Novel techniques for acoustic emission monitoring of fatigue fractures in landing gear.

Acoustic Emission (AE) is a technique for performing Non-Destructive Evaluation (NDE) of structures, whereby ultrasonic transducers are placed upon the surface of the structure in order to detect ultrasound resulting from damage-related events within the structure. Unlike many other NDE techniques, AE is an entirely passive process: the transducers operate in receive mode only.
Advances in the sophistication of AE equipment and computer hardware in general mean that it is now possible to perform AE tests involving many sensors over a large structure whilst recording and storing every waveform received at every sensor. There is much interest in using this data to perform detailed analysis of structural integrity, particularly because AE testing is entirely non-invasive and can be largely automated.
There are many hurdles to be overcome before AE can be routinely used in such a situation: the quantity of data is huge, and it is of a format which is unusual to most engineers - AE signals comprise short, transient, 'burst' like signals. A significant portion of this thesis is given to considering what to do with all the data, and how it may be understood.
The thesis focusses on the development of a data processing method, and its application to landing gear certification tests. The methodology is designed to be generic, in that. it could find application in the on-line monitoring of a variety of engineering structures in the aerospace, automotive and civil-engineering sectors.