Support - Non-linearity

When the Nonlinear tab is selected from the Support Definition dialog, the following dialog displays.

The Label field at the top of the dialog, assigns a label (name) to the support.

Clicking Definition of non-linear model, opens the dialog for defining a curve that specifies the non-linear character of a support. Curves defined in this dialog are visible on selection lists. The non-linear behavior of a support is defined by selecting - for a given degree of freedom - a non-linear model that determines one of the following relationships: force-displacement or moment-rotation. You can select the model when the appropriate direction is blocked.

Note: A non-linear model has information about the degree of freedom (displacement or rotation). Therefore, models are filtered, that is a non-linear model with the force- displacement type set is not visible on the selection lists for RX, RY, and RZ.

Note: The non-linear model describes characteristics of a support at a node, and not on an edge or a surface. If a support using the non-linear model is defined on an edge or surface, then at each of their nodes, a support with the same characteristics is assigned. There is no change in the characteristics of the model that depends on the surface of elements adjacent to the node or distances between nodes on the supported edge.For example, a non-linear elastic support defined on an edge yields a different elasticity depending on how the edge is divided by nodes. A supported edge has the same rigidity as a nodal support only when the edge is divided equally into nodes that are 1m apart.

A diagram of the support being defined is displayed in the lower right of the dialog. Clicking Direction under the digram opens the Support direction dialog, where you can define the direction of the local x axis for the support. The axis is determined by specifying a point, a node, or rotating a support with respect to any axis in the global coordinate system.

Clicking Add, adds the support to the list of active supports.

Clicking Advanced, which is available for nodal and linear supports (it is not available for planar supports), opens a new dialog: Support definition - Advanced