Abstract: Ionic solids are important for electronic and energy storage/conversion devices. Examples include ferroelectrics and solid oxides. Defects in these materials play a central role in enabling their properties: for example, the electromechanics of ferroelectrics occurs by the nucleation and growth of domain wall defects, and solid oxide ionic conduction is through the motion of point defects. I will talk about our efforts to develop multiscale atomistic methods to understand the structure of defects in these materials. The central challenge is the long-range nature of the electrostatic interactions coupled with the nonlinearity of the short-range interactions.

 

Biographical Sketch: Kaushik Dayal is Professor of Engineering at Carnegie Mellon University. He received his B.Tech. at the Indian Institute of Technology Madras and his M.S. and Ph.D. in Mechanical Engineering at Caltech. His research interests are in the area of theoretical and computational multiscale methods applied to functional materials and electromagnetic effects. His research has been recognized by young investigator awards from ARO, AFOSR and NSF, the Eshelby and Leonardo da Vinci medals, and the Carnegie Institute Early Career Fellowship. He has held visiting appointments at the University of Bath, University of Bonn, National Energy Technology Laboratory and Air Force Research Laboratory.

 

Abstract: More than 1.5 million people undergo bone graft procedures annually in the US to repair bone defects that will not heal spontaneously. These defects severely decrease the quality of life and are an economic burden to those affected and to the health care system. The already considerable demand for treatment is growing rapidly as the population ages and life expectancy increases. Allograft and autograft simply cannot adequately address the growing demand. The biggest technical and scientific challenge in treating these defects is in achieving complete osteointegration. There are promising approaches that combine scaffolds with exogenous cells and growth factors; however, these approaches are complex, expensive, and are still often considered to be too risky to the patient. New approaches that are safe, can be implemented in the near-term, and that could be applied to a range of scaffolds, and potentially even allografts, are needed.  My research group focuses on manufacture, design, characterization, and application of CaP scaffolds with multiscale porosity.  Our approach is to use capillary action to self-seed, or impregnate, CaP scaffolds that have multiscale porosity. We hypothesized that capillary force driven self-seeding would enhance bone regeneration. In vitro studies and a mathematical model showed that the micropore-generated capillarity generated was sufficient to draw in cells.  Further, the penetration depth was dependent on cell size and stiffness, with some cell types penetrating further than others.  In the subsequent in vivo study, samples that used capillarity, i.e. dry samples, were implanted and compared to two groups:  wet and non-microporous (NMP).  Wet samples were infiltrated with PBS prior to implantation such that they could not make use of capillarity.  NMP samples did not contain microporosity and therefore had reduced capillarity. After three weeks, the average volume fraction of bone for all groups was the same across groups. However, the distribution of bone and the depth of bone growth were significantly better for dry samples compared to wet and NMP.  The results have important implications in scaffold design, and use of this mechanism will help to address the challenge of repair of critical size bone defects in scaffold-based bone repair. Further, it will do so without the use of growth factors or exogenous cells.

Biographical Sketch: Professor Amy Wagoner Johnson is an Associate Professor in the Department of Mechanical Science and Engineering (MechSE) at the University of Illinois at Urbana-Champaign, an inaugural faculty member of the new Carle Illinois College of Medicine, and a Chair of Excellence with the NanoSciences Foundation (Grenoble, France). Her research focuses on biomaterials and biomechanics, including soft tissue related mechanics to preterm birth and microstructural cues in CaP-based materials for bone regeneration. She received her BS in Materials Science and Engineering from The Ohio State University, and PhD in Engineering from Brown University in 2002 with major in materials science and minor in solid mechanics.  She joined University of Illinois in 2001 as research faculty, became an Assistant Professor in 2005, and Associate Professor in 2012.  She is currently a part-time faculty member of the Beckman Institute for Advanced Science and Technology, and has affiliations with the Department of Bioengineering, and Institute for Genomic Biology, where she is a Core Member of the Regenerative Biology and Tissue Engineering Theme.

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.

 

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.

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.