Which strain tensor is used by Abaqus?

In summary, the question being discussed is about the strain tensors used in geometrically non-linear analysis in Abaqus software. It is mentioned that for geometrically linear analysis, all strain tensors are equal to engineering strain. However, for non-linear analysis, the strain tensors used depend on whether the formulations are done in reference configuration or current frame. It is not explicitly stated in the Abaqus manual which strain tensor is used for non-linear analysis, but it is confirmed that in the UMAT, Abaqus uses the logarithmic strain for non-linear analysis.
  • #1
hari123
8
0
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 ?
 
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  • #2
Have you checked the Abaqus literature?
 
  • #3
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.
 

FAQ: Which strain tensor is used by Abaqus?

1. What is the purpose of using a strain tensor in Abaqus?

The strain tensor is used to describe the deformation or strain of a material in Abaqus. It is a mathematical representation of the change in shape or size of an object under applied stress or load.

2. How is the strain tensor calculated in Abaqus?

The strain tensor is calculated using the displacement and geometry data of a material in Abaqus. It can be calculated using different methods such as finite element analysis or analytical solutions depending on the type of analysis being performed.

3. What are the different types of strain tensors available in Abaqus?

Abaqus offers several strain tensors that can be used for different types of analysis. These include engineering strain, Green-Lagrange strain, Hencky strain, and logarithmic strain. Each type of strain tensor has its own advantages and is suitable for specific types of materials and loading conditions.

4. How do I choose the appropriate strain tensor for my analysis in Abaqus?

The choice of strain tensor depends on the material properties, loading conditions, and the type of analysis being performed in Abaqus. It is important to consult the Abaqus documentation and seek guidance from experienced users to determine the most suitable strain tensor for your specific analysis.

5. Can I define a custom strain tensor in Abaqus?

Yes, Abaqus allows users to define a custom strain tensor if none of the available options are suitable for their analysis. This can be done through user subroutines or by using the Material Orientation option in Abaqus. However, it is recommended to consult with experienced users or Abaqus support before using a custom strain tensor.

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