MEAM Seminar Series Spring 2018

For Fall 2017 Seminars, click here.

Seminars are held on Tuesday mornings beginning at 10:45 am in Wu and Chen Auditorium, in Levine Hall (unless otherwise noted).

To be added to the MEAM Events mailing list (which sends notifications regarding all departmental seminars and events) please email us at meam-events@lists.seas.upenn.edu.

January 16

Joel D. Boerckel, Assistant Professor of Orthopaedic Surgery and Bioengineering, University of Pennsylvania

“Reverse-Engineering Skeletal Development”

Abstract:

Reverse engineering is the practice of disassembling a product to understand how it was made and how it works, to enable replication and manufacture of a similar object. My laboratory is interested in understanding the molecular mechanisms by which mechanical stimuli influence morphogenesis and growth in development; and, using this knowledge, we are developing tissue engineering strategies that reproduce developmental programs for postnatal tissue regeneration. In this talk, I will share two data stories that exemplify this crosstalk in bone development and regeneration. In the first, we solved a long-standing controversy in bone regarding the combinatorial roles of the mechanosensitive transcriptional co-activators, YAP and TAZ. In the second, we demonstrated that mechanical stimuli are essential to mimic the process of endochondral bone development for regeneration of large bone defects.

Bio:

Joel Boerckel received his Ph.D. in mechanical engineering from the Georgia Institute of Technology and postdoctoral training in cellular and molecular medicine as an NIH Ruth L Kirschstein postdoctoral fellow at the Cleveland Clinic. He recently moved his laboratory to the University of Pennsylvania from the University of Notre Dame, and is currently an Assistant Professor of Orthopedic Surgery and Bioengineering.

January 18: SPECIAL PHD SEMINAR

Boyang Qin, Ph.D. Candidate, University of Pennsylvania
Advisor: Paulo Arratia

“Elastic Turbulence & Ciliary Kinematics in Viscoelastic Fluids: Nonlinearity at Low Reynolds Number”

1:00 p.m., Raisler Lounge (Room 225), Towne Building

Abstract:

Fluids with microstructures often display complex and nonlinear physical behaviors that cannot be found in simple fluids like water. One example that is ubiquitous in nature and industry is viscoelastic fluid which contain macromolecules or polymers dissolved in an otherwise Newtonian fluid. In this talk, I report experimental results of two such nonlinear phenomena associated with fluid viscoelasticity that are relevant to industrial polymer processing and human health. First, by conducting high-speed velocimetry on the flow of polymeric fluid in a micro-channel, we report evidence of elastic turbulence in a parallel shear flow where the streamline is without curvature. We found “turbulent” pipe drag increase and enhanced mixing associated with the polymeric flow. Moreover, the spectral characteristics and spatial structure of the velocity fluctuation are different from that in a curved geometry. Second, by analyzing the ciliary swimming of the green algae Chlamydomonas reinhardtii in viscoelastic fluid, we show that fluid elasticity alters the beating pattern of the cilia and adversely hinders the swimmer motility. This result suggests the complex coupling between fluid rheology and ciliary beating in biological processes such as muco-clearance in mammalian airways.


January 23

Aaswath Raman, Assistant Professor of Electrical and Systems Engineering, University of Pennsylvania

"Thermal Nanophotonics: Controlling the heat and light that surrounds us"

Abstract:

Nanoscale photonic structures, by their small length scales, can manipulate light and heat in unprecedented ways, thereby enabling new possibilities for energy efficiency and generation. In this talk, I will show how controlling the electromagnetic fields associated with thermal radiation using nanophotonic structures can enable fundamentally new technological capabilities by allowing us to harness an unexploited, renewable thermodynamic resource: the cold of space.

I will present our body of work on radiative sky cooling, whereby sky-facing, thermal photonic structures can passively cool themselves below their surroundings by emitting their heat as thermal radiation at wavelengths where Earth's atmosphere is most transparent. I will show how this cooling effect can persist during the day and, remarkably, with selective thermal emitters passively reach as much as 45°C below ambient. I will discuss related work on using such thermal photonic approaches to passively maintain solar cells at lower temperatures, while maintaining their solar absorption, to improve their operating efficiency. I will also highlight recent work on using this approach to cool fluids passively and integrate such a system with conventional air conditioning and refrigeration systems to improve their operating efficiency. Exciting new prospects for harnessing this effect for other energy and water-conservation applications will also be introduced.

Finally, I will highlight new fundamental and applied research directions for controlling light, and thermal radiation in particular, at mid-infrared wavelengths. Given decades of progress in nanoscale photonics, we now have the opportunity to tackle important energy and environmental challenges by better controlling the radiative heat transfer happening around us everyday.

Bio:

Aaswath Raman is Assistant Professor of Electrical and Systems Engineering at the University of Pennsylvania. His research interests include nanophotonics, metamaterials, thermal sciences, computational methods and energy systems. He is also Co-Founder of SkyCool Systems, a startup commercializing technology related to radiative sky cooling that he originally developed as a Research Associate at Stanford University beginning in 2013.

Aaswath received his Ph.D. in Applied Physics from Stanford University in 2013, and his A.B. in Physics and Astronomy, and M.S. in Computer Science from Harvard University in 2006. Prior to obtaining his Ph.D. he was a Program Manager at Microsoft. He is the recipient of the Sir James Lougheed Award of Distinction from the Government of Alberta, Canada, the SPIE Green Photonics Award for his work on solar cell research and the Stanford Postdoctoral Research Award. In recognition of his work on radiative sky cooling, in 2015 Aaswath was named one of MIT Technology Review’s Innovators Under 35 (TR35).


January 30

Gretar Tryggvason, Charles A. Miller, Jr. Distinguished Professor and Department Head, Department of Mechanical Engineering, Johns Hopkins University

"Direct Numerical Simulations of Complex Multiphase Flows”

Abstract:

Direct numerical simulations (DNS), where every continuum length and time scale are fully resolved, allow us to follow the evolution of complex flows for sufficiently long time so that meaningful statistical quantities can be gathered. Results for relatively simple multifluid and multiphase systems with bubbles and drops in turbulent flows are now available, but new challenges are emerging. First of all, DNS of very large systems are yielding enormous amount of data that, in addition to providing physical insights, opens up new opportunities for the development of lower order models that describe the average or large-scale behavior. Recent results for bubbly flows and the application of machine learning tools to extract closure models from the data suggest one possible strategy. Secondly, success with relatively simple systems calls for simulations of more complex problems. Multiphase flows often produce features such as thin films, filaments, and drops that are much smaller than the dominant flow scales and are well-described by analytical or semi-analytical models. Recent efforts to combine semi-analytical models for thin films using classical thin film theory, and to compute mass transfer in high Schmidt number bubbly flows using boundary layer approximations, in combination with fully resolved numerical simulations of the rest of the flow, are described.

Bio:

Gretar Tryggvason is the Charles A. Miller, Jr. Distinguished Professor at the Johns Hopkins University and the head of the Department of Mechanical Engineering. He received his PhD from Brown University in 1985 and was on the faculty of the University of Michigan in Ann Arbor until 2000, when he moved to Worcester Polytechnic Institute as the head of the Department of Mechanical Engineering. Between 2010 and 2017 he was the Viola D. Hank professor at the University of Notre Dame and the chair of the Department of Aerospace and Mechanical Engineering. Professor Tryggvason is well known for his contributions to computational fluid dynamics; particularly the development of methods for computations of multiphase flows and for pioneering direct numerical simulations of such flows. He served as the editor-in-chief of the Journal of Computational Physics 2002-2015, is a fellow of APS, ASME and AAAS, and the recipient of several awards, including the 2012 ASME Fluids Engineering Award.

February 1: MEAM SPECIAL SEMINAR

Justin W. Wilkerson, Donald D. Harrington Faculty Fellow, Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, and
Assistant Professor & James J. Cain Fellow, Department of Mechanical Engineering, Texas A&M University

“The Role of Crystallographic Defects in Impact Failure”

10:30 a.m., Room 307, Levine Hall

Abstract:

Over the past five decades there has been an intense effort to understand and control the thermomechanical response of materials in extreme environments. A number of technologies critical to our safety and well-being stand to benefit from such understanding including armor and defense systems, next-generation fission and fusion reactors, spacecraft shielding, vehicular crashworthiness, and advanced manufacturing. Materials in such extreme environments often exhibit complex, somewhat non-intuitive mechanical behavior that is difficult to predict with empirical or phenomenological models. Here we discuss our development of a number of multiscale, mechanism-based models that help unravel this inherent complexity. This seminar will focus primarily on the development of an atomistically-informed crystal plasticity framework for deformation and failure of shock compressed single crystals and polycrystals. We further utilize this multiscale modeling framework to provide key insights into the development of reduced-order models, which are helpful in guiding the microstructural design of advanced light-weight armor and shielding materials.

Bio:

Professor Wilkerson’s research and teaching interests lie at the interface of solid mechanics, material science, and physics. His research is focused on multiscale modeling and fundamental experiments that shed light on the nature of the mechanical behavior of materials subject to the kinds of extreme conditions generated in armor and defense applications, nuclear reactors, hypersonic aircraft, rocket motors, as well as the cores and surfaces of planets and asteroids. Presently, Wilkerson is a Donald D. Harrington Faculty Fellow with the Department of Aerospace Engineering and Engineering Mechanics at the University of Texas at Austin. In 2017, Wilkerson joined the Department of Mechanical Engineering at Texas A&M University as an assistant professor and the James J. Cain Faculty Fellow II. From 2015 to 2017, Wilkerson was an assistant professor in the Department of Mechanical Engineering at the University of Texas at San Antonio. Wilkerson obtained his B.S. with highest honors from Texas A&M, followed by an M.S.E and Ph.D. from Johns Hopkins University. While at Hopkins he worked with Dr. KT Ramesh in the Hopkins Extreme Materials Institute (HEMI). Wilkerson’s academic achievements have been recognized and supported by a number of honors and awards, including the AFOSR Young Investigator (YIP) Award, the Ralph E. Powe Junior Faculty Award, the National Science Foundation (NSF) Graduate Research Fellowship, the National Defense Science and Engineering Graduate (NDSEG) Fellowship, and the Ammon S. Andes Award presented annually to recognize the nation’s top aerospace engineering graduate.


February 6

NO SEMINAR

February 13

NO SEMINAR

February 20

Hadi T. Nia, Postdoctoral Fellow, Massachusetts General Hospital and Harvard Medical School

"Solid Stress and Elastic Energy as New Measures of Tumor Mechanopathology”

Abstract:

Solid stress and tissue stiffness affect tumor progression, metastasis and treatment. Unlike stiffness, which can be precisely mapped in tumors, the measurement of solid stresses is challenging. In this seminar, I will present three distinct and quantitative techniques to obtain two-dimensional spatial mappings of solid stress and the resulting elastic energy in excised or in situ tumors with arbitrary shapes and wide size ranges. I will present major findings from the application of these methods in mouse models of primary tumors and metastasis including: (i) solid stress generation depends on both cancer cells and their microenvironment; (ii) solid stress increases with tumor size; and (iii) mechanical confinement by the surrounding tissue significantly contributes to intratumoral solid stress. Finally, I will discuss my more recent work on neurological and vascular impairments induced by solid stress from primary and metastatic brain tumors, and potential pharmacological remedies to counter these effects.

Bio:

Hadi T. Nia is an NIH postdoctoral fellow at Massachusetts General Hospital and Harvard Medical School, supervised by Dr. Rakesh Jain. His research interests include multiscale cancer mechanobiology, and the development of innovative tools and model systems to investigate the physical microenvironment of tumors. He received his Ph.D. under Profs. Alan Grodzinsky and Christine Ortiz at MIT, investigating the molecular origin of solid-fluid interactions in cartilage and its association with osteoarthritis. Hadi has been awarded fellowships from the National Cancer Institute (F32), Fund for Medical Discovery, and Whitaker Health Sciences Fund.


February 27

Michael Ortiz, Frank and Ora-Lee Marble Professor of Aeronautics and Mechanical Engineering, California Institute of Technology

"The Anomalous Yield Behavior of Fused Silica Glass"

Abstract:

We develop a critical-state model of fused silica plasticity on the basis of data mined from molecular dynamics (MD) calculations. The MD data is suggestive of an irreversible densification transition in volumetric compression resulting in permanent, or plastic, densification upon unloading. The MD data also reveals an evolution towards a critical state of constant volume under pressure-shear deformation. The trend towards constant volume is from above, when the glass is overconsolidated, or from below, when it is underconsolidated. We show that these characteristic behaviors are well-captured by a critical state model of plasticity, where the densification law for glass takes the place of the classical consolidation law of granular media and the locus of constant-volume states defines the critical-state line. A salient feature of the critical-state line of fused silica, as identified from the MD data, that renders its yield behavior anomalous is that it is strongly non-convex, owing to the existence of two well-differentiated phases at low and high pressures. We argue that this strong non-convexity of yield explains the patterning that is observed in molecular dynamics calculations of amorphous solids deforming in shear. We employ an explicit and exact rank-$2$ envelope construction to upscale the microscopic critical-state model to the macroscale. Remarkably, owing to the equilibrium constraint the resulting effective macroscopic behavior is still characterized by a non-convex critical-state line. Despite this lack of convexity, the effective macroscopic model is stable against microstructure formation and defines well-posed boundary-value problems.

Bio:

Professor Ortiz received a BS degree in Civil Engineering from the Polytechnic University of Madrid, Spain, and MS and Ph.D. degrees in Civil Engineering from the University of California at Berkeley. From 1984-1995 he held a faculty position in the Division of Engineering of Brown University, where he carried out research activities in the fields of mechanics of materials and computational solid mechanics. He is currently the Frank and Ora Lee Marble Professor of Aeronautics and Mechanical Engineering at the California Institute of Technology, where he has been in the faculty since 1995 and where he has served as the director of Caltech’s DoE/PSAAP Center on High-Energy Density Dynamics of Materials from 2008-2013. Professor Ortiz has been a Fulbright Scholar, a Sherman Fairchild Distinguished Scholar at Caltech, Midwest and Southwest Mechanics Seminar Series Distinguished Speaker, an elected member-at-large of the US Association for Computational Mechanics and a Hans Fischer Senior Fellow of the Institute of Advanced Studies of the Technical University of Munich. He is a Fellow of the US Association for Computational Mechanics, elected Fellow of the American Academy of Arts & Sciences and an elected Member of the US National Academy of Engineering. Professor Ortiz is the recipient of the Alexander von Humboldt Research Award for Senior US Scientists, the IACM International Computational Mechanics Awards for Research, the USACM Computational Structural Mechanics Award, the ISI Highly Cited Researcher Award, the inaugural 2008 Rodney Hill Prize conferred every four years by the IUTAM and 2015 Timoshenko Medal of the ASME. Professor Ortiz has served in the University of California Office of the President Science and Technology Panel, the Los Alamos National Laboratory T-Division Review Committee, the Lawrence Livermore National Laboratory Predictive Science Panel, the Sandia National Laboratories Engineering Sciences External Review Panel, the Lawrence Livermore National Laboratory Chemistry, Materials, Earth and Life Sciences Directorate Review Committee, in the Lawrence Livermore National Laboratory Engineering Directorate Review Committee and in the National Research Council Panel for the Evaluation of QMU. He has been editor of the Journal of Engineering Mechanics of ASCE and of the Journal of Applied Mechanics of the ASME and is presently associate editor of the Journal of the Mechanics and Physics of Solids, the Archive for Rational Mechanics and Analysis, the International Journal for Numerical Methods in Engineering and of Computer Methods in Applied Mechanics and Engineering Journal.

March 6

SPRING BREAK - NO SEMINAR

March 13

TBA

March 20

Mahesh M. Bandi, Assistant Professor, Collective Interactions Unit, Okinawa Institute of Science and Technology Graduate University

“Applying Higher-order Turbulence Spectra from Energy to UAV”

Abstract:

Kolmogorov’s 1941 theory elucidating the spectrum of turbulent velocity fluctuations forms the cornerstone of contemporary turbulence research. This result requires one to measure the velocity everywhere within the turbulent flow at the same time instant. However, many situations exist where measurements are needed over time at one or few fixed spatial (Eulerian) locations, often involving higher powers of velocity. The physical interpretation of such measurements strongly diverges from the Kolmogorov framework. In this talk, I will review the revised theoretical framework and support it with evidence from our experiments in two and three dimensional flows. I will then explain how this revised framework provides a toolkit to address a diverse range of questions in Energy, UAV mechanics, Environmental Sciences, and even Life Sciences.

Bio:

Mahesh Bandi received his Bachelors’ in Computer Engineering from the University of Madras, India in 1998. After a 2 year stint in the Indian software industry, he returned to academia to pursue further studies. He earned his MS Electrical Engineering in 2002, MS Physics in 2004, and PhD Physics in 2006, all from the University of Pittsburgh. Following postdoctoral stints at Los Alamos National Laboratory (2006 - 2009) and Harvard University (2009 - 2011), Mahesh was appointed to the founding faculty of OIST Graduate University in 2011, where he is currently an Assistant Professor heading the Collective Interactions Unit. He was a visiting faculty with the Brown University’s School of Engineering for the academic year 2011 - 2012, Simons visiting faculty at the National Centre for Biological Sciences, India in summer 2013, and is a visiting Staff Associate with ICTP, Italy starting 2018. Mahesh’s primary research interests lie in the nonlinear and non-equilibrium physics of complex systems with current focus on interfacial fluid dynamics, mechanics of disordered granular solids, fluctuations in renewable energy, and Biomechanics.

March 27

David L. McDowell, Carter N. Paden Jr. Distinguished Chair in Metals Processing and Regents' Professor of Mechanics of Materials, Georgia Institute of Technology

"Microstructure-sensitive Multiscale Crystal Plasticity Modeling"

Abstract:

Crystal plasticity models are useful for considering the influence of anisotropy of elastic and plastic deformation on local and global responses in crystals and polycrystals. This talk considers multiple crystal plasticity model constructs to address evolution of dislocation structures over a broad range of length and time scales. The utility of crystal plasticity in applications for strain rates ranging from quasistatic fatigue under cyclic loading to shock wave propagation in heterogeneous polycrystalline metals. Emphasis is placed on the forms of the internal state variable structure of the models, with dislocation and other defect densities as a basis. Given its mesoscale character, contrasts are drawn between bottom-up (simulations and experimental observations) and top-down (experimental) information in assembling the constitutive relations and informing their parameters. Alternative forms of bottom-up crystal plasticity models are considered that are sensitive to structure of interfaces and lattices, including adaptive quasi-continuum and concurrent atomistic-continuum methods.

Bio:

Regents’ Professor and Carter N. Paden, Jr. Distinguished Chair in Metals Processing, Dave McDowell joined Georgia Tech in 1983 and holds appointments in both the GWW School of Mechanical Engineering and the School of Materials Science and Engineering. He served as Director of the Mechanical Properties Research Laboratory from 1992-2012. In August 2012 he was named Founding Director of the Institute for Materials (IMat), a Georgia Tech interdisciplinary research institute charged with cultivating cross-cuttting collaborations in materials research and education. IMat (see http://www.materials.gatech.edu) has initiatives in both campus materials user facilities and in accelerating materials discovery and development by building on materials data science and informatics approaches.

McDowell's research focuses on the development of physically-based, microstructure-sensitive constitutive models for nonlinear and time-dependent behavior of materials, with emphasis on wrought and cast metals. Topics of interest include finite strain inelasticity and defect field mechanics, microstructure-sensitive computational approaches to deformation and damage of heterogeneous materials, with emphasis on metal fatigue, atomistic and coarse-grained atomistic simulations of dislocations, dynamic deformation and failure of materials, irradiation effects on materials, and multiscale modeling. He has contributed to schemes for computational materials science and mechanics to inform systems design of materials (Integrated Design of Multiscale, Multifunctional Materials and Products, Elsevier, 2009, ISBN-13: 978-1-85617-662-0). Applications of current interest span lightweight structural materials, materials for hot sections of aircraft gas turbine engines, titanium alloys, armor and blast resistant systems, irradiated ferritic and austenitic alloys, and nanocrystalline materials, among others. McDowell currently serves on the editorial boards of the International Journal of Plasticity, npg Computational Materials, and several other journals. He is co-Editor of the International Journal of Fatigue.

April 3

TBA


April 10

Evelyn Wang, Gail E. Kendall Professor of Mechanical Engineering, Massachusetts Institute of Technology

Title TBA

Abstract:

TBA

Bio:

TBA


April 17

TBA


April 24

Mark Alan Fogel, Professor of Pediatrics, Children's Hospital of Philadelphia

Title TBA

Abstract:

TBA

Bio:

TBA