Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The Shifty Nature of Grains

24.06.2005


Qualities of granular materials provide insight into both nature and industry



In separate papers appearing in this week’s Nature, researchers announce findings regarding the little-understood world of granular materials, systems of particles that can dictate the flow of avalanches, the quality of concrete and even the mixing of pharmaceuticals.

In both studies, the researchers developed new analytical tools that combine laboratory simulators with advanced computer simulations and mathematics, bringing additional quantitative methods to a field that relies mostly upon qualitative observations.


Duke University physics and engineering professor Robert Behringer and his graduate student, Trushant Majmudar, used a novel system that includes a bed of thousands of light-bending plastic cylinders to trace the flow of stress, particle by particle, in a 2-dimensional granular set up. The researchers found that stresses applied to one dimension across the bed transferred along jagged pathways from one particle to the next when the other dimension was free from strain. However, when the system was compressed equally on both sides, the pathways, or "force chains," were much shorter.

The findings could prove important for understanding natural hazards such as the recent slope failures at La Conchita and Laguna Beach in California. Strongly shear states with long force chains occur just before the granular material fails, similar to the collapsing sandy cliffs.

The second report comes from the Chicago Materials Research Center at the University of Chicago, one of nearly 30 NSF-supported Materials Research Science and Engineering Center. Physicists Heinrich Jaeger and Sidney Nagel worked with graduate student Eric Corwin to develop a different testing system, in this case comprised of a cylinder filled with up to 100,000 glass beads compressed over hour-long periods by a rotating piston. Their goal was to study shear forces in granular materials.

The Chicago researchers were able to quantify a characteristic change in the way stresses propagate through the materials when the grains shift from a jammed state to a flowing one. The researchers suspect the underlying mechanism, whereby grains acquire an "effective temperature" in their flowing state, has wide-reaching implications for better understanding materials that are jammed at the atomic level, such as glass.

Glass behaves like a solid but can flow like a liquid, particularly at higher temperatures. If the granular studies hold true, this project may have resolved decades-old questions regarding the transition of solids into the more fluid glass-like state.

Joshua Chamot | EurekAlert!
Further information:
http://www.nsf.gov
http://www.duke.edu

More articles from Physics and Astronomy:

nachricht Tracing aromatic molecules in the early universe
23.03.2017 | University of California - Riverside

nachricht New study maps space dust in 3-D
23.03.2017 | DOE/Lawrence Berkeley National Laboratory

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

Inactivate vaccines faster and more effectively using electron beams

23.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>