Nonlinear ultrasonic evaluation of disorderedly clustered pitting damage using an in situ sensor network

Abstract

Pervasive but insidious, pitting damage—from pitting corrosion in maritime structures through electrical pitting in bearings to debris cloud–induced pitting craters in spacecraft—is a typical modality of material degradation and lesion in engineering assets in harsh service environment. Pitting damage may feature hundreds of clustered, localized craters, cracks, and diverse microscopic defects (e.g. dislocation, micro-voids, and cracks) disorderedly scattered over a wide area. Targeting accurate, holistic evaluation of pitting damage (mainly the existence, location, and size of the pitted area), an insight into the generation of nonlinear features in guided ultrasonic waves (i.e. high-order harmonics) that are triggered by pitting damage, is achieved using a semi-analytical finite element approach, based on which a monotonic correlation between the nonlinear ultrasonic features and the holistic severity of pitting damage is established. With such correlation, a structural health monitoring framework is developed, in conjunction with the use of an in situ sensor network comprising miniaturized piezoelectric wafers, to characterize pitting damage accurately and monitor material deterioration progress continuously. The framework is experimentally validated, in which highly complex pitting damage in a space structure, engendered by a hypervelocity debris cloud, is evaluated precisely.

Surface/sub-surface crack-scattered nonlinear rayleigh waves: A full analytical solution based on elastodynamic reciprocity theorem

“…A Rayleigh wave is guided by a free surface of a waveguide and constrains its major energy to the waveguide surface. With the energy dominance near to the waveguide surface, Rayleigh-Lamb waves have been employed to locate [23,24], orientate [25] and evaluate [26][27][28][29] surface or sub-surface flaws. Amongst demonstrated paradigms, the second harmonic generation is one of the wave features that has been exploited extensively.…”

Application of Sensor Path Weighting RAPID Algorithm on Pitting Corrosion Monitoring of Aluminum Plate

“…Some studies have revealed that a method using scanning laser Doppler vibrometer (SLDV) can detect a cluster of pits which are arranged in 3 × 3 × 3 array and have the diameter of 2 mm and the interval of 2 mm in aluminum plate, but most pits except the one at the center of cluster can be identified [ 13 , 14 ]. Recently, Cao et al proposed the NI, which can link the degree of nonlinearity to the size of pitting damage, and both the PZTs network and RAPID algorithm are used to visualize pitting damage, but only an approximate range of pitting corrosion can be located [ 15 ].…”

An elastodynamic reciprocity theorem-based closed-form solution to second harmonic generation of lamb waves by a fatigue crack: Theory & experimental validation

“…The higher order harmonics can be generated upon nonlinear interaction between a probing wave and microstructural degradation in a waveguide that is associated with dislocation, phase change, void nucleation and plastic deformation. There is a rich body of literature, in numerical or experimental natures [9][10][11][12], to reveal that the higher order harmonics of GUWs are more sensitive to contact-type defect (e.g., fatigue cracks or delamination under the modulation of external loads), yet less affected by ambient variations (e.g., environmental noise or temperature fluctuation) than the linear features of GUWs including the coefficients of wave transmission/reflection, distortion of waveform, and delay in wave arrival time [13][14][15][16][17][18][19][20][21]. Amongst the higher order harmonics, the second order harmonics are extensively explored, owing to their relatively stronger magnitudes and easier acquisition, compared with harmonics of higher orders.…”