Structural Testing at Micro and Nano Scales

Civil & Urban Engineering Lunch Seminar

STRUCTURAL TESTING AT THE MICRO AND NANO SCALES:
BREAKING INVISIBLE SPECIMENS WITH ZERO FORCE

Roberto Ballarini, PhD, PE, F.ASCE, F.EMI
Thomas and Laura Hsu Professor and Chair
Department of Civil and Environmental Engineering
University of Houston

Prof. Ballarini will describe how a bunch of clever and hardworking students and research associates have pioneered the use of microelectromechanical systems (MEMS) platforms to measure the mechanical response of materials and structures at the micro and nano scales. Selected examples include measurements of strength, toughness, high cycle and static fatigue of brittle MEMS materials, the strength, ultimate strain capacity and viscoelastic response of individual collagen fibrils, and the
fracture energy of the carbon nanotube-epoxy matrix interface. A brief description of several the theoretical and computational models that were inspired by the experimental observations will also be presented.

Dr. Roberto Ballarini is Thomas and Laura Hsu Professor and Chair of the Civil and Environmental Department at the University of Houston. He formerly served as James L. Record Professor and Head of the Department of Civil Engineering at University of Minnesota, Leonard Case Professor of Engineering at Case Western Reserve University, and F.W. Olin Professor of Mechanical Engineering at the Franklin W. Olin College of Engineering. Ballarini’s multidisciplinary research focuses on the development and application of theoretical, computational and experimental techniques to characterize the response of materials to mechanical, thermal, and environmental loads. He is particularly interested in formulating analytical and computational models for characterizing fatigue and fracture of materials and structures. Ballarini’s research has been applied to problems arising in civil engineering, mechanical and aerospace engineering, materials science, microelectromechanical systems, biological tissues and prosthetic design. He has published more than one hundred papers in refereed journals, including Science and Nature, and several of his research projects have been featured in the popular press, including the New York Times Science Times, American Scientist, Business Week, Financial Times, and Geo. Ballarini’s current research involves bioinspired design of damage tolerant composites; reliability of microelectromechanical systems (MEMS) devices; structural testing of nanoscale biological and synthetic materials such as collagen fibrils, carbon nanotubes and MEMS materials; computational materials science; multiscale modeling of heterogeneous materials; time dependent progressive collapse of concrete structures; the design and testing of a new earthquake energy dissipation system for steel structures; size effects in quasibrittle materials; statistical strength distributions in glass and other types of ceramics; theoretical modeling of fiber reinforced plastics for repair of cracked structures; and fracture mechanics- based design of pavements. Ballarini is Past-President of the ASCE Engineering Mechanics Institute and currently serves as Editor of ASCE Journal of Engineering Mechanics. He was the recipient of the Case Western Reserve University-wide John S. Diekhoff Award for Distinguished Graduate Teaching, and was nominated for numerous undergraduate teaching awards.