Design and operational constraints often require that a linear analysis be performed to evaluate the stress states in the structure. For complicated structures, however, generating proper meshes with suitable refinements in highly stressed regions can be difficult.

Information about local regions of high stresses is often unavailable. In such cases, with suitable refinement criteria, you can apply nonlinear mesh adaptivity to generate progressively refined meshes to accurately evaluate the stresses in all regions.

You can apply nonlinear mesh adaptivity to a (small-deflection) linear analyses (NLGEOM,OFF) provided that a nonlinear solution procedure is invoked to solve the geometrically linear problem. (Material nonlinearity can also be included in a small-strain/-deflection analysis.)