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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Journal of Solid Mechanics
- نوع مقاله: Journal Article
- کلمات کلیدی: Graphene,Buckling,Vacancy Defect,Structural mechanics
- چکیده:
- چکیده انگلیسی: Graphene is a new class of two-dimensional carbon nanostructure, which holds great promise for the vast applications in many technological fields. It would be one of the prominent new materials for the next generation nano-electronic devices. In this paper the influence of various vacancy defects on the critical buckling load of a single-layered graphene nanosheet is investigated. The nanosheet is modeled on the base of structural mechanics approach which covalent bonds between atoms are modeled as equivalent beam elements in a finite element model. The mechanical properties of the nanosheet extracted from the model are in good agreement with those of other research works. Effect of the number of vacancies and their positions on the critical buckling load is investigated in the present work. Our results show that the location of the vacancy has a significant role in the amount of critical buckling load. Furthermore, as the density of the vacancies increases, the value of critical buckling load decreases and the relationship is approximately linear.
- انتشار مقاله: 21-03-1396
- نویسندگان: S.M.H Farrash,M Shariati,J Rezaeepazhand
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Solid Mechanics
- نوع مقاله: Journal Article
- کلمات کلیدی: Taguchi Method,finite element analysis,Semi-Elliptical Crack,Failure assessment diagram
- چکیده:
- چکیده انگلیسی: Safety and failure in gas pipelines are very important in gas and petroleum industry. For this reason, it is important to study the effect of different parameters in order to reach the maximum safety in design and application. In this paper, a three dimensional finite element analysis is carried out to study the effect of crack length, crack depth, crack position, internal pressure and pipe thickness on failure mode and safety of API X65 gas pipe. Four levels are considered for each parameter and finite element simulations are carried out by using design of experiments (DOE). Then, multi-objective Taguchi method is conducted in order to minimize x and y coordinates of Failure Assessment Diagram (FAD). So, desired levels that minimize the coordinates and rises the possibility of safety are derived for each parameter. The variation in FAD coordinates according to the changes in each parameter are also found. Finally, comparisons between the optimum design and all other experiments and simulations have shown a good safety situation. It is also concluded that the more design parameters close to optimum levels, the better safety condition will occur in FAD. A verification study is performed on the safety of longitudinal semi-elliptical crack and the results has shown a good agreement between numerical and experimental results.
- انتشار مقاله: 21-04-1395
- نویسندگان: P Zamani,A Jaamialahmadi,M Shariati
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Solid Mechanics
- نوع مقاله: Journal Article
- کلمات کلیدی: FEM,Buckling,Experimental analysis,cutout,Steel plates
- چکیده:
- چکیده انگلیسی: Steel plates are used in various structures, such as the structures of the deck and body of ships, bridges, and aerospace industry. In this study, we investigate the buckling and post-buckling behavior of rectangular steel plates having circular cutouts with two boundary conditions: first, clamped supports at upper and lower ends and free supports at other edges; second, clamped supports at upper and lower ends and simply supports at other edges, using finite element method (by ABAQUS software) and experimental tests(by an INSTRON servo hydraulic machine). In this research, in addition to the aspect ratio, the effect of changing the location of the cutout on the buckling analysis is investigated. The results of both numerical and experimental analyses are compared and showing a very good agreement between them.
- انتشار مقاله: 17-08-1394
- نویسندگان: M Shariati,Y Faradjian,H Mehrabi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Solid Mechanics
- نوع مقاله: Journal Article
- کلمات کلیدی: Postbuckling,Single-walled carbon nanobeam,Timoshenko and Reddy-Levinson beam theories
- چکیده:
- چکیده انگلیسی: The novelty of this study is presentation of an exact solution for prediction of postbuckling behavior of shear deformable micro- and nano-scale beams based on modified couple stress theory and using principle of minimum potential energy. Timoshenko and Reddy-Levinson beam theories are applied to consider the shear deformation effect and Von Karman nonlinear kinematics is used to describe the nonlinear behavior of the postbuckling, and the Poisson's effect is also considered in stress-strain relation. Also, the size effect is exposed by introducing a material length scale parameter. Finally, the influences of shear deformation, Poisson's ratio and variations of length and thickness are investigated. The results indicate that the classical theory exaggerates the postbuckling amplitude of the nanobeam and overstates the effect of shear deformation on the postbuckling response of the nanobeam.
- انتشار مقاله: 09-04-1394
- نویسندگان: M Akbarzadeh Khorshidi,M Shariati
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Solid Mechanics
- نوع مقاله: Journal Article
- کلمات کلیدی: FGM,exponential,thick-walled cylinder,Cylindrical pressure vessel,Longitudinal variations of elastic modulus
- چکیده:
- چکیده انگلیسی: In this paper, a numerical analysis of stresses and displacements in FGM thick-walled cylindrical pressure vessel under internal pressure has been presented. The elastic modulus is assumed to be varying along the longitude of the pressure vessel with an exponential function continuously. The Poisson’s ratio is assumed to be constant. Whereas most of the previous studies about FGM thick-walled pressure vessels are on the basis of changing material properties along the radial direction, in this research, elastic analysis of cylindrical pressure vessel with exponential variations of elastic modulus along the longitudinal direction, under internal pressure, have been investigated. For the analysis of the vessel, the stiffness matrix of the cylindrical pressure vessel has been extracted by the usage of Galerkin Method and the numerical solution for axisymmetric cylindrical pressure vessel under internal pressure have been presented. Following that, displacements and stress distributions depending on inhomogeneity constant of FGM vessel along the longitudinal direction of elastic modulus, are illustrated and compared with those of the homogeneous case. The values which have been used in this study are arbitrary chosen to demonstrate the effect of inhomogeneity on displacements and stress distributions. Finally, the results are compared with the findings of finite element method (FEM).
- انتشار مقاله: 26-11-1393
- نویسندگان: M Shariati,H Sadeghi,M Ghannad,H Gharooni
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Solid Mechanics
- نوع مقاله: Journal Article
- کلمات کلیدی: CK45 steel,Low cycle fatigue,Cyclic behavior,Damage parameter,SS316 stainless steel
- چکیده:
- چکیده انگلیسی: In this paper, low cycle fatigue life of CK45 steel and SS316 stainless steel under strain-controlled loading are experimentally investigated. In addition, the impact of mean strain and strain amplitude on the fatigue life and cyclic behavior of the materials are studied. Furthermore, it is attempted to predict fatigue life using energy and SWT damage parameters. The experimental results demonstrate that increase in strain amplitude decreases fatigue life for both materials, strain amplitude has a remarkable effect on fatigue life, and the impact of mean strain is approximately negligible. Furthermore, the energy damage parameter provides more accurate prediction of fatigue life for both materials.
- انتشار مقاله: 20-01-1393
- نویسندگان: M Shariati,H Mehrabi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Solid Mechanics
- نوع مقاله: Journal Article
- کلمات کلیدی: cylindrical shell,cutout,Numerical and experimental study,Cyclic combined and axial loading
- چکیده:
- چکیده انگلیسی: Ratcheting behavior of steel 304L cylindrical shell under cyclic combined and axial loading are investigated in this paper, numerically. Cylindrical shells were fixed oblique at angle of 20° and normal with respect to the longitudinal direction of the shell and subjected to force-controlled cycling with non-zero mean force, which causes the accumulation of plastic deformation or ratcheting behavior. Numerical analysis was carried out by ABAQUS software using nonlinear isotropic/kinematic hardening model. Numerical results compared to experimental data that was performed by an INSTRON 8802 servo hydraulic machine. Simulations show good agreement between numerical and experimental results. Also, the effect of length, angle of cylindrical shell and existence of cutout are studied with finite element method. Seen, the bending moment plays a strong role in increase of plastic deformation. It is observed that there is more plastic deformation for cylindrical shell under combined loading in comparison to cylindrical shell under uniaxial loading. Ratcheting behavior is sensitive to cutout and showed that creating the cutout increases the plastic deformation.
- انتشار مقاله: 10-02-1392
- نویسندگان: M Shariati,K Kolasangiani,H.R Epakchi,H Chavoshan
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Ultrafine Grained and Nanostructured Materials
- نوع مقاله: Journal Article
- کلمات کلیدی: Oxidation,nanorod,Photoluminescence,ZnO Nanowires,Resistive Evaporation
- چکیده:
- چکیده انگلیسی: ZnO nanowires with a diameter of 70 nm and nanorods with a diameter in the range of 100-150 nm and two micrometer in length were grown on glass substrates by resistive evaporation method and applying a two step oxidation process at low temperatures, without using any catalyst, template or buffer layer. XRD pattern of these nanostructures indicated a good crystallinity property with wurtzite hexagonal structure. Photoluminescence measurement revealed three band emissions; one sharp strong peak in the UV region and two weaker peaks in the visible region, indicate good optical properties of nanorods synthesized by this method. Heat treatment in oxygen-rich atmosphere results to decrease of deep-level emission intensity in the PL spectra. The relatively high intensity of UV emission implies that this approach is a simple and promising method for fabricating ZnO nanorods in order to be used in optoelectronic devices especially in the UV range of the spectrum.
- انتشار مقاله: 18-02-1391
- نویسندگان: Vahid Ghafouri,Mohsen Shariati,Akbar Ebrahimzad
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Pharmaceutical and Health Sciences (JPHS)
- نوع مقاله: Journal Article
- کلمات کلیدی: acute toxicity,Huso huso,Cyprinus carpio,Nano zinc oxide,blood factors
- چکیده:
- چکیده انگلیسی: In this research, acute toxicity (LC) of zinc oxide nanoparticle on Beluga (Huso huso) and
common carp (Cyprinus carpio) was studied. The experiment was conducted using the
Organization for Economic Co-operation and Development (No. 202) method. For both
species, 96hLC10 was determined to be more than 200 mg/l. To assess the effects of zinc oxide
nanoparticles on blood factors, leukocyte index count (Lymphocyte, Monocytes, Neutrophils,
Eosinophil, and Basophils) was performed, and the results were analyzed using IBM SPSS
software version. According to the results and based on the ANOVA test, there is no significant
difference among mean values of leukocyte index responses (p>0.05), and one should note
that the amount of lymphocyte had decreased while that of neutrophils and monocytes had
increased. Furthermore, with regard to concentration levels, this decrease or increase has not
followed a systematic trend. In Beluga based on ANOVA test, there is a significant difference
between mean values of lymphocytes and neutrophils (p<0.05). Again, compared to control,
lymphocyte count increased while that of neutrophils and eosinophil decreased, and this too, did
not follow a systematic trend. Finally, concentration to 200 mg/l ZnO did not cause mortality in
Huso huso and Cyprinus carpio. Eventually, decline of body resistance against nano zinc oxide
was observed in these species through blood cells study.- انتشار مقاله: 24-08-1394
- نویسندگان: Shahedeh Mohammadnezhad,Fatemeh Shariati,Abdolkarim Keshavarz,Habib Vahabzadeh
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Nutrition,Fasting and Health
- نوع مقاله: Journal Article
- کلمات کلیدی: Bone,Training,Vitamin D,H2O2
- چکیده:
- چکیده انگلیسی: Introduction:studies have shown that the increase of active oxygen species is associated with damage to bone cells and the role of exercise and vitamin D on bone health has been proven;the aim of this study was to investigate the interactive effects of aerobic exercise with vitamin D supplements on bone resorption markers in rats exposed to oxidative damage induced by H2O2.
Methods: Sixty male adult male Wistar rats were randomly divided into 10 groups of six rats including:1)1 mmol/kg H2O2, 2)2 mmol/kg H2O2, 3)1mmol/kg H2O2+vitamin D,4) 1mmol/kg H2O2+aerobic training,5)1mmol/kg H2O2+Vitamin D+aerobic training,6)2 mmol/kg H2O2+Vitamin D,7)2mmol/kg H2O2+aerobic training,8)2mmol/kg H2O2+Vitamin D+aerobic training;9)Sham (D-methyl- Sulfoxide+normal saline); and(10)control and for 8 weeks were under the protocol of intervention.The levels of TRACP/5B and NTX were measured by ELISA method. Two-way and one-way ANOVA with Tukey’s post hoc test was used to analysis of data (p≤0.05).
Results: 1and 2 mmol/kg H2O2 had no significant effect on NTX and TRACP/5B levels(p≥0/05). Eight weeks of aerobic training increased of NTX levels in rats exposed to 2mmol/kg H2O2 (p≤0/05).Eight weeks of Vitamine D had no significant effect on NTX and TRACP/5B levels (p≥0/05).Also eight weeks of aerobic training along with Vitamin D had no interactive effects on increase of NTX and TRACP/5B levels in rats exposed to 1and 2mmol/kg H2O2(p≥0/05).
Conclusion: It seems that doses of 1 and 2mg/kg H2O2 have not significant effect on changes in bone resorption markers,but aerobic exercise had a significant effect on NTX increase in rats exposed to oxidative damage induced by 2mg/kg H2O2.- انتشار مقاله: 21-03-1398
- نویسندگان: Marina Shariati,Mohammad Ali Azarbayjani,Gholam Reza Kaka,Shirin Zilaei Bouri
- مشاهده