| dc.description.abstract | Why do sound experts always fill the loudspeaker stands with steel beads or quartz sand to improve the sound quality of the loudspeaker? The mechanism of this interesting physical phenomenon has not yet been thoroughly studied and clarified. In this study, two-way Couple DEM-FEM Approach was employed to model the dynamic response of commercially available loudspeaker stands equipped with damping particles, and the corresponding physical experiments were performed to validate the proposed numerical model. The effect of particle properties, such as the inter-particle friction coefficient, the particle-wall friction coefficient, the inter-particle restitution coefficient, and the Young′s modulus of particles, on the dynamic response of the loudspeaker stands was further explored, and the outcome can guide the audio industry to select the appropriate particles. This study used damping factors, friction energy dissipation efficiency, collision energy dissipation efficiency and total energy dissipation efficiency to quantify the system′s vibration reduction effect, and innovatively introduced particle transport properties (including local average velocity, fluctuation velocity distribution and granular temperature) to explore the performance of vibration reduction effect. The main findings are highlighted below: (1) As the external force amplitude increases, the dominant energy dissipation mechanism transforms from the damping dissipation mechanism to the friction dissipation mechanism; (2) The particle properties affect the damping effect. Among them, the Young′s modulus of the particles exhibits the most significant effect. In a certain range of Young’s modulus, a tuned mass damper occurs inside the granular solid, leading to the best damping effect; (3) The condition with smaller friction coefficients and larger Young’s modulus and restitution coefficients provides higher friction energy dissipation efficiency. As the external force amplitude increases, the friction dissipation efficiency increases while the collision dissipation efficiency decreases. The resultant effect from both mechanisms causes the total energy dissipation efficiency to decrease. (4) Both simulations and experiments confirmed that filling particles into the loudspeaker stands can attenuate vibrations for the frequencies studied here, especially at frequencies above 1kHz, and change the frequency response of the sound above 1kHz. (5) Filling particles with a larger Young′s modulus can increase the damping effect at frequencies above 1kHz, but decrease the damping effect at frequencies below 1kHz. (6) The damping effect has a significant correlation with the local average vertical velocity, fluctuation velocity distribution and granular temperature of particles. | en_US |