1. School of Mechanical Engineering, Yanshan University, Qinhuangdao, China
2. Aviation Key Laboratory of Science and Technology on Generic Technology of Self-lubricating Spherical Plain Bearing, Yanshan University, Qinhuangdao, China
3. Department of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao, China
4. School of Physics and Physical Engineering, Qufu Normal University, Qufu, China