1. School of Astronautics, Harbin Institute of Technology, Harbin, China
2. College of Aerospace and Civil Engineering, Harbin Engineering University, Harbin, China
3. Department of Civil Engineering, University of Siegen, Siegen, Germany
4. Dynamics and Vibrations Group, Institute of Numerical Methods in Mechanical Engineering, Technische Universität Darmstadt, Darmstadt, Germany