Dynamics of inverted flags: Experiments and comparison with theory

The study of the dynamics cantilevered thin flexible plates in reverse axial flow – also known as inverted flags has become significant interest, partly due to their energy harvesting potential. This paper presents fresh experimental results, aiming enhance our understanding flags, particularly concerning stability and global sensitivity various system parameters, such aspect ratio (i.e. height-to-length ratio) flag material. is achieved through testing dimensions, made from different materials. presented form bifurcation diagrams which tip angle shown a function dimensionless velocity. frequency content oscillatory motions spectrograms. Also, time-histories, phase-plane portraits, well power spectral density probability plots are for regimes. Interesting dynamical features, small- large-amplitude flapping, static divergence, buckling, chaotic motions, have been observed experimentally, some first time. It that very low undeflected equilibrium stable prior subcritical pitchfork bifurcation. For large ratio, on other hand, becomes unstable via supercritical leading divergence (buckling) at sufficiently high velocity; higher velocities, past bifurcation, Hopf materializes flapping motion around deflected equilibrium; even symmetric equilibrium. Interestingly, it found heavy may exhibit right after initial equilibrium, provided they subjected disturbance. In addition experiments, nonlinear analytical models two asymptotic cases zero infinite ratios outlined, results used comparison with results. Theory experiments be reasonably good agreement.