Welding two U profiles together and analyse it

Hello, I am thomas and new to this forum. I tried to solf my problems by making tutoraials and checking youtube videos.

I'm working on a Dakar rally chassis as final case study.

For my chassis I drew two U profiles that will slide in eachother and weld on top and bottum to fit. I already did that in the assembly part. Now I want to analyse it on force and torque.

My question is: do i need to fix the U profiles in some way to achief a smothe simulation run? because i already welded it up in the assembly screen or do i need to use the "Connections advisor" --> Edgeweld --> Fillet Single Sided In that case what shall i select for thin or thick one surface is 2mm thick so that is simply to select, but on the 90deg angle i don't know what to select.

Hopefully someone can give me the golden tip or idea. Our teachers of nowadays know .....

I already did a rollcage in solidworks simulation and that went well!

Thank you!

SolidworksSimulation