From nanocrystals to the Earth's crust, solid materials share similar failure characteristics

Rick Kubetz, Engineering at Illinois
11/17/2015 12:00 AM

Professor of Physics Karin Dahmen
Professor of Physics Karin Dahmen
Apparently, size doesn’t always matter. An extensive study by an interdisciplinary research group suggests that the deformation properties of nanocrystals are not much different from those of the Earth’s crust.

“When solid materials such as nanocrystals, bulk metallic glasses, rocks, or granular materials are slowly deformed by compression or shear, they slip intermittently with slip-avalanches similar to earthquakes,” explained Karin Dahmen, a professor of physics at the University of Illinois at Urbana-Champaign. “Typically these systems are studied separately. But we found that the scaling behavior of their slip statistics agree across a surprisingly wide range of different length scales and material structures.”

“Identifying agreement in aspects of the slip statistics is important, because it enables us to transfer results from one scale to another, from one material to another, from one stress to another, or from one strain rate to another,” stated Shivesh Pathak, a physics undergraduate at Illinois, and a co-author of the paper, “Universal Quake Statistics: From Compressed Nanocrystals to Earthquakes,” appearing in Scientific Reports. “The study shows how to identify and explain commonalities in the deformation mechanisms of different materials on different scales.

“The results provide new tools and methods to use the slip statistics to predict future materials deformation,” added Michael LeBlanc, a physics graduate student and co-author of the paper. “They also clarify which system parameters significantly affect the deformation behavior on long length scales. We expect the results to be useful for applications in materials testing, failure prediction, and hazard prevention.”

Researchers representing a broad a range of disciplines—including physics, geosciences, mechanical engineering, chemical engineering, and materials science—from the United States, Germany, and the Netherlands contributed to the study, comparing five different experimental systems, on several different scales, with model predictions.

As a solid is sheared, each weak spot is stuck until the local shear stress exceeds a random failure threshold. It then slips by a random amount until it re-sticks. The released stress is redistributed to all other weak spots. Thus, a slipping weak spot can trigger other spots to fail in a slip avalanche.

Using tools from the theory of phase transitions, such as the renormalization group, one can show that the slip statistics of the model do not depend on the details of the system.

“Although these systems span 13 decades in length scale, they all show the same scaling behavior for their slip size distributions and other statistical properties,” stated Pathak. “Their size distributions follow the same simple (power law) function, multiplied with the same exponential cutoff.”

The cutoff, which is the largest slip or earthquake size, grows with applied force for materials spanning length scales from nanometers to kilometers. The dependence of the size of the largest slip or quake on stress reflects “tuned critical” behavior, rather than so-called self-organized criticality, which would imply stress-independence. 

“The agreement of the scaling properties of the slip statistics across scales does not imply the predictability of individual slips or earthquakes,” LeBlanc said. “Rather, it implies that we can predict the scaling behavior of average properties of the slip statistics and the probability of slips of a certain size, including their dependence on stress and strain-rate.”

Study co-authors include Jonathan Uhl, Xin Liu, Ryan Swindeman, Nir Friedman, University of Illinois at Urbana Champaign; Danijel Schorlemmer and Georg Dresen, German Research Centre for Geosciences; Danijel Schorlemmer and Thorsten Becker, University of Southern California; Robert Behringer, Duke University; Dmitry Denisov and Peter Schall, University of Amsterdam; Xiaojun Gu, Wendelin J. Wright, Xiaojun Gu and Wendelin J. Wright, Bucknell University; Todd Hufnagel, Johns Hopkins University; Andrew Jennings and Julia R. Greer, California Institute of Technology; and P.K. Liaw, The University of Tennessee; Georgios Tsekenis, Harvard, and Braden Brinkman, Seattle, were part of Dahmen's research group during the original study.

Recent News

  • Research

Developing a superconducting computer that would perform computations at high speed without heat dissipation has been the goal of several research and development initiatives since the 1950s. Such a computer would require a fraction of the energy current supercomputers consume, and would be many times faster and more powerful. Despite promising advances in this direction over the last 65 years, substantial obstacles remain, including in developing miniaturized low-dissipation memory.

Researchers at the University of Illinois at Urbana-Champaign have developed a new nanoscale memory cell that holds tremendous promise for successful integration with superconducting processors. The new technology, created by Professor of Physics Alexey Bezryadin and graduate student Andrew Murphy, in collaboration with Dmitri Averin, a professor of theoretical physics at State University of New York at Stony Brook, provides stable memory at a smaller size than other proposed memory devices.

  • In the Media

As NASA prepares for this evening’s launch of the NICER space astronomy mission, Emeritus Professor of Physics Fred Lamb of the University of Illinois at Urbana-Champaign, is at the Kennedy Space Center, as a member of three of the mission’s Science Working Groups. The launch from the world-famous Pad 39A is scheduled for 5:55 P.M. EST.

Lamb, who continues to hold a post-retirement research appointment at Physics Illinois, is a world-recognized expert on the U.S. ground-based missile defense system. He served as co-chair of the American Physical Society’s Study Group on Boost-Phase Intercept for National Missile Defense, which published its report in July 2003. He has been fielding questions from the media on Tuesday's successful interception of an interncontinental ballistic missile during the latest test of its ground-based intercept system, as reported by the U.S. Missile Defense Agency.

Tuesday's ground-based interceptor launched from Vandenberg Air Force Base in California just after 3:30 p.m. EST. A little more than one hour later, the Pentagon confirmed it had successfully collided with an ICBM-class target over the Pacific Ocean, which had been launched from the Ronald Reagan Ballistic Missile Defense Test Site on Kwajalein Atoll in the Marshall Islands, 4,200 miles away.

In this Q&A, Lamb briefly turns his attention away from the pending NICER launch to answer a few questions on the current status of the U.S. Ground-Based Missile Defense System.

  • Research
  • Particle Physics
  • High Energy Physics

What do you get when you revive a beautiful 20-year-old physics machine, carefully transport it 3,200 miles over land and sea to its new home, and then use it to probe strange happenings in a magnetic field? Hopefully you get new insights into the elementary particles that make up everything.

The Muon g-2 experiment, located at the U.S. Department of Energy’s (DOE) Fermi National Accelerator Laboratory, has begun its quest for those insights. This month, the 50-foot-wide superconducting electromagnet at the center of the experiment saw its first beam of muon particles from Fermilab’s accelerators, kicking off a three-year effort to measure just what happens to those particles when placed in a stunningly precise magnetic field. The answer could rewrite scientists’ picture of the universe and how it works.

  • Accolades
  • Alumni News

Congratulations to Physics Illinois alumnus M. George Craford on being presented today with the IEEE Edison Medal of the Institute of Electrical and Electronics Engineers. The medal is awarded annually in recognition of a career of meritorious achievement in electrical science, electrical engineering, or the electrical arts. The citation reads, “for a lifetime of pioneering contributions to the development and commercialization of visible LED materials and devices.”

 

Craford is best known for his invention of the first yellow light emitting diode (LED). During his career, he developed and commercialized the technologies yielding the highest-brightness yellow, amber, and red LEDs as well as world-class blue LEDs. He is a pioneer whose contributions to his field are lasting.