Analysis Validation By Hand Calculations - Unit Error?

[FEAMonkey]

Hi Everyone,

I have modeled a plate with a center hole in Abaqus as a 3D model and used shell elements. In order to stop the top edge from bending during the load, a Pin(nodes) constraint has been applied on the top edge. I have worked in mm when I modeled this component. My dimensions have to be in mm as I am using the results for further analysis in MATLAB. You can see my setup here.

This is my Von-Mises result: (max 1.451*10^4)

I would like to validate my result using hand calculations. I have found the appropriate (I believe) equations on this website:

https://www.fracturemechanics.org/hole.html

I have created an excel spreadsheet to calculate the maximum stress at the horizontal points of the hole:

https://drive.google.com/file/d/1FlIbYZzWm_dyEQ8MXRLY74dJZ_PxLzLs/view?usp=sharing

As you can see, my results seem to be off by a factor of 4. It must be some sort of conversion error in Abaqus or in my equations.
I don't know how Abaqus calculates its results. Therefore, I don't know how to change my values in my spreadsheet to get the expected results.
Can someone take a look at my spreadsheet and explain to me how I can fix this problem?

Thank you for your help.

 

[FEA way]

I would use 2D elements (plane stress) for that. It’s also important to refine the mesh sufficiently. Check this thread, it might be helpful:

https://www.eng-tips.com/viewthread.cfm?qid=467283

Indeed, all units in Abaqus should be checked for consistency (not only dimensions but also loads and material properties).

 

[FEAMonkey]

Thanks for the tip. I have setup a 2D simulation. My results are very close but they are still out by a factor of 10 for some reason

 

[FEA way]

Make sure that you compare proper stress component. You may have to create cylindrical coordinate system for postprocessing in Abaqus and transform results to this CSYS.