Introduction to DxfSecProp (Dxf Cross-Section Properties)

Dxf file format

The supported format is DXF, from version 11/12 to 2023, in text or binary format. 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.

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.

• 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.

• 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.