Ice accumulation identification and localization method based on ultrasonic guided waves

To achieve regionalized quantitative detection of aircraft icing, we propose a method for ice layer localization and quantitative identification based on the Lamb waves. Firstly, a wave dynamic simulation model of piezoelectric coupling is established. The propagation characteristics and mode conversion process of the Lamb waves in the aluminum plate and ice layers are analyzed with the three-dimensional finite element method. The S₀/B₁ mode is selected as the icing monitoring mode, and a signal analysis method based on wavelet transform is developed to extract the time of delay of S₀/B₁ mode waves. Furthermore, the influence of different ice layer structural sizes on the Lamb wave signals is analyzed. It is found that the time of delay ratio of the B₁ mode waves linearly increases with the increase in the ice layer length (ice accumulation in the direction of wave propagation). The ice layer width (ice accumulation in the direction perpendicular to the wave propagation) has a range of influence on the time delay of the B₁ mode waves. For the range of ice layer width not exceeding 40 mm, the time of delay ratio has a linear relationship with the width of ice. The ice layer thickness shows an approximate positive correlation with the time of delay ratio of the B₁ mode waves, and a good linear relationship exists between them within an ice layer thickness of 1.5 mm. Finally, a simulation model of the Lamb waves piezoelectric array is established, and a modified reconstruction algorithm for the probabilistic inspection is proposed. The ice accumulation level is characterized by the time of delay to verify the feasibility of ice layer localization imaging and quantitative identification in the detection area and improve the ability to rapidly evaluate icing online based on ultrasonic guided waves, laying the foundation for icing quantitative detection via ultrasonic guided waves.