1. School of Mechanical Engineering, Yanshan University, Qinhuangdao, P. R. China
2. Aviation Key Laboratory of Science and Technology on Generic Technology of Self-Lubricating Spherical Plain Bearing, Yanshan University, Qinhuangdao, P. R. China
3. ETDZ, Qinhuangdao, P. R. China
4. Department of Mechanical Engineering, School of Civil and Mechanical Engineering, Curtin University, Perth, WA, Australia