Guided Wave-Based Damage Detection of Square Steel Tubes Utilizing Structure Symmetry

Abstract

Square steel tube, which is widely used in civil engineering, can suffer from a wide variety of damages and aging defects, thus its nondestructive testing (NDT) has attracted wide attention. This work proposes an ultrasonic guided wave (UGW)-based damage detection method for square steel tubes using structure symmetry. Firstly, the dispersion characteristics of square steel tubes are obtained using the semi-analytical finite element (SAFE) method, after which the optimal guided wave modes for damage located on the long and short edges of the steel tube are selected by modal analysis. Then, using the symmetry of the square steel tube’s section, the symmetric layout scheme of the transmitters and the receivers is designed; on this basis, a signal processing strategy for damage detection is proposed by subtracting the receiving signals obtained from symmetric positions. Finally, the effectiveness of the proposed damage detection method is verified by numerical simulations and laboratory experiments. The results show that the proposed method has good inspection accuracy for crack and hole damages on both the long and short edges of square steel tube because the dispersion effect and clutters can be reduced utilizing structure symmetry. It is worth mentioning that the inspection effect for corner holes can be enhanced by modifying the position of the receivers.

Estimation of Lamb Wave Anti-Symmetric Mode Phase Velocity in Various Dispersion Ranges Using Only Two Signals

“…Thus, in order to obtain the dispersion curves of the phase and group velocities, the elastic constants of the material and the object's geometry must be known (Figure 1). Based on this, the maximum distance between two signals was determined according to Equation (7). The calculated mean relative error of the phase velocity (Table 2) obtained in each selected case was around 0.22%.…”

“…Thus, in order to obtain the dispersion curves of the phase and group velocities, the elastic constants of the material and the object's geometry must be known (Figure 1). Based on this, the maximum distance between two signals was determined according to Equation (7). The phase and group velocities determined in the analysed frequency ranges, along with the calculated maximum distances between two possible signals, are presented in Table 3.…”

“…However, the real-time testing of objects remains a complex and challenging task due to the multi-modal nature, dispersive phenomenon, multi-path characteristics of Lamb waves and sensitivity to environmental and operational conditions (EOCs) parameters [6][7][8]. Thus, one of the main reasons that complicates the application of these waves is the dispersion phenomenon [2,4,9].…”

A Two-Step Model-Based Reconstruction and Imaging Method for Baseline-Free Lamb Wave Inspection

“…Hence, reliable and accurate inspection techniques are urgently needed to identify and locate the damages at its early stage with the purpose of increasing structural safety and reducing maintenance costs. The Lamb wave technique has been proven to be one of the most promising structural health monitoring (SHM) and nondestructive evaluation (NDE) techniques for plate-like structures due to its superior capacities in long-distance propagation and sensitivity to various kinds of damages, which allows for the large-scale inspection of plates with a high accuracy and efficiency [1][2][3].…”