PULL-DOWN INSTABILITY OF THE QUADRATIC NONLINEAR OSCILLATORS

A nonlinear vibration system, over a span of convincing periodic motion, might break out abruptly catastrophic instability, but the lack theoretical tool has obscured prediction outbreak. This paper deploys amplitude-frequency formulation for oscillators to reveal critically important mechanism pseudo-periodic and finds quadratic force contributes pull-down phenomenon in each cycle when reaches threshold value, instability occurs. criterion is proposed verified numerically.