The Experts below are selected from a list of 175752 Experts worldwide ranked by ideXlab platform

D.j. Lloyd - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of Surface Roughening in AA6111 Automotive Sheet Under Pure Bending
    Metallurgical and Materials Transactions A, 2015
    Co-Authors: Y. Shi, H. Jin, P. Z. Zhao, D.j. Lloyd
    Abstract:

    The finite element method is used to numerically simulate the topographic development in an aluminum sheet, AA6111, under pure bending. The measured electron backscatter diffraction data are directly incorporated into the finite element model, and the constitutive response at an Integration Point is described by the single crystal plasticity theory. The effects of strain-rate sensitivity, work hardening, and imposed initial surface roughness on surface roughening are studied. It is found that the grains in top surface layers of the sheet play a big role in controlling the outer surface roughness due to the strain gradient across sheet thickness in bending, while the grain size and texture of the surface layers have a direct impact on finishing surface qualities.

  • Analysis of ridging in ferritic stainless steel sheet
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006
    Co-Authors: H. Jin, Y. Shi, D.j. Lloyd
    Abstract:

    The finite element method is used to numerically simulate the development of ridging/roping in ferritic stainless steel sheet under stretching. The measured electron backscattered diffraction (EBSD) data (grain orientations and their spatial distributions) are directly incorporated into the finite element model and the constitutive response at an Integration Point is described by the single crystal plasticity theory. The effects of spatial orientation distribution, imposed deformation path, and inhomogeneous deformation within individual grains on the roping are discussed. It is found that the initial texture and its spatial distribution are the predominant factors for the development of ridging.

  • Analysis of surface roughening in AA6111 automotive sheet
    Acta Materialia, 2004
    Co-Authors: D.j. Lloyd
    Abstract:

    The finite element method is used to numerically simulate the topographic development in an aluminium sheet, AA6111, under stretching. The measured electron backscatter diffraction (EBSD) data are directly incorporated into the finite element model and the constitutive response at an Integration Point is described by the single crystal plasticity theory. The effect on surface roughening of sample geometry, strain rate sensitivity, work hardening, imposed deformation path, as well as the EBSD step size, spatial orientation distribution and inhomogeneous deformation within individual grains are discussed. It is concluded that surface roughening is controlled by the spatial distribution of grain orientations through the thickness of the specimen.

  • Analysis of roping in AA6111 automotive sheet
    Acta Materialia, 2003
    Co-Authors: D.j. Lloyd, A. Bosland, H. Jin, S.r. Macewen
    Abstract:

    Abstract The finite element method is used to numerically simulate the development of roping in an aluminium sheet AA6111 under stretching. The measured EBSD data are directly incorporated into the finite element model and the constitutive response at an Integration Point is described by the single crystal plasticity theory. The effects of spatial orientation distribution, imposed deformation path, loading direction, and inhomogeneous deformation within individual grains on the roping are discussed. Correlation between roping and individual texture components is also explored.

P. Picart - One of the best experts on this subject based on the ideXlab platform.

  • Modelling the constitutive behaviour of thin metal sheet using strain gradient theory
    Journal of Materials Processing Technology, 2002
    Co-Authors: J.-f. Michel, P. Picart
    Abstract:

    Abstract The classical local continuum theory is not well adapted to represent the size effects in metal forming processes because there is no dependence on length or size intrinsic parameters. To simulate the material behaviour for sheet metal forming of very thin components the strain gradient plasticity theory is applied. A length intrinsic parameter associated to the gradient of the effective plastic strain is used. The gradient is computed at each Integration Point through the thickness using a interpolation matrix that only depends on the co-ordinates of the Integration Points. The effective plastic strain is obtained by solving a consistent iterative scheme. The flow chart of the algorithm in a finite element framework is presented so that two numerical examples of sheet metal forming.

H. Jin - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of Surface Roughening in AA6111 Automotive Sheet Under Pure Bending
    Metallurgical and Materials Transactions A, 2015
    Co-Authors: Y. Shi, H. Jin, P. Z. Zhao, D.j. Lloyd
    Abstract:

    The finite element method is used to numerically simulate the topographic development in an aluminum sheet, AA6111, under pure bending. The measured electron backscatter diffraction data are directly incorporated into the finite element model, and the constitutive response at an Integration Point is described by the single crystal plasticity theory. The effects of strain-rate sensitivity, work hardening, and imposed initial surface roughness on surface roughening are studied. It is found that the grains in top surface layers of the sheet play a big role in controlling the outer surface roughness due to the strain gradient across sheet thickness in bending, while the grain size and texture of the surface layers have a direct impact on finishing surface qualities.

  • Analysis of ridging in ferritic stainless steel sheet
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006
    Co-Authors: H. Jin, Y. Shi, D.j. Lloyd
    Abstract:

    The finite element method is used to numerically simulate the development of ridging/roping in ferritic stainless steel sheet under stretching. The measured electron backscattered diffraction (EBSD) data (grain orientations and their spatial distributions) are directly incorporated into the finite element model and the constitutive response at an Integration Point is described by the single crystal plasticity theory. The effects of spatial orientation distribution, imposed deformation path, and inhomogeneous deformation within individual grains on the roping are discussed. It is found that the initial texture and its spatial distribution are the predominant factors for the development of ridging.

  • Analysis of roping in AA6111 automotive sheet
    Acta Materialia, 2003
    Co-Authors: D.j. Lloyd, A. Bosland, H. Jin, S.r. Macewen
    Abstract:

    Abstract The finite element method is used to numerically simulate the development of roping in an aluminium sheet AA6111 under stretching. The measured EBSD data are directly incorporated into the finite element model and the constitutive response at an Integration Point is described by the single crystal plasticity theory. The effects of spatial orientation distribution, imposed deformation path, loading direction, and inhomogeneous deformation within individual grains on the roping are discussed. Correlation between roping and individual texture components is also explored.

J. Huetink - One of the best experts on this subject based on the ideXlab platform.

  • The ALE-method with triangular elements: direct convection of Integration Point values
    International Journal for Numerical Methods in Engineering, 2000
    Co-Authors: M.j. Van Haaren, H.c. Stoker, A.h. Van Den Boogaard, J. Huetink
    Abstract:

    The arbitrary Lagrangian-Eulerian (ALE) finite element method is applied to the simulation of forming processes where material is highly deformed. Here, the split formulation is used: a Lagrangian step is done with an implicit finite element formulation, followed by an explicit (purely convective) Eulerian step. The purpose of this study is to investigate the Eulerian step for quadratic triangular elements. To solve the convection equation for Integration Point values, a new method inspired by Van Leer is constructed. The new method is based on direct convection of Integration Point values without intervention of nodal Point values. The Molenkamp test and a so-called block test were executed to check the performance and stability of the convection scheme. From these tests it is concluded that the new convection scheme shows accurate results. The scheme is extended to an ALE-algorithm. An extrusion process was simulated to test the applicability of the scheme to engineering problems. It is concluded that direct convection of Integration Point values with the presented algorithm leads to accurate results and that it can be applied to ALE-simulations

  • The arbitrary Lagrangian-Eulerian method on grids of triangular elements: a new convection scheme
    1999
    Co-Authors: M.j. Van Haaren, H.c. Stoker, A.h. Van Den Boogaard, J. Huetink
    Abstract:

    This study investigates the Eulerian step of a split ALE nite element method for quadratic triangular elements. To solve the convection equation for Integration Point values, a new method is constructed, directly based on Integration Point values without using intermediate nodal values. The Molenkamp test and a so-called block test were executed to check the performance and stability of the convection scheme. From these tests it is concluded that the new convection scheme shows accurate results.

S.r. Macewen - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of roping in AA6111 automotive sheet
    Acta Materialia, 2003
    Co-Authors: D.j. Lloyd, A. Bosland, H. Jin, S.r. Macewen
    Abstract:

    Abstract The finite element method is used to numerically simulate the development of roping in an aluminium sheet AA6111 under stretching. The measured EBSD data are directly incorporated into the finite element model and the constitutive response at an Integration Point is described by the single crystal plasticity theory. The effects of spatial orientation distribution, imposed deformation path, loading direction, and inhomogeneous deformation within individual grains on the roping are discussed. Correlation between roping and individual texture components is also explored.

  • Large strain behaviour of very thin aluminium sheets under planar simple shear
    Le Journal de Physique IV, 2001
    Co-Authors: Kaan Inal, Kenneth W. Neale, L.d. Kenny, Mukesh K. Jain, S.r. Macewen
    Abstract:

    The finite element method is used to numerically simulate the large strain behaviour of thin rolled aluminium alloy sheets under planar simple shear. The numerical analyses are performed on both macroscopic and mesoscopic' levels. In the macroscopic calculation, each material Point is represented by an aggregate of single crystals, and the Taylor-type polycrystal plasticity model gives the constitutive response at an Integration Point. In the mesoscopic study, a material Point or a polycrystal is represented by an 'unit-cell' in which an element of the finite element mesh represents a single crystal, and the constitutive response at an Integration Point is given by the single crystal constitutive model. Numerical results are compared with experimental data found in the literature. The differences in predicted numerical results between the macroscopic and mesoscopic approaches are discussed.