This message will be displayed any time the software detects nodal deformations exceeding 10% of the model diagonal. Exceeding 10% of this length suggests model mechanics that depart from linearity in response to the applied boundary conditions. Load magnitudes, surface body thicknesses, and contact options, if applicable, should be verified. If these are intended, a nonlinear analysis is advised. To request a nonlinear analysis, set Large Deflection to On in the Details view of the Analysis Settings folder.
For more information on large deflections, kindly refer to this Ansys help link: