GONG Zhi-hui1,2,LI Lin1,ZHOU Shun-feng1,LAN Zhi-chun1
(1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan Univ, Changsha, Hunan410082, China; 2. Key Laboratory of Manufacture and Test Techniques for Automobile Parts of Ministry of Education, Chongqing Univ of Technology, Chongqing400054, China)