Nonlinear oscillations of a portal frame structure excited by a nonideal motor

A simple portal frame with two vertical columns and a horizontal pinned beam excited by a motor with limited power output is considered. Non-ideal excitations as these, coupling between the motion of the support structure and the motor output is observed. Some interesting phenomena occur. With slow increase of power levels we have possibility of occurrence of the Sommerfeld effect (getting stuck in resonance), that is, not enough power to reach higher speed regimes with low energy consumption. There is also possibility of occurrence of saturation of high frequency low amplitude mode and transference of energy to low frequency high amplitude mode. Irregular (chaotic) behavior may be observed, depending on the value of a control parameter of the motor