AbstractThe main focus in this work has been to improve the understanding of how the monitored structure affects the performance of guided wave acoustic emission systems. This was to address poor performance of an Airbus acoustic emission system when it was used to monitor a complex section of an aircraft wing during a fatigue test.
To do this the whole acoustic emission system was modelled. The focus of the modelling effort was in two parts. The first was to define a suitable source for a fatigue crack in aluminium to use as an input to the model. This was found from the literature and compared with results from Airbus tests. The second part was to develop an approach to model the guided wave propagation in large structures. This led to the development of empirical transmission models that could be created with reduced effort compared to other transmission modelling techniques. These transmission models were deliberately conservative in their prediction of amplitude to ensure they could safely be used to determine which transducers would detect acoustic emission events at different locations. The whole system model could then be used to determine acoustic emission system performance for different scenarios. By varying the structure in the model its influence on system outputs such as detection and location of acoustic emission events could be demonstrated. Therefore a tool has been created to aid the future development and deployment of acoustic emission systems.
There are two other major achievements in this thesis. The first is the development of an efficient method to collect guided wave data over large areas using a design of experiments based technique. The second is an analysis of results from a long term active guided wave structural health monitoring experiment. Understanding this behaviour is necessary for the further deployment of these systems.
|Date of Award||25 Sep 2018|
|Supervisor||Anthony J Croxford (Supervisor) & Kathryn Atherton (Supervisor)|