Bubble rafts

Bubble rafts

A material's observable and measurable mechanical properties strongly depend on its atomic and microstructural configuration and characteristics. This fact is intentionally ignored in Continuum Mechanics, which assumes a material to have no underlying microstructure and be uniform and semi-infinite throughout.

Bubble Rafts take on the issue of microstructural and atomic length-scale behavior by modeling the {111} plane of a close-packed crystal. They accomplish this feat by assembling bubbles on a water surface, often with the help of amphiphilic soaps. These assembled bubbles act like atoms, diffusing, slipping, ripening, straining, and otherwise deforming in a way that models the behavior of the {111} plane of a close-packed crystal. The ideal (lowest energy) state of the assembly would undoubtedly be a perfectly regular single crystal, but just as in metals, the bubbles often form defects, grain boundaries, and multiple crystals.

History of Bubble Rafts

The concept of Bubble Raft modelling was first presented in 1947 by Nobel Laureate Sir William Lawrence Bragg and J.F. Nye of Cambridge University's Cavendish Laboratory in the Proceedings of the Royal Society A [1] . Legend claims that Bragg conceived of bubble raft models while pouring oil into his lawn mower. He noticed that bubbles on the surface of the oil assembled into rafts resembling the {111} plane of close-packed crystals [2] . Nye and Bragg later presented a method of generating and controlling bubbles on the surface of a glycerine-water-oleic acid-triethanolamine solution, in assemblies of 100,000 or more sub-millimeter sized bubbles. In their paper [1] , they go on at length about the microstructural phenomena observed in bubble rafts and hypothesized in metals.

Relation to Crystal Lattices

In deforming a crystal lattice, one changes the energy and the interatomic potential felt by the atoms of the lattice. This interatomic potential is popularly (and mostly qualitatively) modeled using the Lennard-Jones potential, which consists of a balance between attractive and repulsive forces between atoms.

The "atoms" in Bubble Rafts also exhibit such attractive and repulsive forces:

U ( ho ) = - pi R^4 ho_{solution} g left ( frac{Beta}{alpha} ight )^2 mathit{A} K_0 (alpha ho) +

egin{cases} 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ho ge 2 \ pi R^4 ho_{solution} g left ( frac{(2- ho)^2}{alpha^2} ight ) ~~~ ho le 2 end{cases}


The portion of the equation to the left of the plus sign is the attractive force, and the portion to the right represents the repulsive force.

U ( ho ) is the interbubble potential

R is the average bubble radius

ho_{solution} is the density of the solution from which the bubbles are formed

g is the gravitational constant

ho is the ratio of the distance between bubbles to the bubble radius

Beta is the radius of ring contact

alpha is the ratio R/a of the bubble radius to the Laplace constant a, where

a^2 = frac {T}{ ho_{solution} g}

T is the surface tension

A is a constant dependent upon the boundary conditions of the calculation

K_0 is a zeroth order modified Bessel function of the second kind [2]


[1] Bragg, L. & Nye, J.F., A Dynamical Model of a Crystal Structure, Proc. R. Soc. Lond. A, 190 (1023), 474-481 [http://www.jstor.org/journals/00804630.html]

[2] Laboratory Handout in MIT's 3.032: Mechanical Properties of Materials. [http://stellar.mit.edu/S/course/3/fa06/3.032/index.html]

Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • Dislocation — For the syntactic operation, see Dislocation (syntax). For the medical term, see Joint dislocation. In materials science, a dislocation is a crystallographic defect, or irregularity, within a crystal structure. The presence of dislocations… …   Wikipedia

  • Abiogenesis — Primordial soup redirects here. For the board game, see Primordial Soup (board game). Origin of life redirects here. For views on the origins of life outside the natural sciences, see Creation myth. Pre Cambrian stromatolites in the Siyeh… …   Wikipedia

  • Earth Sciences — ▪ 2009 Introduction Geology and Geochemistry       The theme of the 33rd International Geological Congress, which was held in Norway in August 2008, was “Earth System Science: Foundation for Sustainable Development.” It was attended by nearly… …   Universalium

  • Wham-O — Infobox Company name = Wham O Toys Inc. type = Private genre = foundation = 1948 founder = Richard Knerr and Arthur Spud Melin location = Emeryville, California, USA locations = origins = key people = area served = industry = Toys products =… …   Wikipedia

  • United States — a republic in the N Western Hemisphere comprising 48 conterminous states, the District of Columbia, and Alaska in North America, and Hawaii in the N Pacific. 267,954,767; conterminous United States, 3,022,387 sq. mi. (7,827,982 sq. km); with… …   Universalium

  • Pelagic fish — A school of large pelagic predator fish (giant trevally) sizing up a school of small pelagic prey fish (anchovies) Pelagic fish live near the surface or in the water column of coastal, ocean and lake waters, but not on the bottom of the sea or… …   Wikipedia

  • Fasouri Watermania — is Cyprus biggest waterpark, both in size and in number of attractions and facilities. It has the biggest wave pool in Europe, and the longest Lazy River in Cyprus. It has been nominated within the top three of Europe s Leading Waterpark… …   Wikipedia

  • Pumice — is a textural term for a volcanic rock that is a solidified frothy lava composed of highly microvesicular glass pyroclastic with very thin, translucent bubble walls of extrusive igneous rock. It is commonly, but not exclusively of silicic or… …   Wikipedia

  • Economic history of Canada — Canadian historians until the 1960s tended to focus on economic history, including labour history. In part this is because Canada has had far fewer political upheavals or military conflicts than other societies. This was especially true in the… …   Wikipedia

  • Disney in the Stars — Hong Kong Disneyland Attraction type Firework Spectacular Opening date September 12, 2005 …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”