Guest Speaker: Dr FAN Zheng
Associate Professor, School of Mechanical and Aerospace Engineering, Nanyang
Technological University, Singapore
Dr Fan earned his Ph.D. degree in Mechanical Engineering from Imperial College London in 2010, and his Bachelor's and Master's degrees in Acoustics from Nanjing University in 2004 and 2006, respectively. Currently, he leads a research team dedicated to developing novel techniques for the non-destructive evaluation, structural health monitoring, and sound manipulation. His work integrates advanced physics and modeling techniques with the development of technologies that can be rapidly deployed in practical settings. Dr Fan maintains strong links with the global industry, collaborating with major companies such as Rolls-Royce, Shell, Lloyd's Register, EDF, and Sembcorp, etc. His research spans from thorough investigations of fundamental theories to the application of science in addressing real-world challenges. The results of his work have been published in over 80 papers in top tier journals. He holds two international patents and has successfully licensed these technologies to industry partners. In 2018, Dr Fan was awarded the Achenbach Medal for his outstanding contributions to structural health monitoring. In 2023, he was ranked among the world's top 2% of scientists by Stanford University. Dr Fan also serves as an Associate Editor for "Structural Health Monitoring – An International Journal" and "Ultrasonics," two leading journals in his field.
Abstract
Ultrasound technology offers immense potential across various disciplines, primarily due to two fundamental aspects: its capacity to convey information about the medium it traverses and its ability to transfer mechanical energy into other forms. Ultrasonic waves, when propagated through a medium, interact with its constituents, modifying the wave in ways that can be measured. These modifications carry detailed information about the medium's properties, including the presence, size, and nature of scatterers. By analyzing the changes in the wave's speed, amplitude, and frequency after it has passed through the medium, it's possible to infer the medium's characteristics. Our focus includes advanced imaging methods that combine numerical models for predicting wave interactions with defects and iterative modeling to reconstruct defect profiles accurately. This innovative approach is key for monitoring defect development over time, aiding in the accurate prediction of structural service life. Furthermore, ultrasound waves carry mechanical energy that, upon interaction with materials, can be transformed into other forms of energy, such as vibration, heat, or even used to achieve levitation. Recent research has unveiled a novel approach to the manipulation of Mie particles in water, employing an acoustic tweezer equipped with a single transducer. This approach utilizes an acoustic lens to generate a vortex, imparting angular momentum to a trapped polymer sphere, causing it to spin rapidly. This spinning enables the sphere to adjust its position and velocity to find equilibrium, enhancing pressure-induced drag and activating the Magnus effect for additional lateral force. This innovative interplay between acoustic radiation and hydrodynamic forces allows for precise, contact-free manipulation of both spherical and non-spherical objects, showcasing the versatility and potential of acoustic tweezers in particle control.
