Dear all,

I'm learning how to export stiffness matrix of a model from abaqus. I found two examples online, one with a two dimensional model and one with a three dimensional. Both of them use *Matrix Generate and *Matrix output. According to the documentation each row of the exported .mtx file is written with the following elements:

1. Row node label

2. Degree of freedom for row node

3. Column node label

4. Degree of freedom for column node

5. Matrix entry 

But in the .mtx file for the 2D model each node has 2 degree of freedoms and for the 3D model each node has 6 DOFs. Could anyone please explain why is that? Aren't the nodes in 3D model suposed to have 3 DOFs(displacement in x y z direction)?

Any advise on this matter would be greatly appreciated!

Best regards,

XU Duo