Seminar: Dr. Zhang and Dr. Tao from Northwestern Polytechnical University in China
Dr. Chao Zhang and Dr. Suo Tao from Northwestern Polytechnical University, China
1.18 LT, Queen’s Building, University of Bristol
Dr. Chao Zhang and Dr. Suo Tao, from the Northwestern Polytechnical University (NPU) in Xi'an, China, will give guest lectures at the University of Bristol on 13 September 2019.
The aim of this visit is to encourage collaboration between Bristol and NPU. Everyone within the University is warmly welcome to attend the seminar.
Mechanical-thermal-chemical coupling behavior of the 2D C/SiC composites under dynamic loading
Dr. Tao Suo, Northwestern Polytechnical University (NPU), China
Thermal structural materials such as ceramics, ceramic matrix composites and super alloys have been widely used in structures of hypersonic vehicles and aero engines, which usually bear extremely high temperatures. They are may be subjected to severe circumstances such as the impact of space debris or inhaled debris inside the engine, and in some cases, they are even accompanied by high temperature. Therefore, full understanding of their dynamic mechanical behaviour at high temperatures is of great importance for structural safety design under anti-impact loading. In the present work, an experimental method for measuring dynamic behaviour of materials with in-situ experimental technique at high temperatures (up to 1600°C) was developed. Based on this method, compressive tests were carried out on 2D C/SiC composites at different strain rates (10-3 /s and 103 /s) and temperatures (from 20°C to 1600 °C). The effects of strain rate and temperature on the mechanical-thermal-chemical coupling behaviour of the material were investigated based on experimental results and micro observations.
Suo Tao is a Professor in the School of Aeronautics, Northwestern Polytechnical University (NPU) in China. He is also the vice-leader of National Joint International Research Laboratory of Impact Dynamics and its Engineering Application (IDEA) and the vice-leader of Shaanxi Key Laboratory of Impact Dynamics and its Engineering Application. He obtained his Bachelor's degree in Flight Vehicle Design and Engineering, and Master's and PhD in Solid Mechanics from NPU in 2009. Subsequently, he worked as a lecturer at NPU and became an Associate Professor in 2010 and Professor in 2013. In 2012, he worked as a visiting professor at the Johns Hopkins University in USA.
His current research interests include mechanical behaviour of advanced materials, dynamic behaviour and failure evolution of materials under impact loading, and analysis, design and verification of aircraft structures under impact loading. He has co-authored more than 100 papers in peer-reviewed international journals. His research accomplishments are recognized through the Young Yangtze River Scholar from Chinese Ministry of Education, New Century Excellent Talent Award from Chinese Ministry of Education, Award for Excellent Young Scholar from National Science Foundation of China. He is now a committeeman of Experimental Mechanics Committee in Chinese Society of Mechanics, committeeman of Structure and Strength in Chinese Society of Aeronautics, and editor of four Chinese journals.
Dynamic interlaminar fracture of unidirectional composite laminate: loading rate effect
Dr. Chao Zhang, Northwestern Polytechnical University (NPU), China
Delamination is one of the most critical damage behaviours in laminated fibre reinforced composites, which can be easily induced during low and high velocity impact loading conditions. However, challenge presents for the measurement of interlaminar fracture toughness, especially under dynamic loading rates. In this work, we present a new test technology using a dual electromagnetic Hopkinson pressure bar test system, which can be used to measure the pure mode-I fracture toughness of composite interlaminar interface under dynamic loadings and to determine the effect of loading rate on the critical energy release rate. The DCB specimens were loaded symmetrically with velocities in the range of 10-30 m/s. The crack initiation is monitored by a pair of strain gage mounted on the surface of DCB arms. The hybrid experiment-numerical method was used to calculate the fracture toughness by employing J-integral technique for quasi-static and dynamic tests. The finite element model takes use of incident stress wave as the boundary conditions for dynamic tests. It shows that the fracture toughness is rate positive at high loading rates, and rate insensitive at low loading rates.
Dr. Chao Zhang obtained his Ph.D. degree from the University of Akron in 2013. He worked as postdoc fellow in the University of North Caronia at Charlotte and National Renewable Energy Laboratory from 2014 to 2016, and joined the Northwestern Polytechnical University as Professor in 2016. Dr. Zhang’s research lies in the area of composites, with a focus on analysing the damage and failure behaviours of composite structures using experimental characterization and numerical simulation combined approaches.
Dr. Zhang has published more than 40 journal papers on international recognised journals, e.g. Composites Science and Technology, Composites Part A, Composites Part B, Composite Structures et. al. He is also an Editorial Board Member for Chinese Journal of Aeronautics. He was awarded Travel Award from the World Congress of Computational Mechanics in 2016, and served as guest editor for Journal of Aerospace Engineering and Advances in Mechanical Engineering.