Correlated motion in the bulk of dense granular flows
Lydie Staron
Numerical simulations of two-dimensional stationary dense granular flows are performed. We check that the system obeys the h phenomenology. Focusing on the spatial correlations of the instantaneous velocity fluctuations of the grains, we give evidence of the existence of correlated motion over sever ... [Phys. Rev. E 77, 051304 (2008)] published Thu May 15, 2008.
Bifurcations to Diversify Geometrical Patterns of Shear Bands on Granular Material
Kiyohiro Ikeda, Yuki Yamakawa, Jacques Desrues, and Kazuo Murota
The mechanism to diversify geometrical patterns on granular material was elucidated using a group-theoretic image analysis of patterned shear bands, with associated numerical bifurcation analysis. Pattern formation of granular materials took the course of the evolution of a diamondlike diffuse bifur ... [Phys. Rev. Lett. 100, 198001 (2008)] published Wed May 14, 2008.
Rheological complexity in simple chain models
Taylor C. Dotson, Julieanne V. Heffernan, Joanne Budzien, Keenan T. Dotson, Francisco Avila et al.
Dynamical properties of short freely jointed and freely rotating chains are studied using molecular dynamics simulations. These results are combined with those of previous studies, and the degree of rheological complexity of the two models is assessed. New results are based on an improved analysis p ... [J. Chem. Phys. 128, 184905 (2008)] published Tue May 13, 2008.
Experimental Investigation of the Painlev[e-acute] Paradox in a Robotic System
Zhen Zhao, Caishan Liu, Wei Ma, and Bin Chen
This paper aims at experimentally investigating the dynamical behaviors when a system of rigid bodies undergoes so-called paradoxical situations. An experimental setup corresponding to the analytical model presented in our prior work Liu et al. [2007, The Bouncing Motion Appearing in a Robotic Syste ... [J. Appl. Mech. 75, 041006 (2008)] published Tue May 13, 2008.
The motion of a freely falling chain tip: Force measurements
Jean-Christophe Geminard and Loic Vanel
A chain is firmly attached at one end while the other falls freely in the gravitational field. We report careful time-resolved measurements of the horizontal and vertical components of the force applied by the chain on the mount. Our results complement previous laboratory measurements and simulation ... [Am. J. Phys. 76, 541 (2008)] published Mon May 12, 2008.
Isochronous oscillations: Potentials derived from a parabola by shearing
C. Anton and J. L. Brun
Any curve derived from a parabola by shearing is a potential in which the anharmonic vibrations are isochronous, with a period independent of the energy. ... [Am. J. Phys. 76, 537 (2008)] published Mon May 12, 2008.
Fragmentation processes in impact of spheres
H. A. Carmona, F. K. Wittel, F. Kun, and H. J. Herrmann
We study the brittle fragmentation of spheres by using a three-dimensional discrete element model. Large scale computer simulations are performed with a model that consists of agglomerates of many particles, interconnected by beam-truss elements. We focus on the detailed development of the fragmenta ... [Phys. Rev. E 77, 051302 (2008)] published Fri May 9, 2008.
Frequency-dependent fluctuation-dissipation relations in granular gases
Guy Bunin, Yair Shokef, and Dov Levine
The Green-Kubo relation for two models of granular gases is discussed. In the Maxwell model in any dimension, the effective temperature obtained from the Green-Kubo relation is shown to be frequency independent and equal to the average kinetic energy, known as the granular temperature. In the second ... [Phys. Rev. E 77, 051301 (2008)] published Fri May 9, 2008.