1. College of Mechanical and Electrical Engineering, Hohai University, Changzhou 213022, P. R. China
2. National Engineering Research Center for Intelligent, Electrical Vehicle Power System School of Mechanical and Electrical Engineering, Qingdao University, Qingdao 266071, P. R. China
3. Institute of Mechanics for Multifunctional Materials and Structures, Qingdao University, Qingdao 266071, P. R. China