1. Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, P. R. China
2. Institute of Systems Engineering, China Academy of Engineering Physics, Mianyang Sichuan 621999, P. R. China
3. Shock and Vibration of Engineering, Materials and Structure Key Laboratory of Sichuan Province, Mianyang Sichuan 621999, P. R. China