Clarkson University Professors Issen and Rengaswamy Join CAMP
Dr. Kathleen Issen joined the Department of Mechanical and Aeronautical Engineering at Clarkson University in 2000. She received her B.S. in General Engineering from the University of Illinois in 1983, and worked in industry for 14 years, prior to obtaining her M.S. and Ph.D. in Theoretical and Applied Mechanics from Northwestern University (1997 and 2000, respectively). Her doctoral studies focused on developing constitutive models and applying bifurcation theory to investigate conditions for compaction localization in porous sandstone.
Professor Issen’s current research involves constitutive modeling and experimental characterization of natural and manufactured porous materials, such as metal foams, honeycombs, cancellous bone, and porous sandstone. Understanding the behavior of natural materials, such as cancellous bone, where the microstructure evolves in response to load, will enable development of improved microstructures for manufactured materials.
Figure 5. Accumulated Axial Surface Strain (%).
Attaching physical strain measurement devices to porous materials is often problematic. Additionally, irregular pore structures induce non-uniform deformation under mechanical loading, which is difficult to fully characterize with discrete strain measurement devices. Therefore, a full field, non-contact method, digital image correlation (DIC), is used. During mechanical testing, digital images of the specimen are acquired at regular time steps. Prior to testing, specimens are painted with black and white speckles. After testing, DIC software (Correlated Solutions, Inc.) is used to determine surface displacements and strains. This is accomplished by finding the optimal match between the light intensity patterns, reflected from subsets of speckles, in the original and deformed images. Thus, the motion of each subset of speckles is determined, and local surface displacements and strains are calculated. Sample results are given in Figure 5, which shows contour plots of axial strain (positive in compression) for two adjacent faces of an aluminum foam specimen under uniaxial compression. The dark regions represent intense axial compaction, corresponding to formation of a through-going collapse band.
DIC techniques can determine full field surface deformations for any material or structure, which has a natural or applied surface pattern that reflects different light intensities, and can be photographed before and after deformation. Thus, DIC is applicable to many types of inhomogeneous deformation, including crack propagation and strain concentrations in complex geometries.
Professor Raghunathan Rengaswamy is an Associate Professor of Chemical Engineering at Clarkson University. He received his Ph.D. in Chemical Engineering from Purdue University in 1995, and B. Tech. in Chemical Engineering from the IIT Madras, India, in 1990. He served as a Visiting Professor at the University of Delaware (summer of 1999), Purdue University (Jan-Dec, 2001), and the University of Alberta (summer of 2002).
Professor Rengaswamy works in the areas of fuel cells and process systems engineering with his graduate students at Clarkson University. A major research focus of his group is on modeling, optimization, diagnostics and control of Proton Exchange Membrane and Solid Oxide Fuel Cells.
Detailed models have been developed to predict the performance of Tubular Solid Oxide Fuel Cells and the models are currently being used in optimization studies. In the area of PEM Fuel Cells, in collaboration with Professor Campbell, layered Membrane Electrode Assemblies (MEAs) with differential platinum loading are being synthesized. This is expected to result in reduced platinum usage in the electrodes. Composite membranes that can operate at higher temperatures are also being developed for PEMFC applications. A NYSERDA project on in-situ diagnostics of PEMFC stacks uses advanced signal processing algorithms for identifying operational problems. This work is being validated on a four cell stack. The research work on fuel cells is supported with data and funding from NYSERDA and various companies. Another NYSERDA project, in collaboration with Professor Campbell, deals with the control of temperature profile during injection molding for improved part production. The screw speed and the back-pressure are automatically set to achieve a desired temperature profile. This is expected to result in decreased scrap production and improved quality. Several multivariable, nonlinear control applications have been demonstrated in Professor Rengaswamy’s lab.
Professor Rengaswamy has published several refereed journal and conference papers, and delivered invited lectures in universities and industries. He has been a consultant to companies such as ABB and Invensys, India. Professor Rengaswamy was the recipient of the Young Engineer Award for the year 2000 awarded by the Indian National Academy of Engineering (INAE) for outstanding engineers under the age of 32. He guided a BS project “Qualitative Simulation in Process Engineering” that won an award as one of the most innovative theses at the Bachelor’s level (all disciplines) awarded by INAE. His paper on fault diagnosis was awarded the CAST Directors’ Award for the Best Poster Presentation at the AIChE Annual meeting in Los Angeles, Nov. 2000. A news item “Networking Sensors – No Easy Task” was published on his work on sensor network design in the newsletter Inside R&D published by John Wiley & Sons, NY in 2000. He was a keynote speaker at the 4th International Federation of Automatic Control (IFAC) workshop on “On-line Fault Detection and Supervision in the Chemical Process Industries” held in Korea, 2001. He was chosen by the students of Chemical Engineering at Clarkson as the Professor of the Year in 2003. A paper that he co-authored was chosen by the International Federation of Automatic Control (IFAC) for the Best Paper Prize, for the years 2002-2005, in the Engineering Applications of Artificial Intelligence Journal in the category, Application-oriented paper on Symbolic AI Approaches. A paper that he co-authored was also judged as the best paper of the session in the American Control Conference (ACC) in Boston, 2004. His research is funded by federal and state agencies like the NSF, ACS-PRF, NYSERDA and companies such as Honeywell, NanoDynamics and KBR.