Meshing > 1D meshing

Creating beam cross sections

Video: Create and assign a standard beam cross section

You can create a cross section and assign it to a mesh of 1D bar or beam elements using the 1D Element Section command. To create a cross section, you can:

Choose from a list of solver-specific standard sections and specify the section dimensions.
Create a cross section from the face of a solid.
Create a cross section from sketch geometry.

After you create a section, you assign it to a 1D mesh in the physical property table for the mesh collector.

You can orient the cross section on the bar or beam mesh by specifying an orientation vector and offsets in the Mesh Associated Data dialog box.

Note:

For LS-DYNA, offsets are valid only when Element formulation (ELFORM) is set to 1 Hughes-Liu in the SECTION_BEAM physical property table.

For Abaqus, see your solver documentation for the types of sections that support offsets.

Element orientation on the cross section

By default, you orient the Y-axis of the 1D element on the cross section, but you can also choose to orient the Z-axis. In either case, you orient the element to a direction in the absolute coordinate system, or you can infer the direction by selecting a vector on the model.

In the following Simcenter Nastran example, the thick yellow arrow represents the section orientation vector. In the first picture, the element Y-axis (1) is aligned with the Y-axis of the absolute coordinate system (2).

In the next picture, the element Y-axis (1) is aligned with the Z-axis of the absolute coordinate system (2).

Note:

Different solvers use different axis labels:

Nastran, Ansys, and Simcenter Samcef: X, Y, Z
Abaqus: t, n1, n2
LS-DYNA: r, s, t

The direction of the 1D element X-axis is determined by the first node selected in the creation of the element. If you defined the element on an edge, the software uses the end closest to where you selected the edge to determine the first node of the element. For Abaqus, t is aligned with the element axis and runs from the first node to the second node. The n1 axis is the first beam section axis and n2 is the normal to the beam.

The direction of the X-axis is important when you orient section types that are not symmetrical, such as the L section. In the two examples below, (1) represents the first node selected in the creation of the 1D element and (2) represents the second node.

Section properties are associative

The cross section properties are associative, including dimensions, orientation, and offset. This means the software updates the section properties whenever changes are made to the data from which they are derived.

For example, suppose you create a cross section using the Face of Solid method to define its dimensions based on the face of solid geometry. Later, you change the dimensions of that geometry in the Modeling application. Then, in the FEM, after you click Update Finite Element Model , the beam section dimensions are updated to match the new dimensions of the geometry.

Beam post-processing

For information about beam post-processing, see Beam post-processing.

Where do I find it?

Choose Home tab→Mesh group→1D Element Section .

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