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Mechanics of Materials Across Nano to Geological Time and Length Scales

09-29-16

A symposium was organized at Brown University on September 16-17, 2016 to celebrate the technical contributions of Professor Ares Rosakis on the occasion of his 60th birthday. The symposium was chaired by Professors Pradeep Guduru, Huajian Gao, and G. Ravichandran. It brought together distinguished engineers and scientists from multiple disciplines to discussion research frontiers relating to the mechanics of materials across nano to geological time and length scales. [Symposium program] [Photos]

Tags: research highlights Guruswami Ravichandran Ares Rosakis Pradeep Guduru Huajian Gao

Modular Space Telescope Could Be Assembled By Robot

09-28-16

Professor Sergio Pellegrino and colleagues including Professor Joel Burdick, are proposing a space observatory with a 100 meters diameter primary mirror. Their design calls for the use of more than 300 deployable truss modules that could be unfolded to form a scaffolding upon which a commensurate number of small mirror plates could be placed to create a large segmented mirror. In this concept, a spider-like, six-armed "hexbot" would assemble the trusswork and then crawl across the structure to build the mirror atop it. [Caltech story]

Tags: research highlights GALCIT MCE Sergio Pellegrino Joel Burdick

Counting on Grains of Sand

08-24-16

José E. Andrade, Professor of Civil and Mechanical Engineering; Executive Officer for Mechanical and Civil Engineering, and colleagues have developed a new method that measures the way forces move through granular materials—one that could improve our understanding of everything from how soils bear the weight of buildings to what stresses are at work deep below the surface of the earth. [Caltech story]

Tags: research highlights MCE Jose Andrade

The Utility of Instability

08-08-16

Professors Dennis M. Kochmann and Chiara Daraio along with colleagues from Harvard have designed and created mechanical chains made of soft matter that can transmit signals across long distances. Because they are flexible, the circuits could be used in machines such as soft robots or lightweight aircraft constructed from pliable, nonmetallic materials. "Engineers tend to shy away from instability. "Though there are many applications, the fundamental principles that we explore are most exciting to me," Kochmann says. "These nonlinear systems show very similar behavior to materials at the atomic scale but these are difficult to access experimentally or computationally. Now we have built a simple macroscale analogue that mimics how they behave." [Caltech story]

Tags: research highlights Chiara Daraio GALCIT MCE Dennis Kochmann

Community Seismic Network Detected Air Pulse From Refinery Explosion

06-30-16

The Community Seismic Network’s (CSN) tight network of low-cost detectors are improving the resolution of seismic data gathering and could offer city inspectors crucial information on building damage after a quake. On February 18, 2015, an explosion rattled the ExxonMobil refinery in Torrance, causing ground shaking equivalent to that of a magnitude-2.0 earthquake and blasting out an air pressure wave similar to a sonic boom. Traveling at 343 meters per second the air pressure wave reached a 52-story high-rise in downtown Los Angeles 66 seconds after the blast. The building's seismometers, which are part of the CSN, noted and recorded the motion of each individual floor. "We want first responders, structural engineers, and facilities engineers to be able to make decisions based on what the data say," explained Monica Kohler, Research Assistant Professor of Mechanical and Civil Engineering, and the lead author of a paper detailing the high-rise's response that recently appeared in the journal Earthquake Spectra. [Caltech story]

Tags: research highlights MCE Monica Kohler

Microseismicity and Large Earthquakes

06-10-16

Nadia Lapusta, Professor of Mechanical Engineering and Geophysics, and Caltech alumnus Dr. Junle Jiang, have linked the patterns of microseismicity to the depth extension of large earthquakes, both through modeling and observationally. They argue that fault segments which do not have concentrated microseismicity at the bottom of the seismogenic zone must have had deeper, larger earthquakes than currently believed. A number of segments on the San Andreas fault appear to fall into that category. The potential for such deeper earthquakes in the future would imply higher seismic hazard. [Science article] [KPCC coverage] [New Yorker Article]

Tags: research highlights MCE Nadia Lapusta alumni Junle Jiang

Tiny Diatoms Boast Enormous Strength

02-08-16

Researchers in the lab of Julia R. Greer, Professor of Materials Science and Mechanics, have recently found that diatom shells have the highest specific strength—the strength at which a structure breaks with respect to its density—of any known biological material, including bone, antlers, and teeth. [Caltech story]

Tags: APhMS research highlights MedE MCE Julia Greer

Extending a Battery's Lifetime with Heat

10-03-15

The research of alumnus Asghar Aryanfar (’15 PhD, ME) along with Professors Goddard and Hoffmann has shown that heat can break down the damaging branch-like structures that grow inside batteries, which may possibly be used to extend battery lifetimes. [Learn more] [Read the paper]

Tags: research highlights MCE ESE William Goddard alumni Michael Hoffmann Asghar Aryanfar

Atomic Fractals in Metallic Glasses

09-18-15

Julia R. Greer, Professor of Materials Science and Mechanics, and colleagues including graduate student David Chen have shown that metallic glasses has an atomic-level structure although it differs from the periodic lattices that characterize crystalline metals. "Our group has solved this paradox by showing that atoms are only arranged fractally up to a certain scale," Greer says. "Larger than that scale, clusters of atoms are packed randomly and tightly, making a fully dense material, just like a regular metal. So we can have something that is both fractal and fully dense." [Caltech story]

Tags: APhMS research highlights MedE MCE Julia Greer David Chen