Numerical Simulation of Springback in Sheet Metal Forming Using Shell Elements

in Proceedings of the Fifth National Belgian Congress on Theoretical and Applied Mechanics (2000)

A Quasi-Coulomb Model for Frictional Contact Interfaces

in MECOM'99 - Proceedings of the 6th Argentine Congress on Computational Mechanics (1999, September)

Frictional contact interfaces have to be modeled in practice when industrial problems such as metal forming operations, crashworthiness, and so on, have to be simulated. Usually a Coulomb model is used in ... [more ▼]

Frictional contact interfaces have to be modeled in practice when industrial problems such as metal forming operations, crashworthiness, and so on, have to be simulated. Usually a Coulomb model is used in order to describe the constitutive law for the frictional case. Following a standard plasticity approach to Coulomb law a non-symmetric tangent operator is found, and so a non-symmetric solver has to be used in order to take full advantage of consistent operators. With respect to symmetric ones, these non-symmetric operators lead to prohibitive computational times. However, in practice different schemes have been proposed in order to recover the symmetric operator, and consequently, use a symmetric solver. In this work an alternative approach based on an idea due to Garcia Garino and Oliver [33] is defined in order to avoid to deal with non-symmetric solvers and thus save a large amount of computational time, which renders the computational simulation more attractive to industry. Applications to metal forming simulations and crashworthiness analysis are envisaged. [less ▲]

A Symmetric Tangent Operator Recovery via Quasi-Coulomb Model for Frictional Contact Between Solids in Large Deformation Analysis

in ECCM’99, European Conference on Computational Mechanics (1999, August)

Frictional contact interfaces have to be modeled in practice when industrial problems such as metal forming operations, crashworthiness, and so on, have to be simulated. Usually a Coulomb model is used in ... [more ▼]

Frictional contact interfaces have to be modeled in practice when industrial problems such as metal forming operations, crashworthiness, and so on, have to be simulated. Usually a Coulomb model is used in order to describe the constitutive law for the frictional case. Following a standard plasticity approach to Coulomb law a non-symmetric tangent operator is found, and so a non-symmetric solver has to be used in order to take full advantage of consistent operators. With respect to symmetric ones, these non-symmetric operators lead to prohibitive computational times. However, in practice different schemes have been proposed in order to recover the symmetric operator, and consequently, use a symmetric solver. In this work an alternative approach based on an idea due to Garcia Garino and Oliver [33] is defined in order to avoid to deal with non-symmetric solvers and thus save a large amount of computational time, which renders the computational simulation more attractive to industry. Applications to metal forming simulations and crashworthiness analysis are envisaged. [less ▲]

ALE Methods for Stationary Solutions of Metal Forming Processes

in Covas, J. A. (Ed.) Proceedings of the Second ESAFORM Conference on Material Forming (1999, April)

In this paper, two efficient convection algorithms are briefly presented in order to update the value stored at the Gauss point during the Eulerian step of an Arbitrary Lagrangian Eulerian computation in ... [more ▼]

In this paper, two efficient convection algorithms are briefly presented in order to update the value stored at the Gauss point during the Eulerian step of an Arbitrary Lagrangian Eulerian computation in solid mechanics. They are based on the finite volume method and on the Streamline Upwind Petrov Galerkin method. An application to cold rolling process is presented. [less ▲]

An extension of the Radial Return Scheme for Springback Similation in Sheet Metal Forming

in 6th ICTP-International Conference on Technology of Plasticity, Nuremberg (1999)

Optimization Methods for Inverse Problems in Large Strain Plasticity

in 1st CanCNSM – Canadian Conference on Nonlinear Solid Mechanics (1999)

A unified radial return scheme for visco-plasticity and mixed hardening

in Seventh International Symposium on Plasticity and its current applications (1999)

Efficient Implicit Schemes for Finite Element Impact Simulation

in International Journal of Crashworthiness (1999), 4(3), 273-285

Optimization techniques for parameter identification of material constitutive laws in large deformation processes

in Journées Samtech (1998, October)

Effective Iterative Solvers for Highly Non-Linear & Large Deformation Pressure Dependent Problems

in Van Keer, R.; Verhegghe, B.; Hogge, M. (Eds.) et al Proceedings of ACOMEN'98, Advanced Computational Methods in Engineering, part 2: Contributed papers (1998, September)

In this paper, we present a stress update scheme for non-deviatoric elastoviscoplastic models, which can be considered as an extension of the radial return method for classical plasticity. We use the ... [more ▼]

In this paper, we present a stress update scheme for non-deviatoric elastoviscoplastic models, which can be considered as an extension of the radial return method for classical plasticity. We use the unconditionally stable backward Euler scheme to obtain the viscoplastic solution at each increment. To solve the large sparse non symmetric iteration matrix, we use the GMRES method. This fast iterative solver, in conjunction with an appropriate preconditioner, can save a lot a memory and CPU time when 3D problem are considered. A comparison between direct and iterative solvers will be discussed on two applications of cold compaction of powders. [less ▲]