An electromagnetic oscillation method for stress measurement of steel strands

Li, Xingxing; Zhang, Benniu; Yuan, Can; Tu, Chong; Chen, Dongjun; Li, Yonglin

doi:10.1016/j.measurement.2018.05.014

Cited by 20 publications

(15 citation statements)

References 21 publications

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“…It has been proved that the stress of strands has a good correlation with the electromagnetic resonance frequency [15,16]. It is feasible to detect the prestress of strands based on the LC resonant circuit.…”

Section: Introductionmentioning

confidence: 99%

“…In order to prove this conflict, experimental study was carried out on the 1.2 m, 10 m, and 15 m steel strand and established two sets of theoretical analysis to study the length effect based on the LC resonant electric circuit. As a kind of ferromagnetic material, according to the magnetoelastic properties of the material, the change of stress will lead to the change of permeability [15,16]. At the same time, considering the principle of material elasticity, we know that the length of steel strands will also change.…”

Section: Introductionmentioning

confidence: 99%

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Study on the Main Factors of Frequency Variation of LC Resonant Prestress Detection Method

Zhang

Zhao

et al. 2020

Advances in Materials Science and Engineering

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Stress loss of prestressed steel strands of existing bridges influences their bearing capacity, so it is of great significance to realize the stress detection. A steel strand that has an inductive property is designed into the resonant circuit, which can realize the stress measurement of the steel strands by testing the resonant frequency. This method is a promising approach for the stress detection of the steel strands. Previous research found that structural stress made the permeability of steel strands change due to the influence of magnetoelastic effect. In the process, the length of steel strands is also changed. Therefore, further research needs to be done to verify the main influence parameter affecting the resonant frequency of the circuit. Furthermore, it is very important to know how the stress affects the resonant frequency to realize the detection of the prestressed force of the steel strands. Therefore, in this paper, the relationship between stress and relative permeability and length is analyzed theoretically, and the theory of stress frequency of steel strands is modified and verified by experiments. The stress-frequency experiments of steel strands and aluminum strands with great difference in relative permeability are carried out. Experiments on stress frequencies of 7-Ф15.20 mm steel strands with different lengths are carried out. The influence of length and permeability parameters on resonance frequency is analyzed. The experimental results show that under the same conditions, the resonant frequencies of steel strands and aluminum strands are almost the same on LC electric circuits, and the resonant frequency decreases linearly with the increase of the natural length of the component and increases linearly with the increase of stress. Consequently, compared with the influence of length change on LC electromagnetic resonance frequency, the relative permeability of the stress change component can be ignored. The stress changes the resonant frequency mainly by changing the length of the strands.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on the Main Factors of Frequency Variation of LC Resonant Prestress Detection Method

Zhang

Zhao

et al. 2020

Advances in Materials Science and Engineering

Self Cite

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“…However, in the case of long‐term fatigue loading, the mechanical properties of steel strands may decline and the strands might even fail. Therefore, the detection of stress state of steel strands is important for evaluating the performance of infrastructures 1–3 . Conventional monitoring methods include resistance strain gauge sensor, magnetic flux sensor 4 and frequency metre sensor.…”

Section: Introductionmentioning

confidence: 99%

Range‐expansion technology and fatigue performance study on the self‐sensing steel strand with an embedded fibre Bragg grating sensor

Qin

Shen

Zhu

et al. 2020

Strain

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For the protection of a fragile optical fibre with a fibre Bragg grating (FBG) sensor, the encapsulating method of embedding the FBG sensor in a longitudinal groove set in the central wire of the steel strand is presented. According to the theoretical analysis of the strain transfer and sensing capacity between the embedded FBG sensor and substrate, the requirements for the cross‐sectional size of the groove and bond‐length of the optical fibre to the self‐sensing steel strand are discussed. A prepressure technology is proposed to overcome the problem of low ultimate tensile strain of FBGs. Experiments for range‐expansion with different prepressure values were carried out. The results showed that a prepressure of 30% Pc produced the optimum range expansion of the FBG sensor with a maximum strain measurement of 12,361 με, which was 1.3 times higher than the yield strain of the strands. The analyses of the fatigue performance and static load tests on self‐sensing steel strands were also carried out. The results indicated that the self‐sensing steel strand exhibited good performance after fatigue loading operation of 2 million cycles with a maximum stress of 0.45 σb and a stress amplitude of 250 MPa. Moreover, the decrease in the monitoring strain sensitivity of the FBG was calculated to be below 3.5%, whereas the experimental data showed good linearity and repeatability. Therefore, for effective lifetime monitoring of steel strands under fatigue loading, it is suggested that the FBG sensors need to be placed under a certain prepressure before the construction and service of self‐sensing steel strand.

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“…Inspired by the magneto-elastic effect, the author proposed a prestressed steel strand stress detection method based on LC electromagnetic oscillation [21,22], indirectly measuring the strand stress through the electromagnetic oscillation frequency. According to the electrical theory, prestressed steel strands exhibit single conductance properties in low frequency oscillating circuits and can be divided into inductors, capacitors and resistors.…”

Section: Introductionmentioning

confidence: 99%

“…The theoretical analysis and experimental results of the study show that the circuit oscillation frequency decreases with the increase of steel strand stress. In another study [22], Taylor’s expansion equation was used to establish the relationship between steel strand stress and oscillation frequency, and a 7-wire prestressed steel strand with a length of 10 m was used for cyclic loading experiments. The research results show that the oscillation frequency of the circuit increases with the increase of stress.…”

Section: Introductionmentioning

confidence: 99%

Length Effect on the Stress Detection of Prestressed Steel Strands Based on Electromagnetic Oscillation Method

Zhang

et al. 2019

Sensors

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Prestress detection of structures has been puzzling structural engineers for a long time. The inductance–capacitance (LC) electromagnetic oscillation method has shown a potential solution to this problem. It connects the two ends of a steel strand, which is simulated as an inductor, to the oscillation circuit, and the stress of the steel strand can be calculated by measuring the oscillation frequency of the circuit through a frequency meter. In the previous studies, the authors found that stress-frequency relation of 1.2 m steel strand was negatively correlated, while the stress-frequency of 10 m steel strand was positively correlated. To verify this conflict, two kinds of electrical inductance models of steel strands were established to fit the lengths. With the models, the stress-frequency relations of steel strands with different lengths were analyzed. After that, two kinds of experimental platforms were set up, and a series of stress-frequency relationship tests were carried out with 1.2 m, 5 m, 10 m and 15 m steel strands. Theoretical analysis and experimental results show that when the length is less than 2.013 m, the stress and oscillation frequencies are negatively correlated; when length is more than 2.199 m, the stress and oscillation frequencies are positively correlated; while when length is between 2.013 m and 2.199 m, the stress-frequency relationship is in transit from negative correlation to positive correlation.

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An electromagnetic oscillation method for stress measurement of steel strands

Cited by 20 publications

References 21 publications

Study on the Main Factors of Frequency Variation of LC Resonant Prestress Detection Method

Study on the Main Factors of Frequency Variation of LC Resonant Prestress Detection Method

Range‐expansion technology and fatigue performance study on the self‐sensing steel strand with an embedded fibre Bragg grating sensor

Length Effect on the Stress Detection of Prestressed Steel Strands Based on Electromagnetic Oscillation Method

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