George Z.H. Zhu, PhD, P.Eng.

Dr. Zheng Hong (George) Zhu is a Professor and Tier 1 York Research Chair of Space Robotics and Artificial Intelligence in the Department of Mechanical Engineering at York University in Canada. He is also the founding Co-Director of Centre for Manufacturing Technology Entrepreneurship and the founding Director of the Space Engineering Lab at the same University. He had served as the Director of Space Engineering undergraduate program in the Department of Earth and Space Science and Engineering, Chair of the Department of Mechanical Engineering, and Inaugural Academic Director of Research Commons in the Office of Vice-President Research & Innovation at York University. His research interests include dynamics and control of spacecraft, space robotics, machine learning, 3D printing in space, and CubeSat technology. He has authored 231 peer-reviewed journal papers and 185 conference articles.

Dr. Zhu is the Editor-in-Chief of Acta Astronautics, the vice-President of International Society of Mechanical System Dynamics and the Honorary Treasurer and Board Member of Canadian Society of Mechanical Engineering. He holds the titles of Academician of International Academy of Astronautics, College Member of the Royal Society of Canada, Fellows of the Canadian Academy of Canada, Engineering Institute of Canada, Canadian Society for Mechanical Engineering, American Society of Mechanical Engineers, Associate Fellow of the American Institute of Aeronautics and Astronautics, and Senior Member of IEEE. He received the 2024 Gold Medal and the 2019 Ontario Professional Engineers Award - Engineering Medal R&D from Professional Engineers Ontario in Canada, the 2024 Solid Mechanical Medal and the 2021 Robert W. Angus Medal from Canadian Society for Mechanical Engineering, and the 2022 President's Research Excellence Award from York University.

Presentation Title: Revolutionizing Space Infrastructure with In-Space Additive Manufacturing

Synopsis of Presentation:

In-Space Additive manufacturing (ISAM) can overcome the current launch vehicle limitations on volume and weight, expanding the feasible domain of space structure design. ISAM involves melting and forming materials in microgravity, where controlling liquid and powder materials is challenging. Consequently, Fused Deposition Modelling (FDM), which uses filament materials, is currently the primary technology for ISAM. Factors such as surface tension, gravity, and atmospheric pressure in FDM influence layer deposition, may affect the dimensional precision and mechanical properties of printed structures and their impacts not well-known. This talk presents some experimental investigation on the effect of gravity on interlayer fusion and mechanical properties in our lab. The gravity effect on the ISAM made structures are simulated by printing specimens at angles ranging from 0° to 90° relative to the gravity direction in 15° intervals. Here, 0° simulates zero gravity (gravity parallel to the deposition layer interface), while 90° represents Earth-like gravity effects. Tensile and compressive specimens were manufactured and tested for mechanical properties such as Young’s modulus, ultimate strength, yield strength, and fracture stress and strain. The results show a noticeable difference between parts printed at different inclination angles due to the effect of gravity. Dimensional analysis underscores gravity's influence on dimensional accuracy. The findings suggest that while zero-gravity conditions weaken interlayer bonds, microgravity has a lesser impact on material strength compared to Earth-bound conditions. These insights are valuable for optimizing polymer 3D printing techniques for ISAM.