Recently it was shown that averaged characteristics of non-linear vibr
ations are potential functions of load parameters in the limit of smal
l dissipation. The question of the range of dissipation for which pote
ntiality takes place remained open. In this paper, we study this quest
ion for the case of non-linear vibrations of a cantilever beam excited
harmonically at the unclamped end. We develop a non-linear one-degree
-of-freedom beam model and show that the existence of a dynamical pote
ntial of beam vibrations can be guaranteed with acceptable accuracy ev
en for sufficiently large dissipation.