Abstract: The water flow through tidal estuaries create a large source of renewable energy that is highly predictable and close to urban centers, yet mostly untapped in the United States.  This presentation gives an overview of recent efforts to develop a hydrokinetic energy harvesting device well-suited for tidal flows, that is based on the oscillating motion of hydrofoils. Inspired from the flapping flight of birds and bats, an oscillating hydrofoil generates energy through lift generation, which is augmented by a large unsteady leading-edge vortex. This talk will highlight the computational efforts that drove prototype development and will examine the flow physics important for energy capture. It will also discuss the formation and downstream trajectory of the leading-edge vortex, which is important for informing the configuration of oscillating foil arrays. Knowing the path and topology of shed vortices can enable downstream foils to be placed strategically and recapture the kinetic energy of vortices, thus boosting the system efficiency of an oscillating foil array.

Biographical Sketch: Dr. Jennifer Franck is an expert in computational fluid dynamics (CFD) and is interested in unsteady flow phenomena and flow control of turbulent flows.  She is currently an Assistant Professor in Engineering Physics at University of Wisconsin-Madison. Prior to moving to Madison, she was on the faculty at Brown University’s School of Engineering for seven years where she won numerous teaching and advising awards.  She received her undergraduate degree in Aerospace Engineering from University of Virginia, followed by a M.S. and Ph.D. from California Institute of Technology. She was awarded an NSF Postdoctoral Fellowship to computationally explore flapping flight mechanisms at Brown University from 2009-2011. Dr. Franck is currently interested in problems related to renewable energy, including wind and tidal energy applications.

Abstract: The mission  of AFRL’s Multidisciplinary Science and Technology Center (MSTC) is to discover, assess, and exploit coupled system behavior for optimization of revolutionary aerospace vehicles through the application of multidisciplinary design, analysis, and optimization (MDAO). To this end, MSTC performs  in-house research and sponsors efforts ranging from basic developments in FEA, CFD, design space exploration, physics-based design, and experimental testing through technology demonstration vehicles including the X-56 and XQ-58A. An area of ongoing interest in MSTC is the development of topology optimization (TO) methodologies for the design of efficient aircraft structure. Commercially available tools for TO have successfully been employed for aircraft components such as lightweight brackets and other localized components. However, it remains a challenge to utilize these density-based methods to design aircraft primary structure that is subject to diverse design constraints including aeroelastic deformations, flutter, panel buckling, stress requirements, and control effectiveness criteria. To address this challenge, a biologically-inspired technique based on the production rules governing cellular division of living organisms has been developed and applied to identify optimal topological layouts of air vehicle structure. Preliminary results demonstrate over 10% reductions in structural weight is from TO compared to optimally-sized structure with conventional structural topology. In addition, the performance  of resulting designs has been validated using 3D printing and static/modal testing of subscale models. This talk will provide an overview of ongoing efforts in AFRL’s MSTC and will introduce the bio-inspired method for the topology optimization of aircraft structures.

Biographical Sketch: Joshua Deaton is a Research Aerospace Engineer in AFRL’s Aerospace Systems Directorate’s Multidisciplinary Science and Technology Center (MSTC). In this role Dr. Deaton develops and applies multidisciplinary computational design technologies and leads collaborative efforts with industry, academia, and other government partners to transition multidisciplinary design technology to support the design of next-generation Air Force platforms. His primary research areas include coupled sensitivity analysis, structural and topology optimization, and nonlinear thermoelasticity. Dr. Deaton received his Ph.D. in Engineering with a focus on Computational Design and Optimization as well as his B.Sc. in Mechanical Eng. from Wright State University. He serves on the AIAA Multidisciplinary Design Optimization (MDO) Technical Committee and recently received the Outstanding Technical Contribution – Science Award from the AIAA Dayton-Cincinnati Section for his contributions in multidisciplinary sensitivity analysis for geometrically nonlinear aerospace structures.

 

Abstract: During development, instabilities develop in the brain, giving it its characteristic wrinkled shape. Other soft tissues, including skin, the bladder, and the airway mucosa, also exhibit instabilities and the resulting folds, wrinkles, and creases. Instabilities in these soft tissues, which often contain multiple layers with distinct properties, are very complex and still not well understood. The focus of this talk will be on the unique features of instabilities in soft layered materials, including their sensitivity to different sources of compression, the interactions of adjacent layers and interfaces, the influence of boundary conditions, and the emergence of heterogeneous layer thickness as a result of wrinkling. I will share results from theoretical, computational, physical, and imaging approaches, and discuss their implications for the study of the developing brain.

Biographical Sketch: Maria Holland is the Clare Boothe Luce Assistant Professor of Aerospace and Mechanical Engineering at the University of Notre Dame in Notre Dame, IN. She earned her M.S. and Ph.D. from Stanford University in the Department of Mechanical Engineering with Prof. Ellen Kuhl, and her bachelor’s degree in mechanical engineering from the University of Tulsa, graduating Phi Beta Kappa. Her research is in computational biomechanics, using solid mechanics and computational tools to address important questions about complex soft materials, including the brain. Through collaborations with clinicians and experimentalists, she aims to understand the development of the human brain and how it relates to the brain’s form and function. Additionally, she works to extend the functionality of traditional engineering methods to encompass soft, growing materials.

Abstract: The rapidly expanding interest in molten salt reactors (MSRs), particularly as small modular reactors, is resulting in the generation of multiple design concepts with efforts at a variety of early developmental stages. Various companies and organizations in a number of countries are looking at such systems to be safe, economical, and rapidly deployable power systems. For efficient design, operation, and regulation of MSRs it will be necessary to have the ability to simulate reactor behavior across the spectrum from neutronics and fluid dynamics to corrosion and salt phase behavior. MSRs have not been considered since the original prototype, the Molten Salt Reactor Experiment, that ran successfully from 1965-1969 at Oak Ridge National Laboratory, and thus there is little legacy of useful information. Aspects of potential modeling and simulation of future molten salt reactors will be discussed with respect to the unique challenges they present. Among the current needs are extensive thermophysical and thermochemical properties describing salts and other reactor materials. In particular, the ability to compute chemical and phase equilibria (e.g., potential solid phase precipitation) throughout the molten salt loop(s). Activities and opportunities in these areas will be discussed as contributing to development of a knowledge base for molten salt reactor technology.

Biographical Sketch: Ted Besmann is Professor and SmartState Chair for Transformational Nuclear Technologies, directing the General Atomics Center at the University of South Carolina. Dr. Besmann received his B.E. in chemical engineering from New York University, M.S. in nuclear engineering from Iowa State University, and Ph.D. in nuclear engineering from the Pennsylvania State University. In 1975 he joined ORNL and subsequently became a Group Leader and Distinguished Member of the Research Staff. Besmann’s nearly 40 years at Oak Ridge National Laboratory included a joint appointment in the Nuclear Engineering Department at the University of Tennessee. Besmann has over 160 refereed publications, and is a Fellow of both the American Ceramic Society and the American Nuclear Society. He is chair of the Organization for Economic Cooperation and Development-Nuclear Energy Agency (OECD-NEA) Working Party on Multi-Scale Modeling of Nuclear Fuels and Structural Materials and is vice-chair of their Thermodynamics of Advanced Fuels-International Database program. Dr. Besmann is also Co-Director of the DOE Energy Frontier Research Center led by USC, the Center for Hierarchical Waste Form Materials.

Abstract: In this talk, I will discuss work related to mechanically “programming” soft sensors to respond to a particular mechanical deformation. Advances in 3D-printing, soft polymer fabrication, and other rapid fabrication processes have made the vision of conformal and stretchable mechanical sensors for wearable devices and soft robotics possible. One limitation of these sensors is their low selectivity between different modes of mechanical deformation, such as strain, torsion, and bending.

I will present recent work in enhancing the selectivity of stretchable sensors by using non-planar sensor morphology to bias the sensor towards a particular deformation mode. I will discuss projects including designing a sensor with electrically-tunable sensitivity and the fabrication origami-patterned, deformation-selective flexible sensors.

Biographical Sketch: Kris Dorsey is an assistant professor of engineering in the Picker Engineering Program at Smith College. She was a President’s Postdoctoral Fellow at the University of California, Berkeley and University of California, San Diego. Dr. Dorsey graduated from Carnegie Mellon University with a Ph.D. in Electrical and Computer Engineering and earned her Bachelors of Science in Electrical and Computer Engineering from Olin College.

She founded The MicroSMITHie Lab at Smith College to investigate micro- and miniature-scale sensor design and to prepare undergraduates for graduate study in engineering. Her current research interests include strain-stable, hyperelastic components, novel morphology soft sensors, and sensors for soft robots and wearable devices.

Dr. Dorsey has co-authored several publications on hyperelastic strain sensors, novel soft lithography processes, and the stability of gas chemical sensors. In 2019, she received the NSF CAREER award.

Abstract: Biofilms are surface-attached communities of bacteria that can cause problems including medical infections, fouling, and clogging in industrial applications. By contrast, beneficial biofilms are crucial in applications including waste-water treatment and microbial fuel cells. In this talk, I will discuss about our recent progress in using Vibrio cholerae as a model biofilm former to reveal the mechanical principles underlying biofilm formation, both at the single cell level and at the continuum level. I will first present a new methodology to image living, growing bacterial biofilms at single-cell resolution, and demonstrate how cell-cell adhesion and cell-surface adhesion balance each other to cause V. cholerae to form an ordered, three-dimensional cluster. Next, I will show how extracellular polysaccharides, proteins, and cells function together to define biofilm mechanical and interfacial properties. Finally, I will present various mechanical instabilities that take place when biofilms grow on soft substrates, and how such instabilities, together with interfacial properties, define the morphogenesis process of bacterial biofilms.

Biographical Sketch: Dr. Yan obtained his bachelor’s degree from the College of Chemistry and Molecular Engineering at Peking University in China. As a graduate student, he studied soft matter physics in the Department of Materials Science and Engineering at the University of Illinois, Urbana-Champaign. During his Ph.D., he developed a series of non-equilibrium colloidal materials with dynamic structures controlled by electromagnetic fields. He transitioned to biology for his postdoctoral training, working at Princeton University jointly in the Department of Molecular Biology and the Department of Mechanical and Aerospace Engineering. His current research focus is on bacterial biofilm formation. Dr. Yan received the Career Award at the Scientific Interface from Burroughs Welcome Fund in 2016. He moved to Yale as an Assistant Professor in the Department of Molecular, Cellular and Developmental Biology and Quantitative Biology Institute at Yale University in 2019.

Abstract: Dermal scales appeared early in the evolutionary history of vertebrates, most notably in fishes. Their remarkable multi-functional roles include protection from predatory attacks, enhancement of locomotion, camouflaging and thermal regulation. This has led to a tremendous variation in scale type, material, shape, size and organization among species (e.g. fishes, snakes) as well as within species (different types of fish scales). This has led to a great deal of interest in their material properties. Less investigated is the role of the scales themselves as geometric units of high performance.  Interestingly, many remarkable behaviors lie in the geometrical form and distribution of the scales. Discretely segmented, geometrically pronounced units emanating from softer, slender substrates allows for a rich interplay of deformation, geometry and functions at multiple length scales underscoring structure-property synergy. Therefore, the primitive scale topology (exoskeleton form) appears across a much wider range of critical biological structures such as papillae on feline tongue, where they dramatically enhance gripping capacity and combine it with fluid wicking properties or on the surface of animal furs, where nanoscale scaly features are known to reduce microbial fouling, or aid in aerodynamic functions. Testament to their remarkable structure-properties enhancements, it is difficult to find slender biological structures that do not exploit some type of concerted external surface texture. These features result in a number of unusual mechanical behavior such as small strain reversible nonlinearities and quasi-rigid locking behavior in bending and twisting deformations even when friction is negligible. When friction is significant, unexpected dissipation and damping behaviors arise. Furthermore, stiff plate like scales on a soft substrate can give rise to perceptible change in indentation response, which can quickly transition away from the Hertzian regime. Since the main sources of such nonlinearities are geometry and interface dictated, such extreme mechanical behaviors can be easily programmed and functionally graded using additive manufacturing, which can be exploited for diverse applications such as multifunctional structures, robotic exoskeletons, prosthetics, flexible electronics and protective coatings.

Biographical Sketch: Dr. Ranajay Ghosh is an Assistant Professor in the department of Mechanical and Aerospace Engineering (MAE) and the Center for Advanced Turbine and Energy Research (CATER) at UCF. He directs the Complex Structures and Mechanics of Solids (COSMOS) Laboratory. His research focuses on the behavior of deformable solids and computational mechanics particularly focusing on modeling multiscale and multiphysics phenomena in heterogeneous and topological solids. Prior to his appointment at UCF, Dr. Ghosh earned his PhD from Cornell University, Ithaca, NY where he was awarded the Harriet-Davis doctoral fellowship. During his PhD he also carried out research at the General Electric’s (GE) Global Research Center at Niskayuna, New York where he was the recipient of GE’s global recognition award for outstanding performance. He subsequent carried out postdoctoral research at the Rensselaer Polytechnic Institute and Northeastern University.  Dr. Ghosh’s research work has led to over 45 peer reviewed journal publications including several cover arts and media coverage in Discovery, Newsweek and the New York Times.  Dr. Ghosh’s research is primarily funded by Siemens Energy, the US Department of Energy (DoE) and the National Science Foundation (NSF).

Abstract: Demand of batteries keeps increasing as electronic devices get widespread and fossil-based systems are being replaced by electricity-based systems. Lithium-ion battery has been considered one of the most promising power sources for mobile and transportation systems, but it faces challenging issues of high cost, low capacity (i.e. short operation hours or driving ranges), and safety issues. Therefore, it is necessary to find the break-through technologies to resolve those issues. In this talk, two promising electrochemical systems will be introduced: aluminum-air battery and multi-valent catalytic flow battery. Aluminum is cheap and abundant, benign to the environment, and stable in moisture. But, due to the problems of self-corrosion and formation of inert oxide film on the surface of aluminum during cell operation, the Al-based rechargeable battery could not reach commercialization stage. Ionic liquid which is a molten salt in liquid form at room temperature is getting intense attention recently as a promising electrolyte to resolve those issues. In this talk, discussion will be made about the effect of the oxide film on performance of the ionic-liquid based Al-air battery and how to control the film with results of research conducted in Dr. Cho’s group at Northern Illinois University (NIU) through experiment and physic-based modeling.Redox flow battery (RFB) is enjoying a renaissance with substantial achievement of research, altering it ultra-high performing and high energy dense system. And also, the excellent feature of RFB decoupling energy from power has been applied as a key design factor to overcome the challenging issues of conventional battery systems. In this talk, new promising “redox-mediated bromate based flow battery” which has theoretical energy density greater than lithium ion battery will be introduced, and characteristic “auto-accelerated” catalytic electrochemical reaction coupled with chemical reaction will be discussed in detail.

Biographical Sketch: Dr. Kyu Taek Cho is an assistant professor of mechanical engineering at Northern Illinois University, Dekalb, IL. He has around 20-year experience in the electrochemical system through works in national lab, industry, and academy. He had worked at Lawrence Berkeley National Lab as a postdoc and then a research staff before he joined NIU in 2014. He also has industrial experience as a research engineer at Hyundai Motor Company, S. Korea to develop a fuel stack for the application to vehicle. Dr. Cho has Ph.D. achieved from Pennsylvania State University under guidance of Professor Matthew Mench. Dr. Cho is a director of Electrochemical Energy Lab at NIU to conduct the fundamental research of advanced electrochemical and thermal energy systems.

Abstract: In standard seakeeping simulations of a ship in irregular seas, the rigid body motions of the ship are computed using a set of semi-analytic integro-differential equations, which model the response of the ship including non-linear and history dependent forces.    Using this type of model allows one to model the response of the ship in incident irregular waves, corresponding to a sea state defined by its significant wave height, H_s, peak spectral period, T_p, dominant wave direction, θ₀, and spectrum type, while allowing fairly quick simulation of the response using standard numerical integration methods.  In this work, we develop and apply such a model to compute ship motions for a large number of sea states. Then, we perform the inverse problem of determining the governing sea state parameters by training a Neural Network, based on the time histories of ship response in roll, pitch, and heave computed with the model. The estimator is then validated against physical model test experiments conducted using irregular waves generated in a towing tank to demonstrate that the numerical model is sufficient for training the Neural Network using simulated data.  The main rationale for this work is to develop a low-cost method for small vessels to estimate local sea state conditions in order to avoid operations in dangerous sea states, however the same techniques could be applied in general to transiting vessels to obtain local and continuous sea state measurements for general science purposes or other uses. 

Biographical Sketches: Jason M. Dahl is an Associate Professor in the Department of Ocean Engineering at the University of Rhode Island.  Dr. Dahl (PhD, Ocean Engineering, MIT; B.S., Naval Architecture and Marine Engineering, Webb Institute) is an expert in fluid-structure interactions and floating body dynamics, with particular expertise in the flow-induced vibration of underwater structures. Dr. Dahl has extensive experience as an experimentalist with towing tank operations, dynamic testing, and quantitative flow visualization.

Stephan T. Grilli is a Distinguished Professor and Chair, in the Department of Ocean Engineering at the University of Rhode Island.  Dr. Grilli (PhD, Ocean Engineering, M.S. Physical Oceanography, M.S. Civil Engineering, University of Liège) has a broad background in Computational Fluids Dynamics related to free surface and wave-structure interaction problems in coastal, naval and ocean engineering, and oceanography. Dr. Grilli has over 30 years of experience with developing higher-order boundary element models and viscous simulations for the solution of free surface potential flows for wave propagation and wave-structure interactions including the modeling of tsunami wave propagation, ship seakeeping in waves, wave breaking, and wave energy systems.