1. College of Science, Chang’an University, Xi’an 710064, China
2. School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi’an 710072, China
3. Key Laboratory of Mechanics on Disaster and Environment in Western China Attached to the Ministry of Education of China, and Department of Mechanics and Engineering Sciences, Lanzhou University, Lanzhou 730000, China
4. School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, P. R. China