Multi-Scale Experiments and Interfacial Mechanical Modeling of Carbon Nanotube Fiber

An experimental investigation on the tangential interfacial properties of graphene: Size effect

“…The wavenumber of the characteristic peaks in the Raman spectrum is related to the lattice deformation, and the peak shift can reflect the strain of a specific material. The strain information of porous silicon [7][8][9], carbon nanotubes [10,11] and graphene [12] has been measured accurately using in-situ Raman spectroscopy. In the Raman spectrum of monolayer graphene, the 2D-Raman peak will shift to lower or higher positions under tensile or compressive load, termed as a red-shift or blue-shift, respectively.…”

Experiment Research on Deformation Mechanism of CNT Film Material

“…Just as Figure 4(b) shows, from the initial loading to the large strain (longitudinal direction is 18%, 45 ∘ direction is 15%) scale of film, G band Raman shift decreases linearly, indicating that CNTs are elastically deformed in this process. Afterwards, G band Raman shift with strain decreased slowly, indicating that slippage among CNT bundles happens within the film [4]. The change of full width at half-maximum (FWHM) of G band provides much information about the stress distribution in the CNT film.…”

“…In this case, even if the applied load is removed, micro units cannot return to original shape. When the network with a number of "long chains" continues to be loaded, due to low shear strength, slippage among bundles will appear in the "long chain" [4,18] and spread among the "long chain," and the accumulation of slippage damage will lead to shear failures of the long chain and entire failure of CNT bundle network eventually. When the film is stretched along the 45 ∘ direction, there are two stress components paralleled and perpendicular to the direction of the CNT bundle micro unit overlapping area, so the micro unit generates two variants: the first is the deformation which has the same process as the longitudinal tension, accompanied with integral rotary of micro unit to loading direction; the second is the bending degree of CNT bundles in micro unit that increases gradually, so that the acute angle between bundles gradually becomes an obtuse angle, and then two rotating bundles present crossing shape while the whole micro unit rotates towards the loading direction.…”

“…At present, some research progress has been made in deformation measurement technology of different scale structures of materials, for example, the effective application of micro-Raman spectroscopy [2,3] in microscale experimental mechanics research field: Deng et al studied multiscale deformation and interface mechanical behavior of CNT fiber, suggesting that bundle interface glide of microscale is the reason for material structure failure [4]; Trakakisa et al assessed stress transfer of high volume fraction CNT complex substance made by buckypaper method from polymer to the individual or fasciculation CNTs [5]; Kao et al researched deformation action and heating influence of SWNT/epoxy resin composite and loading transfer inside double wall CNTs [6,7]; Wagner research institute [8] and Qiu et al [9] measured strain distribution around fiber and microhole inside the composite with CNT as sensing medium; Ma et al researched macroperformance and microstructure deformation of single wall CNT fiber and film under displacement loading [10,11]. In another experiment technique aspect, Li et al developed multiprobe mechanical test system and applied this system into grasp, loading, and measure of Si nanowire and other onedimensional nanostructures [12]; Wang et al used SR X-ray to research inner structure deformation of compressed foamed aluminum combined with X-ray fault technique (SR-CT) and digital image analysis method and calculated porosity, intersecting surface, and other important parameters based on the reconstructed images [13].…”

Detailed investigation on elastoplastic deformation and failure of carbon nanotube fibers by monotonic and cyclic tensile experiments

“…Since the CNT fibers consist of millions of separated CNTs and their self-assembled bundles, the orientation distributions of them can considerably influence the mechanical properties of the CNT fibers. Previous experimental results by Li et al [15,16] indicated that tensile stress-strain curves of the CNT fibers include three stages: elastic stage, strengthen stage and damage-fracture stage. They also pointed out that the self-assembled CNT bundles in the CNT fibers are the main load-carrying parts, and their slipping can lead to plastic deformation of the CNTs fibers.…”