Experimental Investigation on Choosing a Proper Sensor System for Guided Waves to Check the Integrity of Seven-Wire Steel Strands

Abstract

Multiple wire twisted steel strands are commonly used to hoist elevators, concrete structures, etc. Due to frequent and long-time usage, the steel strands are subjected to corrosion, overloads, and aging, making strands may fail unexpectedly. Hence, the health monitoring of steel strands becomes more important to avoid the sudden collapse of hoisting structures. Guided waves (GW) inspection methods have become favorable in recent years due to its long-distance transmission and stability of evaluation in the area of structural health monitoring (SHM) and Non-Destructive Testing (NDT). Many researchers have reported different GW methods to detect different types of defects that occurred in steel strands. However, researchers rarely carry out comparative studies to investigate the effectiveness of each method or system in monitoring the health state of steel strands. This article reports some vital observations revealed from conducting experiments by using contact and noncontact methods, which include three different popular types of GW sensors and methods during their applications in surface-type defect detection. The proper selection of sensors systems has been identified through the present study. The result of the present study is believed to be useful guidance for selecting appropriate GW methods and sensor systems to monitor the integrity of the steel strand and thereby ensure the safety of the hoisted structures.

Performance investigation on the balance of static and dynamic magnetic field strength of magnetostrictive patch transducer with different permanent magnets

“…When the ferromagnetic material under a magnetic field is subjected to a change in the stress field, it exhibits a change in its amount of magnetization. The inverse magnetostriction effect is called the Villari effect [20]. These two effects can be expressed as equation (2.1), as follows:…”

Novel design of an effective pneumatic magnetostrictive patch transducer based on the ultrasonic guided wave for application of fast pipe health inspection

“…The magnetostrictive-based EMAT is a more durable and cost-effective choice for triggering GW, and it is designed to trigger narrowband and single GW modes than other transducers [3]. Among different types of magnetostrictive sensors, Tse et al [4,5] used flexible printed coils (FPCs-a thin-film imprinted with coil) to replace the previous hard solenoid coil to generate the dynamic magnetic field. Its flexibility and lightweight allowed it to be easily mounted onto any pipe, even those with a different diameter.…”

“…Ribichini et al [16] developed a finite element model of the EMAT to compare different EMAT configurations for SH wave inspection. Besides, NDT techniques related to ultrasonic GWs have been developed for various structures like steel strands, bearing, square tubes [5].…”