To specify a geometric nonlinear analysis

Add or edit an existing analysis set in the Analysis Commands dialog .

Select Geometric Non-Linear from the Analysis type drop-down list. This instructs the analysis engine to perform a nonlinear analysis which can account for nonlinear effects of moderate displacement and small strain. This solution holds for where the element distortion is small and small rotations are assumed.

Select the desired Print option for including analysis results in the output file.

Specify nonlinear analysis parameters as necessary:

Type the number of Load steps to use for applying load in stages.
Type the maximum number of Iterations to use to achieve equilibrium in the deform position within the specified tolerance value.
Type a absolute displacement limit for the first analysis step in the Displacement control field.
Type the Tolerance to use for achieving convergence between two sequential iterations.
Select the frequency of Rebuild Steps of the tangent K matrix.

Check the Include KG matrix option to add the geometric stiffness to the stiffness matrix.

(Optional) Check the Target option to specify a displacement target:

Either:

type a Node number

or
click Select to select a node in the view window
Select a Direction (degree of freedom) from the drop-down list.
Type a target Value distance for the displacement limit.

Click OK.