Many common structural features exhibit nonlinear behavior that is status-dependent. For example, a tension-only cable is either slack or taut; a roller support is either in contact or not in contact. Status changes might be directly related to load (as in the case of the cable), or they might be determined by some external cause.

Situations in which contact occurs are common to many different nonlinear applications. Contact forms a distinctive and important subset to the category of changing-status nonlinearities.

See the Contact Technology Guide for information about performing contact analysis.

If a structure experiences large deformations, its changing geometric configuration can cause the structure to respond nonlinearly. An example would be the fishing rod shown in Figure 8.2: A Fishing Rod Demonstrates Geometric Nonlinearity. Geometric nonlinearity is characterized by "large" displacements and/or rotations.

Figure 8.2: A Fishing Rod Demonstrates Geometric Nonlinearity

Nonlinear stress-strain relationships are a common cause of nonlinear structural behavior. Many factors can influence a material's stress-strain properties, including load history (as in elastoplastic response), environmental conditions (such as temperature), and the amount of time that a load is applied (as in creep response).