Anisotropic elasto-plastic finite element analysis using a stress-strain interpolation method based on a polycrystalline model

in International Journal of Plasticity (2004), 20(Issue 8-9), 1525-1560

This paper describes a stress–strain interpolation method to model the macroscopic anisotropic elasto-plastic behavior of polycrystalline materials. Accurate analytical descriptions of yield loci derived ... [more ▼]

This paper describes a stress–strain interpolation method to model the macroscopic anisotropic elasto-plastic behavior of polycrystalline materials. Accurate analytical descriptions of yield loci derived from crystallographic texture [Int. J. Plasticity 19 (2003) 647; J. Phys. IV France 105 (2003) 39] are an interesting alternative to finite element models, where the macroscopic stress is provided by an averaging of microscopic stresses computed on a set of representative crystallites [Acta Metal 22 (1985) 923; Int. J. Plasticity 5 (1989) 67]. The parameters of the analytical functions modeling the yield locus are identified by comparison with a high number of stress tensors computed, for instance, by the well-known Taylor model [J. Inst. Metal 62 (1938) 307]. This identification method depends on the crystallographic texture and should be applied each time that the plastic strain has induced a significant texture evolution. The stress–strain interpolation method accurately describes the anisotropic material behavior in a narrow stress direction defined by only five stress points. The cost of texture updating is then greatly reduced compared to a full analytical function of the yield locus. After the mathematical description of the stress–strain interpolation method, its validity is demonstrated on two non-radial strain paths. The simulations of a deep drawing experiment allow comparing model predictions and measurements. Accuracy and CPU time of the interpolation stress–strain method are judged against two other models, respectively based on a complete analytical yield locus and on the averaging of crystallite stresses. [less ▲]

Lingopti project: semi-continuous casting process of copper-nickel alloys

in Proceedings of the 21st International Congress of Theoritical and Applied Mechanics (2004)

The following text deals with casting of copper-nickel alloys. They are high added values materials. The research contains two main parts. Laboratory tests (completed with bibliography) that provide ... [more ▼]

The following text deals with casting of copper-nickel alloys. They are high added values materials. The research contains two main parts. Laboratory tests (completed with bibliography) that provide thermal and mechanical properties of the ingot and the mould but also heat transfer coefficients between the ingot and its environment (mould, air and water). These parameters are required in the second part : development and validation of numerical modelization by the finite element method to optimise the industrial process. [less ▲]

Identification of elastoplastic model parameters in large deformation problems using gamma methods

in Proceedings of the 5th World Congress on Structural and Multidisciplinary Optimization (2003)

This paper reports on preliminary results of parameter identification problems in finite element non-linear analyses such as metal forming simulations. Two approaches are compared. The first one is the ... [more ▼]

This paper reports on preliminary results of parameter identification problems in finite element non-linear analyses such as metal forming simulations. Two approaches are compared. The first one is the classic Levenberg-Marquardt algorithm. The second one is a trust-region algorithm based on a quadratic model. The two algorithms are compared on two cases, one of them being an actuel experiment. [less ▲]

Finite element analysis of continuous steel casting

in Proceedings of the First International Conference Finite element for process analysis (2003)

In order to analyse the behaviour of steel during continuous casting and to improve the process, two complementary models of steel continuous casting using the finite element code LAGAMINE have been ... [more ▼]

In order to analyse the behaviour of steel during continuous casting and to improve the process, two complementary models of steel continuous casting using the finite element code LAGAMINE have been developed. We propose here a description of both macroscopic and mesoscopic approaches. The first one describes the whole continuous casting process, from the free surface in the mould and through the entire machine, including thermal and mechanical behaviour of the steel. The second approach focuses on the prediction of cracks and is developed at the grain scale. Results concerning the optimisation of the mould taper and the analysis of transverse cracks initiation are presented as industrial applications. [less ▲]

Investigation of transverse cracks initiation in continuous steel casting using a finite element approach

in Advances in Computational & Experimental Engineering (2003)

A numerical model for steel at elevated temperature which is based on a mesoscopic finite element approach is presented. The objective of the research is the analysis of damage evolution in the material ... [more ▼]

A numerical model for steel at elevated temperature which is based on a mesoscopic finite element approach is presented. The objective of the research is the analysis of damage evolution in the material using information from the macroscopic and microscopic scales. As a final application our results are used to study the industrial process of continuous casting of low carbon steel. [less ▲]

Numerical modelling of metal forming - current practice and advanced applications

in Iu, V. P.; Lamas, L. N.; Li, Y. P. (Eds.) et al Computational Methods in Engineering and Science, lu et al. (eds), Proceedings of the 9th International Conference of enhancement and Promotion of Computing Methods for Engineering and Science (2003)

This paper first summarizes the current possibilities and the perspectives of effective modeling of metal forming processes. Practical considerations on manpower requirement and data availability are ... [more ▼]

This paper first summarizes the current possibilities and the perspectives of effective modeling of metal forming processes. Practical considerations on manpower requirement and data availability are included in the discussion. Then, two examples of advanced applications are presented: the micro-macro approach for the modeling of sheet metal forming and the modeling of continuous casting. [less ▲]

Numerical shear tests for different elasto-plastic laws

in Onate, E.; Owen, D. R. J. (Eds.) Proceedings of the VII International Conference on Computational Plasticity (COMPLAS 2003) (2003)

This paper presents the numerical simulation of a cyclic simple shear test. The blank tested is a high strength steel sheet for which we use three different constitutive plastic laws derived from Teodosiu ... [more ▼]

This paper presents the numerical simulation of a cyclic simple shear test. The blank tested is a high strength steel sheet for which we use three different constitutive plastic laws derived from Teodosiu's model. These laws take into account respectively isotropic, kinematic and mixed isotropic-kinematic hardening. The goal of the paper is to provide a first numerical idea of the stress-strain path in the center of an experimental test sample. [less ▲]

Development of a Mesoscopic Cell Modeling the Damage Process in Steel at Elevated Temperature

in Key Engineering Materials [=KEM] (2003), 233-236

An on going project whose goal is the development and identification of a mathematical model of steel at elevated temperature using a mesoscopic approach is presented. The research aims to study the ... [more ▼]

An on going project whose goal is the development and identification of a mathematical model of steel at elevated temperature using a mesoscopic approach is presented. The research aims to study the damage process at elevated temperature using information from the macroscopic and mesoscopic scales. As a final application our results will be used to study the industrial process of continuous casting of low carbon steel. [less ▲]

Micro-macro analysis of steel sheet behaviour in finite element simulations. Application to deep-drawing process.

in Cescotto, Serge (Ed.) Proceedings of the Sixth European Mechanics of Materials Conference (EMMC6) Non Linear Mechanics of Anisotropic Materials (2002, September)

This paper presents a constitutive law based on Taylor’s model implemented in our non-linear finite element code LAGAMINE. The yield locus is only locally described and a particular interpolation method ... [more ▼]

This paper presents a constitutive law based on Taylor’s model implemented in our non-linear finite element code LAGAMINE. The yield locus is only locally described and a particular interpolation method has been developed. This local yield locus model uses a discrete representation of the material’s texture. The interpolation method is presented and a deep-drawing application is simulated in order to show up the influence of the texture evolution during forming processes. [less ▲]

Acceleration of finite element analysis by parallel processing

in Pietrzyk, M.; Mitura, Z.; Kaczmar, J. (Eds.) Proceedings of the 5th international ESAFORM Conference on Material Forming (2002)

The finite element code LAGAMINE developed since 1982 has been adapted to numerous finite elements and constitutive laws. The present researches on micro-macro modelling increase the requirement of CPU ... [more ▼]

The finite element code LAGAMINE developed since 1982 has been adapted to numerous finite elements and constitutive laws. The present researches on micro-macro modelling increase the requirement of CPU time. The parallelization of software is often divided into two main approaches: the coarse grain approach and the fine grain approach. For Finite Element software, the coarse grain method is usually characterized by the use of the mesh partitioning. In the fine grain approach, there is no partition of the mesh. The parallel program is made by the parallelization of instructions issued of the nalysis of dependences between the instructions, and the loops. The efficiency of all these approaches depends on the organization of the memory and on the used exchange protocol (MPI, PVM, or OpenMP). Our approach is intermediate between these two main categories of parallelization. It is characterized by the parallelization of the assembly of the stiffness matrix using a coarse grain approach and the use of a parallel direct solver. Because of the architecture of the available parallel computers, which are shared memory, we decided to use OpenMP protocol. [less ▲]