Lecture: "Structural Health Monitoring for aircraft structures”

Abstract:

Structural health monitoring (SHM) is a major area of interest for the aerospace community, especially considering aging aircraft where the growing maintenance costs, estimated to $10,4 billion worldwide annually, can reduce their economic life. Strategies using ultrasonic guided wave propagation have been proposed for monitoring of simple metallic and composites airframe structures. However, wave interaction with defects in complex structures is addressed in the literature only for specific and limited number of components and types of defects. For instance, interactions of guided waves with cracks in metallic joints and delaminations in composite joints have been investigated to some extent. This talk will provide an insight into how ultrasonic guided waves propagate in typical complex aeronautic structures and how they interact with defects. A review of imaging algorithms that can be used to detect and localize defects in such structures will also be presented, with experimental test cases. Finally, a newly developed algorithm, called the Excitelet algorithm, will be presented to demonstrate some of its advantages, namely: 1) flexibility to take into account and naturally compensate for transducer directivity and dynamics, boundary reflection, mode conversion, multi-layer propagation, damping and dispersive materials, 2) capability to greatly reduce the amount of required transducers without loss of imaging quality, and 3) improvement of precision for near-field imaging.