1. Research Fellow, Protection Technology and Research Center, School of Civil and Environmental Engineering, Nanyang Technological Univ., 50 Nanyang Ave., Singapore 639798; and Group Manager, Dept. Safety Technology and Protective Structures, Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, Am Klingelberg 1, D-79588 Efringen-Kirchen, Germany.
2. Research Associate, Dept. Safety Technology and Protective Structures, Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, Am Klingelberg 1, D-79588 Efringen-Kirchen, Germany.
3. Group Manager, Dept. Safety Technology and Protective Structures, Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, Am Klingelberg 1, D-79588 Efringen-Kirchen, Germany (corresponding author).
4. Professor, Protection Technology and Research Center, School of Civil and Environmental Engineering, Nanyang Technological Univ., 50 Nanyang Ave., Singapore 639798.
5. Professor, Dept. Safety Technology and Protective Structures, Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, Am Klingelberg 1, D-79588 Efringen-Kirchen, Germany.