Extracting reaction forces/moments from parts of an assembly

[g.alshamsi]

Hello everyone,

So I have an assembly of a cold-formed steel shear wall, a screenshot of the meshed assembly can be found here (

https://files.engineering.com/getfi...-0b9860f34703&file=CFS_Wall_annotations.png).

I have validated my model against monotonic and experimental results and my model is showing acceptable agreement in terms of peak load and loading/unloading stiffness (results can be found here:

https://files.engineering.com/getfi...ba4-b955-2b9fd839f5dc&file=FEM_vs._Exp.docx).

Ultimately, I want to propose a design procedure for the walls elements (studs, tracks and sheathing), however in order to do that, I need to determine the force distribution on every member of the assembly. My advisor suggested using the stress output of ABAQUS to back-calculate the forces from the stresses, however the parts of the assembly are subjected to different kind of stresses so just taking the von mises stress output of Abaqus and dividing it by the area of the member is a great oversimplification that would results in wrong results. For instance theory tells us that the columns in a steel frame/wall are subjected to flexural stresses, axial stresses, and torsional stresses. Is there a way to extract different stresses from the parts as to get the different forces acting on a part? Or in other words, is there a method to extract reaction forces on parts that don't have any boundary conditions assigned to them? If anyone has any experience dealing with this kind of stuff or has any ideas feel free to shoot, I need any kind of help I can get here.

Cheers!

 

[g.alshamsi]

Right, forgot the model's details: Explicit solver, S4R shell elements for all parts, displacement control load applied at the top of the wall, and I used a user-defined (VUMAT) linear kinematic hardening model for the steel. Section properties are based on a coupon test.

Best,

 

[FEA way]

You could use the section force (SF) output variable and the free body cut tool. You may also need the NFORC output variable.

 

[g.alshamsi]

This might be what I'm looking for, I'll read on it,,

Thanks for the tip,,,

 

[g.alshamsi]

Unfortunately, the free body cut tool doesn't work with 3D shells. I tried building a simple, elastic beam model and extract the section forces at midspan to compare with hand calculations however I'm getting funky results. Any other tips?

 

[FEA way]

Free body cut works also for shell elements but you have to request the SF (section forces) variable.