shell element local coordinate convention si very well explained in abaqus analysis manual->introduction->syntax and convention...regarding strain calculation, it's no more different from what is there explained in any FEA book.

Hi

For your first question:

You can define a new coordinate system in the visualization module easily. Click on the " Create coordinate system" icon. Then choose one of the coordinate types.

And then go to the menu bar and follow this address :

Result >> Option >> Transformation >> User specified >> choose you new coordinate.

So, all data transformed into the new coordinate.

For your second question :

Why do you want to calculate the derivatives within the coordinate system?

to calculate nodal strain?

If your question is this, you haven't to calculate derivatives. you can add strain into the field output from the step module.

Step module >> field output manager >> edit >>

Now you can choose nay typs of stain.

Hi Meysam,

Thanks for your kind reply. I am actually not using Abaqus. I am just trying to repeat the method of Abaqus to compute strain. I have a shell mesh with triangle elements, and displacements of all the nodes are known. I am wondering how could I compute the strain, which I think Abaqus is well done.

Hi

your welcome. So, you want to calculate strain to the computational method, that's great.

you can find your answers here:

http://ivt-abaqusdoc.ivt.ntnu.no:2080/v6.14/books/usb/default.htm

introduction >> Abaqus syntax and conventions >> conventions