Any basic introduction to SolidWorks Simulation will include a brief lesson on using split lines to your advantage. The first common use of the split line is to give yourself a specific, localized area to apply a mesh control. This is helpful since you can get high levels of detail in certain areas your mesh while keeping the mesh relatively coarse in other areas, saving you some solving time.
The other common use is to give yourself a specific, localized area to apply loads, constraints and connectors without adding unnecessary geometry. This is helpful for those scenarios where you know a load or a support is not being applied across an entire face. Imagine the load of a diver standing on the end of a diving board: the weight of the diver is applied only where the feet touch the board, not across the entire face.
There is a curious side effect to split lines that many people might not notice unless they look closely at their mesh. When the software breaks down a model for meshing, it will automatically place node points along the edges of your surfaces. This happens to the edges of split faces, even if you have no mesh controls applied to them. For example, take a look at the split lines added to this model:
And note how they impact the location of the elements in the meshed version of the model, even though in this example I’ve applied no controls:
This effect can be utilized in a way that will help with your post-processing steps. For example, I’ve taken a flanged spline hub that I found on 3DContentCentral (found here), and decided that I want to see the effect on the shaft when the hub is locked, with a load applied across the hub and a torque applied through the spline faces. By using a split face, my nodes will line up with my split lines.
I can then select those edges while probing my resultant plots, using the “On selected entities” option to get a clear plot of what’s happening at that exact angle, including the ability to create an illustrative graph.here)