Nanocomposites conductivity point measurement using Tunneling AFM (TUNA)

Polymer-matrix composites containing conductive nanoparticles are a potential means for achieving an appealing combination of multifunctional properties for their use as structural parts in the aerospace field. Carbon nanofibers (CNFs) have been being looked forward to as the next generation of new and avant-garde aircraft structures because they are exceptionally coveted competitor materials to replace traditional metal components for lightning strike protection. In this regard, nanocomposites at low concentration of CNFs ranging from 0.05% up to 2% by wt to impart electron conduction in tetrafunctional epoxy resin have been prepared and characterized. The aim of this work concerns the use of Tunneling AFM (TUNA) as revolutionary tool able to correlate the electrical current map with the correspondent local morphology of CNF/resins. TUNA technique has proven to play a leading role in the identification of current paths and electrical interconnections, even without altering the morphology with usual treatments employed to create electrical contacts to the ground. Summing up, the good electrical performance together with the high mechanical properties due to a conductive cross-linked network of CNFs inside the resin demonstrate a charming applicative potential for the formulated nanocomposites as structural materials capable to provide a safe conductive path on the exterior skin, preventing serious damage to the aircraft.

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Effect of Applied Pressure on the Electrical Resistance of Carbon Nanotube Fibers

Materials ◽

10.3390/ma14092106 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2106

Author(s):

Chris J. Barnett ◽

James D. McGettrick ◽

Varun Shenoy Gangoli ◽

Ewa Kazimierska ◽

Alvin Orbaek White ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Electrical Resistance ◽

Copper Wire ◽

Applied Pressure ◽

Radial Strain ◽

Electrical Current ◽

Electrical Contacts ◽

Electrical Performance ◽

Macro Scale ◽

Carbon Nanotube Fibers

Carbon nanotubes (CNTs) can be spun into fibers as potential lightweight replacements for copper in electrical current transmission since lightweight CNT fibers weigh <1/6th that of an equivalently dimensioned copper wire. Experimentally, it has been shown that the electrical resistance of CNT fibers increases with longitudinal strain; however, although fibers may be under radial strain when they are compressed during crimping at contacts for use in electrical current transport, there has been no study of this relationship. Herein, we apply radial stress at the contact to a CNT fiber on both the nano- and macro-scale and measure the changes in fiber and contact resistance. We observed an increase in resistance with increasing pressure on the nanoscale as well as initially on the macro scale, which we attribute to the decreasing of axial CNT…CNT contacts. On the macro scale, the resistance then decreases with increased pressure, which we attribute to improved radial contact due to the closing of voids within the fiber bundle. X-ray photoelectron spectroscopy (XPS) and UV photoelectron spectroscopy (UPS) show that applied pressure on the fiber can damage the π–π bonding, which could also contribute to the increased resistance. As such, care must be taken when applying radial strain on CNT fibers in applications, including crimping for electrical contacts, lest they operate in an unfavorable regime with worse electrical performance.

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Lightning strike thermal damage model for glass fiber reinforced polymer matrix composites and its application to wind turbine blades

Composite Structures ◽

10.1016/j.compstruct.2015.07.027 ◽

2015 ◽

Vol 132 ◽

pp. 1182-1191 ◽

Cited By ~ 42

Author(s):

Y. Wang ◽

O.I. Zhupanska

Keyword(s):

Thermal Damage ◽

Polymer Matrix Composites ◽

Turbine Blades ◽

Damage Model ◽

Fiber Reinforced Polymer ◽

Lightning Strike ◽

Matrix Composites ◽

Wind Turbine Blades ◽

Reinforced Polymer ◽

Glass Fiber Reinforced

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Modeling of thermal response and ablation in laminated glass fiber reinforced polymer matrix composites due to lightning strike

Applied Mathematical Modelling ◽

10.1016/j.apm.2017.08.019 ◽

2018 ◽

Vol 53 ◽

pp. 118-131 ◽

Cited By ~ 11

Author(s):

Yeqing Wang ◽

Olesya I. Zhupanska

Keyword(s):

Polymer Matrix ◽

Polymer Matrix Composites ◽

Thermal Response ◽

Fiber Reinforced Polymer ◽

Lightning Strike ◽

Laminated Glass ◽

Matrix Composites ◽

Glass Fiber Reinforced Polymer ◽

Reinforced Polymer ◽

Glass Fiber Reinforced

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On the Transient Hygroscopic Stresses in Polymer Matrix Laminated Composites Plates with Cyclic and Unsymmetric Environmental Conditions

Polymers and Polymer Composites ◽

10.1177/096739110501300506 ◽

2005 ◽

Vol 13 (5) ◽

pp. 489-503 ◽

Cited By ~ 1

Author(s):

A. Tounsi ◽

M. Bouazza ◽

S. Meftah ◽

E. Adda-Bedia

Keyword(s):

Polymer Matrix ◽

Composite Structures ◽

Polymer Matrix Composites ◽

Matrix Composites ◽

Stress Distributions ◽

Moist Environment ◽

Cyclic Variations ◽

Transient Hygroscopic Stresses ◽

Structural Parts

The use of aircraft structural parts made of polymer matrix composites subjected to severe environment conditions calls for better knowledge of their long – term behaviour, with an emphasis on their ability to withstand important cyclic variations of moisture and temperature. The influence of temperature and moisture on such structures is receiving special attention, because it induces transient residual stresses within the plies. Such stresses must be taken into account in the design of composite materials, particularly aerospace structures, e.g. aircraft. In the present paper the transient hygroscopic stresses induced by cyclic and unsymmetric environmental loadings which simulate an aeronautical application are investigated. It is shown that the heterogeneity and anisotropy of such plates generally result in transient stress distributions which are very different from the equilibrium stress distribution. Some stacking sequences exhibit important stresses within the plies. These stresses have to be taken into account in the design of composite structures submitted to a moist environment.

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Damage by Improvised Incendiary Devices on Carbon Fiber-Reinforced Polymer Matrix Composites

Journal of Composites Science ◽

10.3390/jcs5030072 ◽

2021 ◽

Vol 5 (3) ◽

pp. 72

Author(s):

Sebastian Eibl

Keyword(s):

Polymer Matrix ◽

Large Scale ◽

Polymer Matrix Composites ◽

Sandwich Structures ◽

Laboratory Scale ◽

Electrical Heating ◽

Lightning Strike ◽

Protective Effects ◽

Matrix Composites ◽

Fire Tests

This study focuses on short-term thermal degradation of polymer matrix composites by one-sided impact of improvised incendiary devices (IID). Specimens of two commercial composites HexPly® 8552/IM7 and M18-1/G939 with various thicknesses (1–8 mm) are systematically investigated as well as sandwich structures thereof, applying various amounts of fire accelerant predominantly in laboratory scale fire tests. Results of preceding large-scale fire tests with IIDs justify the chosen conditions for the laboratory-scale fire tests. The aim is to correlate the amount of fire accelerant with heat damage and residual mechanical strength. Thermal damage is characterized visually and by ultrasonic testing, infrared spectroscopy, and residual interlaminar shear strength. Matrix degradation and combustion only contribute to the overall amount of released heat by the fire accelerant for thin and especially vertically aligned panels as tested by a cone calorimeter (without electrical heating), but not for horizontally orientated and thicker panels. Degradation processes are discussed in detail. Protective effects are observed for typical coatings, a copper mesh applied for protection against lightning strike, combinations thereof as well as an intumescent coating. Especially sandwich structures are prone to severe damage by assaults with IID, such as Molotov cocktails.

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