Event Calendar

Oct
17
Thu
Mechanical Engineering Fall Seminar Series: Class 530.803 @ Krieger 205
Oct 17 @ 3:00 pm – 4:00 pm

“Avian Inspired Design”

Presented by Professor David Lentink
Department of Mechanical Engineering, Stanford University

My lab focusses on understanding every aspect of bird flight to improve flying robots—because birds fly further, longer, and more reliable in complex visual and wind environments. I use this multidisciplinary lens that integrates biomechanics, aerodynamics, and robotics to advance our understanding of the evolution of flight. The experimental approaches range from making robotic models to training birds to fly in custom-designed flight arenas to make novel direct aerodynamic force measurements in flight as well as studying their flight control strategies. I will show how these and other ongoing studies in my lab have inspired new biohybrid soft morphing aerial robots.

Professor Lentink’s multidisciplinary lab studies how birds fly to develop better flying robots—integrating biomechanics, fluid mechanics, and robot design. http://lentinklab.stanford.edu. He has a BS and MS in Aerospace Engineering (Aerodynamics, Delft University of Technology) and a PhD in Experimental Zoology cum laude (Wageningen University). During his PhD he visited the California institute of Technology for 9 months to study insect flight. His postdoctoral training at Harvard was focused on studying bird flight. Publications range from technical journals to cover publications in Nature and Science. He is an alumnus of the Young Academy of the Royal Netherlands Academy of Arts and Sciences, recipient of the Dutch Academic Year Prize, the NSF CAREER award, he has been recognized in 2013 as one of 40 scientists under 40 by the World Economic Forum, and he is the inaugural winner of the Steven Vogel Young Investigator Award.

Oct
31
Thu
James F. Bell Memorial Lecture in Continuum Mechanics @ Levering Hall, Glass Pavilion
Oct 31 @ 3:00 pm – 4:00 pm

“At the Crossroads of Additive Manufacturing, Analytics and Advanced Materials”

Presented by Professor Tresa M. Pollock
Materials Department, University of California Santa Barbara

Additive manufacturing promises new pathways for integration of advanced alloys with complex structural component design.  Achieving desired properties mandates control of structure and an improved understanding of the processes that occur at the individual melt pool scale and their superposition as melting occurs on a layer- by-layer basis.  A new technique developed at UCSB, TriBeam tomography, has been employed to acquire chemical, structural and misorientation information on structural alloys printed by electron beam and laser powder based processes.  The data challenges with additive manufacturing and the corresponding 3D quantification of structure will be addressed.  In large 3D datasets, the persistence of grains layer to layer due to remelting / nucleation has been studied as a function of scan strategy.   The benefits of multimodal data for characterization of submicron features will be discussed.   Finally, 3D EBSD data indicates that the accumulation of large crystallographic misorientations during printing is directly related to the alloy solidification path.  Implications for alloy design and new alloys for printed structures are discussed.

Professor Tresa Pollock is the Alcoa Distinguished Professor of Materials at the University of California, Santa Barbara.  Pollock’s research focuses on the mechanical and environmental performance of materials in extreme environments, unique high temperature materials processing paths, ultrafast laser-material interactions, alloy design and 3-D materials characterization.  Pollock graduated with a B.S. from Purdue University in 1984, and a Ph.D. from MIT in 1989.  She was employed at General Electric Aircraft Engines from 1989 to 1991, where she conducted research and development on high temperature alloys for aircraft turbine engines and co-developed the single crystal alloy René N6 (now in service).  Pollock was a professor in the Department of Materials Science and Engineering at Carnegie Mellon University from 1991 to 1999 and the University of Michigan from 2000 – 2010.   Her recent research has focused on development of new femtosecond laser-aided    3-D tomography techniques, additive manufacturing, damage detection and modeling by resonant ultrasound spectroscopy, thermal barrier coatings systems, new intermetallic-containing cobalt-base materials, nickel base alloys for turbine engines, titanium alloys, lightweight magnesium alloys, Heusler-based thermoelectrics and bulk nanolaminates.  Professor Pollock was elected to the U.S. National Academy of Engineering in 2005, the German Academy of Sciences Leopoldina in 2015, and is a Department of Defense Vannevar Bush Fellow and Fellow of TMS and ASM International.  She serves as Editor in Chief of the Metallurgical and Materials Transactions family of journals and was the 2005-2006 President of The Minerals, Metals and Materials Society.

Nov
14
Thu
Mechanical Engineering Fall Seminar Series: Class 530.803 @ 205 Krieger Hall
Nov 14 @ 3:00 pm – 4:00 pm

“Order-Disorder-Property Relationships in Structural Materials: Guided by Randomness”

Presented by Professor Daniel S. Gianola
Materials Department, University of California Santa Barbara

Emerging classes of structural materials that have been developed to meet the demands of aggressive applications requiring structural integrity in extreme environments, such as those encountered in the aerospace and power generation sectors, all share a common theme: complexity across a large range of length scales. A common denominator is the intentional design of randomness – or disorder – in these new materials.  In load-bearing materials, this disorder can manifest as topological disorder (uncertainty in atomic positions) as found in interface-dominated or glassy materials, or chemical disorder (uncertainty in elemental occupancy) as found in compositionally-concentrated alloys. This begs a question that underpins new materials-by-design strategies: should the conventional wisdom of searching for structure-property relationships give way to those that focus on disorder-property ones?  This talk will show two examples that lend credence to the notion of embracing the role of disorder in materials.

The first will highlight the novel materials design paradigm of multi-principal element (MPE) alloying that has shown great success, yet opportunities to advance refractory-based high temperature body centered cubic (BCC) alloys for high temperature structural applications must confront fundamentally different avenues for the accommodation of plastic deformation. We show a unique combination of homogeneous plastic deformability and strength at low temperature in the BCC MPE alloy MoNbTi, enabled by the rugged atomic environment through which dislocations must navigate. In situ observations of dislocation motion and atomistic calculations unveil the unexpected dominance of non-screw character dislocations and numerous equiprobable slip planes for dislocation glide. This remarkable behavior reconciles theories explaining the exceptional high temperature strength of similar alloys.  Our results, when paired with a material density lower than that of state-of-the-art superalloys, provide sharp focus to alloy design strategies for materials capable of performance across the temperature spectrum.

The second example will demonstrate novel synthesis and processing routes for controlling disorder in nanocrystalline materials – and as a consequence, the mechanical properties.  We study relaxation processes at grain boundaries in nanocrystalline materials that facilitate atomic reconfigurations toward a lower energy state such as low temperature annealing, which enhance mechanical strength while promoting shear localization. A particular focus in this talk will be on strategies for rejuvenation at grain boundaries with the goal of suppressing shear localization and endowing damage tolerance. Parallels between our results and rejuvenation processes in glasses, as well as the interplay between grain boundary structure and chemistry through segregation engineering, will be discussed in the context of controlling metastable structural configurations.

Daniel S. Gianola is a Professor of Materials at the University of California Santa Barbara and can be reached at: gianola@engr.ucsb.edu. He is currently the faculty director of the Microscopy and Microanalysis Facility at UCSB, which is a central shared facility with over 400 active users. Dr. Gianola joined the Materials Department at UCSB in early 2016 after holding the positions of Associate Professor and Skirkanich Assistant Professor, all in the Department of Materials Science and Engineering at the University of Pennsylvania. He received a BS degree from the University of Wisconsin-Madison and his PhD degree from Johns Hopkins University. Prior to joining the University of Pennsylvania, Gianola was an Alexander von Humboldt Postdoctoral Fellow at the Forschungszentrum Karlsruhe (now Karlsruhe Institute of Technology) in Germany.  Dr. Gianola is the recipient of the National Science Foundation CAREER, Department of Energy Early Career, and TMS Early Career Faculty Fellow awards. His research group at UCSB specializes in research dealing with deformation at the micro- and nanoscale, particularly using in situ nanomechanical testing techniques.

Nov
21
Thu
Department of Mechanical Engineering 2019 Fall Seminar Series: Class 530.803 @ Krieger 205
Nov 21 @ 3:00 pm – 4:00 pm

Feedbacks between mechanics, geometry and polarity sorting ensures rapid and precise mitotic spindle assembly

Presented by Professor Alex Mogilner
Courant Institute and Department of Biology, New York University

One of the most fundamental cell biological events is assembly of the mitotic spindle – molecular machine that segregates sister chromatids into two daughter cells in the process of cell division. Two existent models of the mitotic spindle assembly are 1) search-and-capture (SAC) and 2) acentrosomal microtubule assembly (AMA). SAC model is pleasingly simple: microtubules (MTs), organized into two asters focused at two centrosomes, undergo dynamic instability: they grow and shrink randomly, rapidly and repeatedly. As soon as a growing MT end bumps into a kinetochore (KT) – molecular complex in the middle of a sister chromatid – the connection between the spindle pole (centrosome) and this chromatid is established. This model predicts that KTs are captured at random times and that slow spindle assembly is plagued by errors. For decades, the SAC model seemed to work. Our data ruins the SAC model and suggests that a hybrid between SAC and AMA models could work. I will explain how we used 3D tracking of centrosomes and KTs in animal cells to develop a computational agent-based model, which explains the remarkable speed and precision of the almost deterministic process of the spindle assembly emerging from random and imprecise molecular events.

Prof. Alex Mogilner received M.Eng. degree in Engineering Physics in 1985 from the Ural Polytechnic Institute. He received PhD degree in Physics from the USSR Academy of Sciences in 1990. He did research in Mathematical Physics until 1992, when he started studying Mathematical Biology at the University of British Columbia. After receiving PhD degree (adviser Leah Edelstein-Keshet) in Applied Mathematics from UBC in 1995, Alex worked at UC Berkeley with George Oster as a postdoctoral researcher, and in 1996 he came to the Math Department at the University of California at Davis as an Assistant Professor. He became an Associate professor in 1999, and in 2002 he became a Professor at the Department of Mathematics and Department of Neurobiology, Physiology and Behavior at UC Davis. Since 2014, Dr. Mogilner is a Professor of Mathematics and Biology at Courant Institute and Department of Biology at the New York University. Alex’s areas of expertise include Mathematical Biology, Cell Biology and Biophysics; he does research on mathematical and computational modeling of cell motility, cell division and galvanotaxis. Alex published about 130 papers in high impact journals including Nature, Science, PNAS. He developed models of keratocyte motility, polymerization ratchet, and search-and-capture mechanism of spindle assembly. His research is/was supported by NIH and NSF grants, Army Office of Research and by United States-Israel Binational Science Foundation. Alex served on editorial boards of many journals including Cell, Biophysical Journal, Current Biology, Journal of Cell Biology, Bulletin of Mathematical Biology, Molecular Biology of the Cell. He gave plenary talks and organized many international conferences on mathematical biology and cell biophysics, and taught at many summer schools. Dr. Mogilner was a panel chair at NIH. Multiple news and views were published about his scientific discoveries.

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