Linear damper acting as line force between frame_a and frame_b. A force f is exerted on the origin of frame_b and with opposite sign on the origin of frame_a along the line from the origin of frame_a to the origin of frame_b according to the equation:
f = d*der(s);
where "d" is a parameter, "s" is the distance between the origin of frame_a and the origin of frame_b and der(s) is the time derivative of "s".
In the following figure a typical animation is shown where a mass is hanging on a damper.