If your model includes a threaded fastener, the simplest model is to use bonded contact to bond a smooth rod that represents a threaded fastener to a smooth hole that might represent a tapped hole or a threaded nut.
A more sophisticated treatment is where the smooth rod and hole have a thread geometry treatment applied in the frictional contact definition. This is more realistic than bonded contact for deformations on the surrounding parts since the stress builds up in the first few threads in a more representative way than the bonded contact which is less realistic. The smooth cylindrical hole had the contact geometry correction of Bolt Thread applied in the contact definition.
The image below shows two holes with a shoulder screw (hidden) tightened down on the outside face. This model is not intended to be a very accurate calculation of the stress in the treads. That is what a detailed model using actual thread geometry is for. This model distributes the force through the parts in a more realistic way than simple bonded contact.
It is recommended to have a mesh density of at least four elements per thread pitch.
Another post has an example of how to evaluate failure in the threads themselves.