Mechanical Engineering-Engineering Mechanics News

Thursday March 22, 2012 4:00-5:00 p.m.
ME-EM building, Room 112

Greg McKenna
Horn Professor, Department of Chemical Engineering, Texas Tech University

Dr. Gregory B. McKenna has a reputation as a pioneering researcher in four areas of polymer and plastics science and technology: Physical Aging and Structural Recovery of Polymer Glasses, Solid Mechanics and Nonlinear Viscoelasticity of Polymers, Thermodynamics and Mechanics of Elastomers and Gels, Molecular Rheology.

He received his Bachelor’s in Engineering Mechanics at the U.S. Air Force Academy, and his MS in the area of composite materials from MIT. He entered active duty as a test and evaluation engineer at Hill Air Force Base in Ogden, Utah. In 1976 he received his Ph.D. in Materials Science and Engineering at the University of Utah. Dr. McKenna started at the National Bureau of Standards (now called NIST) as a National Research Council Postdoc and accepted a permanent position as a staff scientist in 1977. He served
as the head of the Structure and Mechanics Group in the Polymers Division at NIST from 1992-99. In 1989 Dr. McKenna became a Fellow of the American Physical Society and was the recipient of the NIST E.U. Condon Award for excellence in technical exposition for his classic review article “Glass Formation and Glassy Behavior.”

In 1998, he was elected a Fellow of the Society of Plastics Engineers.
After NIST, he joined Texas Tech University as a Professor in the Department of Chemical Engineering and the John R. Bradford Endowed Chair in Engineering. In 2005 he became a Paul Whitfield Horn Professor at TTU.

He is the 2009 recipient of the Bingham Medal of the Society of Rheology, has received the International Award of the Society of Plastics Engineers, and the Mettler Toledo Award from the North American Thermal Analysis Society. He served on the Governing Board of the American Institute of Physics, the Executive Committees of the
Society of Rheology and The Division of High Polymer Physics (DHPP) of the American Physical Society. He was the Chairman of the DHPP, the Society of Engineering Science, and the Polymer Analysis Division of the Society of Plastics Engineers. Currently he is vice-president of the Society of Rheology.

Title: Using Mechanics to Interrogate the Physics of Soft Matter:
From the Glassy to the Rubbery States and from the Macro-scale to the Nano-scale

Abstract: Mechanical measurements offer a unique means of interrogating the physics of am orphous glass-formers and rubbery polymers. Here we present several vignettes to demonstrate the ability of both classical and novel rheological experiments to resolve important questions in condensed matter physics. First, results from torque and normal force measurements aimed at understanding the thermodynamics and m echanics of polymer networks in both dry and swollen states are presented. In particular, we examine the validity of the Frenkel-Flory-Rehner theory of rubber network swelling. Torsion and normal force measurements are also described for a series of polymeric glasses that exhibit similar shear moduli but, surprisingly, very different normal force responses, with one set of materials showing extreme deviations from neo-Hookean behavior and the other being close to neo-Hookean. We then describe the use of a novel torsional dilatometer, which allows simultaneous m easurement of mechanical properties and volume recovery, to investigate the aging and rejuvenation behaviors of glassy polymers.

The temperature dependence of dynamics is probed in glassy polymers that have been aged into equilibrium below the nom inal glass transition temperature and evidence is presented that time-scale divergence m ay not be a true signature of the glass transition itself. Finally, we describe a reduction in scale of the classical m embrane inflation test to allow measurement of the biaxial creep compliance of nanometer thick polymeric films using an atomic force microscope. In each instance em phasis is placed on how the measurements are designed to interrogate the physics of interest in the materials investigated.

http://www.me.mtu.edu/seminars/2011-12/mar15.pdf
Thursday March 15, 2012 4:00-5:00 p.m.
ME-EM building, Room 112
Professor Jon Pharoah, Associate Director -RMC Fuel Cell Research Centre, Queen’s University, Kingston, Ontario, Canada will give a presentation entitled ‘Fuel Cells and Renewable Energy … and Multi-Scale Modelling of Solid Oxide Fuel Cell’ For more information on the ME-EM Graduate Seminar Series visit http://www.me.mtu.edu/seminars/

Abstract
Fuel cells of various types are firmly in the initial stages of commercialization. Phosphoric acid fuel cells have been deployed in the 250 kW range in a vast array of stationary power applications. Molten carbonate fuel cells have also been deployed in capacities from 250 kW to several MW and are fueled by either natural gas or bio gas. Solid oxide fuel cells have been deployed, again for stationary power in the 100 kW size and commercial products have demonstrated AC efficiencies in excess of 60% fueled on natural gas in units as small as 1 kW. Polymer electrolyte fuel cells have also been deployed up to capacities of 1 MW for stationary power. For mobility applications, most leading automotive companies are very close to commercial fuel cell vehicles, and virtually all of them claim that fuel cells are the only technology that can replace existing vehicles with zero emissions and the same functionality. The same fuel cells are operating in the entire fleet of transit buses in the city of Whistler, Canada, where they were introduced for the 2010 winter olympics. Smaller versions of the same fuel cells are continuing to replace lead acid batteries in forklift trucks for distribution centres, and the technology has been clearly demonstrated to give twice the talk time on a mobile phone compared to the current lithium ion battery pack. It is clear that fuel cells are well on their way to commercialization and they will continue to succeed due to their very high efficiencies and zero to low emissions. Fuel cells are also major enablers for the large scale implementation of renewable energy. Most types of fuel cells can be fueled with hydrogen, while some types require hydrogen as a fuel. Hydrogen is an ideal fuel in the sense that it can be produced from many different sources and pathways can be produced locally virtually anywhere results in noemissions at the point of use and is typically used at very high efficiency. It can be reformed from fossil fuels (with corresponding emissions of carbon dioxide), or it can be produced through the electrolysis of water using any available source of electricity. It can be used for remote electricity applications, grid energy applications and as a transportation fuel. The versatility of hydrogen open up several important possibilities for renewable energy systems as well as for utility companies. Conventional renewable energy is predominantly either wind or solar, both if which suffer from severe intermittency and a lack of predictability. When the penetration of these technologies is small, this is not a problem since the electricity grid can absorb the power when it is available and it is not overly missed when it is not. As the level of penetration exceeds around 10% of the energy mix, major problems begin to arise and typically energy grids become more costly to run and often have higher emissions. Fuel cells offer a way to increase the penetration while potentially reducing the cost of the system and certainly the emissions. When excess electricity is available from renewables, hydrogen can be produced and stored and when electricity is needed, this hydrogen can be used to generate electricity. Very few technologies have this general capability on the scale that is needed for grid storage. Hydrogen, however can also be used as chemical fuel or feed, which opens up enormous opportunities for utilities.

Mar 1 Mechanical Engineering–Engineering Mechanics Graduate Seminar: Mr. Zachary Folcik from the Massachusetts Institute of Technology Lincoln Laboratory will give a presentation entitled ‘Predicting Close Approaches in Geosynchronous Orbit’ on Thursday, March 1 at 4:00PM in 112 MEEM.  Seminar poster http://www.meem.mtu.edu/seminar/2011-12/mar01.pdf

Mr. Folcik ha s been a staff member at MIT Lincoln Laboratory since 2000. Mr. Folcik has a Bachelor’s degree in Computer Science from Michigan Technological University and a Master’s degree in Aeronautics and Astronautics from the Massachusetts Institute of Technology. His work has focused on problems in orbit estimation, orbit modeling, observation association, satellite maneuver detection and optimal thrust planning.

Earth orbit has become a crowded environment. The risk of satellite collisions has become a real issue in low earth and geosynchronous orbit. This seminar introduces the current space environment, collision risk assessment and a program at MIT Lincoln Laboratory to mitigate collision risks in geosynchronous orbit. Research and development efforts to improve satellite orbit estimates and uncertainty knowledge will also be discussed.

Donggang Yao, professor from the School of Materials Science and Engineering at Georgia Institute of Technology, will give a presentation, “General Maxwell Model with Logarithmic Strain Measurements,” at 4 p.m., Thursday, Feb. 16, in ME-EM 112.

More information: General Maxwell Model with Logarithmic Strain Measurements