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Experimental and numerical investigation of pulse-shaped split Hopkinson pressure bar test
, Article Materials Science and Engineering A ; Volume 539 , 2012 , Pages 285-293 ; 09215093 (ISSN) ; Ashrafi, M. J ; Arghavani, J ; Sharif University of Technology
2012
Abstract
Employing a proper pulse shaper in the conventional split Hopkinson pressure bar (SHPB) test helps to achieve dynamic equilibrium condition and to fulfill a constant strain rate condition in the test specimen. To this end, the parameters affecting the incident pulse shape, i.e., pulse shaper thickness, pulse shaper diameter, striker bar length and striker bar velocity are experimentally studied. Moreover, simulation results, validated by experimental data together with wave propagation analysis, are exploited to provide general guidelines to properly design a pulse shaper. It is recommended to use a relatively large diameter pulse shaper for testing work-hardening materials. Also, for...
Analysis of Al A359/SiCp functionally graded cylinder subjected to internal pressure and temperature gradient with elastic-plastic deformation
, Article Journal of Thermal Stresses ; Volume 34, Issue 10 , May , 2011 , Pages 1054-1070 ; 01495739 (ISSN) ; Naghdabadi, R ; Arghavani, J ; Sharif University of Technology
2011
Abstract
In this article, an analytical elastic-plastic solution for thick-walled cylinders made of Functionally Graded Materials (FGMs) subjected to internal pressure and thermal loading is presented. Based on the experimental results, a mathematical model to predict the yielding through the thickness of FG AlA359/SiCp cylinder is developed. It is shown that under the temperature gradient loading, there is a point in the cylinder where the circumferential stress changes from compressive to tensile. The position of this point depends on the geometry and material properties of the FG cylinder and is independent of the temperature gradient
A semi-analytical study on helical springs made of shape memory polymer
, Article Smart Materials and Structures ; Volume 21, Issue 4 , 2012 ; 09641726 (ISSN) ; Naghdabadi, R ; Arghavani, J ; Sharif University of Technology
2012
Abstract
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 negligible. This is the case for helical springs with large ratios of the mean coil radius to the cross sectional radius (spring index) and also small pitch angles. Making use of this solution simplifies the analysis of the helical springs to that of the torsion of a straight bar with circular cross section. The 3D phenomenological constitutive model...
A viscoelastic constitutive model for compressible polymers based on logarithmic strain and its finite element implementation
, Article Finite Elements in Analysis and Design ; Volume 62 , 2012 , Pages 18-27 ; 0168874X (ISSN) ; Baghani, M ; Arghavani, J ; Sharif University of Technology
2012
Abstract
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 variables. The formulation is based on the multiplicative decomposition of the deformation gradient into elastic and viscoelastic parts, together with the use of the isotropic property of the Helmholtz strain energy function. Making use of a logarithmic mapping, we present an appropriate form of the proposed constitutive equations in the...
Experimental and numerical study on the effect of aluminum foil wrapping on penetration resistance of ceramic tiles
, Article Scientia Iranica ; Volume 24, Issue 3 , 2017 , Pages 1126-1135 ; 10263098 (ISSN) ; Naghdabadi, R ; Arghavani, J ; Sharif University of Technology
2017
Abstract
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, respectively. For the wrapped tiles, these values are increased to 168 ± 2 and 162 m/s, respectively. Therefore, 13% increase in BLV of the ceramic tiles is obtained by just 2.4% increase in its weight. Moreover, it is shown that energy absorption of the wrapped tiles is at least 11% greater than that of the bare ones. Based on the results, the increase in...
A strain energy function for rubber-like materials
, Article Constitutive Models for Rubber VIII - Proceedings of the 8th European Conference on Constitutive Models for Rubbers, ECCMR 2013 ; 2013 , Pages 205-210 ; 9781138000728 (ISBN) ; Naghdabadi, R ; Arghavani, J ; Sharif University of Technology
2013
Abstract
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 property of deformation mode independency. This reduces the required number of experimental tests for parameter calibration. Results of the model are compared with results of Mooney-Rivlin, Arruda-Boyce, Gent and Gao models as well as the experimental data
A hyperelastic constitutive model for fiber-reinforced rubber-like materials
, Article International Journal of Engineering Science ; Volume 71 , 2013 , Pages 36-44 ; 00207225 (ISSN) ; Naghdabadi, R ; Arghavani, J ; Sharif University of Technology
2013
Abstract
In this paper, a Strain Energy Function (SEF) is proposed to characterize the hyperelastic behavior of transversely isotropic incompressible fiber-reinforced rubbers. The kinematics of the deformation is based on a strain measure consistent with the physics of the deformation. The SEF consists of an isotropic part and an anisotropic one where a simple form of SEF is used for both parts. In order to investigate the capabilities of the proposed model, two fiber-reinforced rubbers under homogeneous deformations are examined. The predictions of the model show a good agreement with the experimental data for both tensile and shear deformations. Also, torsion of a fiber-reinforced rubbery circular...
A large deformation framework for shape memory polymers: Constitutive modeling and finite element implementation
, Article Journal of Intelligent Material Systems and Structures ; Volume 24, Issue 1 , 2013 , Pages 21-32 ; 1045389X (ISSN) ; Naghdabadi, R ; Arghavani, J ; Sharif University of Technology
2013
Abstract
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 variables, a three-dimensional finite deformation phenomenological constitutive model is proposed taking its basis from the recent model in the small strain regime proposed by Baghani et al. (2012). In the constitutive model derivation, a multiplicative decomposition of the deformation gradient into elastic and inelastic stored parts (in each phase) is...
The effect of chitosan and PEG polymers on stabilization of GF-17 structure: A molecular dynamics study
, Article Carbohydrate Polymers ; Volume 237 , 2020 ; Moosavi, A ; Arghavani Hadi, J ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
We examine the interactions of chitosan and polyethylene glycol (PEG) with antimicrobial peptide GF-17 to identify a suitable carrier to improve the peptide drug delivery systems. To this end, the molecular dynamics simulations are used to determine the interactions of a typical antimicrobial peptide GF-17 with the chitosan and PEG polymers. The findings indicate the great potential of the peptide to maintain its secondary structure in the adjacent to chitosan polymers. During the interaction with chitosan polymers, the structure of the peptide has smaller fluctuations compared to the PEG polymers. Also, in the presence of both the polymers, the PEG polymers are situated closer to the...
An energy-based approach for analysis of dynamic plastic deformation of metals
, Article International Journal of Mechanical Sciences ; Volume 66 , January , 2013 , Pages 94-100 ; 00207403 (ISSN) ; Naghdabadi, R ; Arghavani, J ; Sharif University of Technology
2013
Abstract
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 derived energy equation accompanied by a governing kinematics relation and the strain rate equation is numerically integrated to obtain the final deformed profile of the specimen. The results of the energy based model are then compared with those of the commonly used momentum-based approach as well as the existing experimental data in literature for...
A constitutive model for shape memory polymers with application to torsion of prismatic bars
, Article Journal of Intelligent Material Systems and Structures ; Volume 23, Issue 2 , 2012 , Pages 107-116 ; 1045389X (ISSN) ; Naghdabadi, R ; Arghavani, J ; Sohrabpour, S ; Sharif University of Technology
2012
Abstract
In this article, satisfying the second law of thermodynamics, we present a 3D constitutive model for shape memory polymers. The model is based on an additive decomposition of the strain into four parts. Also, evolution laws for internal variables during both cooling and heating processes are proposed. Since temperature has considerable effect on the shape memory polymer behavior, for simulation of a shape memory polymer-based structure, it is required to perform a heat-transfer analysis. Commonly, an experimentally observed temperature rate-dependent behavior of shape memory polymers is justified by a rate-dependent glassy temperature, but using the heat-transfer analysis, it is shown that...
A thermodynamically-consistent 3 D constitutive model for shape memory polymers
, Article International Journal of Plasticity ; Volume 35 , 2012 , Pages 13-30 ; 07496419 (ISSN) ; Naghdabadi, R ; Arghavani, J ; Sohrabpour, S ; Sharif University of Technology
Elsevier
2012
Abstract
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 decomposition of the strain into six parts and satisfying the second law of thermodynamics in Clausius-Duhem inequality form. In the constitutive model, the evolution laws for internal variables are derived during both cooling and heating thermomechanical loadings. The viscous effects are also fully accounted for in the proposed model. Further, we...
Strain and stress concentrations in elastomers at finite deformations: effects of strain-induced crystallization, filler reinforcement, and deformation rate
, Article Acta Mechanica ; Volume 227, Issue 7 , 2016 , Pages 1969-1982 ; 00015970 (ISSN) ; Reese, S ; Arghavani, J ; Naghdabadi, R ; Sharif University of Technology
Springer-Verlag Wien
2016
Abstract
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 evidently. Material parameters are obtained from experimental tests conducted on standard tensile samples of filled and unfilled natural rubber (NR) as well as styrene–butadiene rubber (SBR) as crystallizing and non-crystallizing rubbers, respectively. In all simulations, the strain concentration factor KE is shown to decrease monotonically where the...
Dynamic analysis of a shape memory alloy beam with pseudoelastic behavior
, Article Journal of Intelligent Material Systems and Structures ; Volume 29, Issue 9 , 1 May , 2018 , Pages 1835-1849 ; 1045389X (ISSN) ; Fathi, A ; Dardel, M ; Arghavani Hadi, J ; Sharif University of Technology
SAGE Publications Ltd
2018
Abstract
This article aims at developing a semi-analytic approach for studying the free and forced vibrations of a pseudoelastically behaving shape memory alloy beam. Based on the Euler–Bernoulli beam theory, equations of motion were derived through Hamilton principle, and the obtained partial differential equations were decomposed by applying the Galerkin approach and were solved using Newmark integration method. A three-dimensional phenomenological model of shape memory alloy, which is capable of identifying the main properties of the shape memory alloy, was employed to model the behavior of the shape memory alloy beam. A closed-form numerical algorithm was introduced to simulate the governing...
Basis-free relations for conjugate strains of eshelby-like stress tensors
, Article Mechanics of Materials ; Volume 39, Issue 7 , 2007 , Pages 637-642 ; 01676636 (ISSN) ; Naghdabadi, R ; Arghavani, J ; Asghari, M ; Sharif University of Technology
2007
Abstract
In this paper, a general class of Eshelby-like or weighted stress tensors based on the right stretch tensor is defined as the product of a general type of Lagrangian stress tensor and a class of stretch measure. In addition, basis free relations for conjugate strains of Eshelby-like stress tensors are investigated, which are based on Hill's definition of energy conjugacy. The equations for strain tensors conjugate to Eshelby-like stress tensors are generally determined, but the case in which the conjugate strains are coaxial with the right stretch tensor is mostly investigated. © 2006 Elsevier Ltd. All rights reserved
Study of microstructural growth under cyclic martensite phase transition in shape memory alloys; A molecular dynamics approach
, Article Journal of Intelligent Material Systems and Structures ; Volume 33, Issue 4 , 2022 , Pages 604-616 ; 1045389X (ISSN) ; Taghibakhshi, A ; Nejat Pishkenari, H ; Arghavani, J ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
Shape memory alloys are referred to as a group of alloys that can retrieve the permanent deformation and strain applied to them and eventually return to their original form. So far, various studies have been done to determine the behavior of these alloys under cyclic loading. Most of the studies have mainly been conducted by using the foundations of Continuum Mechanics in order to examine the properties of memory alloys. In this study, instead of using the Continuum Mechanics, a Molecular Dynamics simulation method using Lennard-Jones potential is utilized. The changes in the behavior and properties of memory alloy under cyclic loading are being examined. First, the functional form...
Study of microstructural growth under cyclic martensite phase transition in shape memory alloys; A molecular dynamics approach
, Article Journal of Intelligent Material Systems and Structures ; 2021 ; 1045389X (ISSN) ; Taghibakhshi, A ; Nejat Pishkenari, H ; Arghavani, J ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
Shape memory alloys are referred to as a group of alloys that can retrieve the permanent deformation and strain applied to them and eventually return to their original form. So far, various studies have been done to determine the behavior of these alloys under cyclic loading. Most of the studies have mainly been conducted by using the foundations of Continuum Mechanics in order to examine the properties of memory alloys. In this study, instead of using the Continuum Mechanics, a Molecular Dynamics simulation method using Lennard-Jones potential is utilized. The changes in the behavior and properties of memory alloy under cyclic loading are being examined. First, the functional form...
Analysis of Premium Connections of Oil Well Equipment Under Very High Pressure Conditions
, M.Sc. Thesis Sharif University of Technology ; Arghavani Hadi, Jamal (Supervisor)
Abstract
Thread connections are widely used in tubular downhole equipment. Connections are usually weaker than tubulars and their failure will result in very high cost. Thread connections of downhole equipment are divided into two groups: standard connections and premium connections. Standard connections, despite being widely used, have limitations and will loose their efficiency in complex loadings. According to the mentioned limitations, premium connections have been proposed according to the existing need related to improving the strength of the structure, proper sealing and resistance to galling. One of the most obvious applications of premium connections is in downhole tubulars that are...
Analysis and Optimization of a Two-stage Light Gas Launcher for Shock Consolidation Process
, M.Sc. Thesis Sharif University of Technology ; Arghavani Hadi, Jamal (Supervisor)
Abstract
Powder metallurgy is one of the most important and most usable methods in industries. Nowadays, many of the specimens are made this way. In this method, after powder compaction stage, because of sintering in high temperature, crystallographical structure of the material changes. This change results in poorer strength than initial powde. In order to avoid change and decrease in powder strength, shock consolidation is used. In this research, because of complication of this phenomenon and final quality of the specimen, shock consolidation of metal powders is investigated and analysed. This phenomenon is modeled, simulated, analysed and optimized mathematically.Various methods are used to create...
A finite strain kinematic hardening constitutive model based on Hencky strain: General framework, solution algorithm and application to shape memory alloys
, Article International Journal of Plasticity ; Volume 27, Issue 6 , June , 2011 , Pages 940-961 ; 07496419 (ISSN) ; Auricchio, F ; Naghdabadi, R ; Sharif University of Technology
2011
Abstract
The logarithmic or Hencky strain measure is a favored measure of strain due to its remarkable properties in large deformation problems. Compared with other strain measures, e.g.; the commonly used Green-Lagrange measure, logarithmic strain is a more physical measure of strain. In this paper, we present a Hencky-based phenomenological finite strain kinematic hardening, non-associated constitutive model, developed within the framework of irreversible thermodynamics with internal variables. The derivation is based on the multiplicative decomposition of the deformation gradient into elastic and inelastic parts, and on the use of the isotropic property of the Helmholtz strain energy function. We...