Condition monitoring in composite materials: An integrated systems approach

Abstract

This paper presents the results of a collaborative project, the objective of which was to investigate the potential offered by combining ultrasonic Lamb wave interrogation of composite material structures, insonifying the whole structure, with a single wavefront integrating optical fibre detector. The system, which was designed primarily for condition monitoring rather than defect imaging, proved to be capable of detecting small (centimetre square) delaminations, millimetre-sized holes and impact damages of a few joules, all with insonification wavelengths of the order of 2 cm. Data extraction proved to be extremely important since the damage-detection process relies essentially on analysing scattering signatures rather than attempting to image defects and damage. The systemdubbed SISCO (Structurally Integrated Systems for comprehensive evaluation of COmposites)-indicates that self-monitoring structures can be efficiently designed using controlled insonification and a relatively sparse sensor array, presenting a contrast to the more conventional imaging approach involving far more complex sensing arrays and detection and signal processing algorithms.

Finite-dimensional piezoelectric transducer modeling for guided wave based structural health monitoring

“…However, the ultrasonic transducers used there are not compact enough to be mounted permanently onboard the structure. In recent years, several researchers have used piezoelectric wafer transducers (hereafter referred to as 'piezos') for GW based SHM with encouraging results [1][2][3][4][5][6].…”

Modelling of Lamb waves for damage detection in metallic structures: Part II. Wave interactions with damage

“…Various mechanisms of wave propagation are utilized for damage detection. Lamb wave inspection [1][2][3][4][5][6][7][8] is based on the theory of waves propagating in thin plates [9,10]. These guided ultrasonic waves once introduced into a structure can propagate long distances.…”

Simulation of Guided Wave Propagation in Isotropic and Composite Structures using LISA

“…Acoustic waves such as Rayleigh and Lamb waves have been used for damage detection in metallic and composite structures. 1,2 Rayleigh waves propagate on the surface of semi-infinite media, which is a suitable feature in detecting surface and subsurface defects. On the other hand, Lamb waves can travel long distances over the surface as well as through the thickness of a structure.…”