1. Department of Design, Manufacture and Engineering Management, University of Strathclyde, Glasgow G1 1XQ, Scotland, UK
2. Department of Engineering Mechanics, Chongqing University, Chongqing 400044, P. R. China
3. WPI Research Center, Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan