Report Topic: Effect of Gradation and Particle Shape on the Behavior of Binary Mixtures

Reporter: Prof.Tang-Tat Ng,University of New Mexico

Time: 10:00 am, Jun 29, 2015

Location: Academic hall of state key laboratory

Discrete element method is used to carry out triaxial compression simulations on binary granular mixtures. This granular material contains two types of ellipsoids (large and small particles). The small and large ellipsoids are similar but different sizes. The size ratio of the major-axis between the large and small ellipsoids is 5. Samples are characterized by the particle shape and fine content (volume fraction of the small particles). They are created by the particle growth method instead of the commonly used pluviation method to avoid particle segregation. These created samples are at the densest state (the lowest void ratio). The initial void ratio of the sample is influenced by particle shape and fine content. These very dense samples are then sheared under drained triaxial compression loading to very large strain. Peak shear strength, critical void ratio, and ultimate shear strength are obtained. Peak shear strength is affected by particle shape but just slightly affected by fine content. Critical void ratio is a function of fine content but not particle shape. The ultimate shear strength of the binary mixture is independent on particle shape and fine content.
Professor Tang-Tat Ng, a Fellow of the American Society of Civil Engineers, received B.S. degree from National Taiwan University, M.S. degree from Carnegie Mellon University, and Ph.D. degree from Rensselaer Polytechnic Institute.All degrees are in Civil Engineering.Dr. Ng jointed the Department of Civil Engineering, University of New Mexico since 1990. Currently, he holds the rank of Full Professor. Dr. Ng has also served as a Senior Research Scientist at the United States Air Force Research Laboratory.He is a registered professional engineer in the State of New Mexico.
Dr. Ng current research focuses on nondestructive testing of unknown deep foundations, computational geomechanics, and micromechanics of granular materials.He is a nationally recognized leader in the field of computational micromechanics of granular materials.Dr. Ng has more than83peer reviewed scientific publications. Hehas delivered the keynote lecture to the Hong Kong Society of Theoretical and Applied Mechanics. Dr. Ng is the holder of Chutian Metropolis Scholar Professorat the Wuhan University. He was the past LuoJia Chair Professor and the past president of the New Mexico Chapter of the Chinese Institute of Engineers, USA. Currently, Dr. Ng serves on serveral national committees of professional societies and on several editorial boards of engineering and science journals.