This information is part of the Modelica Standard Library maintained by the Modelica Association.

A flange is described by the connector class Interfaces.Flange_a or Interfaces.Flange_b. As already noted, the two connector classes are completely identical. There is only a difference in the icons, in order to easier identify a flange variable in a diagram. Both connector classes contain the following variables:

   Modelica.SIunits.Position   s "Absolute position of flange";
   flow Modelica.SIunits.Force f "Cut-force in the flange";

If needed, the velocity v and the acceleration a of a flange connector can be determined by differentiation of the flange position s:

     v = der(s);    a = der(v);