1. Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, Ontario K1S5B6, Canada
2. Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, Minnesota 55455, USA
3. Center for Materials Physics and Technology, Naval research Laboratory, Washington, DC 20375, USA
4. STI IGM LAMMM, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne, Switzerland