Stress Wave Propagation through Porous Media: Can Biot’s Theory Be Verified?
Smart Materials and Systems Seminar Series
Professor Yiannis Andreopoulos
Department of Mechanical Engineering
The City College of New York
Results of a research program designed to investigate the interaction of shock waves with monolithic, composite, porous or nano-structured materials will be presented. The response of these materials to high-strain-rate effects caused by the associated shock loading is different. The presentation will focus on the challenging problem of shock wave propagation in porous materials which has been investigated experimentally in a shock tube facility. Short length porous specimens have been placed in front of a long cylindrical rod and they have been impacted with shock waves of various strengths and impulse. As a result of the interaction between the wave and the porous material reflected and diffracted waves are propagating in the solid and gaseous phases of the material which subsequently impinge on the solid rod. The gas phase pressure behind the transmitted wave increases significantly which is expected to increase the strain measured on the rod at various locations. The stress signals are decomposed into low and high frequency contributions and their relation to Biot’s fast and slow waves has been investigated. The transmitted stress depends on the grain morphology of the porous material and wave cancellation has been observed to cause reduction in the transmitted stress.
About the Speaker
Dr. Andreopoulos is the Michael Professor of Energy Research of the Grove School of Engineering
at CCNY. He holds an Engineering Diploma (Dipl.-Ing) in Mechanical and Electrical Engineering from the National Technical University in Athens, Greece, a MSc (Aeronautics) from London University in England, a Diploma of Imperial College degree (DIC) and a PhD in aeronautical engineering from Imperial College of Science, Technology and Medicine of London University, UK. He has extensive experience in laser techniques and optical methods acquired during postdoc research appointments at the University of Karlsruhe, Germany, and at Princeton University. Dr. Andreopoulos’ research expertise is in the areas of fluid dynamics which impact transportation, manufacturing, medicine, biology, energy, the environment, and defense and homeland security. His more than 100 refereed publications have been cited more than 1000 times in the literature. He is a member of two editorial boards of two engineering journals and he is an Associate Fellow of the American Institute of Aeronautics and Astronautics and a Fellow of the American Society of Mechanical Engineers. In 2008 he received the Charles Sharpe Beecher Prize of the Aerospace Industries Divisional Board of the Institute of Mechanical Engineers, UK.