Composite Leading Edge Monitoring with a Guided Wave System

Over the last two decades, a wide variety of metal and composite structural health monitoring techniques have been developed. Most of the tests on composite material reported in academia are run on flat and rectangular structures, but real-world parts are more complex than these simple structures. Usually, the physical features of real-world structures are complex. These parts are large, asymmetric, and non-flat structures. They are made out of several attached pieces and might include holes or fixing elements. The wave transmission does not only depend on the usual test conditions (type of sensor, frequency, and waveform) and composite material properties (anisotropic behaviour and high attenuation), but also on the physical features of the structure under test (irregular shape, curvatures, obstacles,…). As a result, the guided waves used for monitoring show a hard to predict behaviour that can be considered chaotic. This paper introduces the preparation and performance of the SHM laboratory tests carried out on an airplane’s leading edge made of composite. During the tests, specific equipment was used for the generation and acquisition of ultrasonic guided waves. The goal of the tests is to adapt the monitoring techniques applied on simple structures to real-world structures. The tests compare guided wave emission techniques with one and many piezoelectric transducers. The research shows the difficulties to monitor real-world specimens and points out the means and set-up to overcome them.