There are three sources of nonlinearity in structural problems: material, geometric, and boundary (contact). Any combination of these may be present in an ABAQUS analysis.

Geometric nonlinearity occurs whenever the magnitude of the displacements affects the response of the structure. It includes the effects of large displacements and rotations, snap through, and load stiffening.

Nonlinear problems are solved iteratively using the Newton-Raphson method. A nonlinear problem will require many times the computer resources required by a linear problem.

The nonlinear analysis step is split into a number of increments. ABAQUS iterates to find the approximate static equilibrium obtained at the end of each new load increment. ABAQUS controls the load incrementation by using convergence controls throughout the simulation.

The status file allows the progress of an analysis to be monitored while it is running. The message file contains the details of the load incrementation and iterations.

Results can be saved at the end of each increment so that the evolution of the structure's response can be visualized in ABAQUS/Viewer. Results can also be plotted in the form of X–Y graphs.