Sensing the stress in steel by capacitance measurement

Chung, D.D.L.; Shi, Kairong

doi:10.1016/j.sna.2018.03.037

Cited by 18 publications

(13 citation statements)

References 10 publications

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“…It has been mentioned that the scientific origin of the previously reported capacitance-based self-sensing in steels relates to the direct piezoelectric effect [12]. However, this notion was not supported by measurement of the stress dependence of the electric field output or permittivity.…”

Section: Introductionmentioning

confidence: 97%

“…Steels are the most widely used structural materials. It has been recently reported that the self-sensing of stress (demonstrated up to a normal compressive stress of 1.12 kPa only) in steels can be achieved by in-plane capacitance measurement [12]. In other words, the capacitance of the steel changes in response to the stress applied to the steel.…”

Section: Introductionmentioning

confidence: 99%

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Electret, piezoelectret and piezoresistivity discovered in steels, with application to structural self-sensing and structural self-powering

Chung

2019

Smart Mater. Struct.

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Electret, piezoelectret, piezoresistivity and stress-dependent electric permittivity are reported in unmodified steels. Structural stress/strain self-sensing based on piezoelectret/piezoresistivity is demonstrated under tension. Structural self-powering is shown by the electret's inherent electric field, (2.224×10 −5 ) V m −1 and (1.051×10 −5 ) V m −1 , and power density, 29.2 and 41.8 W m −3 , for low carbon steel and stainless steel, respectively, being enabled by the electret's electrical conductivity. The free-electron-movement-enabled electrets are supported by the asymmetry in the polarization-induced apparent resistance relative to the true resistance upon polarity reversal. The electric field increases linearly with the inter-electrode distance l. An l increase causes the amount of participating free electrons to increase and the fraction of free electrons that participate to decrease; when l is tripled, the amount is increased by a factor of 1.011 and 1.021 for low carbon steel and stainless steel, respectively, while the fraction of free electrons that participate is decreased by a corresponding factor of 0.337 and 0.340. The higher values for stainless steel are consistent with the higher relative permittivity (2 kHz), 1.23×10 6 and 2.89×10 6 for low carbon steel and stainless steel, respectively. The capacitance (2 kHz) and electric field (DC) of the piezoelectret decrease nonlinearly with increasing stress, due to electret weakening; the decrease is reversible at stress 210 MPa, but is irreversible at stress 340 MPa (elastic regime). This effect is stronger for low carbon steel than stainless steel. The piezoelectret coupling coefficient d 33 is −(6.6±0.1)×10 −7 and −(3.6±0.2)×10 −7 pC N −1 for low carbon steel and stainless steel, respectively. The relative permittivity (2 kHz) decreases nonlinearly by 14% with stress 340 MPa. The piezoresistivity involves the DC resistivity decreasing nonlinearly and reversibly by 10% with stress 340 MPa; the gage factor is −1030 and −800 for low carbon steel and stainless steel, respectively. The reversibility upon unloading is superior for piezoresistivity than piezoelectret.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Electret, piezoelectret and piezoresistivity discovered in steels, with application to structural self-sensing and structural self-powering

Chung

2019

Smart Mater. Struct.

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“…There is even more limited work on the ability of steel to sense stresses without the need for any external sensors. The first study was carried out using a thin film (Chung and Shi 2018) and the following study used thin film again, but unlike the first study, tensile stress is sensed instead of compressive stress (Xi and Chung 2019). In the last study, experiments are carried out on steel with increased thickness (Xi and Chung 2020).…”

Section: Introductionmentioning

confidence: 99%

Capacitive self tension sensing properties of steel beam: electrode configuration and stress regime

Ozturk

2023

Phys. Scr.

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Self-sensing for steel is valuable for the control and safety of steel structures such as buildings and bridges. The changes in the capacitance of steel in response to cyclic tensile stresses applied in low, medium and high stress regimes are measured by using a Inductnce-Capacitance-Resistance (LCR) meter. Coplanar and parallel plate electrode configuration is used for capacitance measurements. Aluminum foil is used as electrode. A steel beam of 100 mm in length, 30 mm in width and 2.5 mm in thickness is tensioned by holding it at both ends to produce direct tensile stresses in the material. The maximum stresses applied for low, medium and high stress regimes are 6.7 MPa, 33.3 MPa and 66.7 MPa. The capacitance value of the sample with coplanar and parallel plate electrode configurations measured without applying load are 203.42 pF and 196.00 pf, respectively. The fractional changes in capacitance are 0.059%, 0.192% and 0.275% when 6.7 MPa, 33.3 MPa and 66.7 MPa direct tensile stress is created in the steel beam. These values are 0.12%, 0.20% and 0.29% for parallel plate electrode configuration. Test results demonstrates that there is a relation between stress and fractional change in capacitance. In other words, measuring fractional change in capacitance gives information about the stress variations in the material. From the experimental results, parallel plate electrode configuration is found to be more effective in tensile stress self-sensing. In addition, the relationship between stress and fractional change in capacitance is more linear for both electrode configurations in the low stress regime. This paper aims to reveal the tensile stresses occurring in steel by means of capacitance-based sensing. Sensing capability in larger scale structures and factors effecting sensing sensitivity are to be addressed in future work.

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“…The linear spring stiffness factor k , also known as the stubbornness coefficient, is an important property that indicates the ability of the linear spring to resist deformation [ 1 , 2 , 3 ]. Being a kind of elastic object that stores energy, linear springs are widely used in many fields, such as furniture, architecture, machinery, and electronics [ 4 , 5 , 6 , 7 , 8 ]. Depending on the purpose for their usage, different types of linear springs should have different stiffness factors.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Linear Springs’ Stiffness Factor Using Ultrasonic Sensing

Zhang

et al. 2022

Sensors

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We designed an ultrasonic testing instrument that consisted of a single-chip microcomputer module, a digital display module, and an ultrasonic sensor module, which conveniently eliminated the troubles faced by the traditional Jolly’s scale. For comparison purpose, three linear springs’ stiffness factors were measured by Jolly’s scale and by our ultrasonic testing instrument. We found that our instrument could more conveniently and in real time display the distance values between the ultrasonic ranging module and the horizontal bottom plate when loading different weights. By processing these distance data, we found that our instrument was more convenient for obtaining the linear springs’ stiffness factors and that the results were more accurate than those of Jolly’s scale. This study verified that our instrument can accurately realize the performance of Jolly’s scale under diverse temperatures and humidity levels with high data reliability and perfect stability.

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Sensing the stress in steel by capacitance measurement

Cited by 18 publications

References 10 publications

Electret, piezoelectret and piezoresistivity discovered in steels, with application to structural self-sensing and structural self-powering

Electret, piezoelectret and piezoresistivity discovered in steels, with application to structural self-sensing and structural self-powering

Capacitive self tension sensing properties of steel beam: electrode configuration and stress regime

Measurement of Linear Springs’ Stiffness Factor Using Ultrasonic Sensing

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