Non-linear Structural Analysis

Three types of non-linear analysis are currently available: non-linear separating contact, geometric non-linear, and material non-linear.


Separating Contact
This analysis type provides a mechanism where parts may partially or completely separate from each other. When this happens, forces only transfer through the still connected portion of the connection. A friction coefficient is used to define the sticking/sliding threshold. Typical friction values are 0.1 to 0.2.
Changes in geometry as the structure deforms are taken into account by iteratively solving the strain-displacement and equilibrium equations. Follower loads (loads that stay normal to the surface and the geometry deforms/rotates) can be optionally defined. This is considered a large displacement, small strain analysis. That is, while large deformations can be predicted, the material properties remain linear and plastic deformation is not considered. Typical uses for geometric nonlinear analysis are predicting deformations in slender structures in aerospace, civil and mechanical engineering applications and stability (buckling) analyses of all types.
Note: While nonlinear buckling load history cannot be directly calculated, it can be quickly estimated by running multiple geometric nonlinear analyses, each with incrementally larger load values, and examining the resulting deformed shape. Buckling occurs when a small incremental load causes a large increase in the displacement magnitude.

Nonlinear contains additional analysis operations where the solver must iterate to find the value of interest. Expect this to run slightly longer and as such, care should be taken to make sure the analysis defined makes sense physically.