S.W static simulation issues

Hello guys, I am a product designer from the UK and I am in the process of customising a Cafe racer.

I am currently working on the subframe but encounter some issues

here they are:

So I did not use weldment for the tube as I could not upload or find the right tubing dimension. I try to test it as the components as solid, even without interference (trim between tube = 0.1mm) it would not work.

The simulation worked after I used beam, however I am not sure of the result.

I would greatly appreciate your help, and advice me how to do the simulation.

Thank you very much.

R1

SolidworksSimulation