2021/04/19 by Aile Sun, Sun, Aile, Yinqiao Wang +13
Engineering · Materials Science · #FOS: Physical sciences #Granular flow and fluidized beds #Material Dynamics and Properties #Soft Condensed Matter (cond-mat.soft) #Sports Dynamics and Biomechanics
paper · pdf · doi:10.48550/arxiv.2104.09049
openalex publication_date 2021/04/19 · openalex created_date 2021/04/26 · openalex updated_date 2026/07/28
In stark contrast to the jamming of frictionless hard-sphere (hard-disk if in two dimensions) packings, the critical jamming of frictional packings is much more elusive and still under intense debate. Here we show that frictional hard-disk packings self-organize near a critical jamming state when subjected to quasi-static steady-state cyclic shear, displaying scale-free fluctuations in particle velocity fields as characterized by the power spectra E(k)∝ k-α for both longitudinal and transverse modes in wavevector space, with α≈2.0±0.15, and the nearly flat spectra E(ω)∝ const. in angular frequency domain. Our findings agree quantitatively with the predictions of the Langevin-type effective medium theory of S. Henkes and coworkers with two diverging length scales associated respectively with the longitudinal and transverse modes, showing a hallmark of critical behaviors of jamming. Moreover, our findings are consistent with the conceptual framework of general isostaticity but with a key difference that the system self-organizes to a critical jamming state through a strong coupling of mechanical structure and dynamics. Our findings are important in providing microscopic mechanism in understanding the nonlocal rheologies and guide principles in developing constitutive relations of real granular materials.