I am attempting to construct a simulation with loads applied to welded components on a tubular frame. I had run simulations on just the frame model previously and was successful, but I am having difficulties with the full assembly including the welded components so I made this test model to see if I could get it working on a simpler level. However, I am still having issues with under-constrained bodies even after simplifying the model to several simple weldments and one welded component. I am applying fixtures at joints similar to my approach when conducting simulations on just the frame, and am using a bonded contact between the welded component and beam element to simulate the weld joint. Can someone indicate why I am still getting unconstrained body errors when I try to run the simulation? I'm attaching the test assembly I'm using.