Predeformation
Use the Predeformation subnode to specify that the elastic forces in the Spring Foundation or Spring Material 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.
The value of the predeformation can vary during the simulation, so it should not be interpreted as an initial value.
Shell Properties

Spring Predeformation
Based on space dimension, enter the values for the Spring Predeformation u0.
Location in User Interface
Context Menus
Ribbon
Physics tab with Spring Foundation, Spring Foundation, Interface, or Spring Material node selected in the model tree: