scholarly journals Modeling the Effective Conductive Properties of Polymer Nanocomposites with a Random Arrangement of Graphene Oxide Particles

2021 ◽  
pp. 167-180
Author(s):  
M. A Tashkinov ◽  
A. D Dobrydneva ◽  
V. P Matveenko ◽  
V. V Silberschmidt
Keyword(s):  
Finite Element ◽  
Graphene Oxide ◽  
Composite Materials ◽  
Polymer Matrix ◽  
Matrix Cracking ◽  
Tunneling Effect ◽  
Representative Volume ◽  
Representative Volume Elements ◽  
Oxide Particles ◽  
Conductive Properties

Сomposite materials are widely used in various industrial sectors, for example, in the aviation, marine and automotive industries, civil engineering and others. Methods based on measuring the electrical conductivity of a composite material have been actively developed to detect internal damage in polymer composite materials, such as matrix cracking, delamination, and other types of defects, which make it possible to monitor a composite’s state during its entire service life. Polymers are often used as matrices in composite materials. However, almost always pure polymers are dielectrics. The addition of nanofillers, such as graphene and its derivatives, has been successfully used to create conductive composites based on insulating polymers. The final properties of nanomodified composites can be influenced by many factors, including the type and intrinsic properties of nanoscale objects, their dispersion in the polymer matrix, and interphase interactions. The work deals with modeling of effective electric conductive properties of the representative volume elements of nanoscale composites based on a polymer matrix with graphene oxide particles distributed in it. In particular, methods for evaluating effective, electrically conductive properties have been studied, finite element modelling of representative volumes of polymer matrices with graphene oxide particles have been performed, and the influence of the tunneling effect and the orientation of inclusions on the conductive properties of materials have been investigated. The possibility of using models of resistive strain gauges operating on the principle of the tunneling effect is studied. Based on the finite-element modeling and graph theory tools, we created approaches for estimating changes in the conductive properties of the representative volume elements of a nanomodified matrix subjected to mechanical loading.

scholarly journals Computational study of transport phenomena in flake filled composite materials

2020 ◽  
Author(s):  
Ανδρέας Τσιαντής
Keyword(s):  
Composite Materials ◽  
Computational Study ◽  
Transport Phenomena ◽  
Representative Volume ◽  
Improvement Factor ◽  
Representative Volume Elements ◽  
Filled Composite

Σκοπός αυτής της εργασίας είναι η διερεύνηση του τρόπου με τον οποίο μεταβάλλεται o συντελεστής διαπερατότητας ενός σύνθετου υλικού, ενισχυμένου με φυλλίδια, με έμφαση στις πολυμερικές μεμβράνες. Οι ιδιότητες των υλικών αυτών μεταβάλλονται από την παρουσία και τις ιδιότητες των φυλλιδίων, όπως η αναλογία διαστάσεων (α), το κλάσμα όγκου (φ), ο προσανατολισμός (θ) και η διακύμανση του προσανατολισμού (θ+ε). Δείχνουμε ότι ως αποτέλεσμα της διασποράς των φυλλιδίων στο υλικό, παράγονται υλικά με βελτιωμένες ιδιότητες φραγμού αφού η ύπαρξη των φυλλιδίων προκαλεί αύξηση στην διαδρομή που πρέπει να ακολουθηθεί από τα μόρια, ιόντα κλπ, διαμέσου του υλικού. Αυτός ο βαθμός δυσκολίας περιγράφεται από τον συντελεστή Barrier Improvement Factor (BIF) ο οποίος χρησιμοποιείται για την ποσοτικοποίηση της επίδρασης της παρουσίας φυλλιδίων στις ιδιότητες φραγμού. Εκτός από την τεχνολογική σημασία αυτού του θέματος, πρόσθετο κίνητρο για την έρευνα αυτή ήταν το γεγονός ότι τα ήδη προτεινόμενα μοντέλα έχουν δείξει ένα μικρό εύρος εφαρμογής και γενικά έχουν περιορισμένη επιτυχία στην παροχή ενός ενοποιητικού πλαισίου για την περιγραφή των ιδιοτήτων φραγμού των εν λόγω υλικών. Για να αντιμετωπίσουμε αυτό το ζήτημα, πραγματοποιήσαμε μια ολοκληρωμένη υπολογιστική μελέτη και προτείνουμε νέα θεωρητικά μοντέλα ικανά να περιγράψουν το BIF για μια σειρά μεγεθών, συγκεντρώσεων και προσανατολισμών φυλλιδίων. Στην παρούσα διατριβή χρησιμοποιήσαμε 2D & 3D RVEs (Representative Volume Elements) με περιοδικές γεωμετρίες και περιοδικές οριακές συνθήκες που δημιουργήθηκαν χρησιμοποιώντας μια ποικιλία υπολογιστικών εργαλείων που περιλαμβάνουν εφαρμογές και αλγορίθμους που γράφτηκαν και υλοποιήθηκαν για τις ανάγκες αυτής της μελέτης. Στη συνέχεια δημιουργήθηκαν γεωμετρίες και εκτελέστηκαν προσομοιώσεις χρησιμοποιώντας την εργαλειοθήκη του OpenFOAM στο εργαστηριακό μας cluster το οποίο στήθηκε στην αρχή αυτής της διατριβής. Με αυτόν τον συνδυασμό υφιστάμενων και νέων υπολογιστικών εργαλείων καταφέραμε να δημιουργήσουμε μια ακολουθία ενεργειών που μας επέτρεψε να τρέχουμε χιλιάδες προσομοιώσεις και οι οποίες καλύψανε όλες τις παραμέτρους που μελετήθηκαν στο πλήρες εύρος τους και αποτελούν - όσο γνωρίζουμε - την πιο ολοκληρωμένη μελέτη στη βιβλιογραφία μέχρι στιγμής. Επίσης αντίθετα με προηγούμενες μελέτες οι προσομοιώσεις πραγματοποιήθηκαν σε RVEs με ρεαλιστική πολυπλοκότητα, που περιείχαν περισσότερα από 1000 φυλλίδια. Ελέγξαμε επίσης τα αποτελέσματά μας σε σχέση με υπάρχοντα μοντέλα που περιγράφονται στη βιβλιογραφία και εξετάσαμε μερικές κοινές παρανοήσεις και προβλήματα που υπάρχουν στον τομέα.

Multiscale Finite Element Simulation of Thermal Properties and Mechanical Strength of Reduced Graphene Oxide Reinforced Aluminium Matrix Composite

2019 ◽  
Vol 821 ◽  
pp. 39-46
Author(s):  
Peter Nyanor ◽  
Omayma A. El Kady ◽  
Atef S. Hamada ◽  
Koichi Nakamura ◽  
Mohsen A. Hassan
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Finite Element ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Matrix Composite ◽  
Effective Properties ◽  
Representative Volume ◽  
Reduced Graphene ◽  
Multiscale Finite Element

The effective properties of metal matrix composites (MMCs) depend on matrix material and reinforcement property specifications as well as bonding at interphase. The use of numerical methods such as finite element (FE) and mean field homogenization (MFH) can assist in predicting MMC properties thus reducing time and cost of optimizing composite properties through experiments. In the present work, a multiscale representative volume element (RVE) of the microstructure of reduced graphene oxide (rGO) reinforced Aluminium (Al) matrix composite (rGO/Al) is created in MSC DigiMat and analysed using Abaqus software. The effect of porosity and rGO reinforcement on thermal conductivity and strength of the rGO/Al composites is studied. The variation in thermal conductivity between FE-RVE and experimental data is a maximum of 2.2% and a minimum of 0.07% for rGO reinforcement of 1 wt.% and 3 wt.% respectively. The results show good agreement between FE-RVE simulation, MFH and experimental data. This approach can provide an efficient technique for selecting matrix and reinforcement phase properties for MMC fabrication. Keywords: Al/rGO composite, Multiscale finite element-representative volume, Thermal and mechanical properties

Prediction of mechanical and thermal properties of polymer nanocomposites reinforced by coiled carbon nanotubes for possible application as impact absorbent

2019 ◽  
Vol 234 (4) ◽  
pp. 882-902
Author(s):  
Armin Kianfar ◽  
Mir Masoud Seyyed Fakhrabadi ◽  
Mahmoud Mosavi Mashhadi
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Finite Element ◽  
Effective Thermal Conductivity ◽  
Representative Volume Element ◽  
Volume Element ◽  
Volume Fractions ◽  
Finite Element Software ◽  
Representative Volume ◽  
Representative Volume Elements

This paper presents three-dimensional finite element modeling of nanocomposite materials made from polyethylene polymer reinforced by coiled carbon nanotubes. A method of Python scripting was used to generate representative volume elements in order to determine the mechanical behavior in elastic and plastic zones as well as effective thermal conductivity using the finite element software. The properties of the nanocomposites are investigated by considering the interphase zone between carbon nanofillers and matrix. The effects of different volume fractions, geometrical parameters, and orientations of the nanofillers on the elastic and thermal characteristics of the nanocomposites are studied considering both cohesive interaction and perfect bonding between the fillers and matrix. Moreover, the effects of applying strain on the effective thermal conductivity of the representative volume elements are analyzed. The results reveal that both stress–strain curves and thermal conductivity coefficients of the nanocomposites are following similar trends vs. the changes of the volume fractions as well as the geometries and orientations of the coiled carbon nanotubes. Analysis of the tensile toughness of all samples reveals that it is affected by both stress and the number of fillers in the representative volume element. In addition, thermal-displacement analysis shows that thermal conductivity coefficient decreases by increasing the applied strain on the representative volume element, while the intensity of decrease of the nanocomposite thermal conductivity depends on the volume fraction and interaction of the nanofillers and interphase zone. Finally, crashworthiness analysis of the nanocomposite material proves that they are appropriate candidates for absorbing energy under impact loadings in comparison to metals.

FINITE ELEMENT MODELING OF TRANSVERSE DEFORMATION IN REPRESENTATIVE VOLUME ELEMENTS OF CERAMIC MATRIX COMPOSITES (CMCs)

2010 ◽  
Vol 02 (01n02) ◽  
pp. 107-126 ◽  
Author(s):  
C. TANG ◽  
M. A. SHEIKH ◽  
D. R. HAYHURST
Keyword(s):  
Finite Element ◽  
Weibull Distribution ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Transverse Deformation ◽  
Stress Strain ◽  
Fiber Failure ◽  
Representative Volume ◽  
Representative Volume Elements

The paper reports the use of the finite element method to model longitudinal and transverse deformation of representative volume elements (RVE) of ceramic matrix composites subjected to uniaxial loading parallel to fibers. Cohesive elements have been used to model two forms of damage: fracture initiation and propagation both within the matrix, and along the fiber–matrix interface. From the knowledge of the constituent materials behavior, the FE technique has been used to predict the stress–strain behavior and the variation of Poisson's ratio of the RVE due to these two damage forms; but the model does not cater for fiber failure. The RVE predictions have been benchmarked against experimental results for Nicalon-CAS material and good agreement has been obtained. Comparison of the predicted behavior of the single Nicalon-CAS RVE with experimental data for unidirectional tows indicates that the stress–strain curve is predominantly controlled by the Weibull distribution of fiber failure stress, while the degradation of Poisson's ratio is determined by the Weibull distribution of interfacial strength. The same approach has been used for a HITCO C/C material for which transverse deformation behavior is unknown. The results for the HITCO C/C material, as for the Nicalon-CAS, show that the fiber behavior determines the ultimate failure of the RVE, and that interface debonding is the controlling mechanism for the variation of the Poisson ratio with axial strain.

scholarly journals A Virtual Testing Strategy to Determine Macroscopic Properties of Elasto-Plastic Heterogeneous Composite Materials

2021 ◽  
Author(s):  
◽  
Mahshid Ranjbarestalkhjani
Keyword(s):  
Finite Element ◽  
Composite Materials ◽  
Three Dimensional ◽  
Analytical Models ◽  
Testing Strategy ◽  
Virtual Testing ◽  
Explicit Finite Element ◽  
Yield Criteria ◽  
Representative Volume ◽  
Wide Range

The objective of this work is to determine an e˙ective yield criteria for porous pressure sensitive solids and investigate the anisotropic yield behavior by employing a virtual testing strategy. The work is concerned with the pressure sensitivity typically displayed by geometarials, such as sandstone and composite materials consisting of a series of parallel layers, such as sedimentary rock and underground salt.Virtual testing strategy is based on computational homogenization approach for the definition of the elasto-plastic transition. Representative volume elements (RVEs) containing single-centered and distributed ellipsoidal voids are analyzed using three-dimensional finite element models under both small and finite strains. Yield curves are obtained following a unified variational formulation, which provides bounds on the e˙ective material properties for a given choice of the Representative Volume Element (RVE).In order to estimate the e˙ective properties of porous solid, the constitutive behavior of the continuum matrix is assumed to follow the standard Drucker-Prager elasto-plastic model. The computationally generated e˙ective yield criteria are compared against the recently proposed analytical estimates for Drucker-Prager type solids and the SR4 constitutive model for soft rocks. The developed computational approach is applied to estimate the e˙ective properties of a realistic rock sample. To illustrate a wide range of potential engineering applications, the computationally e˙ective yield surface are also obtained under the explicit finite element method.Finally, based on the simulated yield stress point of composite materials, the pa-rameters for proposed analytical models are acquired with ellipse fit by Taubin’s method.

Role of exterior statistics-based boundary conditions for property-based statistically equivalent representative volume elements of polydispersed elastic composites

2018 ◽  
Vol 52 (21) ◽  
pp. 2919-2928 ◽  
Author(s):  
Dhirendra V Kubair ◽  
Maxwell Pinz ◽  
Kaitlin Kollins ◽  
Craig Przybyla ◽  
Somnath Ghosh
Keyword(s):  
Boundary Conditions ◽  
Matrix Composite ◽  
Representative Volume Element ◽  
Polymer Matrix ◽  
Microstructural Characterization ◽  
Experimental Tests ◽  
Volume Element ◽  
Polymer Matrix Composite ◽  
Representative Volume ◽  
Representative Volume Elements

The property-based statistically equivalent RVE or P-SERVE has been introduced in the literature as the smallest microstructural volume element in non-uniform microstructures that has effective material properties equivalent to those of the entire microstructure. An important consideration is the application of appropriate boundary conditions for optimal property-based statistically equivalent representative volume element domains. The exterior statistics-based boundary conditions have been developed, accounting for the statistics of fiber distributions and interactions in the domain exterior to the property-based statistically equivalent representative volume element. This paper is intended to validate the efficacy of the exterior statistics-based boundary condition-based property-based statistically equivalent representative volume elements for evaluating homogenized stiffnesses of a unidirectional polymer matrix composite with a polydispersed microstructure characterized by nonuniform dispersion of carbon fibers of varying sizes in an epoxy matrix. Experimental tests and microstructural characterization of the polymer matrix composite are conducted for calibration and validation of the model. Statistically equivalent microstructural volume elements are constructed from experimental micrographs for direct numerical simulations. The performance of the property-based statistically equivalent representative volume element with exterior statistics-based boundary conditions is compared with other boundary conditions, as well as with the statistical volume elements. The tests clearly show the significant advantages of the exterior statistics-based boundary conditions in terms of accuracy of the homogenized stiffness and efficiency.

Microscale deformation behavior of rheocast Al–7Si–0.3 Mg alloy

2016 ◽  
Vol 230 (6) ◽  
pp. 1041-1061
Author(s):  
Prosenjit Das ◽  
Sk. Tanbir Islam ◽  
Sudip K Samanta ◽  
Santanu Das
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Failure Mode ◽  
Strain Localization ◽  
Deformation Behavior ◽  
Uniaxial Tensile ◽  
Process Conditions ◽  
Plastic Strain Localization ◽  
Representative Volume ◽  
Representative Volume Elements

In the present work, microscale deformation behavior, plastic strain localization, and plastic instability of rheocast Al–Si–Mg (A356) alloy have been investigated using micromechanical approach. For this purpose, two-dimensional microscale models (representative volume elements) have been developed using actual microstructure of the cast samples made under three different process conditions. Microstructure of the above-mentioned alloy consists of two different phases, such as aluminum-rich primary phase and silicon-rich eutectic phase. In line with that, composite micromechanical models have been developed to analyze them within the finite element framework. Rheocasting has been performed using cooling slope with two different slope angles of 45° and 60°, and comparison has been made with the conventional cast samples of the alloy that has been cast directly from the superheated molten state. Different boundary conditions have been assumed to perform finite element based simulation, using a popular finite element solver ABAQUS, depending upon the position of representative volume elements on the cylindrical tensile specimen. Under uniaxial tensile loading, ductile failure mode is predicted in the form of plastic strain localization due to incompatible deformation between the phases. This indicates inhomogenity of microstructure that determines the damage initiation process within this material, as there is no damage or failure criterion specified during the finite element analysis. Grain size, shape, and orientation of the primary aluminum phase are found to play a vital role on deformation behavior and failure mode of the materials investigated in this study.

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