This component is used to exert a line force between the origin of frame_a and the origin of frame_b by attaching components of the 1-dimensional translational mechanical library of Modelica (Modelica.Mechanics.Translational) between the two flange connectors flange_a and flange_b. Optionally, there is a point mass on the line connecting the origin of frame_a and the origin of frame_b. This point mass approximates the mass of the force element. The distance of the point mass from frame_a as a fraction of the distance between frame_a and frame_b is defined via parameter lengthFraction (default is 0.5, i.e., the point mass is in the middle of the line).
In the translational library there is the implicit assumption that forces of components that have only one flange connector act with opposite sign on the bearings of the component. This assumption is also used in the LineForceWithMass component: If a connection is present to only one of the flange connectors, then the force in this flange connector acts implicitly with opposite sign also in the other flange connector.