1. Department of Mechanical, Materials Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221
2. Division of Applied Mechanics, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993
3. Fellow ASME Department of Mechanical, Materials Engineering, College of Engineering and Applied Science, University of Cincinnati, 593 Rhodes Hall, ML 0072, Cincinnati, OH 45221 e-mail: