In this study, a combined analytical and finite element‐based micromechanical modeling is performed to characterize the elastic properties of carbon nanotube (CNT) reinforced polymer nanocomposites and validated with experimental work. First, coordinates of armchair and zigzag type CNTs are generated using MATLAB based on the geometric structure of the CNTs and imported to the computational software ANSYS to model and characterize the elastic properties of the individual single‐walled CNT (SWCNT) and multi‐walled CNT by applying various loading and boundary conditions. The present developed finite element method (FEM) model of CNTs is validated with the available literature in terms of elastic properties. Subsequently, the equivalent elastic properties of CNT reinforced epoxy nanocomposites are determined through representative volume element (RVE) model by finite element simulations and Mori‐Tanaka homogenization techniques by replacing CNTs with equivalent fibers as microinclusions. The equivalent elastic properties of nanocomposite obtained by the FEM and analytical model are compared and validated with the experimental results. Further, the detailed parametric study is performed to investigate the influence of tube chirality, volume fraction, and orientation of CNT in terms of the elastic properties of the nanocomposite. It was observed that the armchair type CNT reinforced nanocomposites are stiffer than the zigzag type SWCNT reinforced nanocomposites in terms of elastic moduli. Further, it was noticed that the tube chirality and the number of walls of CNTs have significantly influenced the elastic behavior of nanocomposites. It can be concluded that the presented combined model provides an efficient methodology and comprehensive understanding to analyze the elastic behavior of CNTs and CNT reinforced nanocomposites. So, the presented combined numerical and experimental study could serve as a guideline in micromechanical modeling and characterization of elastic behavior of CNT‐reinforced polymer nanocomposites.
In laminated composite structures, delamination is one of the most common defects. The delamination affects the vibration characteristics of laminates, and thus these indicators can be used to detect the potentially catastrophic failures and measures the health characteristics of laminates. In this study, particle swarm optimization (PSO) and artificial neural network (ANN) are used to optimize and predict the influences of location and size of delamination on the dynamic behavior of composite plates. The classical laminated plate theory
In this study, the instability regions of a honeycomb sandwich plate are investigated for different end conditions under periodic in-plane loading. The core layer of the sandwich plate is made of carbon nanotube (CNT)/glass fiber-reinforced honeycomb and the face layers of CNT/glass fiber- reinforced laminated composite. The governing equations are derived using classical laminated plate theory (CLPT) and solved numerically by using finite element formulation. The effectiveness of the developed finite element formulation is demonstrated by comparing the results in terms of natural frequencies with those available in the literature. The effects of CNT wt.% on the core material, CNT wt.% on the skin material, ply orientation and various end conditions on the variation of natural frequencies, loss factors and instability regions are studied. Finally, some inferences for the effects of CNT reinforcement on the honeycomb sandwich plate subjected to the periodic in-plane loads are discussed.
In this study, first ply failure (FPF) analysis of multi-walled carbon nanotubes (MWCNTs)/epoxy/glass fiber laminated curved composite panels with various taper configuration under transverse uniform pressure load distributed over the panel surface has been performed. In this regard, various failure criterion were considered, including Hoffman, Tsai–Wu, Tsai–Hill, and maximum stress, to investigate the numerical FPF load using finite element (FE) formulation with displacement fields derived from high order shear deformation theory (HSDT) with displacement field having seven degrees of freedom. The effectiveness of the proposed formulation was validated by comparing the numerically predicted FPF load with experimentally obtained FPF load using a universal testing machine from displacement/strain measurement. Finally, the effects of aspect ratio, different weight fraction of MWCNTs, taper configuration, curved geometry, and aspect ratio on the FPF load of the laminated tapered composite panels are studied. The numerical and experimental studies of the first ply failure behavior have demonstrated that the use of MWCNTs ensures a significant improvement in the FPF load of the analyzed laminated tapered curved composite panels. The taper configuration 3 (TC-3) with hyperbolic curved geometry exhibited the highest resistance to failure than taper configuration 1 (TC-1) and taper configuration 2 (TC-2). Moreover, the aforementioned parameters significantly influence the FPF load of laminated curved panels with various taper configurations. Furthermore, this study can be effectively used as a benchmark problem for researchers and as a tool to design practical laminated tapered curved composite panels with sufficient accuracy.
The research work aims to utilize one of the cheapest and most abundantly available natural fibre, sisal fibre, to fabricate a hybrid nanocomposite possessing high performance efficiency. Glass fibre (GFC), sisal fibre (SFC) and hybrid glass/sisal fibre reinforced epoxy laminate composites (HFC) were prepared and subsequently, three of the most promising nano-fillers, MXene (HFCMXN), Graphene nanoplatelet (HFCGNP) and Multi-walled carbon nanotube (HFCCNT), were added into the hybrid composite. The fabricated composites were comprehensively assessed and analysed for their mechanical properties, swelling and flammability behaviour. It was observed that the glass fibre reinforced composite had lowest void content (6.3%) and glass/sisal fibre reinforced laminate had the highest void content (17.2%). The addition of nano-fillers did not further enhance the void content owing to the relatively uniform dispersion of the nanoparticle, which was particularly ensured during the whole fabrication process. The incorporation of nano-fillers led to a significant enhancement in the mechanical properties; tensile and flexural strength being highest for composites containing two dimensional nano-fillers. The GFC exhibited minimum weight gain (2.25%) and least swelling thickness (1.66%) upon soaking. Among hybrid composites, nano-filler reinforced composites had relatively less weight gain post in comparison to the hybrid composite without any nano-filler. HFCGNP had a weight gain of 6.69%, as opposed to 8.51% observed in case of HFC. The nano-fillers acted as an effective water barrier that reduced the tendency of water absorption. Furthermore, upon flammability test it was found that the burning rate decreased in order of GFC, HFC, HFCCNT, HFCMXN, HFCGNP and SFC. The addition of nano-fillers led to a decrease in the burning rate owing to the promising flame retardant properties of graphene which suppressed flame propagation and helped in extinguishing the flame.
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