Papers by Author: Cain Doherty

Abstract: This paper reports on findings that extend previous work for the purpose of in-situ structural health monitoring of defects on the blind side of open holes using plate waves. A series of computational studies is presented to understand how and why the ultrasonic scattered wave field can be detected on the accessible surface. The uniqueness of these findings is that the length-scale of the defect and the incident waves are comparable. The combination of the experimental-computational-analytical approach gives rise to new insights and guidance for the quantification of defects located in hard-to-inspect regions of future unitised metallic and composite structures. The outcomes advance the knowledge base of inspection of hard-to-access regions with actuators and sensors placed in easily accessible locations.

Abstract: Doherty and Chiu reported on the potential use of propagating stress waves for monitoring fatigue crack development in a series of hard-to-inspect weep holes in the wing spar of an aging aircraft. New experimental evidence showed an interesting scattering phenomenon at the defect and demonstrated the ability to use this phenomenon to monitor the development of an upward developing fatigue crack. It was found that a scattered field can be used to highlight the presence of a source of a secondary wave mode arising from the interaction of the incident wave field with the defect. A detailed investigation into these observations will contribute to the creation of new basic scientific understanding of this phenomenon with the potential development of a novel and optimised approach for quantitative inspection of hard-to-inspect regions in a structure.