Using short beams allows the studs to rotate about each end. For example, with just the bottom rail and one stud connected with a beam, I can apply 0.25 lbf to the top of the stud and see a 10” displacement at the top.
The beam is acting as a spring. The 0.25 lbf for the 10" deflection was for a beam with a 0.05" radius. If you change the radius to 0.1" then the force to deflect 10" becomes 2.0 lbs and the stud starts to show some flexing. So the beam diameter and length control its spring rate. There are beam bending formulas if you want to know the exact spring rate.
If you zoom in on the bottom of the stud, you will see it is rotating.
This is not exactly what you want, you could offset the beam to align with the edge of the stud.
Here the beam was at the center of the face:
Now it is offset to the edge of the stud.
Here is the deformation of 10" at the top.
If you used Frictional Contact, you could get the same effect, but that would slow down the simulation.
The best way to speed up the simulation would be to change the sheathing from a solid model to a Mid-Surface. Then the sheathing is meshed with shell elements that are assigned the thickness of the sheathing. I have done that for one OBS panel.
Another way to speed up the simulation is if you have multiple cores on your computer.
The way to apply force to the top rail is to use DesignModeler. Create a plane on the top, create a sketch on that plane, and use a Face Split. I have done that at a 100 mm dimension from the end as shown in the Standard. This creates a line to apply the load to in Mechanical. You can see the Surface of the sheathing in the image below.
You can use beams to connect the sheathing to the frame. You need to create a point on the midsurface that represents the sheathing. While you can connect a beam to a point on a shell element on a surface, special consideration is needed to connect a beam to a solid element node on a vertex of the solid.
Beam and shell elements have nodes with six degrees of freedom: 3 translations and 3 rotations. Solid element nodes have only 3 translation degrees of freedom. If you cantilever a beam element off a shell, it will support load. If you cantilever a beam element off one node on a solid, it will fall over, since there is no rotational stiffness on a single node on the solid element. However since one end of the beam is on the shell, this may work for your model. (When you have to cantilever beams off of solids, you have to pick a face and make a bonded contact between the face and the beam vertex.)
Use DesignModeler to create a point on each side by creating planes to slice the sheet and rail and stud along their centerplanes where I imagine a nail would go. In the image below, I have hidden the face of the surface body in the corner of the sheathing to show the beam going between the two vertices.
The top rail is now 4 bodies, so they need to be put in their own part. The stud is now 2 bodies, so put them along with the web and the other stud into a part called Stud1. With Shared Topology set to Automatic for Stud1, those bodies will be held together by sharing common nodes at the coincident faces, so there is no need for bonded contact to hold them together. That will speed up your simulation slightly.
However, now the Imprints described in the previous post can't be used to cut out a small piece of the bottom rail. Instead, create a plane and make a sketch to use Face Split to form a rectangle at the bottom of the stud for the beam to be connected.
Finally, I added two Remote Displacements. The each have zero displacement for the X coordinate. Those act as the lateral supports allowed for in the Standard, and one of them is the Racking Load, which is input as a displacement. You use the Force Reaction to measure how much force is used to rack that end by the entered displacement.
That is a lot to absorb. Good luck!