Inspection of complex structures using ultrasonic feature guided waves

Speaker:Prof.Zheng Fan (NTU)

Time and Date: 9:30-11:00, Jun. 25, 2014

Place: Room 521, Physics Building, Handan Campus

 

 

Abstract

Ultrasonic guided wave testing is attractive for large-area inspection since it offers the potential for rapid screening from a single transducer position and remote inspection of physically inaccessible areas of the structure. Applications have been developed successfully for the inspection of one-dimensional structures such as pipelines and rails. The idea is also being pursued for the screening of large areas of plate structures, such as storage tanks, pressure vessels, and airframes. However, the area inspection is more complicated by the extra dimension and the presence of structural features which lead to complicated signals. Therefore, the main focus on the research of large area inspection has been to detect and locate defects in the large open areas, despite the presence of the structural features, such as welds, ribs or stiffeners. However, a recent experiment discovered that there existed an interesting type of ‘feature-guided wave’, which could concentrate the energy around the feature and propagate along it for long distance. Therefore, instead of seeing features as a problem, they could be used to focus the energy of guided waves in order to detect defects in or near them. Modal studies have been carried out to investigate the feature guiding phenomenon. It not only brought the understanding of the compression wave which was observed in the previous experiment, but also discovered a non-leaky and little dispersive shear wave which is very attractive to be used for long distance feature inspection. The physical reason for the energy trapping phenomena has been well explained by studying the mode shapes of the guided modes. Two attractive applications with feature guided waves have been explored, one of which is to inspect for defects in or around a weld and another is to monitor the bondline of an adhesively bonded stiffener.

 

 

Biography

Dr. FAN Zheng (David) is currently an Assistant Professor at the School of Mechanical & Aerospace Engineering at Nanyang Technological University.

Dr. Fan obtained his PhD in Mechanical Engineering at Imperial College London in 2010. He spent another 3 years at Imperial College as post-doctoral researcher, and since 2013 he joined NTU as assistant professor. His research motivation is to solve inspection and monitoring problems in industry, achieved by conducting thorough scientific research. His current research focus is to develop novel Non-Destructive Testing and Structural Health Monitoring techniques, by integrating physics and modeling techniques with the development of rapidly exploitable technologies.