This information is part of the Modelica Standard Library maintained by the Modelica Association.
All massless line force elements should be based on this base model. This model defines frame_a and frame_b, computes the (guarded) relative distance s and provides the force and torque balance of the cut-forces and cut-torques at frame_a and frame_b, respectively. In sub-models, only the line force f, acting at frame_b on the line from frame_a to frame_b, as a function of the relative distance s and its derivative der(s) has to be defined. Example:
model Spring parameter Real c "spring constant", parameter Real s_unstretched "unstretched spring length"; extends Modelica.Mechanics.MultiBody.Interfaces.PartialLineForce; equation f = c*(s-s_unstretched); end Spring;
Type: Distance (m)
Description: Prevent zero-division if distance between frame_a and frame_b is zero
Description: =true, if rotation frame_a.R is fixed (to directly connect line forces)
Description: =true, if rotation frame_b.R is fixed (to directly connect line forces)