1. Theoretical and Applied Mechanics Group, Department of Mechanical Engineering and Mechanics, Drexel University, 2991 W. School House. Ln., Apt. PW21, Philadelphia, PA 19144
2. National Center for Supercomputing Applications; Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
3. Theoretical and Applied Mechanics Group, Department of Mechanical Engineering and Mechanics, Drexel University, 3141 Chestnut St., Philadelphia, PA 19104 e-mail: