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For resolving deficiencies of conventional tension measurement methods, this paper proposes a novel eddy current sensor with a single-coil structure based on the inverse magnetostrictive effect. An inductor-resistor-capacitor (LRC) model of eddy current sensor, which considers more parameters than the traditional inductor-resistor (LR) model, was es...
Citations
... Operating the ECT probe at 80 frequencies close to its electrical resonance can enhance the 81 sensitivity and SNR by measuring the shifting of electrical 82 resonant frequency as the impedance at this frequency can 83 reach the maximum [20], [21]. Xiu et al. [22] proposed a [24], [25], [26], [27]. An LC sensor [26], [28], [29]. ...
Wheel-rail contact force measurement is one of the key issues in rolling stock monitoring. Traditional methods using strain gauges are a relative measurement, which require strong bonding on the wheel webs with complicated telemetry transmission systems. This paper proposes a wireless inductive-capacitive (LC) resonance sensing approach for non-contact measurement of wheel-rail contact forces. The proposed LC resonance sensor is low-cost, high sensitivity, and consists of a dual-layer rectangular inductance coil and a parallel capacitor. Validation using a standard dog-bone specimen tested on a universal testing machine was performed, with the resonant frequency of the proposed LC resonance sensor increasing monotonically with loading force. Investigation of lift-off and aspect ratio of the inductance coil shows that lower lift-off and lower aspect ratio offer better sensitivity. The proposed LC resonance sensing with LDC chip approach has great potential for rolling stock monitoring.
... By using the proposed system, the corrosion through thick barriers was detected and the suitability of the resolution and the sensitivity of the MR sensors were indicated. Xiu, et al. [31] used a coil and a test specimen as the solenoid core, similar to elastomagnetic sensors. In the measurements, the sensor impedance was used as a measure of the amount of tension. ...
The growing demand towards life cycle sustainability has created a tremendous interest in non-destructive evaluation (NDE) to minimize manufacturing defects and waste, and to improve maintenance and extend service life. Applications of Magnetic Sensors (MSs) in NDE of civil Construction Materials to detect damage and deficiencies have become of great interest in recent years. This is due to their low cost, non-contact data collection, and high sensitivity under the influence of external stimuli such as strain, temperature and humidity. There have been several advancements in MSs over the years for strain evaluation, corrosion monitoring, etc. based on the magnetic property changes. However, these MSs are at their nascent stages of development, and thus, there are several challenges that exist. This paper summarizes the recent advancements in MSs and their applications in civil engineering. Principle functions of different types of MSs are discussed, and their comparative characteristics are presented. The research challenges are highlighted and the main applications and advantages of different MSs are critically reviewed.
... The eddy current originates from the relative motion between the magnetic field and metal conductor, and is a type of electric current circulating within a conductor. The eddy current has some practical applications, including the eddy current brake, magneto-rheological damper [16], non-destructive testing [17,18], sensor [19], separation equipment [20], composite materials [21], induction heating device [22], solid conducting cylinder [23] and so forth. There are still some puzzles in the theoretical study of eddy current, for instance, the time-harmonic eddy-current problem [24], surface impedance model [25], torsional moment [26], electrical surface charge [27], hybrid electric-magnetic methods [28] and others. ...
The paper aims to apply the algebra of octonions to explore the contributions of external derivative of electric moments and so forth on the induced electric currents, revealing a few major influencing factors relevant to the direct and inverse piezoelectric effects. J. C. Maxwell was the first to adopt the algebra of quaternions to describe the physical quantities of electromagnetic fields. The contemporary scholars utilize the quaternions and octonions to research the physical properties of electromagnetic and gravitational fields. The application of octonions is able to study the physical quantities of electromagnetic and gravitational fields, including the octonion field strength, field source, linear moment, angular moment, torque and force. When the octonion force is equal to zero, it is capable of achieving eight independent equations, including the force equilibrium equation, fluid continuity equation, current continuity equation, and second-precession equilibrium equation and others. One of inferences derived from the second-precession equilibrium equation is that the electric current and derivative of electric moments are able to excite each other. The external derivative of electric moments can induce the electric currents. Meanwhile the external electric currents are capable of inducing the derivative of electric moments. The research states that this inference can be considered as the underlying mechanism for the direct and inverse piezoelectric effects. Further the second-precession equilibrium equation is able to predict several new influencing factors of direct and inverse piezoelectric effects.
... This method has the advantages of high sensitivity, no close contact with the tested object, and no coupling agent [24]. However, the eddy current method cannot avoid the skin effect [25]. The eddy current method is unsuitable for monitoring cables whose diameters are large. ...
Cable tension monitoring is important to control the structural performance variation of cable-supported structures. Based on the elasto-magnetic effect and the self-induction phenomenon, a new non-destructive evaluation method was proposed for cable tension monitoring. The method was called the elasto-magnetic induction (EMI) method. By analyzing the working mechanism of the EMI method, a set of cable tension monitoring systems was presented. The primary coil and the induction unit of the traditional elasto-magnetic (EM) sensor were simplified into a self-induction coil. A numerical analysis was conducted to prove the validity of the EMI method. Experimental verification of the steel cable specimens was conducted to validate the feasibility of the EMI method. To process the tension monitoring, data processing and tension calculation methods were proposed. The results of the experimental verification indicated that different cables of the same batch can be calibrated by one proper equation. The results of the numerical analysis and the experimental verification demonstrated that the cable tension can be monitored both at the tension-applying stage and the tension-loss stage. The proposed EMI method and the given monitoring system are feasible to monitor the cable tension with high sensitivity, fast response, and easy installation.
... This method assumes that the anchorage nut is fixed with the FSSB and anchor plate, which does not reflect the actual connection condition and hence results in a large error in measured tensions. Other testing methods on the effective tension of FSSBs such as the uses of resistance strain gauges, the force sensors between the nut and the anchor plate, ultrasonic waves [5], and the magnetoelasticity of ferromagnetic materials (i.e., P/S steel) [6][7][8][9][10] are applicable only to scientific research and may not be reused, making them unable to be used practically. Due to these reasons, a real-time, non-destructive, and rapid testing method for determining the effective tension in FSSBs is therefore proposed and discussed in this paper, which can ensure the effective tension to meet the design requirement. ...
This paper presents a new non-destructive dynamic tensile test for fine-rolled screw-threaded steel bars (FSSBs) in prestressed concrete box-girder bridges. In this study, the anchorage nut and anchor plate are connected by a coupling spring, so are the steel bar and nut threads. A discrete dynamic model of a spring–mass system was therefore established to evaluate the bending vibration of the anchorage system. The tensile force in prestressing FSSBs can be determined indirectly using the measured natural frequency of the exposed section. Based on the force transmission characteristics of threads, a frequency correction equation is proposed to correct the test error in the tensile force. The laboratory model and field tests of multiple bridges show that the proposed test method for tensile force is feasible and practical. The proposed tension test method is rapid, non-destructive, and can be used repeatedly. It has no impact on the construction and offers potential wide applications. The study results are significant in terms of the testing and analysis of the induced tensions in mechanical components and similar structures of civil engineering.
... In various magnetic techniques, eddy current stress measurement technology, based on piezoresistive effect and magneto mechanical effect, has attracted great attention of researchers, and has become one of the frontiers and focuses in the nondestructive testing of stress [11][12][13][14]. In recent years, researchers have done a lot of work in the mechanism and methods in eddy current stress measurement [15][16][17][18][19][20][21][22][23], which made great contribution to the research of eddy current stress measurement. However, only few researches in the testing of stress in ferromagnetic material have been reported. ...
Estimation of the stress distribution in ferromagnetic components is very important for evaluating the working status of mechanical equipment and implementing preventive maintenance. Eddy current testing technology is a promising method in this field because of its advantages of safety, no need of coupling agent, etc. In order to reduce the cost of eddy current stress measurement system, and obtain the stress distribution in ferromagnetic materials without scanning, a low cost eddy current stress measurement system based on Archimedes spiral planar coil was established, and a method based on BP neural network to obtain the stress distribution using the stress of several discrete test points was proposed. To verify the performance of the developed test system and the validity of the proposed method, experiment was implemented using structural steel (Q235) specimens. Standard curves of sensors at each test point were achieved, the calibrated data were used to establish the BP neural network model for approximating the stress variation on the specimen surface, and the stress distribution curve of the specimen was obtained by interpolating with the established model. The results show that there is a good linear relationship between the change of signal modulus and the stress in most elastic range of the specimen, and the established system can detect the change in stress with a theoretical average sensitivity of -0.4228 mV/MPa. The obtained stress distribution curve is well consonant with the theoretical analysis result. At last, possible causes and improving methods of problems appeared in the results were discussed. This research has important significance for reducing the cost of eddy current stress measurement system, and advancing the engineering application of eddy current stress testing.
Prestressed rebars are usually used to apply vertical prestress to concrete to prevent web cracking. The reduction of working stress will affect the durability of the structure. However, the existing working stress detection methods for prestressed rebars still need to be improved. To monitor the working stress of rebars, a magnetic resonance sensor was introduced to carry out experimental research. The correlation between rebar stress and the sensor’s induced voltage was theoretically analyzed using the magnetoelastic effect and magnetic resonance theory. A working stress monitoring method for prestressed rebars based on magnetic resonance was proposed. Working stress monitoring experiments were carried out for 16 mm, 18 mm, and 20 mm diameter rebars. The results showed that the induced voltage peak-to-peak value and the rebar prestress were nonlinearly correlated under different working conditions. Correlations between the characteristic indicators and the rebar working stress were obtained using nonlinear and linear fit. The cubic polynomial segmented fit outperformed the gradient overall linear fit, with the goodness of fit R2 greater than 0.96. The average relative error values of working stress monitoring were less than 5% under different working conditions. This provides a new method for working stress measurement of vertical prestressed rebars.
Eddy current testing (ECT) is a non-contact inspection widely used as non-destructive testing and evaluation (NDT&E) of pipeline and rail lines due to its high sensitivity to surface and subsurface defects, cheap operating cost, tolerance to harsh environments, and capability of a customisable probe for complex geometric surfaces. However, the remote field of transmitter-receiver (Tx-Rx) ECT depends on the Tx-Rx coils gap, orientation, and lift-off distance, despite each coil responding to the effect of sample parameters according to its liftoff distance. They bring challenges to accurate defect detection and characterisation by weakening the ECT probe’s transfer response, affecting sensitivity to the defect, distorting the amplitude of the extracted features, and responding with fewer feature points at non-efficient energy transfer. Therefore, this study proposed a magnetically-coupled resonant wireless power transfer (WPT)-based ECT (WPTECT) concept to build the relationship between Tx-Rx coil at maximum energy transfer response, including shifting and splitting (resonance) frequency behaviour. The proposed WPTECT system was investigated in three different studies viz., (1) investigated the multiple resonance point features for detection and characterisation of slots on two different aluminium samples using a series-series (SS) topology of WPTECT; (2) mapped and scanned pipeline with a natural dent defect using a flexible printed coil (FPC) array probe based on the parallel-parallel (PP) topology of WPTECT; and (3) evaluated five different WPTECT topologies for optimal response and extracted features and characterised entire parameters of inclined angular Rolling Contact Fatigue (RCF) cracks in a rail-line material via an optimised topology. Multiple feature extraction, selection, and fusion were evaluated for the defect profile and compared in the study, unattainable by other ECT methods. The first study's contribution investigated multiple resonances and principal component analysis (PCA) features of the transfer response from scanning (eight) slots on two aluminium samples. The results have shown the potential of the multiple features for slot depth and width characterisation and demonstrated that the eddy-current density is highest at two points proportionate to the slot width. The second study's contribution provided a larger area scanning capability in a single probe amenable to complex geometrical structures like curvature surfaces. Among the extracted individual and fused features for defect reconstruction, the multi-layer feed-forward Deep learning-based multiple feature fusion has better 3D defect reconstruction, whilst the second resonances feature provided better local information than the first one for investigating pipeline dent area. The third study's contribution optimised WPTECT topology for multiple feature points capability and its optimal features extraction at the desired lift-off conditions. The PP and combined PP and SS (PS-PS) WPTECT topologies responded with multiple resonances compared to the other three topologies, with single resonance, under the same experimental situation. However, the extracted features from PS-PS topology provided the lowest sensitivity to lift-off distances and reconstructed depth, width, and inclined angle of RCF cracks with a maximum correlation, R2 -value of 96.4%, 93.1%, and 79.1%, respectively, and root-mean-square-error of 0.05mm, 0.08mm, and 6.60 , respectively. The demonstrated magnetically-coupled resonant WPTECT Tx-Rx probe characterised defects in oil and gas pipelines and rail lines through multiple features for multiple parameters information. Further work can investigate the phase of the transfer response as expected to offer robust features for material characterisation. The WPTECT system can be miniaturised using WPT IC chips as portable systems to characterise multiple layers parameters. It can further evaluate the thickness and gap between two concentric conductive tubes; pressure tube encircled by calandria tube in nuclear reactor fuel channels.
Alternating prestress is difficult to measure. By analyzing the inverse magnetostriction effect and the magnetic hysteresis, a theoretical model was established to describe the prestress-inductance relationship. The results of the prestress monitoring experiment showed that the inductance was influenced by the irreversible magnetization, the plastic deformation, and the hysteresis effect. Keeping the stress range constant, the inductance range was unaffected by the number of load cycles. The inductance can be used to judge whether the prestress is reasonable. The parabolic fitting method was employed to establish the mapping from the inductance to the prestress. When the stress range was 10% design prestress or 20% design prestress, the prestress monitoring error, less than 12.56% or 18.77%, was close to the magnetoelastic method and the frequency-based method. Based on the proposed calculation method, the MI method could monitor the alternating prestress of steel strands.
To increase the test sensitivity, the resonance theory was introduced to the magnetoelastic method. After analyzing the correlation between the stress and the induced voltage, the resonance enhanced magnetoelastic (REME) method was proposed. A REME sensor with a low resonant frequency was made to carry out the experiment. The results showed that the resonant frequency, the resonant voltage, and the induced voltage could be used to measure stress, the test errors were 12.5%, 11.9%, and 9.5%, respectively. To measure stress, the excitation frequency should be close and lower than the resonant frequency. Enhanced by the resonance theory, the sensitivity of the REME method was 132.47% and 286.50% higher than that corresponding to the resonant voltage and the resonant frequency. The REME method has the advantages of low power supply and good dynamic response. Besides, using the resonance theory to enhance the measurement is applied to other coil-based sensors and methods.
