Shear Direction in FEM Shell

[lawrence_budzisz]

Hello Everyone,

I was hoping that someone might have a clear answer for me on the shear directions when reading the FEM results. On the image below I am displaying Qyy forces and as you can see the local 'y' direction is right to left. I am trying to average shear generated along the edge (adjacent plate has pinned linear release - not visible in this view) but I am finding that in order to get the correct values on the panel cut I have to display the force in Qxx direction. 

Could anyone explain why this is the case? 

Thank you for any help on the subject. 

[Krzysztof_Wasik]

Hi @lawrence_budzisz 

Check this article 

How Qyy shear force for shell elements should be interpreted in Robot Structural Analysis.

[lawrence_budzisz]

Hi Krzysztof,

Thank you for a prompt response to my query. I have read that post before and I understand that the Qyy is shear force on finite element plane perpendicular to results y direction (in local axis). What confused me a little bit was the fact that in order to get the same values on the 'panel cut' results I had to change the direction to Qxx in order to display values of Qyy.

In the example below (simple panel spanning between two support) I was able to read the Qyy values using 'panel cut' Qyy but if you notice on the first screen shot I had to switch 'panel cut' results to Qxx in order to read Qyy values. 

[Krzysztof_Wasik · Accepted solution]

Hi @lawrence_budzisz 

In the first post you have used local direction for panel cut  results presentation(cut line direction). 

In the second example Automatic direction is set in both dialogs.

[lawrence_budzisz]

Thank you Krzysztof.

I completely missed that.