Belt Connection

Identifier: Mechanics.Mechanics2D.ConnectionRol
Version: 3.6


The Belt Connection transfers the strand angle (belt orientation) in the model plane and the uncoiled belt length between two Belt Connectors(see also figure 6 in chapter Pulleys and Drums). Furthermore it can transmit the computed mass from a free belt section to the connected pulleys or drums.

The Belt Connection has not internal computation and can be seen as a bi-directional signal transfer connection.
A Belt Connection can only connect two belt connectors, which means it cannot be branched. This is for the protection of connecting different belt elements to the same belt contact point of a pulley, and for the protection of modeling branched belts.

Usually a Belt Connection connects the belt connector of a pulley with a belt connector of belt element, as it is shown in the following figure 1:

Figure 1: Belt drive with drum and pulley connected by belt sections

  • Uncoiled belt length :
    The connection gets this value by the first pulley and writes this value to a second pulley and vice versa. From this the belt model computes the length depending belt stiffness and belt mass.
  • Strand angle (belt orientation) :
    The connection writes these angles to the pulleys. By this, the pulleys compute the position of the belt contact point (tangent). A graphical demonstration can be found in figure 6 in chapter Pulleys and Drums.
  • Belt section mass part :
    Belt section elements as i.e. Belt Spring writes (a part) of its mass to the connection. The pulleys take this mass and add it to the mass of the contacting belt section.


(for variables see Belt Connectors):

The index p1 is for the port 1 of the connection (= 1st connector). The index p2 is for the port 2 of the connection (= 2nd connector).

Propagation of Belt Properties:

Some of the belt properties have to be equal for all belt sections within the same belt drive (circuit). The reason is, you want to represent the same belt in a circuit, but this belt is modeled by several free belt section elements and several pulleys or drums with a contacting belt part.

Thus, the Belt Connection propagates belt properties from belt sections to pulleys, drums, and further belt elements. The big advantage is that the belt properties must only entered once to a free belt section element. SimulationX ensures, that all belt drive components work with the same parameter values.

Propagated belt properties (parameters) are:

  • linear density for the computation of mass - rhol
  • axial stiffness of the belt - EA
  • factor B for the belt damping estimation bi = B*sqrt(ki)
  • belt color and transparency - colorB, alphaB
  • kind of belt cross section geometry - kindBA
  • cross section geometry parameters - dB, h, w, delta, b0, h0, bw, en, h1, noV