Overview of Displacement and Rotation

Parameter Name	Formula
DISP_X, DISP_Y, DISP_Z	$u_{i}$
ROT_X, ROT_Y,ROT_Z	$θ_{i}$
DISP_X_ABS, DISP_Y_ABS, DISP_Z_ABS	$\sqrt{{u_{i}}^{2}}$
DISP_ABS	$\sqrt{{u_{x}}^{2} + {u_{y}}^{2} + {u_{z}}^{2}}$

Analysis Types: Static Linear or Non-Linear Analysis

K u = F

where K may be linear or non-linear.

For displacements and rotations the following table shows the allowed combinations between strategy and the items OBJ_FUNC and CONSTRAINT with C for controller and S for sensitivity based optimization. S* means that nonlinear analyses are allowed.

	TOPO	SHAPE	BEAD	SIZING
OBJ_FUNC	S*		S	S
CONSTRAINT	S*		S	S

Displacements and rotations are the primary variables in the FEM solution. They are also very often the main interest of the FEM-analyst, e.g. the maximal displacement. Displacements and rotations should be defined using a nodal id, although node groups may also be referenced. Large node groups can lead to major performance issues, see Group operations for design responses.

Displacements and rotations can also be referenced in a local coordinate system.

Important:

It is always strongly recommended that the user defines design elements attached to nodes used in displacement definitions or reaction definitions (DRESP) as frozen elements. This stabilizes the optimization iterations and often leads to a significant lower number of optimization iterations.