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UMAT-convergence problem

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  • UMAT-convergence problem


    I'm simulating the behavior of anisotropic material using a UMAT subroutine. The UMAT works fine when using single element. However, when I use multiple elements (C3D8R), I get convergence problems.

    The problem is as follows:
    The simulation stops suddenly with error 'Too many attempts.....'. The point where the simulation stops depend on the elements size. When I increase the element size (coarser mesh) I get better convergence, but for finer meshes, the simulation isn't completed.

    I've tried to increase the hourglass stiffness, and I found that for higher values, the simulation is completed, but the resulting forces are higher !

    Is this problem coming out from the definition of the DDSDDE matrix inside the UMAT, or it's a result of using reduced elements (C3D8R)?

    Thank you in advance.

    Best Regards.

  • #2
    Hi everybody.
    Wishing you all a ggod day.
    WHile using UMAT, I am getting following errors.
    WindowsError: [Error 2] The system cannot find the file specified UMAT
    This is the 1st and last line of the error and nothing else.
    (Know that I linked my Fortran and Abaqus in Target)
    Kindly help.
    Thanks in advance.