Cross Section

BarElement is modelled as a 1D element, and it needs to have geometrical values of it’s cross section (like A, Iy, Iz, etc.). BarElement.CrossSection does define a cross section for BarElement. The type Base1DSection is base class that is used for defining a cross section for bar element. This class is a general class which can gives every information of section’s geometric properties at specific location of length of element. All other cross sections of bar element are inherited from Base1DSection class.

UniformParametric1DSection

Inherited from Base1DSection, defines a uniform section for the BarElement. Uniform section means that section does not change along the length of bar. Parametric means that properties are parametrically defined one by one. for example if we have a circular section, with Iy = Iz = J/2 = 1e-6 m^4, A = 2e-6 m^4 then:

var section = new UniformParametric1DSection();
section.A = 1e-4;
section.Iy = section.Iz = 1e-6;
section.J = 2e-6;

var bar = new BarElement();
bar.CrossSection = section;

Hint

Note that two properties Ay and Az of UniformParametric1DSection, are about shear areas of section and their value will not be used unless BarElement have one of `TimoshenkoBeam` behaviours.

UniformGeometric1DSection

Inherited from Base1DSection, defines a uniform section for the BarElement. Uniform section means that section does not change along the length of bar. Geometrix means that section properties are defined as polygon.

Important Note: In UniformGeometric1DSection it is only possible to define one polygon. if polygon contains nested holes etc., then it should convert to one polygon. See Sections for BarElement

Important Note: The way that geoemtric properties are calculated for section is defined here: (https://en.wikipedia.org/wiki/Second_moment_of_area#Any_polygon). Maybe this method be not applicable to thin walled section.

Important Note: there is no analystical solution for findind torsional constant J for noncircular sections, in those cases user must set UniformGeometric1DSection.JOverrided property to correct value, otherwise polar area moment will be used (https://github.com/BriefFiniteElementNet/BriefFiniteElement.Net/issues/38)

Important Note: The geometric section is defined in Y-Z plane of local coordination system of element. the X axis in local coordination system is the beam length direction.