The 29th International Conference on Automation and Computing (ICAC 2024)

 Sunderland, UK, 28-30 Aug. 2024.

Keynote Speakers

Prof Ning Hu

Vice President of Hebei University of Technology, China

Title:

Damage Inspection and Monitoring Based on Zero-frequency Mode of Nonlinear Lamb Waves

Abstract

From the nineteen nineties to date, non-linear ultrasonic Lamb waves have been extensively investigated. Some substantive breakthroughs in fundamental theories, methodologies and practical engineering applications for the on-line monitoring and off-line evaluation of structures, materials and equipment have been obtained. However, in general, the research works in this field have been mainly focused on second harmonics. Moreover, to satisfy the conditions to generate the cumulative second harmonics caused by micro-damages (e.g., micro cracks) or material nonlinearities, the current techniques based on non-linear ultrasonic Lamb waves mainly employ the wave pairs of primary wave mode and second harmonic mode, which are chosen in high frequency domain, e.g., S1-S2. The disadvantages of this technique are obvious, e.g., employment of expensive devices, weak signals, low capability of anti-noise interference, etc. To overcome the above mentioned disadvantages, we will mainly describe some recent achievements on zero-frequency mode of nonlinear Lamb waves in our group in this speech. By using perturbation method and mode superposition technique with consideration of zero-frequency mode, we theoretically studied the solutions of non-linear wave equation and derived the generation conditions and characteristics of sum-frequency, difference-frequency and second harmonic wave modes. We revealed the generation mechanism and the feature of symmetric-deformation mode of zero-frequency signal induced by material nonlinearities. Moreover, by using numerical simulations and experiments, we explored the generation and propagation characteristics of zero-frequency mode and verified its distinctive advantages at the aspects of signal intensity and signal variation characteristics versus propagation distance compared with traditional second harmonics. The above achievements will promote the research and development of the evaluation and monitoring techniques for early-stage micro-damages, property degradation of materials, etc., based on non-linear ultrasonic Lamb waves.

Biograph

Dr. Hu finished his education from undergraduate to PhD in Chongqing University, China from 1981-1991. After graduation, he has been working at Nanjing University of Aeronautics and Astronautics (China), Tohoku University (Japan), Tsinghua University (China), The Johns Hopkins University (USA), Chiba University (Japan), Hunan University (China) and Chongqing  University  (China)  as Post-doctoral researcher, Assistant Professor, Associate Professor and Full Professor. Before his back to China in 2013, he was a Full Professor, the Chairman of Department of Mechanical Engineering, and the Head of Division of Artificial System Science, Chiba University (Japan). From the end of 2013, he founded College of Aerospace Engineering in Chongqing University (China) and worked as the first Dean. From April, 2019, he started his work as a vice president of Hebei University of Technology (China).

His main research interests include: solids mechanics, functional and structural nanocomposites and conventional fiber reinforced composites, analysis and design of metal and composite structures, computational materials science (e.g., multi-scale simulations), on-line structural health monitoring and off-line non-destructive evaluation techniques, sensing/energy harvesting techniques, etc. To date, in the above fields, he has published 3 books in English, 1 textbook in Chinese, and generated around 650 peer-reviewed journal articles in Chinese, English and Japanese (including 560 SCI English journal papers). These articles have been cited over 20000 times with H-Index=68. Also, he has obtained over 40 Japanese and Chinese patents. He is now working as Associate Editor and an Editorial Board Member of 13 academic journals including 11 international academic journals. He has also received some important awards, e.g., “Outstanding Young Scholar from NSF (Type B), China, 2007”, “National Distinguished Experts (Thousand Talents Plan ), China, 2013”, etc. He was also selected by Elsevier as one of “The Most Highly Cited Chinese Researcher” from 2014 to 2023 in the field of mechanics of materials and mechanical engineering. He was also continuously selected as World’s Top 2% Scientists (Career Scientific Impact and Single year Scientific Impact) from 2020-2023.