Which strain tensor is used by Abaqus?

[hari123]

Hi all,
I have some doubts regarding the strain tensors Abaqus uses for the case of Geometrical non linear analysis.

In the case of geometrically linear analysis, all the strain tensors will be equal to engineering strain, So it doesn't matter which strain tensor Abaqus uses.

But for non-linear analysis i have learned in theory that, if the formulations are done in reference configuration we use Green Lagrange / Karni Reiner strain tensors, and if the formulations are done in current frame, some other strain tensors are used.

But which type these formulations Abaqus uses and with which strain tensor it does the calculations ?

I am asking this question because, I am working with UMAT, and I am doing geometrical non linear analysis. In UMAT Abaqus uses the variable STRAN for strain. I would like to know which strain is it ?

 

[Chestermiller]

Have you checked the Abaqus literature?

 

[hari123]

Hi,

Thank you for your reply @Chestermiller .

Yup, I have gone through Abaqus manual, but it wasn't mentioned clearly, regarding this topic.
But anyway, now i came to know that for the case of nonlinear analysis Abaqus uses logarthmic strain in its UMAT.