1. Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street MC-244, Urbana, Illinois 61801, USA
2. Aerospace Engineering, University of Illinois at Urbana-Champaign, 104 S. Wright St. MC-236, Urbana, Illinois 61801, USA
3. Materials Research Laboratory, University of Illinois at Urbana-Champaign, 104 S. Goodwin Ave. MC-230, Urbana, Illinois 61801, USA