Semnan University
Mechanics of Advanced Composite Structures
2423-4826
2423-7043
5
1
2018
04
01
Cured Poly(ethylene-g-maleic anhydride)/Graphene Nanocomposite: Properties and Characterization
1
12
EN
Behrouz
Jafari
Iran polymer and petrochemical institute,polymerization engineering department
behrouz.jafari69@yahoo.com
Shokoufeh
Hakim
0000-0003-0565-599X
Iran Polymer and petrochemical institute, Polymerization engineering department, p.o. Box:14975-115
s.hakim@ippi.ac.ir
Mohammad
Nouri
Iran polymr and petrochemical institute, Processing faculty, Tehran, Iran
m.razavi@ippi.ac.ir
10.22075/macs.2018.12250.1120
Poly(ethylene-g-maleic anhydride) (PEMA)/graphene nanoplatelets (xGn) (PEMA-xGn) composites were prepared by melt dispersion in an internal shear mixer. By adding dicumyl peroxide (DCP), cured poly(ethylene-g-maleic anhydride) C-PEMA was also produced. Different amounts of xGn were introduced into the PEMA in range of 0.5–5 wt. %. The effects of the sequence of feeding additives into the mixer on gel content, morphology, and mechanical properties allowed thermal, dynamic mechanical, and rheological behaviors to be studied. Results demonstrated that the incorporation of graphene into the polymer matrix decreased gel content and the rate of crosslinking. Scanning electron microscopy micrographs of the PEMA and C-PEMA nanocomposites showed that below 1 wt. % graphene, its dispersion in the matrix was desirable with no agglomerates.. Crystallization temperature increased due to heterogeneous nucleation by xGn. By curing the nanocomposites with DCP, crystallization temperatures decrease due to crosslinking and decreased crystallinity. The results of crosslinked nanocomposites revealed that, with the exception of C-PEMA containing 0.5 wt. % of xGn, mechanical properties decreased as xGn concentrations increased. Dynamic mechanical analysis showed that the increase of xGn in the PEMA matrix of up to 1 wt. % led to increased storage and loss modulus values. It was also revealed that α-transitions of the PEMA and α- and γ-transitions of C-PEMA were affected by polymer chain branching and graphene nanoplatelets. This could be attributed to interactions and potential bond formations between xGn and the maleic anhydride of PEMA. Rheological properties of the PEMA nanocomposites showed a quick change in the xGn fraction at about 1 wt. %.
Poly(ethylene-g-maleic anhydride),Graphene,Curing,DCP Curing,Nanocomposites
http://macs.journals.semnan.ac.ir/article_2951.html
http://macs.journals.semnan.ac.ir/article_2951_f815837d435095534cc1540a72959867.pdf
Semnan University
Mechanics of Advanced Composite Structures
2423-4826
2423-7043
5
1
2018
04
01
Bending, buckling and free vibration responses of hyperbolic shear deformable FGM beams
13
24
EN
Atteshamuddin
S.
Sayyad
Department of Civil Engineering, SRES&#039;s College of Engineering, Savitribai Phule Pune University, Kopargaon,-423601
attu_sayyad@yahoo.co.in
Yuwaraj
M.
Ghugal
Department of Applied Mechanics, Government College of Engineering, Karad-415124, Maharashtra, India
ghugal@rediffmail.com
10.22075/macs.2018.12214.1117
This study investigated bending, buckling, and free vibration responses of hyperbolic shear deformable functionally graded (FG) higher order beams. The material properties of FG beams are varied through thickness according to power law distribution; here, the FG beam was made of aluminium/alumina, and the hyperbolic shear deformation theory was used to evaluate the effect of shear deformation in the beam. The theory explains the hyperbolic cosine distribution of transverse shear stress through the thickness of a beam and satisfies zero traction boundary conditions on the top and bottom surfaces without requiring a shear correction factor. Hamilton’s principle was employed to derive the equations of motion, and analytical solutions for simply supported boundary conditions were obtained using Navier’s solution technique. The non-dimensional displacements, stress, natural frequencies, and critical buckling loads of FG beams were obtained for various values of the power law exponent. The numerical results were compared to previously published results and found to be in excellent agreement with these.
Hyperbolic shear deformation theory,FGM beam,Bending,Buckling,vibration
http://macs.journals.semnan.ac.ir/article_2988.html
http://macs.journals.semnan.ac.ir/article_2988_bd60671cbee7081b8db3c8a0b5c6b4c2.pdf
Semnan University
Mechanics of Advanced Composite Structures
2423-4826
2423-7043
5
1
2018
04
01
Sensitivity Analysis of Fiber-Reinforced Lamina Micro-Electro-Mechanical Switches with Nonlinear Vibration Using a Higher Order Hamiltonian Approach
25
39
EN
Ali
Kabiri
Iran University of Science and Technology
alikabiri1994@gmail.com
Sadegh
Sadeghzadeh
School of new Technology, Iran University of Science and Technology
sadeghzadeh@iust.ac.ir
10.22075/macs.2018.1635.1078
In this paper, the nonlinear free vibration of fiber-reinforced lamina micro-switches is investigated, and a sensitivity analysis (SA) is given. The switches are modeled as solid rectangular beams consisting of an isotropic matrix with transversely and longitudinally isotropic reinforcements, incorporating a higher order Hamiltonian approach. An SA of the proposed micro-switch is presented by calculating the numerical derivatives of the presented nonlinear model with respect to the design parameters. The SA of geometric parameters, such as dimensionless length, thickness, initial gap, applied voltage, axial load, and effective modules of the system, was conducted using the Sobol method. It was found that the natural frequency varied when changes were made to the proposed parameters; this finding can be used to optimize future designs.
Nonlinear Vibration,MEMS Switches,Higher Order Hamiltonian,Sensitivity Analysis
http://macs.journals.semnan.ac.ir/article_2953.html
http://macs.journals.semnan.ac.ir/article_2953_fc3f430b909e7ba84fe9c447964216f9.pdf
Semnan University
Mechanics of Advanced Composite Structures
2423-4826
2423-7043
5
1
2018
04
01
Experimental Study on Amine-Functionalized Carbon Nanotubes’ Effect on the Thermomechanical Properties of CNT/Epoxy Nano-composites
41
48
EN
Seyyed Mahdi
Hosseini Farrash
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, 9177948974, Iran
smhofarrash@gmail.com
Jalil
Rezaeepazhand
Department of Mechanical Engineering, Ferdowsi University of Mashhad
jrezaeep@um.ac.ir
Mahmoud
Shariati
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, 9177948974, Iran
mshariati44@um.ac.ir
10.22075/macs.2017.10985.1106
This paper investigated the effect of the amine-functionalized carbon nanotubes (CNTs) on the thermomechanical properties of CNT/epoxy nanocomposites. Mechanical stirring and ultra-sonication were utilized to uniformly disperse CNTs into the epoxy matrix. Non-functionalized and amine-functionalized CNTs with different weight percentages (wt. %) were mixed into the epoxy resin. Using standard tensile and dilatometry test specimens, this paper determined Young’s modulus, ultimate strength, strain at break, coefficients of thermal expansion, glass transition temperature (<em>T<sub>g</sub></em>), and thermal strain at <em>T<sub>g</sub></em> of the specimens. Neat epoxy, non-functionalized CNT/epoxy (0.25 and 0.5 wt. % CNTs), and functionalized CNT/epoxy (0.25 and 0.5 wt. % functionalized CNTs) nanocomposites were studied. The results indicated that adding 0.25 wt. % functionalized CNTs into the epoxy resin had the greatest effect on Young’s modulus and the nanocomposites’ coefficient of thermal expansion. Moreover, adding CNTs into the epoxy resin decreased the ultimate strength, strain at break, and coefficient of thermal expansion of the specimens.
Functionalization,Carbon Nanotubes,Nanocomposites,Thermomechanical Properties
http://macs.journals.semnan.ac.ir/article_2625.html
http://macs.journals.semnan.ac.ir/article_2625_1c420ea7236910afad2350a823c749b8.pdf
Semnan University
Mechanics of Advanced Composite Structures
2423-4826
2423-7043
5
1
2018
04
01
Three-dimensional elasticity solution for vibrational analysis of thick continuously graded sandwich plates with different boundary conditions using a two-parameter micromechanical model for agglomeration
49
66
EN
Vahid
Tahouneh
Department of Mechanical Engineering, Islamshahr Branch, Islamic Azad University, Tehran, Iran.
vahid.tahouneh@ut.ac.ir
10.22075/macs.2018.11539.1111
An equivalent continuum model based on the Eshelby-Mori-Tanaka approach was employed to estimate the effective constitutive law for an elastic isotropic medium (i.e., the matrix) with oriented straight carbon nanotubes (CNTs). The two-dimensional generalized differential quadrature method was an efficient and accurate numerical tool for discretizing equations of motion and for implementing various boundary conditions. The proposed rectangular plates have two opposite edges simply supported, and all possible combinations of free, simply supported, and clamped boundary conditions were applied to the other two edges. The CNTs volume fraction varied based on the thickness of the functionally graded carbon nanotube-reinforced plate and the generalized power-law distribution of four parameters. The effects of geometrical and material parameters and boundary conditions on the frequency parameters of the laminated functionally graded nanocomposite plates were investigated, and the results revealed that the natural frequencies of the structure were significantly affected by the influence of CNT agglomeration.
Mori-Tanaka approach,Two-parameter micromechanical model of agglomeration,Sandwich structures,2D generalized differential quadrature method,Vibration analysis
http://macs.journals.semnan.ac.ir/article_2955.html
http://macs.journals.semnan.ac.ir/article_2955_11697d928c36d26f68d178c1a0e0b992.pdf
Semnan University
Mechanics of Advanced Composite Structures
2423-4826
2423-7043
5
1
2018
04
01
Theoretical, numerical, and experimental analyses of free vibrations of glass fiber reinforced polymer plates with central cutouts and free boundaries
67
74
EN
Sina
Soleimanian
Department of Materials and Manufacturing Processes, Malek Ashtar University of Technology, Lavizan, Tehran, Iran
sina.soleimanian@gmx.com
Ali
Davar
Malek Ashtar University of Technology
davar78@gmail.com
Reza
Azarafza
Department of Materials and Manufacturing Processes, Malek Ashtar University of Technology, Lavizan, Tehran, Iran
azarkntu@yahoo.com
Jafar
Eskandari Jam
Department of Materials and Manufacturing Processes, Malek Ashtar University of Technology, Lavizan, Tehran, Iran
jejaam@gmail.com
Mohammad Reza
Zamani
Department of Mechanical Engineering, MalekAshtar University of Technology, Tehran, Iran
a_mrzamani@mut.ac.ir
10.22075/macs.2018.12167.1116
This study explored the free vibration problem in relation to glass fiber reinforced polymer (GFRP) plates with central cutouts and free boundaries using theoretical, experimental, and numerical methods. The theoretical formulations were derived from the classical lamination plate theory. The rectangular cutout was mathematically modeled into the stiffness matrix of the plate by multiplying Heaviside distribution functions. The theoretical values for the fundamental frequency were obtained by solving the standard eigenvalue problem, and the theoretical solution was validated by comparison to the literature. Modal testing was performed in the laboratory. For additional validation, the accuracy of theoretical and experimental results was checked using the finite element method and ABAQUS. The results of all three methods agreed; thus, the applicability of the Heaviside functions to stiffness modeling of structures with cutouts was proven. It was also observed that the fundamental frequency decreased when cutout size increased.
Free Vibration,GFRP Plates,Cutout,Free Boundaries
http://macs.journals.semnan.ac.ir/article_2956.html
http://macs.journals.semnan.ac.ir/article_2956_99fb2e3bd593da8932575f351c9d2815.pdf
Semnan University
Mechanics of Advanced Composite Structures
2423-4826
2423-7043
5
1
2018
04
01
Evaluation of hardness and wear resistance of nano-sized titanium-carbide-reinforced commercially cast aluminum alloy matrices
75
81
EN
Mohammad
Mafi
Semnaun University
msina222@gmail.com
Behrooz
Ghasemi
SEMNAN
bghasemi@semnan.ac.ir
Omid
Mirzaee
Semnan University
omidmirzaee@yahoo.com
10.22075/macs.2018.1770.1091
Production of aluminum matrix composites is widespread because these material provide enhanced mechanical properties compared to aluminum. One the most important parameters of metal matrix composite production is uniform distribution of reinforcing nanoparticles in matrices using the stir-casting method. Second is ensuring high wettability, which is determined by evaluating the properties of materials on a nano-scale. In this study, aluminum composites were reinforced with titanium carbide nanoparticles coated with aluminum to increase wettability. Particles were prepared and added to a molten aluminum alloy. After stirring the particle mixture as a variable parameter, casting was conducted in a sand mold. To evaluate the mechanical properties of the composite, the Brinell test was used to determine hardness and the pin-on-disk test was used to measure wear rate and the friction coefficient. The results showed that the hardness of the composite increased from 84 BHN to 134 BHN as nanoparticles were added to the alloy. Additionally, as stirring time increased, weight loss decreased with respect to the base alloy, while the coefficient of friction increased.
Metal–matrix Composites,Mechanical Testing,Casting
http://macs.journals.semnan.ac.ir/article_2954.html
http://macs.journals.semnan.ac.ir/article_2954_031d4ce1697226b1bd0f9aadd37894bd.pdf
Semnan University
Mechanics of Advanced Composite Structures
2423-4826
2423-7043
5
1
2018
04
01
Capillary Effects on Surface Enhancement in a Non-Homogeneous Fibrous Porous Medium
83
90
EN
Mohammad Reza
Shahnazari
K. N. Toosi University
shahnazari@kntu.ac.ir
Milad
Esfandiar
K. N. Toosi University
miladsfandyar2000@gmail.com
10.22075/macs.2017.1558.1074
The evaluation of a free fluid surface in a porous medium has several mathematical applications that are important in industries using molds, particularly in the fluid injection process. The vacuum-assisted resin transfer molding (VARTM) process is a promising technology in the primary composite industry. An accurate computational simulation of the VARTM process would be a cost-effective tool in the manufacturing of composites. In this paper, capillary effects were incorporated into an existing resin transfer molding model to simulate VARTM processing. To increase the accuracy of the VARTM process simulation, the effect of capillary pressure on a surface without flow was studied using the boundary element method. The simulation results were close to the experimental data reported by other researchers. It can be concluded that better reliability and accuracy could be achieved from theoretical predictions by examining the effects of capillary pressure on flow injection into porous materials.
Vacuum-assisted resin transfer molding,Free surface,Capillary pressure,porous media,Finite element
http://macs.journals.semnan.ac.ir/article_2740.html
http://macs.journals.semnan.ac.ir/article_2740_8835c626c473a9e1eeed616aec820975.pdf
Semnan University
Mechanics of Advanced Composite Structures
2423-4826
2423-7043
5
1
2018
04
01
Geometric Effects on Nanopore Creation in Graphene and on the Impact-withstanding Efficiency of Graphene Nanosheets
91
102
EN
Sadegh
Sadeghzadeh
School of new Technology, Iran University of Science and Technology
sadeghzadeh@iust.ac.ir
10.22075/macs.2018.1546.1073
Abstract<br /> Single- and multilayer graphene sheets (MLGSs) are projectile-resisting materials that can be bombarded by nanoparticles to produce graphene sheets of various sizes and distributions of nanopores. These sheets are used in a variety of applications, including DNA sequencing, water desalination, and phase separation. Here, the impact-withstanding efficiency of graphene nanosheets and the primary factors affecting creation of nanopores in these sheets were studied using a molecular dynamics method. The velocity of impacting nanoparticles and resulting displacement in graphene nanosheets are not sufficient criteria for evaluating the impact resistance of sheets with more than six layers. Instead, visual inspection of the bottom side of a graphene sheet should be used. Self-healing is the most important aspect of MLGSs because it closes the paths of penetrating nanoparticles in the upper layers of the sheets. For nanosheets with few layers, self-healing is observed only at very small nanoparticle velocities; however, when the number of layers is more than six, self-healing occurs even at high nanoparticle velocities. In nanoribbon simulations, it was found that layer boundaries improve resistance against projectile impacts that create well-defined oval shapes. By increasing the distance between layers, the carbon atoms of each layer experience more collisions with the carbon atoms of other layers. Thus, increasing the interlayer distance causes the number of unwanted collisions between carbon atoms to increase and the graphene nanosheets to disintegrate. Additionally, as the circularity of nanopores increases, they become more circular and homogeneous, in turn increasing interlayer spacing, the impact-withstanding efficiency of the sheets, and the circular shape of created nanopores.
Single-layer Graphene Sheets,Impact-withstanding Efficiency,Nanopore,Withstanding Properties,Molecular Dynamics
http://macs.journals.semnan.ac.ir/article_2952.html
http://macs.journals.semnan.ac.ir/article_2952_dbdb038810499c861cf432fead93f41c.pdf