Vibration-induced "thermally activated" jamming transition in granular media

Abstract

The quasi-static frequency response of a granular medium is measured by a forced torsion oscillator method, with forcing frequency $f_p$ in the range $10^{-4}$ Hz to 5 Hz, while weak vibrations at high-frequency $f_s$, in the range 50 Hz to 200 Hz, are generated by an external shaker. The intensity of vibration, $\Gamma$, is below the fluidization limit. A loss factor peak is observed in the oscillator response as a function of $\Gamma$ or $f_p$. In a plot of $\ln f_p$ against $1/\Gamma$, the position of the peak follows an Arrhenius-like behaviour over four orders of magnitude in $f_p$. The data can be described as a stochastic hopping process involving a probability factor $\exp (-{\Gamma }_j/\Gamma )$ with ${\Gamma }_j$ a $f_s$-dependent characteristic vibration intensity. A $f_s$-independent description is given by $\exp (-{\tau }_j/\tau )$, with ${\tau }_j$ an intrinsic characteristic time, and $\tau ={\Gamma }^n/2\pi f_s$, n=0.5-0.6, an empirical control parameter with unit of time. $\tau$ is seen as the effective average time during which the perturbed grains can undergo structural rearrangement. The loss factor peak appears as a crossover in the dynamic behaviour of the vibrated granular system, which, at the time-scale $1/f_p$, is solid-like at low $\Gamma$, and the oscillator is jammed into the granular material, and is fluid-like at high $\Gamma$, where the oscillator can slide viscously.

Final version to appear in PRE

References in corpus (5)

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Cited by in corpus (3)

• Wet Granular Materials
• Flux through a hole from a shaken granular medium
• Extreme events driven glassy behaviour in granular media