1. School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
2. Singapore Institute of Manufacturing Technology, Singapore 638075, Singapore
3. School of Mechanical and Power Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, P. R. China
4. Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P. R. China