The Ohio State University

Abstract:
Measurement of the mechanical properties of bone is important for estimating the stresses and strains due to loading experienced on a macro-scale. Nano- and micro-mechanical properties of bone are also of interest to the pharmaceutical industry, when drug therapies have intentional or non-intentional effects on bone mineral density and strength. The interactions that can occur between nano- and micro-indentation creep test condition parameters were considered in this study, and average hardness and elastic modulus were obtained as a function of indentation test conditions (maximum load, load/unload rate, and load-holding time). The results suggest that the measured indentation response of bone changes when indentation load increases from the nano- to the micro-scale range (N to N), which was measured using both low- and high-load indentation testing systems. A four-parameter visco-elastic/plastic constitutive model was then applied to simulate the indentation load vs. depth response over both load ranges. Good agreement between the experimental data and finite element model was obtained when simulating the visco-elastic/plastic response of bone. The results highlight the complexity of bone as a biological tissue and the need to understand the impact of testing conditions on the measured results.

Bio:
Timothy Ovaert is currently a professor of Aerospace and Mechanical Engineering at the University of Notre Dame. Prior to joining Notre Dame, he was a professor in the Department of Mechanical and Nuclear Engineering at Penn State. Dr. Ovaert also worked in industry as a plant engineer for the DuraBar Division of Wells Manufacturing. He received his BSME degree from the University of Illinois; and Master of Engineering Management and Ph.D. degrees from Northwestern University. He has been active in research from both government and industry sources, including a National Young Investigator Award from NSF. He is a Fellow of ASME and the recipient of its Burt L. Newkirk award. Dr. Ovaert is also the recipient of the Ralph Teetor Award from SAE. He is outgoing Chair of the 2007 ASME/STLE International Joint Tribology Conference, a member of the ASME Research Committee on Tribology, and a past associate editor of the Journal of Tribology. He currently teaches courses in mechanical design, continuum mechanics, heat transfer, solid mechanics, tribology, reliability, and experimental methods. Dr. Ovaert's research interests include nano-mechanical characterization, biomechanics, orthopaedic tribology, cartilage-friendly biomaterials development, and manufacturing.

Hosted by Professor Bharat Bhusan, 292-0651, bhusan.2@osu.edu
For information on ME 888 seminars contact Professor Walter Lempert at 292-2736 or lempert.1@osu.edu.