Nanoindentation derived elastic constants of carbon fibres and their nanostructural based predictions

Abstract

Elastic constants of single carbon fibres were estimated by a novel nanoindentation based method and subsequently predicted by modified two-and three-phase Eshelby-Mori-Tanaka (EMT) micromechanical models which takes into account both crystalline, amorphous phases and microvoids of the fibre structure. This case study was carried out on a T-300 PAN-based carbon fibre reinforced SiC composite material at room temperature. Transversal and longitudinal cross-sections of individual fibres were indented by a sharp Berkovich tip up to the maximum depth of 150 nm. Assuming transverse isotropy of the fibres, their five elastic constants were deduced from the measured indentation moduli using numerical (Vlassak-Nix) and analytical

Mechanical anisotropy of PAN-based and pitch-based carbon fibers

“…5, where the average indentation modulus of the PAN-based carbon fiber for axial, 45° and radial direction is 73.4 ± 5.5 GPa, 28.3 ± 1.6 GPa and 20.9 ± 2.0 GPa, respectively. These values are in agreement with a recent nanoindentation report on PAN-based carbon fibers (Csanádi, et al 2017). On the other hand, the pitch-based carbon fiber in the axial direction exhibits a similar indentation modulus (76.5 ± 11.6 GPa) in comparison to the PAN-based carbon fiber for the same orientation, whilst the indentation moduli of the pitch-based carbon fiber in the 45° and radial direction are smaller than those of PAN-based carbon fiber (13.3 ± 2.1 GPa and 5.7 ± 1.4 GPa).…”

“…On the other hand, there are some studies examining the transverse elastic modulus (i.e. an elastic property in the radial direction) and mechanical anisotropy (Maurin, et al, 2008;Csanádi, et al, 2017;Naito, et al, 2017;Tane, et al, 2019). However, in the above previous studies, PAN-based carbon fibers have been widely used and there is a current lack of knowledge in the literature regarding mechanical properties of pitch-based carbon fibers which possess a significantly different Keiichi SHIRASU* , **, Chiemi NAGAI** and Kimiyoshi NAITO** microstructure and mechanical properties (630-940 GPa in tensile modulus) compared with the PAN-based carbon fibers whose tensile moduli are 230-290 GPa for high-strength PAN-based fibers and 350-560 GPa for high-modulus PAN-based fibers (Naito, et al, 2008(Naito, et al, , 2017.…”

“…Especially, micro-and nanoindentation tests are widely applied in materials with small size. They have been used to study mechanical behaviors of carbon fibers (Maurin, et al, 2008;Sun, et al, 2014;Csanádi, et al, 2017) as well as metals (Gouldstone, et al, 2000) and ceramics (Page, et al, 1992). We also systematically investigated the crystallinity and nanostructure of carbon fibers by means of SEM, TEM and Raman spectroscopy.…”

Investigation of anisotropic mechanical properties of textured KSr2Nb5O15 ceramics via ab‐initio calculation and nanoindentation

“…The Young's modulus values along the X and Z axes ([100] and [001] directions) are the reciprocal of the corresponding components of the compliant tensor (), , and E z = 1/ s 33 . In addition, the three‐dimensional orientation dependence of Young's modulus is calculated by rotating the compliant tensor around the Z and X axes of the tetragonal KSN crystal, as reported in . This dependence is expressed as follows: Here, α and β correspond to the tilt angle from the [001] direction and the rotation angle from [100] to [010] around the c‐axis of the crystal, respectively.…”

“…In addition, the three-dimensional orientation dependence of Young's modulus is calculated by rotating the compliant tensor around the Z and X axes of the tetragonal KSN crystal, as reported in. 46 This dependence is expressed as follows:…”