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![Table 2 . Mechanical properties of multiwalled carbon nanotube [49,50].](publication/327475143/figure/tbl1/AS:667897634517000@1536250613447/Mechanical-properties-of-multiwalled-carbon-nanotube-49-50_Q320.jpg)
: In this study, the mechanical behavior of epoxy/carbon nanotubes (CNTs) nanocomposite is predicated by a two-scale modeling approach. At the nanoscale, a CNT, the interface between the CNT and the matrix and a layer of the matrix around the CNT are modeled and the elastic behavior of the equivalent fiber (EF) has been identified. The CNT/epoxy in...
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Researchers have been aiming to replace copper with carbon nanotube/copper nanocomposites, which are lighter and exhibit better electrical, mechanical, and thermal properties. However, the strength is far below pure carbon nanotube assembly and even much lower than some copper-based alloys. This disadvantage hinders the extensive application of car...
This paper addresses the effect of microstructure uncertainties on elastic properties of nanocomposites using FEA simulations. Computer simulated microstructures were generated to reflect the variability observed in nanocomposite microstructures. The effect of waviness, agglomeration and orientation of CNTs were investigated. Generated microstructu...
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... Firstly, referring to the experimental results of Javadinejad et al. [44], the average length and diameter of untreated CNTs were 15 µm and 7.5 nm, respectively, with an aspect ratio of 2000, axial Young's modulus of 1 TPa, and radial Young's modulus of 30 GPa. The Young's modulus of a pure epoxy matrix was 2.6 GPa. ...
... Physical values used in the calculation for comparison with Javadinejad et al.[44]. The effect of the aspect ratio of CNT fillers on the interfacial Young's modulus and overall Young's modulus of CNTs-reinforced nanocomposites. ...
The mechanical/thermal/electrical properties on-demand design of CNTs-reinforced nanocomposites is a key scientific issue that limits the development of new-generation smart nanomaterials, and the establishment of a corresponding unified theoretical prediction model for the mechanical/thermal/electrical properties is the foundation of nanocomposites. Based on the equivalent medium theory (EMT) obtained by Maxwell far-field matching, a unified mechanical/thermal/electrical modified EMT model is established by introducing Young’s modulus, thermal conductivity, and electrical conductivity to the thin filler–matrix’s interlayer. According to literature, the proposed model was employed to theoretically calculate the variations in the overall Young’s modulus, thermal conductivity, and electrical conductivity of CNTs-reinforced nanocomposites with respect to the volume concentration of CNT fillers. Then, the applicability of the proposed theoretical model was validated in comparison with the experimental measurements. Numerical calculations showed that the interface is a key factor affecting the mechanical/thermal/electrical properties of CNTs-reinforced nanocomposites, and strengthening the interfacial effect is an effective way to enhance the overall properties of nanocomposites. In addition, the aspect ratio of CNT fillers also significantly affects the material properties of the CNT fillers interface phase and the CNTs-reinforced nanocomposites. By fitting the experimental data, the calculation expressions of the aspect ratios of CNT fillers on the Young’s modulus, thermal conductivity, and electrical conductivity of the CNT fillers interfacial phase are quantitatively given, respectively.
... The other is to incorporate more complicated features, such as waviness and/or agglomerations in the study. For the latter, some approaches have been proposed to address the specific issues on waviness and agglomeration, [34][35][36] but not for a comprehensive understanding of a practical material system which involves different types of filler, interface, and distribution besides waviness and agglomeration. For either case, the current work has laid out a foundation for these possible future studies. ...
Many studies, experimental, theoretical, and numerical, have been done on polymer nanocomposites, but nearly all of them have focused on a particular type of material system or some specific material properties. A comprehensive understanding of this complicated material system is still quite lacking. The objective of this study is to use mesoscale finite element simulation to gain insights on the reinforcing efficiencies of different types of carbon nanofillers as distinguished by their geometries and interfacial strengths. It is demonstrated that CNT (carbon nanotube) and CNF (carbon nanofiber) have larger load carrying capacity and potentially higher reinforcing efficiency than GNP (graphite nanoplatelet) due to their larger aspect ratio and physical length. However, the higher load carrying capacity is also associated with higher interfacial stress which can lead to earlier debonding, particularly for CNT. GNP, on the other hand, has lower load carrying capacity, and is thus less sensitive to the bonding condition and less susceptible to debonding. The overall reinforcing efficiency is a manifestation of the interplay between the load carrying capacity of the filler, which is limited by filler’s geometry, and the load transfer capability at the interface, which is limited by the filler/matrix interfacial strength. This interplay is also reflected in the effects of filler orientation on reinforcing efficiency. The insights gained from this study can be used to devise a strategy for developing advanced nanocomposites, such as hybrid composites.
... This can be justified by the SEM image is shown in Figure 13. Javadinejad et al. [95] applied numerical FEM to demonstrate the clustering effect of CNTs in the composite as shown in Figure 14. Figure 14 shows a 3D view of four colonies in different volume fractions of CNTs. The colonization/agglomeration effect increases with the increase of vol% of CNTs in epoxy resin is shown in Figure 15. ...
... 3D view of the RVE with clustering of CNTs in four colonies in epoxy resin: (a) 0.18 wt%, (b) 0.36 wt%, (c) 0.9 wt%, and (d) 1.8 wt%[95]. (a) Variation of YS of CNT/epoxy nanocomposite with respect to MWCNT volume fraction, and (b) Effect of CNTs agglomeration on YS of CNT/epoxy nanocomposite for four colonies model and 1 vol% CNT loading[95]. ...
... 3D view of the RVE with clustering of CNTs in four colonies in epoxy resin: (a) 0.18 wt%, (b) 0.36 wt%, (c) 0.9 wt%, and (d) 1.8 wt%[95]. (a) Variation of YS of CNT/epoxy nanocomposite with respect to MWCNT volume fraction, and (b) Effect of CNTs agglomeration on YS of CNT/epoxy nanocomposite for four colonies model and 1 vol% CNT loading[95]. ...
Carbon nano tubes (CNTs), comprising one dimensional (1D) carbon tubes that
significantly strengthen the base matrix when added as a reinforcement element. It is light in weight
and very low weight fractions (vol% or wt%) of well-dispersed CNTs enhance mechanical properties
effectively. Due to its poor wettability during liquid mixing, CNTs reinforced composites are mostly
prepared by solid-state processing, extrusion, hot pressing, etc. after premixing of the matrix and
CNTs powders in nano size. Irrespective of the production routes, matrices, and chemical treatments,
CNTs agglomerate within the matrix structure. That leads to dispersion problem of CNTs in matrix
materials and weaken the properties of the composites. CNTs produce small clusters/agglomerates
due to their high affinity and affect the texture of grain boundaries. This review discusses the effect
of CNTs agglomerations in composites formation for various CNTs reinforced composites. The study
covers the effect of vol%, wt%, and dispersion medium for reinforcement.
... This can be justified by the SEM image is shown in Figure 13. Javadinejad et al. [95] applied numerical FEM to demonstrate the clustering effect of CNTs in the composite as shown in Figure 14. Figure 14 shows a 3D view of four colonies in different volume fractions of CNTs. The colonization/agglomeration effect increases with the increase of vol% of CNTs in epoxy resin is shown in Figure 15. ...
... 3D view of the RVE with clustering of CNTs in four colonies in epoxy resin: (a) 0.18 wt%, (b) 0.36 wt%, (c) 0.9 wt%, and (d) 1.8 wt%[95]. (a) Variation of YS of CNT/epoxy nanocomposite with respect to MWCNT volume fraction, and (b) Effect of CNTs agglomeration on YS of CNT/epoxy nanocomposite for four colonies model and 1 vol% CNT loading[95]. ...
... 3D view of the RVE with clustering of CNTs in four colonies in epoxy resin: (a) 0.18 wt%, (b) 0.36 wt%, (c) 0.9 wt%, and (d) 1.8 wt%[95]. (a) Variation of YS of CNT/epoxy nanocomposite with respect to MWCNT volume fraction, and (b) Effect of CNTs agglomeration on YS of CNT/epoxy nanocomposite for four colonies model and 1 vol% CNT loading[95]. ...
... Different RVE shapes like circular [38], square [21] and hexagonal [25] have been chosen. RVE with one aligned CNT [19], one inclined CNT [24], equal length of CNT and RVE [23,31], CNT length less than RVE [19,26], many aligned CNTs [45][46][47][48], many CNTs at different angles [48][49][50][51][52] have been modeled by various researchers. But in all the above approaches of RVE analyses for nanocomposites, the boundary conditions as mentioned in [17] have not been applied, resulting in the estimation of the elastic properties of nanocomposites, which are not validated. ...
... But in all the above approaches of RVE analyses for nanocomposites, the boundary conditions as mentioned in [17] have not been applied, resulting in the estimation of the elastic properties of nanocomposites, which are not validated. With the exception of Bhuiyan et al. [46,47], in all the above RVE analyses [48][49][50][51][52], experimental comparison of estimated values is not provided. ...
Single-wall carbon nanotube (SWCNT) has very high measured elastic modulus. But nanocomposites manufactured using SWCNT does not exhibit dramatic increase in the elastic modulus due to various reasons. One of the defects noticed during the manufacturing of nanocomposites is the agglomeration of SWCNT. A novel methodology is proposed in the present paper to model the SWCNT agglomerates. Subsequently, finite element model of representative volume element (RVE) of nanocomposite is generated using validated boundary conditions and the axial elastic modulus is estimated, which is found to be in close agreement with the experimental results. The validated finite element model is used to estimate other elastic properties of nanocomposites, which can avoid costly experiments. Parametric study is carried out to understand the effect of length, diameter of SWCNT agglomerates and chirality of SWCNT on the elastic properties of nanocomposite. Finally, empirical relations are given to estimate all the elastic moduli of RVE if the diameter (hence chirality) of SWCNT and diameter of SWCNT agglomerates are measured after manufacturing nanocomposite with PVA matrix. The methodology described here can be easily extended for the nanocomposite with any other matrix.
Carbon nanotubes (CNTs) have been proven to show exceptional mechanical properties such as longitudinal elastic modulus of up to 1TPa and elastic strain of around 5%. Possessing these excellent properties, while having a fibre-like structure, CNTs have considerable potential to act as fillers in highly strong and light CNT composite (CNTC) materials. However, from experiments conducted, the biggest challenge before these nanocomposites can become a reality is that they do not show the expected excellent properties. This has led to extensive research into determining the effective properties of the CNTC using the preferred method of fully or semi-continuum modelling through the application of the finite element method (FEM). In this paper a review on aspects of the continuum representation of CNTCs is conducted. It covers the development, analysis and results of partial or full continuum modelling conducted in the last decades. A close-to-reality model must consider at least 5 CNT characteristics: length, interphase, waviness, orientation and agglomeration that cover 4 scales from nanoscale through micro- and meso- to macro-scale. The earlier nanocomposite continuum representatives mostly consisted of a CNT fibre surrounded by a matrix that could only catch the CNT characteristics at nano- and micro-scales and thus provided nanocomposite properties that were close to the rule of mixture (ROM) values but very far from experimental values. However, the recent representations manage to reach macro-scale level while representing important CNT characteristics such that the results were found to be close to the experimental results.
This study aims to review and highlight the important modelling methodologies used for studying carbon nanotubes (CNTs) and their composites. Understanding appropriate modelling methods for specific applications is crucial as CNTs become integral in achieving lighter, multifunctional composite structures. This paper explores a range of techniques, including finite element modelling (FEM), Molecular Dynamics (MD), Molecular Structural Mechanics (MSM), as well as nonlocal models, and the Cauchy-Born (CB) rule. Emphasis is placed on factors such as interphase effects between CNTs and the matrix, bonding interactions, non-bonded van der Waals (vdW) forces, and dynamic behaviour. Multiscale modelling is extensively discussed as a pivotal approach for efficiently addressing various length scales in nanocomposites. Modelling of failure, damage and its propagation, delamination, and instabilities such as buckling and fracture have been highlighted, and research gaps have been pointed out.
In this paper, a multiscale approach is presented for strength and tensile modulus prediction of carbon nanotube (CNT) reinforced glass-epoxy composite. At the micro-scale, the three-dimensional representative volume element is obtained by randomly orienting the carbon nanotube in the resin according to the weight percentage. The interphase of the nanotube and resin is modeled using a cohesive element method. The behavior of the resin is accounted with a quasi-brittle non-local damage model. At the Mesoscale, the representative volume element is estimated by using the weight percentage of glass fiber and resin generalized with nanotubes. Finite element analyses were conducted to estimate the effective mechanical properties through numerical homogenization. The effect of different percentages of carbon nanotubes on tensile behavior was investigated experimentally and numerically. The results show that adding carbon nanotubes improves the tensile modulus by about 25% and the tensile strength by about 53%. In the numerical study, the strength of the composite is predicted with good accuracy by modeling the damage of resin, glass fibers, and fracture toughness mechanisms of carbon nanotubes such as bridging and pull-out of carbon nanotubes. A good agreement was observed between the simulation results and the experimental results at different percentages of carbon nanotubes.
This work is aimed at studying the stiffness evolution of clustered composites and nanocomposites by FEM analysis. In fully dispersed composites and nanocomposites, proper modeling requires accounting for nanoparticle aspect ratio, volume fraction, and angle of orientation. In addition to these, the FEM model proposed in this work accounts for number of nanoparticles and volume fraction of nanoparticles in the cluster. The proposed approach allowed to calculate the longitudinal modulus and the other elastic constants of clustered composites, showing significant differences with the modulus of fully disperse composites.
