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User materials and NLGeom!

2 Posts
2 Users
Posts: 3
Topic starter
New Member
Joined: 15 years ago

Hi there,

I have a question. As you know when you specify that a step should consider nonlinear geometry (enabling NLGEOM) the strain rates would be then true strain or logarithmic strains rather than simple or engineering strains. I have a model with which I test a vumat routine that Ive developed. When I use nlgeom I encounter some problems regarding convergency which do not exist when NLGEOM is disabled. My question is that should my vumat code be something different than what I use as small strain without nlgeom. I thought maybe I should use another definition for updating the stress as the strain is now different from when nlgeom is not used. Any suggestion is appreciated.


1 Reply
Posts: 3993
Joined: 4 years ago

I have not heard of that problem before. As far as I know, the same user-material model should work equally well for both small-strain and large-deformation analyses.

- Jorgen

1 Reply