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Issue #98 open

MFront: check if the behaviour is small strain or finite strain

Helfer Thomas
created an issue

Currently, one can use a MFront finite strain behaviour with GDEF_LOG, leading to a severe crash. Whether a MFront behaviour is a finite or small strain behaviour shall be checked by Code_Aster. This piece of information is given by the <behaviour>_BehaviourType symbol exported in the library.

A small strain behaviour shall be usable in HPP, GROT_GDEP and GDEF_LOG. A finite strain behaviour shall only be usable with SIMO_MIEHE. (and with GROT_GDEP for MFront >= 3.1 and Code_Aster >= 14.0 (?))

Regards, Thomas

Comments (4)

  1. Pierre_J

    Hi Thomas, I read: "A finite strain behaviour shall only be usable with SIMO_MIEHE. (and with GROT_GDEP for MFront >= 3.1 and Code_Aster >= 14.0 (?))". Am I missing something? I thought GDEF_LOG is also a formulation oriented toward handling of finite strain. Is the limitation on MFront side? I thank you in advance for your reply. Bests, Pierre

  2. Helfer Thomas reporter

    Hi Piere, One have to distinguish two kinds of finite strain behaviours: - The true ones takes the deformation gradient as input and handle the kinematic assumptions. Those behaviours shall be used with SIMO_MIEHE in CODE_ASTER. - The others ones where the choice of the strain and conjugated stress is made prior the call of the behaviour (GDEF_LOG, GROT_GDEP). From the Mfront point of view, those behaviours are written just like "small strain" behaviours.

    This can be confusing. In short, MFront+GDEF_LOG works well together, but the user has to be aware of what he is doing (as always :)) Regards, Thomas

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