题目：Characterization of Materials Fabricated of Materials Fabricated by Additive Manufacturing Method Using Line Focused Ultrasonic Transducer

报告人：Qing-Ming Wang, PhD

               Professor of Mechanical Engineering and Materials Science

              University of Pittsburgh

时间：2018年7月10日上午8：30

地点：betway必威动力与机械学院报告厅

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Abstract text:

Single crystal materials are anisotropic in nature, and their structures and properties are directional dependent. While most metal alloys are often taken as isotropic when their elastic and mechanical properties are evaluated in macroscale, however, for metal alloys fabricated by additive manufacture, it has been noticed that the elastic and mechanical properties of some metal alloys show some anisotropic behavior due to the particular manufacture processing used. This anisotropy can be characterized using traditional tensile testing method, but multiple samples must be made at different fabrication direction to conduct tensile testing. In this study, we propose a non-destructive testing system using a line-focus ultrasonic transducer to characterize the elastic property anisotropy by evaluating the Rayleigh Surface Wave velocity on the solid surface. The Rayleigh Surface velocity is calculated by using time resolved defocusing method which based on the change of time delay wave form at different focusing location.

The elastic property anisotropy of metal alloys caused by fabrication process is investigated by measuring different metal alloys fabricated by various additive manufacturing approaches, while the elastic anisotropy of single crystal silicon wafer is studied along different surface wave propagation directions. The results show a variation of the elastic properties along different measurement directions. This study demonstrated the line-focused ultrasonic transducer system would be applied to for elastic property characterization nondestructively for materials processing evaluations.

Biography:

Dr. Qing-Ming Wang is a professor in the Department of Mechanical Engineering and Materials Science, at the University of Pittsburgh, Pennsylvania. He received the B.S. and M.S. degrees in Materials Science and Engineering from Tsinghua University, Beijing, China, in 1987 and 1989, respectively, and the Ph.D. degree in Materials from the Pennsylvania State University in 1998. Dr.Wang’s primary research interests are in functional materials and devices, microelectromechanical systems (MEMS) and microfabrication; thin film bulk acoustic wave resonators (FBAR), and acoustic wave sensors; and piezoelectric and electrostrictive thin films and composites for transducer, actuator, and sensor applications. Dr. Wang’s research is well funded by US National Science Foundation (NSF), DOE-NETL, ARO, and industry. He has published over 100 papers in international journals and his work has been presented in numerous international conferences. He is the recipient of IEEE-UFFC outstanding paper award in 2006, and MEMS department visiting committee excellent educator award in 2015.  He is a member of IEEE, IEEE-Ultrasonics Ferroelectrics and Frequency Control, ASME, and the American Society of Engineering Education (ASEE).