In most modern cities throughout the world, steel strands and pipes are utilized to convey water, oil, and gas and are frequently used as engineering support structures. Severe rust, corrosion, damage, and even rupture of steel strands and pipes can cause catastrophic disasters that cost huge losses to the human population and the economy of urban areas. Therefore, their continuous operation is of significant importance for the economy of the cities and human lives. To prevent any disastrous incident, the integrity of such structures must be previously monitored, examined, and repaired quickly.

Ultrasonic Guided Wave (UGW) is an effective non-destructive testing (NDT) technique for detecting defects of steel strands and pipe-like structures. Unlike some other techniques like a conventional ultrasonic wave, UGW can inspect the whole structure from a single point, and it can cover all cross-sections of the tested structures. In addition, UGW with less attenuation can have a longer inspection distance than other inspection methods. However, some challenges for the UGW application are still existed and need to be addressed; for example, the smart patch is bonded with the tested pipe tightly with epoxy glue, and it is very hard to be removed from the pipe, which would cause the electrochemical corrosion if not well taken care of. In this thesis, a pneumatic magnetostrictive patch transducer (PMPT) is presented that not only fixes the problems listed above but also takes advantage of the patch in the magnetostrictive sensor (MsS). A theoretical foundation is given, including how to use the UGW theory for NDT on pipes, the fundamentals of magnetostriction, and Hooke's law combined with the passion ratio for PMPT design. On the job site, pipe defects can be quickly and accurately detected with the help of this type of UGW sensor. Through theoretical analysis and experimental investigation, the detection ability of PMPT has been validated. Applying the suggested PMPT to in-service pipes of various diameters and corrosion surfaces is relatively straightforward and easy due to its adaptable, flexible design and portable structure.

Elevators, concrete buildings, and other heavy objects are frequently hoisted using multiwire steel strands. Steel strands are vulnerable to corrosion, overloading, and aging as a result of repeated and extensive use, which can cause the strands to fail suddenly. In order to prevent the unexpected collapse of lifting structures, it is therefore more crucial than ever to check the condition of steel strands. Numerous researchers have reported using various UGW techniques to find various kinds of flaws in steel strands. The usefulness of each approach or sensor system in assessing the health of steel strands has been the subject of few comparative NDT investigations, nevertheless. Using three different popular UGW sensor systems, including MsS, piezoelectric transducer (PZT), and laser-based UGW systems, in experiments using contact and noncontact methods during their applications in surface-type defect detection for steel strands, a portion of this thesis reports some crucial observations. The experiment and analytical investigation have helped to determine the best way to choose sensor systems for health monitoring of steel strands. The thesis's findings are thought to provide useful direction for choosing suitable UGW techniques and sensor systems to check the steel strand's integrity in various scenarios and so secure the security of their hoisted constructions.

The benefits of this newly proposed PMPT and the streamlined framework of choosing the proper UGW sensor system for steel strand defect detection are as follows.

(1) On-site pipe inspection can be completed with a significant reduction in labor costs and time.

(2) Offer a helpful evaluation framework so that the concerned engineers can select appropriate and efficient NDT methods to examine the sound condition of the seven-wire twisted steel strand in light of various real-world circumstances.