Sensitive strain monitoring of SiC fiber/epoxy composite using electrical resistance changes

2007 ◽  
Vol 67 (6) ◽  
pp. 955-962 ◽  
Author(s):  
T OGASAWARA ◽  
S AIZAWA ◽  
T OGAWA ◽  
T ISHIKAWA
Keyword(s):  
Electrical Resistance ◽  
Epoxy Composite ◽  
Sensitive Strain ◽  
Strain Monitoring ◽  
Sic Fiber

Largely Deformable and Highly Sensitive Strain Sensor Using Carbon Nanomaterials

2017 ◽  
Author(s):  
Kanji Yumoto ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Aspect Ratio ◽  
Growth Condition ◽  
Electrical Resistance ◽  
Carbon Nanomaterials ◽  
Flexible Substrate ◽  
Strain Sensor ◽  
Sensitive Strain ◽  
Synthesis Process ◽  
Pressure Sensitivity ◽  
Highly Sensitive

A new type tactile sensor with spatial resolution less than 1 mm and the minimum pressure sensitivity less than 10 kPa was proposed by applying MWCNTs (Multi-Walled Carbon Nanotubes). The sensor was embedded into a highly deformable flexible substrate (PDMS: Polydimethylsiloxane) and the obtained gauge factor of the developed sensor was about 5. Since the electronic properties of MWCNTs vary drastically depending on their deformation under mechanical stress, it is important to make appropriate aspect ratio of MWCNTs for improving their stress-sensitivity. The aspect ratio of MWCNTs are mainly dominated by their growth condition such as the average thickness of catalyst layer, growth temperature, pressure of resource gases and so on. Thus, the optimum growth condition was investigated for forming the MWCNTs with high aspect ratio, in other words, high pressure sensitivity. In addition, in this study, the authors fabricated high quality carbon nano-materials to develop highly sensitive strain sensor. A thermal CVD synthesis process of MWCNTs was developed by using acetylene gas. After the synthesis of MWCNTs, flexible isolation material (PDMS) was coated around the grown MWCNT. Then, the interconnection film was deposited by sputtering. After that, PDMS was coated again to fabricate an upper protection layer. Finally, the bottom interconnection layer was sputtered and patterned. The change of the electrical resistance of the grown MWCNTs was measured by applying a compression test in the load range from 0 to 10 mN. It was found that the electrical resistance of the MWCNTs bundle increased almost linearly with the applied compressive load and this sensor showed the high load sensitivity of 10 mN that is higher than human fingers.

Monitoring Damage in Non-Oxide Composites at High Temperatures Using Carbon-Containing CVD SiC Monofilament Fibers As Embedded Electrical Resistance Sensors

2020 ◽  
Author(s):  
Ragav P. Panakarajupally ◽  
Joseph Elrassi ◽  
K. Manigandan ◽  
Yogesh P. Singh ◽  
Gregory N. Morscher
Keyword(s):  
Crack Growth ◽  
Electrical Resistance ◽  
Composite System ◽  
Elevated Temperatures ◽  
Ceramic Composites ◽  
Fatigue Tests ◽  
Matrix Cracking ◽  
Fiber Reinforced ◽  
Damage Initiation ◽  
Sic Fiber

Abstract Electrical resistance has become a technique of interest for monitoring SiC-based ceramic composites. The typical constituents of SiC fiber-reinforced SiC matrix composites, SiC, Si and/or C, are semi-conducive to some degree resulting in the fact that when damage occurs in the form of matrix cracking or fiber breakage, the resistance increases. For aero engine applications, SiC fiber reinforced SiC, sometimes Si-containing, matrix with a BN interphase are often the main constituents. The resistivity of Si and SiC is highly temperature dependent. For high temperature tests, electrical lead attachment must be in a cold region which results in strong temperature effects on baseline measurements of resistance. This can be instructive as to test conditions; however, there is interest in focusing the resistance measurement in the hot section where damage monitoring is desired. The resistivity of C has a milder temperature dependence than that of Si or SiC. In addition, if the C is penetrated by damage, it would result in rapid oxidation of the C, presumably resulting in a change in resistance. One approach considered here is to insert carbon “rods” in the form of CVD SiC monofilaments with a C core to try and better sense change in resistance as it pertains to matrix crack growth in an elevated temperature test condition. The monofilaments were strategically placed in two non-oxide composite systems to understand the sensitivity of ER in damage detection at room temperature as well as elevated temperatures. Two material systems were considered for this study. The first composite system consisted of a Hi-Nicalon woven fibers, a BN interphase and a matrix processed via polymer infiltration and pyrolysis (PIP) which had SCS-6 monofilaments providing the C core. The second composite system was a melt-infiltrated (MI) pre-preg laminate which contained Hi-Nicalon Type S fibers with BN interphases with SCS-Ultra monofilaments providing the C core. The two composite matrix systems represent two extremes in resistance, the PIP matrix being orders of magnitude higher in resistance than the Si-containing pre-preg MI matrix. Single notch tension-tension fatigue tests were performed at 815°C to stimulate crack growth. Acoustic emission (AE) was used along with electrical resistance (ER) to monitor the damage initiation and progression during the test. Post-test microscopy was performed on the fracture specimen to understand the oxidation kinetics and carbon recession length in the monofilaments.

scholarly journals Investigation of the effect of carbon nanotubes on electrical properties of woven fiberglass/epoxy composite laminate

2019 ◽  
Vol 196 ◽  
pp. 00019
Author(s):  
Elivazeta Kalugina
Keyword(s):  
Electron Microscopy ◽  
Electrical Properties ◽  
Fatigue Test ◽  
Electrical Resistance ◽  
Composite Laminate ◽  
Epoxy Composite ◽  
Microstructural Analysis ◽  
Lcr Meter ◽  
Cracking Zone ◽  
Scanning Electron

The effect of epoxy modified by 0.05 wt. % of CNTs on electrical properties of woven fiberglass/epoxy composite laminate was examined. The electrical resistance was measured using 4-point probe method and LCR-meter during cyclic tensile and fatigue test. Microstructural analysis using field emission scanning electron microscopy (FESEM) was carried out. Based on the experimental data, the increase in load is accompanied by growth in electrical resistance. The change in resistance after 20 cycles was up to 3 %. During fatigue test, the change in resistance was considerable and made up to 25 % in cracking zone of the sample and over 110 % at the failure mode.

QDs-Epoxy Resin for Strain Monitoring

2016 ◽  
Vol 853 ◽  
pp. 508-513
Author(s):  
Qi Xin Zhong ◽  
Shao Feng Yin ◽  
Zi Ming Zhao ◽  
Wei Ling Luan
Keyword(s):  
Epoxy Composite ◽  
Mechanical Strain ◽  
Tensile Tests ◽  
Transmission Electron Microcopy ◽  
Cyclic Loading And Unloading ◽  
Strain Monitoring ◽  
Transmission Electron ◽  
Before And After ◽  
Loading And Unloading ◽  
Pl Intensity

The discovery of the variation of the photoluminescence (PL) intensity of quantum dots (QDs) with mechanical deformation has stimulated the interest of developing QDs-based structures for the measurement and monitoring of stress or strain. In this work, tensile bars with the coating of QDs-epoxy composite are subjected to cyclic loading and unloading tests, and the PL intensity of the coating of QDs-epoxy composite is measured as a function of mechanical strain. There are four types of responses in the PL intensity, depending on the loading condition. Transmission electron microcopy is used to examine the rearrangement of QDs in the coatings before and after the tensile tests for understanding the change in the PL response.

Cyclic Behavior of Electrical Resistance Type Low Stiffness, Large Strain Sensor by Using Carbon Nanofiber/Flexible Epoxy Composite

2011 ◽  
Vol 462-463 ◽  
pp. 1200-1205 ◽  
Author(s):  
Yoshinobu Shimamura ◽  
Kyohei Kageyama ◽  
Keiichiro Tohgo ◽  
Tomoyuki Fujii
Keyword(s):  
Electrical Conductivity ◽  
Electrical Resistance ◽  
Carbon Nanofiber ◽  
Epoxy Composite ◽  
Large Strain ◽  
Conductive Polymer ◽  
Cyclic Behavior ◽  
Resistance Change ◽  
Sensing Applications ◽  
Electrical Resistance Change

Carbon nanofiber (CNF) has good electrical conductivity. Addition of a few percentages of carbon nanofiber to polymer yields electrical conductivity but hardly affects the mechanical properties of polymer. This conductive polymer may be useful for sensing applications such as strain sensors and chem-resist sensors. Many researchers have reported on the electrical conductivity, but the electrical resistance change under strain of the carbon nanofiller composites is not fully investigated. In this study, the electrical resistance change under strain of CNF/flexible-epoxy composites was investigated experimentally. More than 100% of quasi-static strain can be measured by using CNF/flexible-epoxy composite with Young’s modulus of less than 1MPa. Cyclic and unloading behaviors were also measured and discussed. It was found that the cyclic behavior was strongly affected by viscoelasticity and damage.

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