth of clothing customization demand and the…

Abstract

Purpose

Global economic growth provides new opportunities for the development of clothing enterprises, but at the same time, the rapid growth of clothing customization demand and the gradual increase of clothing costs also pose new challenges for the development of clothing enterprises. In this context, 3D printing technology is injecting new vitality and providing a new development direction for the vigorous development of clothing enterprises. However, with the application of 3D printing technology, more and more clothing enterprises are facing the problem of business model innovation. In view of the lack of relevant research, it is necessary to carry out exploratory research on this issue.

Design/methodology/approach

The business model canvas method was adopted to design business model for clothing enterprises using 3D printing. The simulation model of the designed business model was constructed by a system dynamics method, and the application of the designed business model was analysed by a scenario simulation.

Findings

Mass selective customization-centralized manufacturing (MSC-CM) business model was constructed for clothing enterprises using 3D printing, and a static display was carried out using the BMC method. A dynamic simulation model of the MSC-CM business model was constructed. The future scenario of clothing enterprises using 3D printing was developed, and a simulated enterprise was analysed. The results show that the MSC-CM business model has a good application value. The simulation model of the MSC-CM business model performs the function of a business strategy experiment platform and also has a good practical application value.

Research limitations/implications

The MSC-CM business model is only a typical business model for clothing enterprises using 3D printing. It is necessary to further develop other business models, and some elements of the MSC-CM business model need to be further improved. In addition, the MSC-CM business model simulation uses a general model, which is not suitable for all clothing enterprises using 3D printing. When the model is applied, the relevant enterprises can further adjust and optimize it, thereby improving the validity of the simulation model.

Originality/value

To the best of the authors’ knowledge, this is the first paper on the MSC-CM business model for garment enterprises using 3D printing. Secondly, it is the first time that the business model of clothing enterprises using 3D printing has been simulated. In particular, the proposed business model simulation provides the possibility for testing the business strategy of clothing enterprises using 3D printing. In addition, a positive attempt has been made in the collaborative research of using both a static display business model and a dynamic simulation business model.

Article
Publication date: 1 March 1996

Takashi Hara, Shiro Kato and Hiroshi Nakamura

Reinforced concrete (R/C) hyperbolic cooling towers are the largest thin‐shell structures ever constructed. These towers stand more than 150m tall and have wall thicknesses of…

466

Abstract

Reinforced concrete (R/C) hyperbolic cooling towers are the largest thin‐shell structures ever constructed. These towers stand more than 150m tall and have wall thicknesses of 0.20‐0.25m. Therefore, these can be classified as thin‐shell structures. Analyses the influences of both the reinforcing ratio and the tensile strength of the concrete on the strength of the R/C cooling tower shells. In the numerical analysis Port Gibson tower is adopted for the numerical model and the finite element method is applied to examine the non‐linear behaviour of the cooling tower shells. From the load displacement curves the initial crack strength and the ultimate strength are determined. Also presents the stress redistribution processes and demonstrates the influences of these problems on the strength of the cooling tower shells.

Details

Engineering Computations, vol. 13 no. 2/3/4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 9 August 2011

Mondher Wali, Moez Abdennadher, Tahar Fakhfakh and Mohamed Haddar

The purpose of this paper is to analyse the dynamic behaviour of an elasto‐plastic sandwich subjected to low velocity impact.

Abstract

Purpose

The purpose of this paper is to analyse the dynamic behaviour of an elasto‐plastic sandwich subjected to low velocity impact.

Design/methodology/approach

A numerical model is developed with the assumption that the plastic deformation is confined under the contact area. The structure is analyzed using the in‐house finite element code with an appropriate contact law. During the impact progression, two phases (elastic and plastic) related to the impact intensity are considered in the dynamic model. The proportional viscous damping is incorporated in the model. An elasto‐plastic impact algorithm is established to determine the impact force, the sandwich structure displacement and indentation.

Findings

The numerical results are validated by experimental dropping weight impact tests. The influences of the impactor radius, the core material variation and the impactor initial velocity on the dynamic behaviour of the impacted structure are studied.

Originality/value

In order to study the low velocity impact problems by considering the caused plastic deformations, a simple numerical elasto‐plastic impact model of sandwich structure is proposed.

Details

Multidiscipline Modeling in Materials and Structures, vol. 7 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

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