Use the Predeformation subnode to specify that the elastic forces in
Spring Foundation,
Spring Foundation, Interface,
Thin Elastic Layer, or
Thin Elastic Layer, Interface are nonzero at zero displacement. Thus you can model cases where the unstressed state of the spring is in another configuration than the one described by the geometry.
Physics tab with Spring Foundation,
Spring Foundation, Interface,
Thin Elastic Layer, or
Thin Elastic Layer, Interface node selected in the model tree: