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]
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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]
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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]
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MCE
Nadia Lapusta
alumni
Junle Jiang
Moriah Bischann Wins SURF Speaking Competition
02-04-16
Material science undergraduate student Moriah Bischann, mentored by aerospace postdoctoral scholar, Dr. Owen Kingstedt, is the winner of the Doris S. Perpall Summer Undergraduate Research Fellowships (SURF) Speaking Competition. She was recognized as the best speakers-out of the 200 students who presented their SURF research. Her summer research focused on exploring the next generation of structural materials. During her ten week SURF project she studied the effects of alloying and processing on the dynamic behavior of magnesium (Mg). This work was done to address the larger question of whether Mg is a useful material for the automotive, aerospace, energy, and defense industries where a material is needed that has low density, but also the strength to withstand high impact forces.
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GALCIT
Moriah Bischann
Owen Kingstedt
Cancer Treatment in a Painless Patch
11-05-15
Mechanical engineering undergraduate student, Teo Wilkening, spent this past summer working with Professor Morteza Gharib to test the preliminary design for an alternative—and possibly much less painful—method of chemotherapy drug delivery through a patch. To avoid the pain caused by the large needle traditionally used for such an intravenous injection, the team envisioned a patch containing hundreds of micrometer-scale needles, too small in diameter to be sensed by the nerves in the skin. [Caltech story]
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GALCIT
MedE
MCE
Morteza Gharib
Teo Wilkening
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]
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MedE
MCE
Julia Greer
David Chen
