[1] Penn State Univ, Dept Engn Sci & Mech, 227 Hammond Bldg, University Pk, PA 16802 USA
[2] Purdue Univ, Sch Mech Engn, W Lafayette, IN 47907 USA
[3] Georgia Inst Technol, Woodruff Sch Mech Engn, Atlanta, GA 30332 USA
[4] MIT, Dept Nucl Sci & Engn, 77 Massachusetts Ave, Cambridge, MA 02139 USA
[5] MIT, Dept Mat Sci & Engn, Cambridge, MA 02139 USA