Past Seminars

Design and Scalable Synthesis of Nanoscale Materials for Solar Energy Conversion

Abstract: My research is aimed at creating materials that will be the building blocks of economical, large-scale, clean energy technologies of the future. The key to creating effective energy conversion materials is controlling the flow of energy, matter and electricity at the nanoscale by careful design of the shape, size and composition of materials at the same scale. I am primarily interested in developing materials for cheap yet efficient solar cells that either generate electricity or directly generate chemical fuels. As an example, I will present semiconductor/liquid junction solar cells constructed on metal oxide nanowire scaffolds that achieved record photocurrents, and also new results on metal sulfide materials. Equally important is the development of methods for the rapid, economical synthesis of highly structured nanomaterials in quantities that match the scale of our energy problem. As an example, I will describe novel flame-synthesis methods for the bottom-up growth of arrays of single-crystal metal oxide nanowires and composites over large areas on electrically conductive substrates. Technologies like this may someday remove barriers to the practical implementation of nanotechnology in solar energy conversion devices.

Biographical Sketch: Pratap Rao is an Assistant Professor in the Mechanical Engineering Department at the Worcester Polytechnic Institute (WPI). He received his BS in 2007 from WPI and his PhD in 2013 from Stanford University. He has co-authored 27 peer-reviewed papers that have collectively been cited over 1,700 times. His work on materials for solar energy conversion and electrocatalysis is currently funded by the National Science Foundation and the Massachusetts Clean Energy Center. At WPI, he is the recipient of the Mechanical Engineering Excellence in Research Award and the James Nichols Heald Research Award.

 

Mechanics at the Mesoscale: Testing, Modeling, and Re-Engineering Living Soft Matter

Abstract: Research in the Simmons Lab works to understand the feedback loop between cell-level processes and tissue-level mechanics. We have developed our own characterization equipment to effectively compare excised tissues, synthetic hydrogels, and engineered constructs. With our custom tools and models, we are studying a novel animal, the African Spiny Mouse, that is capable of regenerating skin, cardiac muscle, and skeletal muscle without fibrosis, and we are attempting to recreate these regenerative processes in vitro. To study pancreatic cancer, we are using cells from patients to engineer tumors-in-a-dish that have the same mechanical properties of the original tumors for translational and clinical applications.

Biographical Sketch: Chelsey S. Simmons, Ph.D., joined the Department of Mechanical and Aerospace Engineering at the University of Florida in Fall 2013, following a visiting research position at the Swiss Federal Institute of Technology (ETH) Zurich. Her research lab investigates the relationship among cell biology and tissue mechanics, and their projects are funded by the National Science Foundation, National Institutes of Health, and American Heart Association. She has received numerous fellowships and awards, including BMES-CMBE’s Rising Star Award (2017) and ASME’s New Faces Award (2015). In addition to her engineering research and coursework, Simmons received a Ph.D. Minor in Education and is the PI of a $600k Research Experiences for Teachers Site. She teaches undergraduate Mechanics of Materials and graduate BioMEMS courses and received Teacher of the Year in 2017. Simmons received her B.S. cum laude from Harvard University and her M.S. and Ph.D. from Stanford University.

Power-to-Gas and Hydrogen Energy Storage for a 100% Renewable Future

Abstract: Renewable, ultra-low emissions and high efficiency energy conversion systems will be required to introduce energy resource and environmental sustainability. In particular the dynamic dispatch, massive energy storage capacity, and ubiquitous transmission and distribution of energy that the power-to-gas and hydrogen energy storage concepts provide will become essential to enable a 100% renewable economy.  In addition, these concepts enable zero greenhouse gas and zero criteria pollutant emissions energy conversion that spans across applications in the built environment, to transportation, to utility grid network support and sustainability.  Recent research on the dynamics and control of electrochemical energy conversion systems to enable this future will be discussed.

 

Biographical Sketch: Prof. Brouwer is an energy system dynamics expert with research interests in advanced and alternative energy systems development; electrochemical conversion devices and systems such as fuel cells, electrolyzers and batteries; dynamic simulation and control systems development; energy system thermodynamics, design, and integration; turbulent reacting flows; chemical kinetics; and electrochemical reactions with concurrent heat, mass and momentum transfer.

 

Mechanical Engineering Lightning Talks

Join us to learn about the exciting research that some of our Faculty and their groups are doing at our Department at our ME Lightning Talks!  Pizza will be provided.  Since space is limited, this event is limited to ME graduate students and faculty, and a limited number of ME undergraduate seniors. If you are an undergraduate senior and would like to attend, please RSVP at https://goo.gl/forms/HypP70ShGSqKTNay2  (spots will be granted in the order that confirmations are received until capacity is filled). You will receive later in the week an email confirming your attendance.

 

Prof. Thanh Nguyen – Novel processing of biodegradable and biocompatible polymers at small scales for medical applications. Biodegradable polymers have a significant impact to medical field. In my talk, I will present researches which aim to further fabricate and process the polymers at small scales, enabling their special functions for use in important medical implant devices. The first part of this talk will be focused on a novel manufacturing technology, which allows to create versatile 3D microstructures of biodegradable polymers for vaccine/drug delivery. The second part of this talk will be emphasized on a new approach, which enables the polymers to be electromechanically-active for use in an implanted biodegradable force-sensor. The presented works, while significantly enhancing functionality and usefulness of the polymers, do not compromise their excellent biodegradability and biocompatibility for medical use.

 

Prof. Georgios Matheou – Numerical model error in simulations of turbulence. Although turbulent flows are prominent and ubiquitous in many applications, their prediction remains challenging. Simulation has the potential to become the primary tool for discovery by utilizing recent advances in computing power. Thus, high fidelity simulations with good characterization of model errors are required. A study of numerical model error in passive scalar mixing is discussed. The range of values of scalar fields in turbulent flows is bounded by their boundary values, for passive scalars, and by a combination of boundary values, reaction rates, phase changes, etc., for active scalars. In practice, this fundamental constraint is often violated with scalars exhibiting unphysical excursions. Analysis of scalar-excursion statistics shows that unphysical scalar excursions in large-eddy simulations result from dispersive errors of the convection-term discretization where the subgrid-scale model provides insufficient dissipation to produce a sufficiently smooth scalar field.

 

Prof. Dianyun Zhang – An Integrated Multi-Scale and Multi-Physics Modeling Tool for Advanced Composite Structures. Fiber-reinforced polymer matrix composites have been increasingly used in aerospace structures owing to the weight and life-cycle cost savings they provide. However, manufacturing these lightweight materials involves curing an epoxy resin under elevated temperatures, which inevitably results in dimensional change and residual stress build-up. To minimize these manufacturing-induced imperfections through an optimal cure cycle, it is critical to develop a physics-based process model underlying the fundamentals of resin curing kinetics and the correlation between the process parameters and the final structural performance. In this talk, an integrated multi-physics and multiscale model will be used to predict the residual stress generation and dimensional change of a composite laminate. Predictions of the warpage of an unsymmetrical panel and the spring-in angle of an L-shaped composite flange will be used to illustrate the advantages of the proposed modeling tool.

Structure Genome: A Revolutionary Multiscale Approach to Bridging Materials Genome and Structural Analysis

Abstract: Materials Genome Initiative (MGI) and Integrated Computational Materials Engineering (ICME) have the potential to accelerate discovery, developing, manufacturing, and deploying of advanced materials. However, it is usually not the material performance, but the structural performance or system performance we are pursuing. To fill the gap between materials genome and structural analysis, the concept of Structure Genome (SG) is proposed. SG is the smallest mathematical building block containing all the constitutive information for a structure. The Mechanics of Structure Genome (MSG) represents a revolutionary approach to multiscale modeling drastically different from the conventional bottom-up multiscale modeling approaches. The principle of minimum information loss (PMIL) is used to avoid a priori assumptions commonly invoked in other approaches. MSG confines all approximations to the constitutive modeling which can construct constitutive models for all types of structures including 3D solids, 2D plates/shells, and 1D beams, directly linking the structural properties with microstructural details. MSG simplifies multiscale constitutive modelling to answer three fundamental questions: 1) what is the original model needed for capturing relevant physics? 2) what is the model wanted for a particular design? 3) what is the SG? MSG allows one to choose the starting scale and ending scale and capture details as needed and affordable without invalid scale separation and assumptions within scales. A companion code called SwiftComp is developed as a general-purpose constitutive modeling software which can be used as a standalone code for virtual testing of structures and materials and as a plugin for conventional finite element software packages such as Abaqus, Ansys, Nastran with efficient high-fidelity composites modeling capabilities. SG concept is applicable to any structures and materials featuring heterogeneity and anisotropy including but not limited to composite materials, 3D printed materials, metamaterials, biomaterials, auxetic materials, smart materials, soft materials, etc.

Biographical Sketch: Dr. Wenbin Yu is a Professor in the School of Aeronautics and Astronautics at Purdue University after serving ten years as a faculty at Utah State University. He received his PhD in Aerospace Engineering from Georgia Tech and MS in Engineering Mechanics from Tsinghua University, China. He serves as Director for the Composites Design and Manufacturing HUB (cdmHUB.org), and Associate Director for the Composites Virtual Factory HUB (cvfHUB.org), and is the CTO for AnalySwift LLC (analyswift.com). His expertise is in micromechanics and structural mechanics with applications to composite/smart materials. He has developed several computer codes used today by thousands of researchers and engineers in government labs, universities, research institutes and companies. He is an ASME Fellow and AIAA Associate Fellow. He served as the chair for ASME Structures and Materials Technical Committee and currently serves as the vice chair for AIAA Materials Technical Committee. He serves on the editorial boards of two international journals.

Computational Design Optimization

Abstract: Our ability to manufacture now greatly exceeds our ability to design. Engineers are no longer merely inconvenienced by inefficient trial-and-error design; rather, they are nearly incapacitated by the vast space of possible designs afforded by Advanced Manufacturing (AM) technologies. There are no systematic methods to design systems with such complexity, especially those that exhibit nonlinear, transient, multiscale, and multiphysics phenomena with uncertain behavior.

The opportunity and need to fundamentally transform design is one of the most compelling frontiers of engineering research.  To this end, the Lawrence Livermore National Laboratory’s newly instantiated Center for Design and Optimization is developing algorithms that can optimize immensely complex systems in High Performance Computing (HPC) environments. The complexity comes from two sources, design and physics. Design complexity refers to the intricate shape and material layouts that are made possible by today’s AM technologies; it can take the form of structural composites with intricate morphologies. It also refers to the multifunctional metrics that we optimize, e.g., we maximize electromagnetic response subject to local strength and global mass constraints. And finally, it refers to constraints dictated by the AM processes to ensure manufacturable designs. Physics complexity comes from the mathematical models that are used to predict the performance of our designs. Such models require the solution of partial differential equations that contain complicated nonlinearities, transients, multiple scales, multiple physics, and uncertainties. We iterate through the design space, solving the physics equations using numerical methods. Because our design Degrees-Of-Freedom (DOF) and physics DOF are in excess of 100 million, we must develop efficient, large-scale HPC algorithms. This effort will enable engineers to optimize designs that exhibit unprecedented performance relative to current practice; it is not optional: it is an absolute necessity if we want to drive future innovation.  The work offers immense challenges in engineering, math and HPC.

Biographical Sketch: Daniel A. Tortorelli is the Director for the Center of Design and Optimization at the Lawrence Livermore National Laboratory and the George B. Grim Professor Emeritus at the University of Illinois at Urbana-Champaign (UIUC).  He received his BSME degree from the University of Notre Dame du Lac in 1984 and his MSME and PhD degrees from the UIUC in 1985 and 1988.  His professional career began as senior project engineer for General Motors Advanced Engineering Staff.  In 1990, he embarked on an academic career at UIUC and stayed there until he retired in 2016 to begin his new career at LLNL.

Origami Acoustics and Mechanical Metamaterials: Recent Discoveries with Adaptive Structural and Material Systems for Elastic and Acoustic Wave Propagation Control

Abstract: As form follows function, so shape governs the properties of structural and material systems. Recent studies on adaptive structures have capitalized on these connections to realize unprecedented tunability of system properties and functionality by passive or active transformations of system configuration. This two-part presentation describes integrated theoretical and experimental research efforts that advance these principles to deliver large control over wave propagation properties of adaptive structural and material systems. In the first part, a method is presented that broadly enhances capabilities for acoustic transducer arrays to guide wave energy via harnessing foldable, origami-based tessellations. The foldable arrays enable orders of magnitude change in acoustic energy delivery to points near and far from the surface of the tessellation using shape transformations and without resorting to digital control, and may find future application for instance for medical ultrasound therapy devices transported and deployed in the human body. In the second part of the presentation, strategies to leverage cellular architecture within elastomeric material systems are described that give rise to unusually large elastic wave damping properties. Using this concept, shock energy into the elastomeric metamaterials is found to be dramatically dissipated by tuned pre-compression constraint, and dampened more effectively than the heavier solid elastomer material. This concept is prime for future applications of lightweight personal protective equipment and recoverable shock absorbers. All together, these results encourage ongoing study to probe relations between shape and properties in adaptive structural and material systems to capitalize on potentials for large wave propagation control.

Biographical Sketch: Ryan L. Harne is an Assistant Professor in the Department of Mechanical and Aerospace Engineering at The Ohio State University where he directs the Laboratory of Sound and Vibration Research. Dr. Harne received the Ph.D. degree in Mechanical Engineering at Virginia Tech in 2012. From 2012 to 2015, Dr. Harne was a Research Fellow at the University of Michigan. His research expertise falls in the areas of vibration, acoustics, mechanics, and nonlinear dynamics. The outcomes of his research efforts have included several patents pending, one book, over 40 journal publications, and over 40 conference proceedings, alongside numerous students mentored and guided through their academic programs. Dr. Harne is active in ASME, ASA, and SPIE, where he serves in several elected and appointed roles. Dr. Harne was awarded a 2017 Air Force Research Lab Summer Faculty Fellowship from the Air Force Office of Scientific Research, the 2017 ASME Best Paper Award in Structures and Structural Dynamics, the 2016 Haythornthwaite Young Investigator Award from ASME, and the 2011 ASA Royster Award. He currently serves as an Associate Editor for The Journal of the Acoustical Society of America, Proceedings of Meetings on Acoustics.

Shaping Shells with Swelling

Abstract: Induced by proteins within the cell membrane or by differential growth, heating, or swelling, spontaneous curvatures can drastically affect the morphology of thin bodies and induce mechanical instabilities. In this talk, we aim to describe how the differential swelling of soft materials induces a spontaneous curvature that can dynamically shape materials. The dynamics of fluid movement within elastic networks, and the interplay between swelling and geometry play a crucial role in the morphology of growing tissues, the shrinkage of mud and moss, and the curling of cartilage, leaves, and pine cones. Small volumes of fluid that interact favorably with a material can induce a spontaneous curvature that causes large, dramatic, and geometrically nonlinear deformations and instabilities, yet, the interaction of spontaneous curvature and geometric frustration in curved shells remains still poorly understood. This talk will examine the geometric nonlinearities that occur as slender structures are exposed to a curvature-inducing stimulus – surfaces crease, fibers coalesce and curl apart, plates warp and twist, and shells buckle and snap. I will describe the intricate connection between materials and geometry, and present a straightforward means to permanently morph 2D sheets into 3D shapes. If we can engineer adaptive structures that programmatically morph on command we will enable opportunities for deployable structures, soft robotic arms, mechanical sensors, and rapid-prototyping of 3D elastomers.

Biographical Sketch: Douglas Holmes is an Assistant Professor in the Department of Mechanical Engineering at Boston University.  He received degrees in Chemistry from the University of New Hampshire (B.S. 2004), Polymer Science & Engineering from the University of Massachusetts, Amherst (M.S. 2005, Ph.D. 2009), and was a postdoctoral researcher in Mechanical & Aerospace Engineering at Princeton University. Prior to joining Boston University, he was an Assistant Professor of Engineering Science and Mechanics at Virginia Tech. His group’s research specializes on the mechanics of slender structures, with a focus on understanding and controlling shape change. He received the NSF CAREER Award and the ASEE Ferdinand P. Beer and E. Russell Johnston Jr. Outstanding New Mechanics Educator award.

The Role of Gas Turbines in Global Energy Conversion

Abstract: It has been remarked that “invention is the mother of necessity” – not the other way around. Technology breakthroughs of themselves, can and do create world markets. In a very short period of history, the gas turbine, youngest of major energy conversion devices, has changed and created global markets in aviation, in marine propulsion and in generation of electric power. In this talk we will discuss how in less than 80 years the gas turbine has come to dominate aircraft propulsion and now, global electrical power generation. In 1939, the first gas turbines had a thermal efficiency of about 18%. Over the years, many thousands of engineers and researchers in academia, government and industry have worked to raise turbine inlet temperatures, increase pressure ratios, enhance combustion, perfect new materials and improve designs, so that modern gas turbines now achieve 40-45% in simple cycle operation. In combined cycle operation, the gas turbine has become the thermal efficiency superstar of the electric power plant world, bringing about combined cycle thermal efficiencies exceeding 60%. Today, gas turbine technology and testing improvements continue apace, and some of these will be discussed. Fuel usage is being drastically reduced in newer land-based gas turbines through the first practical use of recuperators and intercoolers. Small gas turbines are now being used to produce electricity from greenhouse gases at municipal waste water treatment plants. A commercial closed cycle helium gas turbine has been proposed to generate electricity, using a pebble bed modular nuclear reactor as a heat source. The engine in production for the F-135 Joint Strike Fighter is pushing the limits of jet engine technology and will lead to future improvements in gas turbine technology.

Biographical Sketch: Lee Langston received a BSME (1959) from the University of Connecticut, and an MS (1960) and a Ph.D. (1964) from Stanford University. He was with Pratt and Whitney Aircraft as a research engineer working on fuel cells, heat pipes and jet engines from 1964 to 1977. During these years, he also participated in mountain climbing activities in various parts of the world. He joined the mechanical engineering faculty at the University of Connecticut in 1977, rising to the rank of Professor in 1983. At UConn, he has taught graduate and undergraduate courses in heat transfer and fluid mechanics, with research activities involving the measurement, understanding and prediction of secondary flows in gas turbines. He served as Interim Dean of the School of Engineering in 1997-98 and became Professor Emeritus in 2003. He is a Life Fellow of the American Society of Mechanical Engineering Engineers (ASME), has served as Editor, ASME Journal of Engineering for Gas Turbines and Power (2001-2006) and was a member of the Board of Directors of the ASME International Gas Turbine Institute (IGTI). In 2015, he was the recipient of IGTI’s R. Tom Sawyer Award, for outstanding contributions in the field of gas turbines. For the past seventeen years Professor Langston has written a column and a variety of articles on gas turbine technology for IGTI and ASME’s Mechanical Engineering Magazine.