Capacitance-based self-sensing of flaws and stress in carbon-carbon composites, with reports of the electric permittivity, piezoelectricity and piezoresistivity

Xi, Xiang; Chung, D.D.L.

doi:10.1016/j.carbon.2019.01.062

Cited by 33 publications

(13 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The cantilever type acceleration sensor is a kind of capacitive sensors [ 57 , 58 ], and it follows the capacitor characteristic in the following equation [ 59 , 60 ]:

where C is the capacitance, ε 0 is the electric permittivity of vacuum, ε r is the relative permittivity of dielectric, A is the area, and d is the thickness of the dielectric. The parameter ε 0 is known as a constant 8.85 × 10 −12 F/m.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Cantilever Type Acceleration Sensors Made by Roll-to-Roll Slot-Die Coating

Lee

2020

Sensors

View full text Add to dashboard Cite

This paper presents the fabrication by means of roll-to-roll slot-die coating and characterization of air gap-based cantilever type capacitive acceleration sensors. As the mass of the sensor moves in the opposite direction of the acceleration, a capacitance change occurs. The sensor is designed to have a six layers structure with an air gap. Fabrication of the air gap and cantilever was enabled by coating and removing water-soluble PVA. The bottom electrode, the dielectric layer, and the sacrificial layer were formed using the roll-to-roll slot-die coating technique. The spacer, the top electrode, and the structural layer were formed by spin coating. Several kinds of experiments were conducted for characterization of the fabricated sensor samples. Experimental results show that accelerations of up to 3.6 g can be sensed with an average sensitivity of 0.00856 %/g.

show abstract

“…The cantilever type acceleration sensor is a kind of capacitive sensors [ 57 , 58 ], and it follows the capacitor characteristic in the following equation [ 59 , 60 ]:

Section: Resultsmentioning

confidence: 99%

“…The cantilever type acceleration sensor is a kind of capacitive sensors [57,58], and it follows the capacitor characteristic in the following equation [59,60]:…”

Section: Electrical Characteristics Of the Sensor Samplesmentioning

confidence: 99%

Cantilever Type Acceleration Sensors Made by Roll-to-Roll Slot-Die Coating

Lee

2020

Sensors

View full text Add to dashboard Cite

show abstract

“…A small fraction of the carriers such as electrons interact with the atoms in the metal or carbon, thereby causing polarization and hence substantial permittivity. This has been shown by this research group recently for a variety of metals (aluminum, steels, nickel and tin-lead solder) [11][12][13][14] and carbons (carbon fibers, isotropic graphite, exfoliated-graphitebased flexible graphite, carbon fiber polymer-matrix composite and carbon-carbon composite) [14][15][16][17][18][19][20][21][22][23]. Furthermore, the ability of the carriers in a metal or carbon in a continuous form to move by a long distance promotes the permittivity.…”

Section: Introductionmentioning

confidence: 85%

Absorption-dominant radio-wave attenuation loss of metals and graphite

Guan

Chung

2021

J Mater Sci

Self Cite

View full text Add to dashboard Cite

Absorption-dominant radio-wave (0.2-2.0 GHz) attenuation loss is comparatively reported for materials of high electrical conductivity, namely metals (aluminum and steel) and graphite. These materials exhibit similarly high absorption loss (B 91.5%) and similarly low reflection loss (C 8.5%), both as fractions of the total loss in dB. The absorption loss is high (\ 55 dB) and the reflection loss is low (\ 10 dB) for both graphite and the metals. The absorptiondominant attenuation loss of these high-conductivity materials is in contrast to the notion that high conductivity (due to the high impedance mismatch with air) generally causes reflection-dominant attenuation loss. The metals and graphite are in foil form, with the graphite being thicker than the metals. The linear absorption coefficient (directly related to the absorption loss per unit thickness) is lower for graphite (B 93 mm -1 ) than the metals (B 394 mm -1 ), due to the greater thickness of the graphite. The absorption loss and fractional absorption loss contribution increase with increasing frequency, whereas the reflection loss decreases, as consistent with electromagnetic theory. On the other hand, from the viewpoint of the fractional loss in power, reflection dominates over absorption for all three materials in the entire frequency range. For shielding, the metals are more effective than graphite if the absorption loss per unit thickness (\ 3400 dB/mm) is considered. For stealth, graphite is advantageous to the metals in the low reflection loss, though it is disadvantageous in the low absorption loss per unit thickness.

show abstract

“…Nevertheless, these composites are susceptible to delamination owing to their inherently high porosity and high operating temperatures. Xi et al [87] recently reported strain and flaw monitoring in C/C composites based on the self-sensing principle. The composites were fabricated from PAN-based biaxially woven carbon fiber fabric with a density of 1.5 g/cm 3 after densification.…”

Section: Self Sensing In Carbon Compositesmentioning

confidence: 99%

Piezoresistive Sensing Approaches for Structural Health Monitoring of Polymer Composites—A Review

Nauman

2021

Eng

View full text Add to dashboard Cite

Structural health monitoring (SHM) is an emerging paradigm of real-time in situ structural evaluation for the detection of damage and structural degradation. This is achieved while the structure is kept in-service as against traditional non-destructive evaluation (NDE) techniques which require scheduled interventions while the structure is kept offline. SHM offers great advantages over traditional regimens of condition monitoring (CM) by improving structural reliability and safety through timely detection of structural defects also known as “diagnosis”. Polymeric composite materials offer the unique opportunity of integrating different phases for designing self-sensing smart systems capable of self-diagnosis. Polymers are unique in the sense that they can be designed in various configurations as they generally have facile manufacturing procedures. Among other properties, piezoresistance is the one that can be detected in composites in real-time as a function of strain. Conductive polymers including intrinsic and extrinsic conductive polymers can be used to induce piezoresistivity in composites. Careful design procedures can be adopted to maximize the sensitivity of these piezoresistive composites in order to fully exploit the potential of this property for SHM. Various manufacturing/integration strategies can be employed to effectively use piezoresistance in composites for structural health monitoring. These include self-sensing in carbon fiber-reinforced composites, use of surface deposited/mounted sensing films and patterns, integration of filaments and yarns during reinforcement manufacturing or lay-up and impregnation of reinforcements with piezoresistive matrices. A comprehensive review of these techniques is presented with the view of their utility in the SHM of composites. A selection criterion for these techniques is also presented based on sensitivity, manufacturing method and detection capability.

show abstract

Capacitance-based self-sensing of flaws and stress in carbon-carbon composites, with reports of the electric permittivity, piezoelectricity and piezoresistivity

Cited by 33 publications

References 33 publications

Cantilever Type Acceleration Sensors Made by Roll-to-Roll Slot-Die Coating

Cantilever Type Acceleration Sensors Made by Roll-to-Roll Slot-Die Coating

Absorption-dominant radio-wave attenuation loss of metals and graphite

Piezoresistive Sensing Approaches for Structural Health Monitoring of Polymer Composites—A Review

Contact Info

Product

Resources

About