Unprecedented Capacitance-Based Nondestructive Evaluation of Steels

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

doi:10.1007/s11665-019-04062-7

Cited by 7 publications

(1 citation statement)

References 23 publications

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“…This aspect is beyond the scope of this paper. However, this research group has shown capacitance-based damage sensing of steels [52].…”

Section: Discussionmentioning

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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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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“…This aspect is beyond the scope of this paper. However, this research group has shown capacitance-based damage sensing of steels [52].…”

Section: Discussionmentioning

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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Pyropermittivity as an emerging method of thermal analysis, with application to carbon fibers

Chung

2022

J Therm Anal Calorim

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Piezoelectret-based and piezoresistivity-based stress self-sensing in steel beams under flexure

Chung

2020

Sensors and Actuators A: Physical

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Unprecedented Capacitance-Based Nondestructive Evaluation of Steels

Cited by 7 publications

References 23 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

Pyropermittivity as an emerging method of thermal analysis, with application to carbon fibers

Piezoelectret-based and piezoresistivity-based stress self-sensing in steel beams under flexure

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