CNT-reinforced Composites Research Articles

Sensitivity Analysis of Compressive Strength in CNT-Reinforced Composites: A Comparative Study of Sample-Based, Linearization, and Global Methods

Sensitivity Analysis of Compressive Strength in CNT-Reinforced Composites: A Comparative Study of Sample-Based, Linearization, and Global Methods

A review on improved physical and thermal properties of oxide nanoparticles reinforced epoxy composites

Epoxy resins are well-known because of their desirable thermal and mechanical characteristics in a variety of fields, including the automotive, construction, and aerospace sectors. However, the inherent brittle nature of highly cross-linked epoxy resins generally leads to weakness in resisting the formation of cracks and their movement. The brittleness of the epoxy resins is one of the major obstacles inhibiting its use at a wider scale. Therefore, many researchers focused on reinforcement of epoxy resins by different types of nanostructures including carbon nanotubes (CNTs), organic/inorganic nanofillers to provide higher strength, without diminishing other essential thermo-physical characteristics of the nanocomposites. Most of the review articles focused on the CNT-reinforced epoxy composites and very limited review articles are available that focus on the oxide nanofiller reinforced epoxy composites. In this review article, epoxy nanocomposites reinforced with alumina (Al2O3), titania (TiO2), silica (SiO2), and zirconia (ZrO2) nanoparticles have been investigated. The influence of the oxide nanoparticles in modifying the physical and thermal properties of the epoxy nanocomposites has been presented, compared, and critically analysed to optimize the performance of epoxy nanocomposites.

Ceramic Nanocomposites Reinforced with Multi-Walled Carbon Nanotubes (MWCNTs) for Aerospace Engineering

In recent years, nanotechnology has played a pivotal role in advancing aerospace engineering, addressing the ongoing demand for high-durability materials characterized by low density and superior thermo-mechanical properties. Carbon nanotube (CNT)-based composites have emerged as a prominent solution in this realm, leveraging their remarkable properties to fuel a range of multidisciplinary applications in various industries. Carbon nanotubes, consisting of rolled-up carbon sheets at the nanoscale, exhibit exceptional thermal and mechanical characteristics at a reduced density. This makes them an ideal choice for reinforcing composites in aerospace applications. The high Young's modulus and chemically inert nature of CNTs position them at the forefront of material research, spanning applications from water purification to aerospace technologies, with the latter remaining particularly enigmatic. Despite the extensive research on CNT-based materials, there is a notable scarcity of studies focusing on their application in aerospace engineering. This review aims to fill this gap by comprehensively exploring the processing and synthesis techniques, thermal and mechanical properties, and select industrial applications of CNT-reinforced ceramic composites. Additionally, the review sheds light on potential advancements in additive manufacturing techniques for fabricating CNT/ceramic composites and their prospective applications within the aerospace industry.

A review of the performance of fibre-reinforced composite laminates with carbon nanotubes

Abstract Impact loads lead to the failure of structures and significantly diminish their operational lifespan. The necessity to enhance impact performance has shown gradual progress, resulting in utilising nano-fillers as an additional reinforcement within the matrix. Despite the significant number of studies that have been done on this unique hybrid material, there have only been a few reviews published that discuss the effect of production processes on mechanical properties and performance in these hybrid composites under projectile impact. There have been conflicting results obtained in experimental results from the literature. The disparity is related to the variation in dispersion, bonding states, and inconsistent fabrication processes. This work defines the pros and cons of carbon nanotube (CNT)-based composites along with a systematic representation of the development of CNT-reinforced composites under projectile impact using experimental, analytical, and numerical techniques. The potential of CNT reinforcement on fibre-reinforced polymers (FRPs) and its effect on mechanical properties have been discussed. Furthermore, different impact test setups are explored to determine the effective method to determine the impact performance of CNT-reinforced laminates. Moreover, the impact of surface treatment is discussed using different non-destructive methods, and the influence of CNT reinforcement is determined. In addition, mechanical and impact response with varying configurations of fibres is gathered from the available literature, and optimal design based on the required application is suggested. Also, analytical methods developed to determine the impact response of laminates are discussed to determine the parameters dominating the impact response of the laminate. This review will help researchers find the right combination of FRP materials for a given application.

Thermo-electrical postbuckling behavior of carbon nanotubes-reinforced composite beams with piezoelectric layers and tangentially restrained ends

An analytical investigation on the buckling and postbuckling behavior of carbon nanotube-reinforced composite beams integrated with surface-bonded piezoelectric layers under uniform temperature rise is presented in this paper. Carbon nanotubes (CNTs) are reinforced into isotropic matrix through uniform distribution and functionally graded distributions. The properties of material constituents are assumed to be temperature-dependent and effective properties of CNT-reinforced composite are estimated using an extended rule of mixture. Equilibrium equations of the beams are established based on Euler-Bernoulli theory including von Kármán nonlinearity and solved using analytical solutions and Galerkin method. Critical temperatures and postbuckling load-deflection paths are determined using an iteration algorithm. Parametric studies are performed to examine the influences of CNT distribution and volume fraction, applied voltage, in-plane and out-of-plane conditions of the ends, slenderness, and thickness ratio of layers on the critical loads and postbuckling load carrying capacity of beams. Results reveal that CNT volume fraction and degree of in-plane ends constraint have slight and significant influences on the critical temperatures and thermal postbuckling paths, respectively. The study also finds that negative and positive voltages increase and decrease the thermal buckling temperatures of piezoelectric CNT-reinforced composite beams.

Effect of Defects and Oxidation on CNT-Copper Interface: First-Principles Calculation and Experiment.

In this paper, the effects of carbon nanotube defects and a copper surface oxide layer on a carbon nanotube-copper interface were studied via first-principles. A defect-free CNT-Cu interface, Stone-Wales defect CNT-Cu interface, single-hole and double-hole defect CNT-Cu interface, and Cu2O-Cu interface were simulated and calculated. By simulating the differential charge density, atomic population, bond population and density of states of the interface model, the effects of various defects on the interface bonding and electrical conductivity of the composites during the preparation of the CNT-reinforced copper matrix composites were analyzed, which provided theoretical guidance for the preparation of CNT/Cu composites. After that, copper matrix composites with different CNT defect contents were prepared via different rolling deformation processes. Their hardness and electrical conductivity were tested, and the results were consistent with the results obtained via the first-principles calculations.

Friction and Wear Characteristics of Additive Manufactured CNT-Reinforced HDPE Composites in Dry Contact

The tribological properties of three-dimensional (3D) printed polymeric composites are often less explored due to the complexity involved related to their softness, poor mechanical properties, and lower thermal conductivities. Keeping this in view, this work reports the influence of carbon nanotubes (CNTs) on the tribological properties of high-density polyethylene (HDPE) composites. Fused deposition modeling was adopted to develop the composites with varying CNT contents from 0.5 wt% to 2 wt%. The tribological properties were studied by subjecting them to friction-on-wear test using a pin-on-disc setup. The tests were conducted with varying applied loads (5 to 20 N) and sliding speeds (0.262 to 1.048 m/s). A scanning electron microscope (SEM) was employed to study the morphology of the filaments and to analyze the worn surfaces after testing. The printed composite parts displayed a good dispersion of CNTs, showed a good print quality, and were free from warpage or shrinkage defects. With the increase in load and sliding velocity, both the wear rate and coefficient of friction of all the developed samples tend to increase. Out of all the developed samples, some showed poor wear resistance, while composites with the highest CNT contents of 2 wt% showed significant resistance to material loss, which is attributed to the reduced contact area and the CNT acting as an anchor to prevent the polymer chain from being detached. The worn surface analysis revealed adhesive wear as the dominant mechanism for pure HDPE, and abrasive wear as the primary mechanism for HDPE composites. Overall, this work showed that CNTs can be used as an effective filler for reducing the friction coefficient and increasing the wear resistance.

Hybrid influences of interphase and grain-size on material responses of CNT-reinforced metal matrix composites

In this investigation, a theoretical model is developed to consider the coupled influence of interphase and grain-size of metal on the nonlinear response of CNT-reinforced MMCs. A multiscale theoretical framework based on the energy-based effective strain method and the field fluctuation method is established. The second-order stress moment and dislocation density model are also adopted to predict the entire grain-size dependent stress-strain relations. The energy-based effective strain method is proposed to better exhibit the energy stored in the three-phase composites by replaced average-strain. The microstructure variables include volume fraction, moduli of interphase, geometrical size factor, aspect ratio of CNTs, and grain size in metal matrix. The accuracy of the present predictions is verified by some available experimental data. As a result, the proposed model can be used to define the mechanical behavior and make an optimum design of CNT reinforced MMCs as well as advanced engineering composites.

다구찌 기법을 이용한 탄소나노튜브 강화 고분자 복합재료의 기계적 물성 향상을 위한 공정 최적화

Purpose: This study aims to optimize and improve the mechanical properties of fused carbon nanomaterial (FCN) and short carbon nanotube (S-CNT) reinforced polymer composites via statistical analysis and the Taguchi method.BRMethods: Tensile specimens were fabricated based on the orthogonal array of the Taguchi method to investigate the change in tensile strength with a change in the fabrication process. Sensitivity analysis was performed with main effect plots using tensile strength data. Based on this analysis, the optimal process was found to improve the tensile strength of FCN and S-CNT-reinforced polymer composites. Furthermore, the analysis of variance (ANOVA) was performed to analyze the contribution of process parameters and significance level concerning the optimal process.BRResults: The tensile strengths of FCN and S-CNT-reinforced polymer composites increased by 6.18% and 10.28%, respectively, compared to the total mean strength obtained from the orthogonal array.BRConclusion: Various CNT-reinforced polymer composites can achieve enhanced mechanical properties via the optimal process suggested in this study.

Fracture analysis of CNT-reinforced composites under thermo-mechanical loading using XIGA

Fracture analysis of CNT-reinforced composites under thermo-mechanical loading using XIGA

Strengthening Ni-Coated CNT/Mg Composites by Optimizing the CNT Content.

The dispersion of carbon nanotubes (CNTs) is the bottleneck in CNT-reinforced metal matrix composites. In this work, CNT/Mg composites were prepared by grinding Mg powder and then dispersing CNTs via ball milling and hot pressing. The uniform distribution of Ni-coated CNTs in the matrix was achieved by optimizing the content of CNTs. Scanning electron microscope, high-resolution transmission electron microscopy and X-ray diffraction, optical microscopy, and compression tests were employed. With the CNT content being less than 1%, the CNTs can be evenly distributed in CNT/Mg composites, resulting in a sharp increase in strength. However, with the higher CNT content, the CNTs gradually cluster, leading decreased fracture strain and strength. Furthermore, the coated Ni in the CNTs reacts with the magnesium matrix and completely transforms into Mg2Ni, significantly enhancing the interface bonding. This strong interface bonding and the diffusely distributed Mg2Ni in the matrix significantly strengthen the CNT/Mg composite.

Thermomechanical buckling and wrinkling characteristics of softcore sandwich panels with CNT reinforced composite face sheets

This article explores the local and global stability of CNT reinforced composite (CNTRC) sandwich shell panels consist of softcore material. The shell panel's face sheets are reinforced with functionally graded nanotube particles. The effective properties of CNTRC face sheets are determined considering the extended rule of mixture technique, and a multi-layer approach is used to examine the local and global stability phenomena. The material properties of the face sheets are assumed to be temperature-dependent. The formulation account for the core compressibility effect by considering higher-order polynomial terms for transverse core displacement. The governing equations for each layer of the sandwich panel are derived by minimizing the total potential energy of the system. The Galerkin's technique is adopted to obtain a set of non-linear algebraic equations from the derived partial differential equations. Global buckling and wrinkling loads of sandwich shell panels under thermomechanical loadings are obtained by solving standard eigenvalue problem. The nonlinear responses for sandwich shell panels subjected to mechanical and thermal stresses are traced through the arc-length approach and iterative approach, respectively. The obtained responses elucidate the influence of CNT gradation, volume fractions and core thickness on the local and global stability behaviour of CNTRC sandwich shell panels.

Plain Kevlar and a CNT-reinforced Kevlar epoxy polymer composite: Comparative study of its mechanical, low velocity and ballistic impact properties

Plain Kevlar and a CNT-reinforced Kevlar epoxy polymer composite: Comparative study of its mechanical, low velocity and ballistic impact properties

Multi-level micromechanics-based homogenization for the prediction of damage behavior of multiscale fiber-reinforced composites

A multi-level micromechanics-based homogenization is proposed here to investigate the damage behavior of composites with multiscale fibers such as carbon nanotube (CNT) and carbon fiber. First, a molecular unit cell is constructed considering the interfacial characteristics between the CNT and a polymer matrix, after which molecular dynamics simulation and micromechanics are utilized to obtain the elastic properties of CNT-reinforced composites. A micromechanics-based progressive damage model is then adopted to predict the damage behavior of the CNT and carbon fiber-reinforced composites. Tensile tests are also conducted to investigate the stress–strain behaviors of the composites. To verify the applicability of the proposed model, the present predictions are compared with those obtained from the tensile test results. The proposed multi-level homogenization has shown to provide a close match to the experimental results. The proposed modeling scheme may facilitate a thorough investigation of the damage behavior of multiscale fiber-reinforced composites, proving the importance of each constituent at a different level.

Ensemble Machine Learning approach for evaluating the material characterization of carbon nanotube-reinforced cementitious composites

Time and cost-efficient techniques are essential to avoid extra conventional experimental studies with large data-set for material characterization of composite materials. This study is aimed at providing a correlation between the structural performance and mechanical properties of carbon nano-tubes reinforced cementitious composites through efficient predictive Machine Learning (ML) models. The Flexural (FS) and Compressive (CS) Strength of Carbon Nanotube (CNT)-reinforced composites were predicted based on the data-rich framework provided in the literature. Two different ensembled ML methods including Random Forest (RF) and Gradient Boosting Machine (GBM) were implemented on those data for predicting the CNT-reinforced cement-based composites. Data-set were utilized for training the proposed models through employing SciKit-Learn library in Python, followed by hyper-parameter tuning and k-fold cross-validation method for obtaining an optimum model to predict the target values. It was shown that the CS values predicted by the proposed models were more accurate than the FS counterparts and the developed model of GBM has less sensitivity to the alteration of test data than the proposed RF model. Finally, sensitivity analysis was conducted through Sobol algorithm and the parameters with highest contribution were identified.

Carbon Nanotube (CNT) Composites and its Application; A Review

Due to their superior mechanical, thermal, electrical, and tri-biological characteristics, carbon nanotubes (CNTs) have been widely used in a variety of industries, from aerospace to energy, since their discovery in 1991. Their compact size, amazing tensile strength, and light weight They are often used as reinforcements in metals, plastics, and even additive manufacturing due to their popularity and conductivity. In this analysis, we present a list of these structures and an in-depth discussion of the CNT-reinforced materials can be processed using a variety of techniques, including chemical vapor deposition (CVD), ball milling, both laser melting and hot pressing. The restrictions in the production and processing of these composites additionally discussed, strengthened by many authored works. To comprehend how these composites' properties change in relation to other parameters, such as a wide range of variables, such as temperature, CNT length, diameter, etc. A summary is given, explaining various methods for performing experimental analysis and providing convincing arguments for putting the changes' causes in. Therefore, we investigate the specialized uses of these CNT-reinforced composites in industries like aerospace, energy, biomedicine, and auto, and how they can be handled further, altered to make room for less expensive and more effective fixes going forward.

Contemporary review on carbon nanotube (CNT) composites and their impact on multifarious applications

Abstract Since their discovery in 1991, carbon nanotubes (CNTs) have found widespread use in various industries, from aerospace to energy, due to their excellent mechanical, thermal, electrical, and tribological properties. Their lightweight nature, small size, incredible tensile strength, and conductivity have made them very popular as reinforcements in metals, polymers, and even finding employment in additive manufacturing. In this review, we provide a rundown of these structures and discuss in detail the numerous methods used to process CNT-reinforced materials, such as chemical vapor deposition (CVD), ball milling, hot pressing, and selective laser melting. The limitations of manufacturing and processing these composites are also discussed, strengthened by the support of different published works. To understand the changes in the properties of these composites in terms of varying parameters such as temperature, CNT length, diameter, etc., an extensive summary is provided, describing several techniques to perform experimental analysis and giving plausible reasons for attributing these changes. Consequently, we explore the specific areas of applications for these CNT-reinforced composites in fields such as aerospace, energy, biomedical, and automobile, and how they can be further processed and changed to allow for more affordable and efficient solutions in the future.

Novel approach for damage detection in multiscale CNT-reinforced composites via wireless Joule heating monitoring

A novel method for strain and crack propagation monitoring based on Joule heating capabilities of multiscale carbon nanotube reinforced glass fiber composites (GFRP-CNT) is reported. The manufactured GFRP-CNT composites show good Joule heating capabilities with heating rates ranging from 3 to 56 °C min−1 at applied voltages from 30 to 105 V, respectively. Multiscale GFRP-CNT composites present similar tensile strength and Young's Modulus than conventional GFRP but very enhanced failure strain due to the toughening effect of CNTs. The wireless monitoring via Joule heating shows a very high sensitivity and strain resolution (with values ranging from 0.01 to 0.1%) for early crack initiation and subsequent propagation. Finally, the thermal IR imaging also allows to create a complete mapping of the health of the structure during the whole test, allowing the detection, localization and quantification of early damage and, thus, proving an outstanding potential for Structural Health Monitoring (SHM) applications in comparison to other conventional techniques.

Fatigue crack growth in CNT-reinforced polymer composite

Carbon nanotubes (CNT)-reinforced polymer composite has many engineering applications due to attractive properties, like high strength to weight ratio. These materials are subjected to cyclic fatigue loading during their service life. This work proposed a dual scale modeling approach to predict fatigue crack growth behavior of CNT-reinforced polymer composite under the thermo-mechanical loading environment. The effective orthotropic property of CNT-reinforced polymer composite is estimated using the mean-field homogenization technique in meso-scale modeling. Further, the equivalent composite property is used for macro-scale fatigue crack growth study using higher-order extended finite element method. To present the efficiency of the proposed modeling approach, various combinations of polymer composite (by volume fraction of reinforcement at 7.5%, 10%, 12.5%, 15%, 17.5%, and 20%) are taken for analysis. At macro-scale modeling, XFEM with higher-order enrichment terms is employed to improve the solution accuracy at the crack tip region. The proposed computational approach has been employed with the in-house developed MATLAB code and DIGIMAT software. Several numerical examples are considered with geometrical discontinuities like multiple holes and cracks.

Recrystallization mechanisms during high-temperature XRD and oxidation behavior of CNT-reinforced NiAl composites

In this study, a new perspective is presented on the CNTs-reinforced NiAl intermetallic composites, focusing on the influence of CNT addition on their high-temperature behavior. The obtained results revealed an effective grain boundary pinning effect of CNTs in hindering recrystallization and grain growth of the reinforced composites at high temperatures, leading to significantly smaller grain sizes. CNTs were observed to be beneficial for the high-temperature oxidation resistance at lower concentrations, but detrimental to the oxide scale adherence at higher concentrations. Subsequently, the NiAl-0.5CNT composites exhibited the lowest weight gain due to the stabilizing effect of carbon on the NiAl phase.