Structure Type

Open Structure Type dialog window, which selects a structure type to be created, using either method:

When opened, you can create one of the following: building, 2D truss, 3D truss, 2D frame, 3D frame, grillage, plate, shell, plane stress structure, plane deformation structure, axisymmetric structure, or a volumetric structure.

Robot can analyze the structure types in the following chart, which shows the coordinates and the nodal degrees of freedom that are defined when creating a structure. U denotes displacements in the X, Y, or Z direction in a global coordinate system, and R denotes rotations around the axes.

STRUCTURES

COORDINATES

NODAL DEGREES OF FREEDOM

2D frames

X, Y

UX , UY , - , - , - , RZ ,

2D trusses

X, Y

UX , UY , - , - , - , - ,

Grillages

X, Y

- , - , UZ , RX , RY , - ,

3D trusses

X, Y, Z

UX , UY , UZ , - , - , - ,

3D frames

X, Y, Z

UX , UY , UZ , RX , RY , RZ,

Plates

X, Y

- , - , UZ , RX , RY , - ,

Shells

X, Y, Z

UX , UY , UZ , RX , RY , RZ,

Plane stress structures

UX , UY , - , - , - , - ,

Plane deformation structures

UX , UY , - , - , - , - ,

Axisymmetric structures

UX , UY , - , - , - , - ,

Volumetric structures

X, Y, Z

UX , UY , UZ , - , - , - ,

Building is a structure template available in Robot. Building is not a structure type, but a template which facilitates defining this structure type. Available coordinates and nodal degrees of freedom for the building are identical as for shells.

Note: It is impossible to combine 3D bar models (the 3D frame type) with the following structure types: plate, plane deformation structure, or a plain stress structure.
Note: For 2 structure types (plane deformation structures and axisymmetric structures), the transversal dimension is always assumed to be 1 m, irrespective of the unit length specified in the Job Preferences dialog. This means that a structure sector of 1-meter thickness is modeled, which affects the interpretation of loads and reactions. For example, if the force unit [N] and the length unit [mm] are specified, then:

A sum of reactions is interpreted analogously (always on the length of 1 m).

Note: For volumetric structures, you can define a 3D bar model (3D frame) or a shell structure. These element types that can be used in volumetric structures have 6 degrees of freedom: UX, UY, UZ, RX, RY, and RZ.

See also:

Options for generating a planar finite element mesh

Types of volumetric finite elements