1. Departments of Civil and Environmental Engineering and Mechanical Engineering; Northwestern University; Evanston Illinois 60208 USA
2. Center for Mechanics and Materials; Tsinghua University; Beijing 100084 China
3. Department of Materials Science and Engineering; Frederick Seitz Materials Research Laboratory; University of Illinois at Urbana-Champaign; Urbana Illinois 61801 USA
4. College of Mechanical Engineering; Yanshan University; Qinhuangdao 066004 China
5. Department of Electronic Engineering; Pusan National University; Busandaehak-ro 63beon-gil Geumjeong-gu Busan 609-735 Republic of Korea
6. AML, Department of Engineering Mechanics; Tsinghua University; Beijing 100084 China
7. Department of Materials Science and Engineering; Chemistry, Mechanical Science and Engineering; Electrical and Computer Engineering; Beckman Institute for Advanced Science and Technology; University of Illinois at Urbana-Champaign; Urbana Illinois 61801 USA
8. Center for Engineering and Health and Skin Disease Research Center; Northwestern University; Evanston IL 60208 USA