1. Department of Mechanics, Beijing Jiaotong University , Beijing 100044, China
2. Department of Mechanics, Beijing Jiaotong University , Beijing 100044, China ; , Tianjin 300350, China
3. Department of Mechanics, Tianjin University , Beijing 100044, China ; , Tianjin 300350, China
4. Department of Mechanics, Tianjin University , Tianjin 300350, China