1. Graduate Student, College of Mechanics and Materials, Hohai Univ., 8 Focheng Xilu, Nanjing 211100, PR China.
2. Researcher, China Yangtze Power Co., Ltd., Tan Nan Rd., Beijing, PR China.
3. Professor, College of Mechanics and Materials, Hohai Univ., 8 Focheng Xilu, Nanjing 211100, PR China (corresponding author).