Seminar - Inspection and monitoring of bond line defects in composite structures using ultrasonic feature guided wave by Professor Zheng Fan
日期：2017 年 05 月 10 日 ( 星期三)
Time：11:00 am – 12:00 pm
Adhesive bonding is widely used in aerospace composite structures, being the most common means to fix skins to reinforcing elements, such as spars and stiffeners. A continuous well-cured bond can offer uniform stresses, good joint strength, and improved fatigue and impact resistance, and is therefore crucial to the performance of the entire structure. This talk presents a novel technology to use feature guided waves (FGW) for rapid screening of the bond-line between a stiffener and a carbon-fiber-reinforced-polymer (CFRP) composite panel. Such FGW is capable of concentrating the energy along the stiffener and bond-line, with little energy leaking into the plate. Semi-Analytical Finite Element (SAFE) method is applied to understand the modal properties of FGWs that exist in the structure, using both the homogeneous and the heterogeneous model for the composite panel. Promising modes with little dispersion and little attenuation are identified from the modal analysis. Both 3D Finite Element (FE) simulations and experiments are performed to study the interaction of the selected FGW mode with defects in the adhesive bond, and the results show excellent agreement. The reflection behavior and the wave-defect resonance phenomenon are investigated, which demonstrate the capability of the FGW for the bond line inspection. A new structural health monitoring (SHM) technique based on a synthetically focusing method using a sparse array of sensors is also presented.
Prof. Fan obtained his PhD degree at Imperial College London, specialized in Non-Destructive Evaluation (NDE). Prof Fan’s research motivation is to solve real inspection and monitoring problems in industry, achieved by conducting thorough scientific research. Prof. Fan is currently an Assistant Professor in the School of Mechanical and Aerospace Engineering at Nanyang Technological University, leading a research team with more than 15 people from 7 countries including PhD students and postdoctoral fellows. The research focus of his team is to develop novel NDE techniques for metal and composite inspection, structure health monitoring and material characterization, by integrating physics and modeling techniques with the development of rapidly exploitable technologies. He has collaborated with varies industries including Rolls-Royce, Shell, Lloyds Register, Sembcorp etc for different research and consultancy projects. His research work has gained worldwide recognition, and he has recently been appointed as an Associate Editor to “Ultrasonics” – one of the top-tier journals published by Elsevier in this field.