An equivalent mechanical model with nonlinear damping for sloshing rectangular tank with porous media

Abstract

In this paper, the impulsive and harmonic experiments are carried out to investigate the sloshing frequencies and the linear and nonlinear damping of sloshing liquid in a rectangular tank occupied by porous media. As the oscillatory responses remain linear in the impulsive-excitation tests, the damping ratios are obtained by the free-vibration decay method. The analytical method, which is an equivalent mechanical model based on Darcy's law, is developed for comparison. As the dynamic responses become nonlinear in the harmonic excitations, the relationships between the sloshing force and the ground displacement are constructed and the damping ratio is determined by the resonance energy loss method. The relationships between the equivalent damping ratio, wave amplitude, and ground displacement amplitude for the large-excitation cases are established to justify the nonlinear damping effect. A modified mechanical model with a nonlinear damping mechanism is provided.