With COSMOSXPRESS, you can define a force and see the displacement. And then tune the force to produce you desired K.
Perhaps COMOSworks can do better, but I haven't played with it.
The SN curve for sure you'll find in a book about different materials
Hi Alex. Yes. In SolidWorks Premium (which includes Simulation, static analysis), you can define a non-zero displacement on the component using "Advanced Fixtures" command. Run. Next, list reaction forces on the entity with the non-zero displacement, so you can calculate K.
For S/N curves for that particular material, you will likely need to locate a test facility who would love to sell you that data.
Hope that helps.