Modeling and analysis of magnetic impedance sensor with circuitry integration for damage detection

Abstract

In the magnetic impedance approach for damage detection, there is no direct contact between the sensor and the host structure, and the impedance sensor can be moveable above the structure surface. This has promising aspects, especially for online health monitoring of structures with complicated geometries and boundaries. In an earlier study, we have demonstrated that integrating a synthetic, tunable negative resistance and a tunable capacitor with the magnetic transducer can amplify both the measurement magnitude and the damage-induced impedance anomaly and yield much higher signal-to-noise ratio and detection sensitivity. In this research, we formulate detailed modeling and carry out comprehensive analysis to investigate the enhanced magnetic impedance sensing with circuitry integration. Specifically, aiming at providing design and implementation guidelines, we investigate systematically the magnetomechanical coupling effect in such a sensing scheme, which focuses on elucidating quantitatively the influence of various sensor parameters to the impedance measurements. The modeling and analysis are validated by experimental studies.

A locally resonant non-contact absorber based on electromagnetic induction for vibration suppression

“…These eddy currents can be thought of as a distribution of current across a set of fictitious loops with a differential width 𝑑𝑟 and thickness 𝑑𝑧, encompassing a cylindrical volume with a diameter 𝑊 𝑏 and thickness 𝑡 𝑏 . The magnetic flux density at any point surrounding a thin cylindrical magnet of thickness 𝑑𝑧 0 can be derived from the Biot-Savart Law [7,22]…”

“…In contemporary research, this approach has been extended to several novel applications in structural health monitoring and adaptive control. For example, in the associated works of Wang et al [6,7] and Shuai et al [8,9], variations in the electrical impedance of an EMAT coil resulting from a change in mass or stiffness, was used for damage identification of a beam. In 2008, Sodano and Inman [10] proposed a novel non-contact vibration control system combining an electromagnetic transducer with a thin copper plate bonded to a beam.…”

Direct compensation of lift-off oscillation effect in magnetic impedance–based damage detection

“…In literature, it is commonly referred to as an electro-magnetic acoustic transducer (EMAT) typically employed as an actuator (Jian et al, 2006;Thomas et al, 2009;Wilcox et al, 2005). Owing to the two-way magneto-mechanical coupling between the transducer and metallic structures, an EMAT-type magnetic transducer has recently been explored in the so-called impedance-based structural damage detection (Wang and Tang, 2012;Zagrai, 2009), in which it is employed as actuator (to excite the dynamic response in the structure monitored) and sensor (to sense the change of dynamic response) simultaneously. In this approach, the change in the transducer impedance, which is caused by the damage-induced change in the structural response, is employed as damage indicator.…”

Improved modeling of magnetic impedance sensing system for damage detection

“…Furthermore, this mathematical model can help elucidate the underlying physics and provide guidelines for sensor optimization There have been efforts on developing mathematical models to characterize magneto-mechanical interactions between the magnetic transducer and the structure. In one type of these methods, the reciprocity eddy current analysis is performed [15][16][17]. The magnetic field, the eddy current, the Lorentz force and the varied magnetic flux density in the electric coil are modeled in detail.…”

“…The stored magnetic energy is neglected, which has actually considerable influence to the impedance of the magnetic transducer. In [17], experimental data under a given lift-off distance are used to extract the coupling coefficient and normalize the computed impedance curve. As the magnetic transducer is expected to work at different lift-off distance, one would need to repeat this experimental process for all lift-off distances.…”