In modeling a system's behavior properly, it may be important to consider its stress state. That stress state will influence the values of the stiffness matrix terms. The stress state from a previous structural solution may be included when the stiffness matrix is formed in a superelement generation pass. Stress stiffening can provide strength in a structure which would normally not have any resistance to certain loadings. For example, a stretched cable can resist a normal loading while a slack cable cannot. Stress stiffening can also change the response frequencies of a system which affects both modal and transient dynamic problems.

For more information about prestressed substructure analysis, see General Procedure for Linear Perturbation Analysis in the Structural Analysis Guide.