Ultrasonic Guided Wave Monitoring And Diagnostic Techniques On Plate-like Structural Damage

Structural health monitoring has been widely used in the field of aerospace, civil engineering and machinery. For active monitoring, Lamb waves has the advantages of propagation attenuation small, wide detection range, sensitive to small damage, and having been applied for a long time in the field of non-destructive testing. So it can be well applied to the structure health monitoring. This paper is committed to ultrasonic guided wave propagation based on the theory of plate-like structure and the plate-like structural damage numerical simulation of ultrasonic guided waves, getting its propagation law, on this basis, the damage location positioning method, and the sensing element temperature effect of ultrasonic guided wave in the theoretical and experimental analysis is researched in this paper. The main contents are as follows:It analyses the damage test effects with different guided wave modes based on plate-like structure ultrasonic guided wave propagation theory and optimizes excitation frequency of guided waves based on dispersion curve of plate-like structure ultrasonic guided wave. The Coupling between the piezoelectric ceramic plate layer interfacial shear mechanism, Lamb wave propagating in the plate dispersion and the expression of spatial displacement have also been discussed. This paper establishes effective finite element models about Lamb wave propagation on plate-like structure using the finite element software-ABAQUS, carrying out a detailed analysis and discussion about different models guide wave propagation, verifying the validity of the model.Damage location identification is one of the main purposes of structural health monitoring. Lamb wave scattering signal contains the information of damage location, extent and type. People can locate and identify the damage by signal processing. In this paper, damage location is implemented with four-point arc positioning method, calculating the geometric by extracts the flaw echo the peak arrival time based on relationship between incentives, sensing and damage.It is confirmed by theoretical that the received signal of piezoelectric would be affected by the temperature due to the temperature effect of the piezoelectric and monitoring material itself. In this paper, some experiments have been carried out to study the influence of the temperature effect on the sensor signal.The above studies have shown that finite element model established by ABAQUS software can well simulate the propagation of Lamb waves on the plate-like structure, which provides a convenient and powerful research tool for further studies, in the field of the damage location, the four-point arc method has high positioning accuracy, suitable on plate-like structural; temperature has a greater effect on the sensor signal amplitude sensing, which exists a corresponding function with another.