Vibro-impact damper dynamics depending on system parameters

Abstract

Abstract Purpose The considered vibro-impact damper corresponds to the scheme of single-sided vibro-impact nonlinear energy sink (SSVI NES). Although the vibration engineering has been studying the problem of mitigation the undesirable vibrations for many years, it remains relevant today. The dynamic behavior and efficiency of many different NES types are strongly dependent on system parameters and initial conditions. The present research aims to show the rich complex dynamics of vibro-impact damper with optimized parameters and its effectiveness when changing parameters both its own and periodic exciting force. Methods We assume that an impact has a finite duration and simulate it using nonlinear Hertz contact force. The direct numerical integration of stiff differential motion equations is carried out using the software Octave. The optimization of the damper parameters is performed by the Octave and MatLab solvers. We analyze the displacements and velocities time histories, the phase trajectories, the topological structure of numerical Poincaré maps, the contact forces graphs for the oscillatory regimes diagnostics. Results Two dampers versions with optimized parameters mitigate the primary structure vibrations; the absorber with a larger mass reduces them more strongly. The system motion with a lighter damper is almost periodic with rare bursts of irregular movement, but the system motion with a heavier damper is essentially irregular with complex dynamics. The vibrations mitigation occurs in a wide range of the exciting force amplitudes, but in the range of its frequencies only above the resonant one; the damper presence shifts the resonant peak. Conclusions The efficiency of SSVI NES with optimized parameters is demonstrated when changing the exciting force parameters. The parameters ranges where the vibrations mitigation occurs are shown. The results of damper parameters optimization may be ambiguous and should be checked and analyzed. They can determine such parameters values that provide good vibrations reduction, but create irregular motion regimes with complex dynamics; this should be taken into account when designing a SSVI NES.