Reza Naghdabadi

Reza Naghdabadi
Sharif University of Technology | SHARIF · Department of Mechanical Engineering and Institute for Nano Science and Tecnology

Doctor of Philosophy

About

178
Publications
28,997
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4,106
Citations
Citations since 2017
23 Research Items
2326 Citations
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
Introduction

Publications

Publications (178)
Article
Tunable metamaterials functionalities change in response to external stimuli. Mechanical deformation is known to be an efficient approach to tune the electromagnetic response of a deformable metamaterial. However, in the case of large mechanical deformations, which are usually required to fully exploit the potential of the tunable metamaterials, th...
Article
Tunable metasurfaces can shift their resonant frequency through different approaches, one of which is applying mechanical deformations. Here, we show the effects of two key factors on the tunability of deformable metasurfaces; the resonator geometry and substrate stiffness. To show the effects, we compared the tunability of unit cells with three re...
Article
Piezoresistive strain sensing of multiwalled carbon nanotube (CNT)‐reinforced polymer nanocomposites considering the effect of agglomeration is experimentally investigated. Thermoplastic polyurethane is used as composite matrix with melt mixing method for fabricating the nanocomposite. The electrical resistance of the nanocomposite specimens is mea...
Article
Full-text available
We leverage the crucial hyperelastic properties of a multifunctional structured surface to optimize the reconfigurability of the electromagnetic transmission under large nonlinear mechanical deformations. This multiphysics, multifunctional, hyperelastic structured surface (HSS) offers two simultaneous intriguing functionalities; tunability and swit...
Article
Amorphous lithium metal alloys (Li M, with M=Si, Ge, Sn,. . .) are attractive anode materials for lithium-ion batteries owing to their high energy-storage capacity and safety characteristics. However, repeated insertion of lithium often leads to chemo-mechanical degradation of the alloy, which can severely reduce the battery capacity and cycle life...
Preprint
A new inelastic mechanism, detwinning-induced plasticity (DIP), is proposed to model the response of NiTi SMAs to cyclic loading, based on thermodynamic considerations. DIP is incorporated into a constitutive framework for NiTi SMA. The constitutive framework also includes well established inelastic mechanisms of phase transformation,transformation...
Preprint
In this study the mechanisms of transformation-induced plasticity (TRIP), detwinning-induced plasticity (DIP), and accumulation of residual martensite, are incorporated into a finite-deformation crystal plasticity model of NiTi SMA for the first time. The constitutive model is constructed at the single-crystal scale and also includes phase transfor...
Article
In the present study, for the first time, a thermodynamically consistent large deformation theory is developed to model the multi physics problem of axonal swelling which is the hallmark of most of the brain diseases. To this end, first, relevant axonal compartments are explained and then the corresponding model parts are introduced. Next, the prob...
Article
A new inelastic mechanism, detwinning-induced plasticity (DIP), is proposed to model the response of NiTi SMAs to cyclic loading, based on thermodynamic considerations. DIP is incorporated into a constitutive framework for NiTi SMA. The constitutive framework also includes well-established inelastic mechanisms of phase transformation, transformatio...
Article
Upon incubation of nanoparticles in biological uids, a new layer called as protein corona is formed on their surface affecting the interactions between nanoparticles and targeted cell during the endocytosis process. In the present study, a mathematical model based on the diffusion of membrane mobile receptors is proposed. Opposing the endocytosis p...
Article
The initial and subsequent yield surfaces for architected pyramidal lattice materials are investigated analytically. Considering lattice struts as elastic-perfectly plastic thin beams subjected to both axial force and bending moment, a set of nonlinear elastic-plastic constitutive relations for a strut is proposed. Moreover, we phenomenologically p...
Conference Paper
Full-text available
Here, we present the different challenges one might face in the multiphysics simulation of an electromagnetic metasurface unit cell under mechanical deformation. The principal problem stems from the required air layers as a propagating medium for the electromagnetic analysis, which are not involved in the mechanical analysis. In this regard, the av...
Article
Once in biological fluids, the surface of nanoparticles (NPs) is rapidly covered with a layer of biomolecules (i.e., “protein corona”) whose composition strongly determines its biological identity, regulating interactions with biological entities including cells and the immune system, and consequently direct biological fate and pharmacokinetics of...
Article
Gels are composed of crosslinked polymer network and solvent molecules. When the main chain network is incorporated with functional groups that can undergo photo-chemical reaction upon light irradiation, the gel becomes light-responsive. Under irradiation, the photosensitive groups may undergo photo-ionization process and generate charges that are...
Article
Full-text available
یکی از انواع گیرنده‌های مکانیکی که در گونه‌های سلولی متفاوتی از مهره‌داران و بی‌مهرگان وجود دارد، نانوکانال‌های یونی تحریک شونده با نیروی مکانیکی (MSCs) هستند که با دریافت و انتقال سیگنال‌های مکانیکی به محیط درون سلولی، علاوه بر حسگری فشار، لمس، ارتعاش و شنوایی، در بسیاری از فرایندهای تنظیمی درون سلولی و پاسخ‌های بیولوژیکی نقش اساسی ایفا می‌کنند. ه...
Article
Self-healing materials, as a class of intelligent materials, are capable to recover a part of the weakened mechanical properties induced by damage. In this article, based on the thermodynamics of irreversible processes, employing the effective configuration in the continuum damage-healing mechanics, a viscoelastic–viscoplastic constitutive model is...
Article
Full-text available
In this work, energy absorption of ceramic tiles wrapped by aluminum foil on its impact face is experimentally and numerically studied. Penetration tests as well as numerical simulations are employed to obtain Ballistic Limit Velocity (BLV) of the tiles. Experimental and numerical results yield BLV of bare tiles as 145 ± 2 and 141.5 m/s, respective...
Article
Full-text available
Gating of mechanosensitive (MS) channels is driven by a hierarchical cascade of movements and deformations of transmembrane helices in response to bilayer tension. Determining the intrinsic mechanical properties of the individual transmembrane helices is therefore central to understanding the intricacies of the gating mechanism of MS channels. We u...
Conference Paper
Full-text available
A finite element simulation is developed to study thermo-mechanical behavior of a metallic lattice material, fabricated by selective laser melting (SLM) process. SLM is widely used in manufacturing three-dimensional functional parts layer by layer. A physics-based layer build-up approach coupled with a surface moving heat flux and a material proper...
Conference Paper
This research exhibits an experimental and numerical investigation on impact behavior of plain concrete panels. PC panels are subjected to impact by 4340 steel ogive-nose projectiles. The initial impact velocity of projectile is measured experimentally and the energy absorbed is calculated. Penetration depth and perforation thickness results are co...
Article
In-stent restenosis (ISR) is one of the main drawbacks of stent implementation which limits the long-term success of the procedure. Morphological changes occurring within the arterial wall due to stent-induced mechanical injury are a major cause for activation of vascular smooth muscle cells (VSMCs), and the subsequent development of ISR. Consideri...
Article
Mechanical properties of nano-composites produced by shock wave sintering of aluminum and silicon carbide nano-powders are investigated using Molecular Dynamics (MD) simulations. In this regard, the shock wave response of aluminum and silicon carbide nano-particles, arranged in a BCC super-lattice, is studied via the NPHug Hugoniostat method. Moreo...
Article
In this paper, employing the Hencky strain, viscoelastic-viscoplastic response of self-healing materials is investigated. Considering the irreversible thermodynamics and using the effective configuration in the Continuum Damage-Healing Mechanics (CDHM), a phenomenological finite strain viscoelastic-viscoplastic constitutive model is presented. Cons...
Article
Dynamic behavior of concrete specimens is investigated experimentally and numerically by split Hopkinson pressure bar (SHPB) tests. In order to accurately determine dynamic properties of brittle materials such as concrete, specimens should be subjected to particular pulse loading that can be generated by using pulse shapers. Choosing proper pulse s...
Article
Full-text available
Gating of mechanosentive (MS) channels is driven by a hierarchical cascade of movements and deformations of transmembrane helices in response to bilayer tension. Determining the intrinsic mechanical properties of the individual transmembrane helices is therefore central to understanding the intricacies of the gating mechanism of MS channels. We use...
Article
In manufacturing amorphous silicon solar cells, thin films are deposited at high temperatures (200–400 °C) on a thick substrate using sputtering and plasma enhanced chemical vapor deposition (PECVD) methods. Since the thin films and substrate have different thermal expansion coefficients, cooling the system from deposition temperature to room tempe...
Article
In this paper, employing the definition of an effective configuration in the continuum damage mechanics, mechanical response of a compressible viscoelastic–viscoplastic material is investigated. We present a phenomenological viscoelastic–viscoplastic–viscodamage constitutive model, developed within the framework of irreversible thermodynamics. The...
Article
Full-text available
Strain and stress concentrations are studied for elastomers at finite deformations. Effects of strain-induced crystallization, filler reinforcement and deformation rate are also investigated, and micromechanical descriptions are provided for the observed results. A simple problem is subjected to finite element simulations to show the results eviden...
Article
In this work, a model is developed to continuously predict homogeneous and inhomogeneous swelling behavior of pH/temperature sensitive PNIPAM hydrogels. Employing the model, homogeneous swelling of the pH/temperature sensitive hydrogel is investigated for free and biaxial constrained swelling cases. Comparing the model results with the experimental...
Article
Full-text available
Forming limit diagram is often used as a criterion to predict necking initiation in sheet metal forming processes. In this study, the forming limit diagram was obtained through the inclusion of the Marciniak–Kaczynski model in the Nakazima out-of-plane test finite element model and also a flat model. The effect of bending on the forming limit diagr...
Article
Full-text available
The linear static elastic-plastic behavior of sandwich cylindrical shell panels under a generally distributed loading with thick flexible core is studied. The core modeling is based on high-order theory of sandwich structures in which the in-plane stresses of the core are neglected. The faces are modeled based on Kirchhoff–Love shell theory. The ma...
Article
Inelastic phenomena such as stress softening and unrecoverable inelastic deformations induced by supra-physiological loading have been observed experimentally in soft tissues such as arteries. These phenomena need to be accounted for in constitutive models of arterial tissues so that computational models can properly predict the outcome of interven...
Article
Full-text available
The hydrophobic mismatch between the lipid bilayer and integral membrane proteins has well-defined effect on mechanosensitive (MS) ion channels. Also, membrane local bending is suggested to modulate MS channel activity. Although a number of studies have already shown the significance of each individual factor, the combined effect of these physical...
Article
The present work develops three-dimensional phenomenological constitutive models for dense and porous shape memory alloys (SMAs). The models are extensions of a recent work and considers pressure dependent behavior for porous SMAs as well as the coupling effects of transformation and plasticity for both dense and porous SMAs. In contrast to dense S...
Conference Paper
Full-text available
Strain rate dependence of plastic yield and failure properties displayed by most metals affects energies, forces and forming limits involved in high speed forming processes. First, Split Hopkinson Tensile Bar (SHTB) experiments are carried out to determine the influence of the strain rate on the materials’ stress-strain curves. Then, the SHTB resul...
Conference Paper
Full-text available
In this paper, by using split Hopkinson indirect tensile bar test, the dynamic behavior of C10200 copper under different strain rates is studied. After post-processing achieved data in program, stress-strain curves of copper under different strain rate are presented. Using these curves, Johnson-Cook model’s constants have been determined. According...
Article
Full-text available
Mechanosensitive (MS) channels are ubiquitous molecular force sensors that respond to a number of different mechanical stimuli including tensile, compressive and shear stress. MS channels are also proposed to be molecular curvature sensors gating in response to bending in their local environment. One of the main mechanisms to functionally study the...
Article
In this study, a three-dimensional (3D) beam element based on Timoshenko beam theory is introduced for shape memory alloys (SMAs). Employing the microplane approach, we use a 3D SMA constitutive model extended from a 1D model proposed by Brinson. The SMA model is implemented into a user-defined subroutine (UMAT) in the nonlinear finite element soft...
Article
Self-healing concrete materials have the capability to recover a part of the weakened mechanical properties induced by damage. In this paper, a constitutive model is proposed to investigate damage and healing phenomena in concrete materials. In order to consider the different behavior of concretes in tension and compression, a spectral decompositio...
Article
In micron-scale, powder consolidation process is driven by diffusion phenomenon, while in nano-scale the higher surface energy of particles leads to some anomalous behaviors within the process. In order to investigate the nano-sintering occurrence, an atomistic approach is employed via molecular dynamics simulations. Within this approach, the effec...
Conference Paper
Full-text available
In amorphous silicon solar cells, thin films are deposited at the temperature above room temperature on a thick substrate using sputtering and plasma enhanced chemical vapor deposition (PECVD) methods. Since thin films and substrate have different thermal expansion coefficients, cooling the system from deposition temperature to the room temperature...
Article
Full-text available
Nafion membrane encounters many different thermal conditions and mechanical loadings because of its wide range of applications as a proton exchange membrane (PEM). Molecular dynamics simulation of hydrated Nafion at different temperatures is carried out to investigate the alteration of the physical properties of Nafion under unixial loading over a...
Article
Full-text available
In this work, inhomogeneous swelling of the temperature-sensitive PNIPAM hydrogel is investigated with application to micro-valves. In this regard, a modified model is considered, and an analytical solution of the inhomogeneous swelling of a hydrogel jacket coated on a rigid pillar is performed, which is valuable for the conceptual design of the mi...
Article
Full-text available
Porous shape memory alloys are a class of very interesting materials exhibiting features typical of porous metals and of shape memory alloys. In contrast to dense shape memory alloys, considerable plastic strain accumulates in porous shape memory alloys even during phase transformation. Moreover, due to the microstructure of porous materials, phase...
Conference Paper
Full-text available
Making use of continuum mechanics approaches and Finite Element (FE) simulation, gating mechanism of mechanosensitive ion channels (MSCs) has been studied in terms of the relationship among their continuum structure, their interaction with the lipid bilayer, extra cellular matrix and mechanical forces. We have shown that due to the generation of st...
Article
Full-text available
The aim of this work is to develop a model to continuously predict inhomogeneous and homogeneous swelling behavior of temperature-sensitive poly-(N-isopropylacrylamide) hydrogels. Employing this model, some benchmark homogeneous problems such as free, unidirectional constrained and biaxial constrained swelling as well as swelling of core-shell stru...
Article
Full-text available
In this paper, strain gradient thermo-elasticity formulation for axisymmetric Functionally Graded (FG) thick-walled cylinders is presented. For this purpose, the elastic strain energy density function is considered to be a function of gradient of strain tensor in addition to the strain tensor. The material properties are assumed to vary according t...
Article
The purpose of this paper is to present efficient and accurate analytical expressions for deflection of a shape memory polymer (SMP) beam employing Euler-Bernoulli beam theory in a thermomechanical SMP cycle. Material behavior is considered using a recently 3D thermodynamically consistent constitutive model available in literature. In different ste...
Article
The thermal transition of Nafion is studied using a molecular dynamics simulation through a chemically realistic model. Static and dynamic properties of polymer melts with different water contents are investigated over a wide range of temperatures to obtain viscometric and calorimetric glass transition temperatures. The effect of cooling rate of th...
Article
Full-text available
Many physiological processes such as cell division, endocytosis and exocytosis cause severe local curvature of the cell membrane. Local curvature has been shown experimentally to modulate numerous mechanosensitive (MS) ion channels. In order to quantify the effects of local curvature we introduced a coarse grain representative volume element for th...
Conference Paper
The main goal of this study is to investigate the effects of plaque structure on its stress distribution. Rupture of plaque causes cerebrovascular diseases which lead to high mortality rates all over the world. Computers are powerful tools to understand the mechanism of plaque rupture. In this study, 3D fluid structure interaction simulation is con...
Article
In many engineering applications, shape memory polymers (SMPs) usually undergo arbitrary thermomechanical loadings at finite deformation. Thus, development of 3D constitutive models for SMPs within the finite deformation regime has attracted a great deal of interest. In this paper, based on the classical framework of thermodynamics of irreversible...
Article
A three-dimensional visco-hyperelastic constitutive model is developed to describe the rate-dependent behavior of rubber-like materials at large deformations. The model encompasses a hyperelastic part which uses the “Exp–Ln” strain energy function to characterize the equilibrium response and a viscous part capturing the rate sensitivity using a her...
Article
A molecular dynamics simulation of the shock-wave propagation in the face-centered cubic (FCC) structured C60 fullerene along the , and crystallographic directions is performed. For this purpose, the response of the material under different shock-wave loadings is studied through Hugoniot curves. Three regimes of the material behavior have been obse...
Article
Full-text available
The perfluorinated sulfonic acid membrane (Nafion) shows among ionomers high water uptake and cationic conductivity. These properties allow Nafion to be used in nanocomposite actuators, sensors and fuel cells. In situ experiments have shown that there is a water gradient within the Nafion membrane. The water gradient causes the alteration of other...
Article
Full-text available
Elastomers have wide and ever increasing applications in several industries. In this work a compressible visco-hyperelastic approach is employed to investigate the behavior of elastomeric materials. The time-discrete form of the material model is developed to be used in numerical simulations. This formulation provides a recursive relation to update...
Article
In this paper, decomposition of the total strain into elastic and plastic parts is investigated for extension of elastic-type constitutive models to finite deformation elastoplasticity. In order to model the elastic behavior, a Hookean-type constitutive equation based on the logarithmic strain is considered. Based on this constitutive equation and...
Article
Full-text available
In this article, the one-dimensional phenomenological constitutive model originally proposed by Brinson for shape memory alloys is improved to predict asymmetric behavior in tension and compression. We propose an approach that decomposes stress-induced martensite volume fraction into two parts, one in tension and one in compression. Results of nume...
Article
The theoretical need to recognize the link between the basic microstructure of nonlinear porous materials and their macroscopic mechanical behavior is continuously rising owing to the existing engineering applications. In this regard, a semi-analytical homogenization model is proposed to establish an overall, continuum-level constitutive law for no...
Article
A molecular dynamics (MD) simulation is employed to study the phase transition process in argon induced by shock wave transmission. Deriving the relation between the shock and piston velocities, the theoretical equation of state for argon is presented. Also, argon equation of state is obtained by measuring the quantities directly from simulations t...
Article
Hyperelastic behavior of isotropic incompressible rubbers are studied to develop a strain energy function. The proposed function includes only three material parameters which are related to physical properties of the material molecular network. Furthermore, the model benefits from well suitting in all ranges of stretch as well as possessing the pro...
Article
In this paper, a hyperelastic plastic damage-induced anisotropic constitutive model is proposed based on the logarithmic strain in finite deformations. The evolution equations are written in terms of the material time derivative of the stress tensor conjugate to the logarithmic strain. The dissipation inequality is considered in the intermediate co...
Article
In this paper, for obtaining an overall size-dependent yield function for nanocomposites containing aligned cylindrical nanofibers, the effects of interface residual stress and interface elasticity are taken into account within a micromechanical framework. Toward this goal, the modified Hill’s condition is used, and then, in order to consider effec...
Article
Hyperelastic behavior of isotropic incompressible rubbers is studied to develop a strain energy function which satisfies all the necessary characteristic properties of an efficient hyperelastic model. The proposed strain energy function includes only three material parameters which are somehow related to the physical quantities of the material mole...
Article
Solids usually show complex material behavior. If deformation is finite, the description of the kinematics makes the mechanical model complicated. In fact, one of the basic questions in the formulation and analysis procedures of finite deformation thermoelasticity is: “How can the finite deformation thermoelasticity response be best accounted for i...
Article
In this paper a shell formulation is proposed for analyzing the torsional instability of carbon nano-peapods (CNPs), i.e., the hybrid structures composed of C60 fullerenes encapsulated inside carbon nanotubes (CNTs), based on the nonlocal elasticity theory. The nonlocal elasticity theory, as a well-known non-classical continuum theory, is capable t...
Article
An energy-based ordinary differential equation is derived for a plastic wave propagating through a Taylor impact test specimen. Using the definition of true strain, an analytical equation is presented to calculate the strain rate across the plastic wave front. Having considered a Johnson–Cook plasticity model for the projectile material, the derive...
Article
Shape memory polymers commonly experience both finite deformations and arbitrary thermomechanical loading conditions in engineering applications. This motivates the development of three-dimensional constitutive models within the finite deformation regime. In the present study, based on the principles of continuum thermodynamics with internal variab...
Article
In this paper, employing the logarithmic (or Hencky) strain as a more physical measure of strain, the time-dependent response of compressible viscoelastic materials is investigated. In this regard, we present a phenomenological finite strain viscoelastic constitutive model, developed within the framework of irreversible thermodynamics with internal...
Article
Interaction of Carbon Nanotubes (CNTs) and nanovoids embedded in a metal matrix is studied comparatively. For this purpose, two nearby CNTs/nanovoids are modeled as two similar cylindrical inclusions/holes in an infinite matrix. The nonlocal stresses around the CNTs/nanovoids are obtained by applying the integral constitutive equation of the nonloc...
Article
Recent studies have shown that the surface/interface free energy plays an important role in the effective mechanical properties of solids with nanosized inhomogeneity. In the present study, an analytical model is developed for 3D axisymmetric analysis of short fiber nanocomposites including the fiber end region, subjected to an applied axial load c...
Article
The ever increasing applications of shape memory polymers have motivated the development of appropriate constitutive models for these materials. In this work, we present a 3 D constitutive model for shape memory polymers under time-dependent multiaxial thermomechanical loadings in the small strain regime. The derivation is based on an additive deco...
Article
In this article, a constitutive model in the framework of continuum damage mechanics is proposed to simulate the elastic behavior of concrete in tension and compression states. We assume two parts for Gibbs potential energy function: elastic and damage parts. In order to obtain the elastic-damage constitutive relation with the internal variables, t...
Article
Mechanical properties of a material near the surfaces and interfaces are different from those of the same material far from the surfaces/interfaces. The effect of this difference on the effective mechanical properties of heterogeneous materials becomes significant when the size of inhomogeneities is at the scale of nanometers. In this article, with...
Article
Dynamic and static fracture properties of Graphene Sheets (GSs) and Carbon nanotubes (CNTs) with different sizes are investigated based on an empirical inter-atomic potential function that can simulate nonlinear large deflections of nanostructures. Dynamic fracture of GSs and CNTs are studied based on wave propagation analysis in these nanostructur...
Article
Full-text available
In this paper, the responses of shape memory polymer (SMP) helical springs under axial force are studied both analytically and numerically. In the analytical solution, we first derive the response of a cylindrical tube under torsional loadings. This solution can be used for helical springs in which both the curvature and pitch effects are negligibl...