1. Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
2. Department of Civil and Environmental Engineering, and Department of Mechanical Engineering; Northwestern University; Evanston IL 60208 USA
3. Center for Mechanics and Materials; Tsinghua University; Beijing 100084 China
4. College of Mechanical Engineering; Yanshan University; Qinhuangdao 066004 China
5. Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health and Skin Disease Research Center; Northwestern University; Evanston IL 60208 USA
6. Department of Materials Science and Engineering Chemistry, Mechanical Science and Engineering, Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology and Frederick Seitz Materials, Research Laboratory; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA