Good video, but stresses are not calculated in the elemend nodes. Only displacements are. After the initial calculation of the displacement, the stresses are calculated in the Gaussian points in the element. So the stresses on the nodes are interpolated from the gaussian points
We fix mounting locations because those are gonna stay immovable relative to the rest of your body. Like nails in a door hinge. For complicated assemblies, we rigidly link bolted joints and fix ground locations (where it is connected to immovable structure or grounded to Earth simply)
In this case you need to perform a bolted joint analysis. Perform the FEA using idealised rigid link and extract forces from all three axes. Input those values in an online bolted joint calculator to see if its sufficient.
