A7A
Mechanical
- Nov 20, 2016
- 2
Hi,
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.
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.
