2024/04/13 by Filip Novkoski, Jules Fillette, Chi-Tuong Pham +2 · 1 voice
Engineering · #Vibration and Dynamic Analysis #Fluid Dynamics and Vibration Analysis #Dynamics and Control of Mechanical Systems
paper · pdf · doi:10.1016/j.physd.2024.134164
We show that the natural resonant frequency of a suspended flexible string is significantly modified (by one order of magnitude) by adding a freely pivoting attached mass at its lower end. This articulated system then exhibits complex nonlinear dynamics as bending oscillations, similar to those of a swing becoming slack, thereby strongly modifying the system resonance that is found to be controlled by the length of the pivoting mass. The dynamics is experimentally studied using a remote and noninvasive magnetic parametric forcing. To do so, a permanent magnet is suspended by a flexible string above a vertically oscillating conductive plate. Harmonic and period-doubling instabilities are experimentally reported and are modeled using the Hill equation, leading to analytical solutions that accurately describe the experimentally observed tonguelike instability curves.