DxfSecProp (Dxf Cross-Section Properties)

Born from the passion for the finite element method and the need for a rigorous method for the characterization of the arbitrary beam cross-sections, this online calculation tool uses a known format for importing section shapes. The input of the shape and the material can be done via DXF.

Dxf file format

The supported format is DXF version 11/12. Any BLOCK that is not anonymous (anonymous block names start with an asterisk *) is read and becomes a section.

The shape of the cross-section must be drawn with: 2d polylines made of lines and circumference arcs; circles. Of these elements are considered the coordinates X and Y.

How to draw the cross-section.

The materials can be assigned to the elements associating them with the layers with appropriate names. For the calculation of the properties it is sufficient to know the parameter ν (Poisson's coefficient), and if the material is not recognized a material is assigned ν=0.3.

Arbitrary cross section

Examples: "HE200A-HE220A S235.dxf", "schuco ADS65.dxf".

Calculated properties

The properties of the cross-sections are divided into two parts:

  • Properties determined in an exact manner based on contour integrals, the drawing elements are used directly:
    • area;
    • elastic modulus;
    • plastic modulus;
    • moment of inertia;
    • centroid with coordinates with respect to the reference system in BLOCK;
    • principal axes of inertia;
    • radius of rotation;
    • coordinates of the most stressed edges with respect to the centroid.
    The results refer to two coordinate system:
    • origin in the centroid and oriented axes in X and Y of the local coordinate system of BLOCK, referring to X and Y in subscripts;
    • origin in the centroid and oriented axes with the principal axes of inertia, referring to X0 and Y0 in subscripts.
Arbitrary cross section, inertia shear and symmetries
  • Properties determined in a approximate manner by FEM method, a mesh of triangular elements with 6 nodes is generated:
    • shear center with coordinates with respect to the coordinate system of BLOCK;
    • shear principal system;
    • shear areas (stiffness);
    • primary and secondary torsion constant;
    • warping constant.
    The results refer to a coordinate system with origin in the shear center and axes oriented with the principal shear system, reference to XC and YC in the subscripts.
Arbitrary cross section, fem triangular mesh

Main bibliographic references