Jamming (physics)

Jamming is the physical process by which some materials, such as glasses, foams, collections of grains, and other complex fluids, become rigid with increasing density. The jamming transition has been proposed as a new type of phase transition, with similarities to a glass transition but very different from the formation of
crystalline solids.cite journal
last=Biroli
first=Giulio
date=April 2007
title=Jamming: A new kind of phase transition?
journal=Nature Physics
volume=3
pages=222–223
doi=10.1038/nphys580
url=http://www.nature.com/nphys/journal/v3/n4/full/nphys580.html
accessdate=2008-03-28] While a glass transition occurs when the liquid state is cooled, the jamming transition happens when density is increased. This crowding of theconstituent particles prevents them from exploring phase space, making the aggregate material behave as a solid. The system may be able to unjamif the temperature is increased, or external stressed are applied.

The jamming phase diagram relates the jamming transition to inverse density, stressand temperature.cite journal
last=Trappe
first=V.
coauthors=et al.
date=14 June 2001
title=Jamming phase diagram for attractive particles
journal=Nature
volume=411
pages=772–775
doi=10.1038/35081021
url=http://www.nature.com/nature/journal/v411/n6839/full/411772a0.html
accessdate=2008-03-28] The density at which systems jam is determined by many factors, including the shape of their components, the deformability of the particles, frictional interparticle forces, and the degree of dispersity of the system. The overall shape of the jamming manifold may depend on the particular system. For example, a particularly interesting feature of the jamming transition is the difference between attractive and repulsive systems. Whether the jamming surface diverges for high enough densities or low temperatures is uncertain.

Simulations of jammed systems study particle configurations leading to jamming in both static systems and systems under shear. Under shear stress, average cluster size may diverge after a finite amount of strain, leading to a jammed state. A particle configuration may exist in a jammed state with a stress required to “break” the force chains causing the jam.

References

External links

*cite journal
last=Cates
first=M.E.
coauthors=et al.
date=August 1998
title=Jamming, Force Chains, and Fragile Matter
journal=Physical Review Letters
volume=81
pages=1841–1844
doi=10.1103/PhysRevLett.81.1841
url=http://link.aps.org/abstract/PRL/v81/p1841
accessdate=2008-03-28
*cite journal
last=Lu
first=Kevin
coauthors=et al.
date=April 2008
title=A thermodynamic unification of jamming
journal=Nature Physics
volume=4
pages=404–407
doi=10.1038/nphys934|ISSN 1745-2473
url=http://www.nature.com/nphys/journal/v4/n5/full/nphys934.html
accessdate=2008-03-28
*cite journal
last=To
first=Kiwing
coauthors=Pikyin Lai, H.K. Pak
date=January 2001
title=Jamming of Granular Flow in a Two-Dimensional Hopper
journal=Physical Review Letters
volume=86
pages=71–74
doi=10.1103/PhysRevLett.86.71
url=http://link.aps.org/abstract/PRL/v86/p71
accessdate=2008-03-28
*cite journal
last=Liu
first=Andrea J.
coauthors=Nagel Sidney R.
date=November 1998
title=Jamming is not just cool any more
journal=Nature
volume=396
pages=21-22
doi=10.1038/23819
url=http://www.nature.com/doifinder/10.1038/23819
accessdate=2008-08-25