Reza Ansari

University of Guilan · Faculty of Mechanical Engineering

Carbon–nitrogen nanostructures are promising candidates for various technologies due to their unique behavior and potential applications, motivating extensive experimental and theoretical research. N-triphenylene-Graphdiyne (N-TPG) is a carbon–nitrogen nanostructure derived by doping nitrogen atoms into the Graphdiyne family. This work investigates...

The effects of the vacancy-type defects in the graphene sheet (GR) and volume fraction (\({\text{v}}_{\text{f}}\)) of the GR on Young’s and shear moduli of polylactic acid (PLA) nanocomposite strengthened by the GR (GR/PLA) are investigated. The molecular dynamic (MD) method is implemented and stress–strain evolutions are extracted to explore elast...

In this paper, an efficient numerical approach is developed to address the linear bending, free vibration and buckling problems of beams made of functionally graded graphene origami-enabled auxetic metamaterials (FG-GOEAMs). It is considered that the beam is composed of multiple GOEAM layers with graphene origami (GOri) content which changes in lay...

Agglomeration of carbon nanotubes (CNTs) refers to their tendency to form clusters, an inevitable phenomenon that markedly influences the performance of composite/nanocomposite materials. Comprehending and managing agglomeration are crucial for tailoring the effective properties of nanocomposites, especially those reinforced with high concentration...

There exists a pressing need for polymeric nanocomposites exhibiting enhanced electrical properties when subjected to external electric fields. Via the development of an efficient model based on the physical-analytical relations, the electrical conductivity and percolation threshold of ternary nanocomposites enriched with the synergy of carbon nano...

Based on the variational differential quadrature (VDQ) method, the bending and buckling characteristics of circular plates made of functionally graded graphene origami-enabled auxetic metamaterials (FG-GOEAMs) are numerically studied in this paper. It is considered that the plate is composed of multiple GOEAM layers with graphene origami (GOri) con...

Inter-cluster bridging of carbon nanotubes (CNTs) and carbon black (CB) nanoparticles conjoins inactive branches of carbonaceous nanofillers within the matrix and reduces the electron tunneling distance. This mechanism moderately overcomes quantum tunneling and provides percolative polymer networks exhibiting favorable electrical responses. This st...

This study aims to examine how moisture absorption affects the impact behavior of a recently developed sandwich structure designed for use as a water-resistant system in the marine industry. For this purpose, two types of balsa-cored sandwich systems were manufactured, one with conventional glass fiber-epoxy (GE) skins and the other with novel fibe...

Stimuli-responsive shape memory polymer (SMP) nanocomposites, characterized by their shape memory capability and customizable properties, have significantly expanded their range of applications when compared to pristine SMPs. This pioneering paper is centered on describing an efficient numerical approach for evaluating the thermomechanical behavior...

Thermoelastic constants seem to be important in designing metal-based composite structures under temperature variations. In the current research, the finite element (FE) model has been utilized as a numerical tool to predict equivalent thermoelastic constants of the aluminum matrix composite (AMC) filled with carbon nanotubes (CNTs). The representa...

This study employs density functional theory calculations to analyze the structural and mechanical properties of stanene nanosheets (SnNs), including elastic moduli, Poisson’s ratio, and plastic behavior under various loads. Parameters of the Morse potential function governing stanene atom interactions are explored. The nanosheets demonstrate isotr...

This study investigates the impact of doping with carbon (C), fluorine (F), and phosphorus (P) atoms on the structural and mechanical properties of 2 × 2 and 3 × 3 ZnO monolayers using Density Functional Theory (DFT) calculations. Our analysis reveals a notable decrease in both the elastic and bulk moduli of the monolayers upon doping, with the...

In this paper, the quantum effects of fine scaling on the buckling behavior of carbon nanotubes (CNTs) under axial loading are investigated. Molecular mechanics and quantum mechanics are respectively utilized to study the buckling behavior and to obtain the molecular mechanics coefficients of fine-scale nanotubes. The results of buckling behavior o...

First principle calculations are used here to obtain the mechanical properties of the monolayer zigzag phosphorene nanosheet. These properties are used to compute some force constants. A finite element model is proposed to investigate the mechanical properties of the zigzag phosphorene nanosheets which is formed by some beam elements. The propertie...

In this study, we investigate the mechanical properties of armchair phosphorene nanotubes using a combination of density functional theory (DFT) and the finite element method (FEM). Utilizing DFT, we determine the Young’s modulus, flexural rigidity, and Poisson's ratio of armchair phosphorene nanotubes. Subsequently, employing the finite element me...

A three-dimensional finite element model is used to investigate the vibrational properties of double-walled silicon carbide nano-cones with various dimensions. The dependence of the vibrational properties of double-walled silicon carbide nano-cones on their length, apex angles and boundary conditions are evaluated. Current model consists a combinat...

In this paper, the nonlinear large-amplitude vibrations of shallow arch structures made of functionally graded materials (FGMs) under cooling shock have been investigated. It is considered that the FG shallow arch is made of low carbon steel \(\left(\mathrm{AISI }1020\right)\) and stainless steel \((\mathrm{SUS }304)\), whose material properties ch...

The optimal performance of composites enriched with hollow spheres has been reported in contemporary literature, whereas their thermal properties have received less attention. In this regard, a finite element method (FEM)-based micromechanical model has been developed systematically to investigate the role of intra-matrix embedding of hollow sphere...

In the current study, the density functional theory is utilized to investigate the elastic, plastic and electronic properties of the 2 × 2 and 3 × 3 pristine and transition metal (TM) doped germanene. Different atoms, including V, Co, Fe, Mn, Cr, Ti, Ni and Sc are selected for this purpose. It is shown that doping of the transition metal atoms woul...

A micromechanics procedure performed by the finite element method (FEM) was developed for the sake of examining the synergistic effects of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) hybrids on the elastic and viscoelastic properties of polymer nanocomposites. The representative volume element (RVE) approach was employed owing to its...

Progressive innovations in the field of nanotechnology demonstrate that through the radial growth of aligned carbon nanotubes (CNTs) on the circumferential surfaces of fibers known as fuzzy fibers, the transverse elastic properties of fiber-reinforced composites are notably improved. The main objective of the present work is to numerically examine...

Effects of incorporating carbon nanotubes (CNTs) and short carbon fibers (SCFs) into the polyvinylchloride (PVC) foam core on the flexural behavior of sandwich beams are investigated. Upper and lower skins are made of laminated composites and an initial debonded interface among the upper skin and core is considered. The mechanical properties of the...

The nonlinear vibration response of rectangular plates made of functionally graded porous materials (FGPs) induced by hygrothermal loading is investigated in this article using a numerical approach. The effect of elastic foundation on the vibrations is taken into account according to the Winkler–Pasternak model. Hygroscopic stresses produced due to...

One mechanism that is expected to play a key role in the enhanced properties of fiber-reinforced composites is adding nano-scale fillers as the second reinforcing agents in the polymer matrix. In this paper, micromechanical analysis of a hybrid smart nanocomposite in which continuous BaTiO3 fibers are embedded into the graphene nanosheet (GNS)-cont...

In this paper, a novel numerical approach is proposed to study the geometrically nonlinear large-amplitude vibrations of circular plates subjected to hygrothermal loading resting on an elastic foundation. It is considered that the plates are made of functionally graded (FG) porous materials whose hygro-thermo-mechanical properties are estimated bas...

A micromechanical model implemented with the finite element method (FEM) using the representative volume element (RVE) approach is developed to investigate the creep compliance behavior of carbon nanotube (CNT)-polymer nanocomposites. Effects of the CNT waviness, orientation, volume fraction and aspect ratio on the creep compliance of the nanocompo...

In this paper, the effect of growth on the stability of elastic materials is examined through a numerical approach. Growth and resorption are considered to have two main effects from the stability standpoint. Corresponding to the change in mass, the geometry of a system changes, and the critical length of the system can be modified. In addition, th...

In this paper, thermally induced vibrations of beams made of functionally graded materials (FGMs) subjected to cooling shocks are investigated. It is considered that the beam has been made of a mixture of stainless steel (SUS 304) and low-carbon steel (AISI 1020). To model the displacement field, the third-order beam theory, known as the Reddy beam...

A molecular dynamics (MD)-finite element (FE) modeling scheme is proposed to study the effective Young’s modulus of polymer nanocomposites reinforced by functionalized silicon carbide nanotubes (fSiCNTs). By evaluating the tensile and shear properties of the polymer matrix strengthened by hydroxyl (O–H)-, fluorine (F)-, and hydrogen (H)-fSiCNTs (O-...

Free vibration of single-layered graphene sheets (SLGSs) subjected to compressive in-plane loads and embedded in a Winkler–Pasternak elastic medium in the pre- and post-buckled configurations is examined herein. To consider both geometric and material nonlinearities and include the size-dependent mechanical behavior of small-scale structures withou...

This paper presents two hyperelastic models for the micromorphic hyperelasticity which can be efficiently utilized for materials with high dependence on the microdeformation gradient. To this end, two new microdeformation gradient-based strain measures are introduced and used in hyperelastic formulation. The developed formulation for the micromorph...

In this paper, the free vibrations of beam-type structures subjected to rapid heating are analyzed within the framework of micropolar thermoelasticity using a novel numerical approach. The equations of motion are derived based on the micropolar elasticity theory and the Timoshenko beam theory using Hamilton’s principle. The transient 1D Fourier-typ...

Several non-classical elasticity theories are used for considering the size-dependent behavior of structures at small scales. The nonlocal theory is widely used to reflect the softening behavior of material at small scales, and theories like the strain gradient theory are employed to reflect the hardening behavior. In this article, the most general...

The tensile properties and fracture mechanism of hydroxyl-functionalized silicon carbide nanotubes (O-fSiCNTs) inserted into polymer matrices are explored and the outcomes are compared to results for the hydroxyl-functionalized carbon nanotubes (O-fCNTs) incorporated in similar matrices. The molecular dynamics (MD) method is used and the simulation...

Shell-type structures are frequently used in aerospace, marine and civil engineering. In this paper, a numerical approach called as VDQ-transformed is introduced to analyze the large deformations of hyperelastic shell-type structures based on the Saint Venant–Kirchhoff constitutive model in the context of three-dimensional (3D) nonlinear elasticity...

In this article, a numerical approach is presented for the large deformation analysis of shell-type structures made of Neo-Hookean and Kirchhoff–St Venant materials within the framework of the seven-parameter shell theory. Work conjugate pair of the second Piola–Kirchhoff stress and Green–Lagrange strain tensors are taken for the macroscopic stress...

In this work, the nonlinear vibrations of functionally graded (FG) porous circular plates under hygro-thermal loading is studied utilizing a numerical approach. Hygroscopic stresses generated due to the nonlinear rise in moisture concentration, even and uneven porosity distributions, and temperature dependency of material properties are all taken i...

In this paper, the incremental equilibrium equations and corresponding boundary conditions for the isotropic, hyperelastic and incompressible shells are derived and then employed in order to analyze the behavior of spherical and cylindrical shells subjected to external pressure. The generalized differential quadrature (GDQ) method is utilized to so...

In this paper, the dynamic buckling of functionally graded (FG) porous shallow arches under hygro-thermal loading is studied through a numerical approach. Even and uneven porosity imperfections, hygroscopic stresses generated due to the nonlinear rise in moisture concentration, and the temperature dependence of material properties are all taken int...

A two-stage molecular dynamics (MD)-finite element (FE) modeling method is developed based on the concepts of representative volume element (RVE) and equivalent solid fibers (ESFs) containing functionalized carbon nanotubes (ESFs-fCNTs). First, the influences of nanotubes’ chirality, different percent of functionalization (Pfunc), various functiona...

Based on the micromorphic theory (MMT), the vibrational behavior of annular sector plates with different angles and subjected to various boundary conditions (BCs) is studied. To this end, the linear formulation of three-dimensional (3D) MMT is first presented and the matrix representation of this formulation is given. Then, a 3D size-dependent 8-no...

A new numerical approach is presented to compute the large deformations of shell-type structures made of the Saint Venant-Kirchhoff and Neo-Hookean materials based on the seven-parameter shell theory. A work conjugate pair of the first Piola Kirchhoff stress tensor and deformation gradient tensor is considered for the stress and strain measures in...

In this paper, the elastic and plastic properties of 2×2 and 3×3 pristine and transition metal (TM) doped silicene nanosheets are studied using the density functional theory (DFT) calculations. Cr, Co, Cu, Mn, Ti, V, Zn and Ni atoms are selected as doping atoms. It is observed that Young’s and bulk moduli of both 2×2 and 3×3 pristine structures dec...

Nowadays, the attention of many structural designers is focused on research methods for increasing the impact resistance of advanced structures. Meanwhile, Kevlar fiber is considered a well-known material in the field of impact-resistant materials. But the use of brittle base materials such as epoxy, which is necessary to bond Kevlar fibers togethe...

Despite the unique superior properties of balsa such as reasonable price and excellent mechanical properties, the hydrophilicity and high sensitivity of this material to moisture absorption have posed a serious challenge to its increasing use in the construction of advanced marine structures. If moisture can penetrate into the composite skins, the...

In this paper, the nonlinear thermally induced vibration in rectangular plates made of porous functionally graded materials (FGMs) due to thermal shock is studied based on a new numerical approach. The shear deformation influences are taken into consideration via Mindlin’s plate theory. The properties of the materials are also assumed to be tempera...

A 3D Monte Carlo simulation and percolation network model for hybrid nanocomposites reinforced by carbon nanotubes (CNTs) and carbon black (CB) nanoparticles (NPs) is established to investigate the percolation probability and piezoresistivity considering electron tunneling effect. Firstly, a Monte Carlo algorithm is developed to form a representati...

In this article, the nonlinear hygrothermally induced vibrational behavior of bidirectional functionally graded porous beams is studied through a numerical approach. Two-dimensional material and temperature distributions, even and uneven porosity distributions, temperature-dependent nature of material properties, and hygroscopic effects are all tak...

In this paper, the geometrically nonlinear thermally induced vibration response of beams made of porous functionally graded materials (FGMs) under thermal shock is investigated using a novel numerical approach. The material properties are considered to be temperature- and position-dependent. It is also assumed that the beams are embedded in an elas...

The mechanical characteristics of reinforced polymer nanocomposites with Hydrogen (H)- and Fluorine (F)-functionalized silicon carbide nanotubes (H-and F-fSiCNTs) are investigated herein using molecular dynamics (MD) simulations. The effects of covalent functionalization and chirality of SiCNT, and diverse polymer materials on Young's modulus, maxi...

Presented herein is a numerical variational approach to the two-dimensional (2D) incompressible nonlinear elasticity. The governing equations are derived based upon the minimum total energy principle by considering the displacement and a pressure-like field as the two independent unknowns. The tensor equations are replaced by equations in a novel m...

Herein, the effects of halogen and metal atomic adsorption on the mechanical and structural characteristics of silicene are studied using density functional theory (DFT) calculations. Cl, Br, Au, Ca, Ga, Li, and Na atoms are selected as the adsorption atoms. Moreover, the phonon dispersion and electron localization function are investigated to show...

In this paper, the free vibration of hybrid carbon boron-nitride heteronanotubes (CBNNTs) is analyzed through molecular dynamics (MD) simulations. In the vibration analysis, various CBNNTs (Cx ∣ (BN)y and C-BN models) according to two geometrical arrangements of constituent segments are considered. By introducing vacancy defects in nanotubes, the i...

This paper uses the higher-order shear deformation theory (HOSDT) to analyze the nonlinear resonance of functionally graded graphene platelet-reinforced porous (FG-GPL-RP) circular cylindrical shell with geometrical imperfections subjected to the harmonic transverse loading. The shell considered is surrounded by the elastic Winkler–Pasternak founda...

In this work, a numerical study is presented for the free vibration behavior of piezoelectric Bernoulli–Euler nanoscale beams considering flexoelectric and nonlocal effects. Strain-driven nonlocal formulations of Eringen’s theory in both differential and integral forms are used to capture nonlocal influences. By Hamilton’s principle, the equation o...

A novel one-step Monte-Carlo approach considering the orientation effect of carbon nanotubes (CNTs) in synergism with uniformly distributed ellipsoidal graphene nanoplatelets (GNPs) teamed up with percolation model is developed to study the percolation probability and gauge factor of hybrid CNT-GNP piezoresistive conductive network composite. A rep...

In this study, the free vibrations of functionally graded graphene platelet-reinforced porous nanocomposite plates with various shapes such as rectangular, elliptical and triangular ones embedded on an elastic foundation are analyzed. To mathematically model the considered plate and elastic foundation, the first-order shear deformation plate theory...

Purpose The paper aims to presents a numerical analysis of free vibration of micromorphic structures subjected to various boundary conditions. Design/methodology/approach To accomplish this objective, first, a two-dimensional (2D) micromorphic formulation is presented and the matrix representation of this formulation is given. Then, two size-depen...

https://www.sciencedirect.com/science/article/abs/pii/S0925963521005276

This article deals with new soliton solutions of the generalized nonlinear Schrödinger equation with variable coefficients by the direct algebraic method. Once the variables of this technique are considered as special values, we could achieve the solitary waves that are unique from those attained by the other methods. It can be inferred that the so...

In the present work, molecular dynamics (MD) simulations are used to investigate the impact behavior of single-walled carbon nanotubes (SWCNTs) with free boundary conditions in two directions, i.e. vertical and horizontal. To consider the effect of consecutive impacts, the number of carbon nanotubes (CNTs) participated in simulations is chosen from...

The endohedral functionalization of carbon nanotubes (CNTs) with nanowires (NWs), i.e., NWs@CNTs, has been the center of attention in a lot of research due to the applications of NWs@CNTs in nanoelectronic devices, heterogeneous catalysis, and electromagnetic wave absorption. To this end, based on the classical molecular dynamics (MD) simulations,...

Piezoresistivity and electrical conductivity of carbon nanotube (CNT)/graphene nanoplatelet (GNP)-filled polymer nanocomposites are investigated using a 3D Monte Carlo analytical-geometrical model. GNPs and CNTs are considered as randomly distributed solid thin rectangular cube and cylinder, respectively. After establishment of a random CNT/GNP net...

Recently, the mechanical behavior of micro-/nano-structures has sparked an ongoing debate, which leads to a fundamental question: what steps can be taken to investigate the mechanical characteristics of these structures, and characterize their performance? From the standpoint of the non-classical behavior of materials, size-dependent theories of mi...

In this article, a new solution approach is developed to numerically compute large deformations of 3D hyperelastic solids based on the compressible nonlinear elasticity. The governing equations are derived by the minimum total potential energy principle, and the Neo-Hookean model is used for the hyperelastic character of material. One of the key no...

The micropolar continuum theory (MPT) is able to describe the influence of micro-structures on the mechanical behavior of materials where the classical theories of elasticity are unable to interpret. In this paper, the free vibration analysis of three-dimensional (3D) micropolar structures with different geometries is presented. To this aim, first,...

A two-step analytical model based on a percolation network model and electron tunneling theory has been developed to predict the electrical resistivity and percolation threshold of a hybrid nanocomposite system comprising carbon black (CB) and carbon nanotube (CNT). The nanostructure of a tunneling network consisting of CNT and CB agglomerates has...

In this paper, antimonene nanosheets are simulated using finite element modeling. First, the elastic properties of antinomene are obtained using the density functional theory as well as the element properties, which are used to represent Sb-Sb bonds in the structure of antimonene. Then, developed model is used to calculate Young’s modulus, critical...

Based on Reddy’s third-order shear deformation theory and mixed formulation, a new numerical approach in the variational framework is developed to analyze the geometrically nonlinear free vibration behavior of cylindrical panels having cutouts with various shapes (e.g., square, circular, elliptical) under arbitrary boundary conditions. It is also a...

In this paper, an investigation into the thermal conductivity of cross-linked functionalized carbon nanotubes under physical adsorption of polyethylene (PE) chains (cfCNTs/PE) is performed using molecular dynamics (MD) simulations. To have a comprehensive study, the covalently attached functional groups with two types of distribution patterns, name...

Introduced in this paper is the complete nonlinear model of the micropolar theory (MPT) for shell-type materials. Considering the three-dimensional kinematic model in a convected curvilinear coordinate system, the Lagrangian description of micromorphic theory (MMT) is formulated first. Due to certain assumptions, i.e. skew-symmetricity of micro-dis...

Presented herein is a size-dependent Bernoulli–Euler beam model for the buckling analysis of piezoelectric nanobeams under electrical loading with the consideration of flexoelectricity influence. In order to capture size effects, the stress-driven model of nonlocal theory is utilized. Moreover, it is considered that the nanobeams are embedded in an...

A numerical investigation is performed to examine the static bending behavior of piezoelectric nanoscale beams subjected to electrical loading, considering flexoelectricity effects and different kinematic boundary conditions. The nanobeams are modeled by the Bernoulli–Euler beam theory, and the stress-driven integral nonlocal model is used in order...

Based on the ideas of variational differential quadrature (VDQ) method and position transformation, an efficient numerical variational strategy is proposed in this paper to analyze the large deformations of hyperelastic structures in the context of three-dimensional (3D) compressible and incompressible nonlinear elasticity theories. Based on the mi...

A physics-based hierarchical modeling approach considering tunneling resistance through polymer is proposed to predict the percolation threshold and resistivity of carbon nanotube (CNT)/graphene nanoplatelet (GNP)-reinforced polymer hybrid nanocomposites. At first, a method is developed to calculate the resistivity of CNT-polymer nanocomposites. Th...

This article is concerned with analyzing exact optical soliton solutions to Kudryashov’s model. To this end, the sine-Gordon expansion and Kudryashov methods are exerted and a bunch of new optical soliton solutions is acquired. The implementation and algebraic methods are discussed in detail. Finally, singular and bright-dark soliton solutions emer...

Based on the micropolar theory (MPT), a two-dimensional (2D) element is proposed to describe the free vibration response of structures. In the context of the MPT, a 2D formulation is developed within the ABAQUS finite element software. The user-defined element (UEL) subroutine is used to implement a micropolar element. The micropolar effects on the...