Ultrasonic guided wave focusing in waveguides with constant irregular cross-sections

Guided wave‐based damage assessment on welded steel I‐beam under ambient temperature variations

“…Considering the performance of the experimental instrument in this study, the searching frequency range was set at 35–70 kHz at 5‐kHz increments (35, 40, 45, 50, 55, 60, 65, and 70 kHz) to avoid the multimode characteristic at higher frequency range. First, the proper wave modes were searched for a higher‐energy concentration in the weld zone 28 . Figure 3 shows the 12th and 13th wave modes at 40 kHz, which show the in‐plane and out‐of‐plane motions of two flanges.…”

“…Among them, the ultrasonic guided wave method has been recognized as one of the efficient nondestructive testing (NDT) approaches to scan long structural members. It has been applied to inspect pipelines, 22,23 cables, 24,25 rails, 26–28 and many other types of structures 29–31 . One of the common NDT strategies using guided waves is called the pulse‐echo method, where the transducer simultaneously works as the actuator and sensor 32 …”

“…Cawley and Alleyne showed the potential of Lamb waves for the quick inspection of large structures such as pipes 17 . For structural members with complex geometric cross‐sections such as rails, the semi‐analytical finite element (SAFE) method has been proposed to investigate the guided wave characteristics 25,28,36,and …”

The propagation of symmetric Lamb wave in the hollow cylinder

“…In acoustic waveguide testing, guided waves propagating along the products are used: Pochhammer, Lamb, SH-waves [1][2][3][4][5][6][7][8][9]. Typically, these types of waves used in the low frequency range, are capable of traveling up to 200 m from the point of excitation, and do not require scanning [5,9].…”

“…The main studies in the field of guided wave propagation are related to the influence of bends and complex pipe geometry [15,20], alternative methods of wave excitation and reception [16,[21][22][23], their use in tomography systems [17,24], development of systems for excitation and receiving waves in circumferential direction of the pipe [16,[22][23][25][26][27][28], the possibilities of increasing sensitivity due to wave focusing technique [7,29], the influence of defects on mode conversion [14,23,27], the possibilities of implementing excitation and reception of various modes and types of waves [29][30][31][32][33]. In most works, with the exception of Viktorov's works for a surface wave [34], there is no information on the difference in the propagation velocity of guided waves in the axial and circumferential directions on a cylindrical surface, which can be significant for a small diameter and a large wall thickness of pipe.…”