Journal of Applied and Computational MechanicsJournal of Applied and Computational Mechanics
http://jacm.scu.ac.ir/
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http://jacm.scu.ac.ir/
Feed provided by Journal of Applied and Computational Mechanics. Click to visit.Shape and geometrical parameters effects of a bimorph piezoelectric beam on energy harvesting ...
http://jacm.scu.ac.ir/article_12781_1522.html
In this paper, the shape influence of piezoelectric beams including triangle, trapezoid, rectangle, inverted trapezoid, convex parabola, concave parabola, and comb-shaped that is a combination of two triangular beams with a connector of 4 mm length has been considered and analyzed by FEM. The analysis is performed for a bimorph piezoelectric beam. The analyzed parameters are the beam length, thickness and width of the piezoelectric layer. The study is performed by using COMSOL Multiphysics software for all seven shapes. The results show that due to the mechanical properties of the beams, the natural frequency of the triangular beam is more for all considered parameters. Also, as the width of the beam end increases the natural frequency is reduced. Since the natural frequency is inversely related to electric power, the inverted trapezoidal beam has the highest electric power and the triangular beam has the lowest one.Wed, 31 May 2017 19:30:00 +0100Perturbation Solutions for the Study of MHD Blood as a Third Grade Nanofluid Transporting Gold ...
http://jacm.scu.ac.ir/article_12889_1522.html
In this paper, the flow, thermal and concentration analyses of blood as a third grade with gold as nanoparticles through a porous channel are carried out using regular perturbation method. The analysis are carried out using Vogel’s model of temperature-dependent viscosity. The developed models were used to investigate the effects of the nano particles on the concentration, temperature and velocity of the fluid as it flows through the porous medium of a hollow channel in the presence of magnetic field. Also, the effects of fluid parameters such as Brownian motion, thermophoresis, viscous dissipation, non-Newtonian, porosity, magnetohydrodynamics (MHD), diffusion constant at various values on the fluid were established. The results generated in this work were found to be in good agreement with the results found in litereture.Wed, 31 May 2017 19:30:00 +0100Analytical Investigations of the Effects of Tool Pin Profile and Process Parameters on the Peak ...
http://jacm.scu.ac.ir/article_12652_1522.html
In this work, effects of different tool pin profiles of flat and tapered shoulder geometries on the peak temperature in friction stir welding are investigated analytically. The developed models used for the analytical investigations considered the welding process as a combination or mixture of the pure sliding and the pure sticking. From the results, the amount of heat generation and the peak temperature are directly proportional to the number of edges in the pin profiles in such a way that the heat generated and peak temperature in the profiles increases from the triangular pin profile to hexagonal pin profile. Also, the rate of heat generation and the peak temperature in flat shoulder are greater than in tapered/conical shoulder. The results in this work are validated with experimental and the past theoretical results and good agreements are achieved.Wed, 31 May 2017 19:30:00 +0100Electromechanical Performance of NEMS Actuator Fabricated from Nanowire under quantum vacuum ...
http://jacm.scu.ac.ir/article_12713_1522.html
The Casimir attraction can significantly interfere the physical response of nanoactuators. The intensity of the Casimir force depends on the geometries of interacting bodies. The present paper is dedicated to model the influence of the Casimir attraction on the electrostatic stability of nanoactuators made of cylindrical conductive nanowire/nanotube. An asymptotic solution, based on path-integral approach, is employed to consider the Casimir force. The continuum theory is employed to derive the constitutive equation of the actuator. The governing nonlinear equations are solved by three different approaches. Various perspectives of the issue including comparison with the van der Waals (vdW) force regime, the variation of instability parameters and effect of geometry are addressed.Wed, 31 May 2017 19:30:00 +0100Size Effect Impact on the Mechanical Behavior of an Electrically Actuated Polysilicon Nanobeam ...
http://jacm.scu.ac.ir/article_12741_1522.html
In this paper, the dynamic response of resonating nano-beams is investigated using a strain gradient elasticity theory. A nonlinear model is obtained based on the Galerkin decomposition method to find the dynamic response of the investigated beam around its statically deflected position. The mid-plane stretching, axial residual stress and nonlinear interaction due to the electrostatic force on the deflected beam are included in the proposed nonlinear beam model. Comparing the beam natural frequency using strain gradient theory with experimental data shows an excellent agreement among both approaches. The normalized natural frequency is shown to be increasing nonlinearly with the decrease of the applied DC voltage as well as beam thickness. The results also reveal that increasing the tension axial stress increases the natural frequency; however its influence decreases when decreasing the beam thickness. To investigate the effect of AC actuation voltage on the beam resonant frequency, a Lindstedt-Poincare based perturbation method is utilized and validated by comparison with experimental data. The results show that increasing the AC actuation voltage makes the beam stiffer by increasing its resonant frequency.Wed, 31 May 2017 19:30:00 +0100Performance Analysis of Segmentation of Hyperspectral Images Based on Color Image Segmentation
http://jacm.scu.ac.ir/article_12639_1522.html
Image segmentation is a fundamental approach in the field of image processing and based on user’s application .This paper propose an original and simple segmentation strategy based on the EM approach that resolves many informatics problems about hyperspectral images which are observed by airborne sensors. In a first step, to simplify the input color textured image into a color image without texture. The final segmentation is simply achieved by a spatially color segmentation using feature vector with the set of color values contained around the pixel to be classified with some mathematical equations. The spatial constraint allows taking into account the inherent spatial relationships of any image and its color. This approach provides effective PSNR for the segmented image. These results have the better performance as the segmented images are compared with Watershed & Region Growing Algorithm and provide effective segmentation for the Spectral Images & Medical Images.Wed, 31 May 2017 19:30:00 +0100Thermodynamic Study of water activity of Single Strong Electrolytes
http://jacm.scu.ac.ir/article_12425_1522.html
Today, due to the natural decline of oil exploitation, the use of methods of oil recovery, has made significant progress. However, this method usually is accompanied by accumulation and deposition of mineral deposits in oil field installations. In the present study , aqueous solutions, strontium sulfate , barium sulfate, manganese sulfate and nickel sulfate is studied, according to EUNIQUAC model and genetic algorithms. Based on the results this article, as the temperature increases, in order to increase the solubility of the system, the ionic strength is decreased; But with increasing pressure, with associated increases. Also in this article, to evaluate water activity, aqueous solution of manganese sulfate and nickel sulfate has been studied.Wed, 31 May 2017 19:30:00 +0100Multi-boiling Heat Transfer Analysis of Convective Fin with Temperature-Dependent Thermal ...
http://jacm.scu.ac.ir/article_12637_0.html
In this study, heat transfer in a longitudinal rectangular fin with temperature-dependent thermal properties and internal heat generation under multi-boiling heat transfer where the local heat transfer coefficient is considered to vary with a power-law function of temperature has been analyzed using finite volume method. The coexistence of all the boiling modes is considered in this study. The developed heat transfer models and the corresponding numerical solutions were used to investigate the effects of various thermo-geometric parameters on the thermal performance of the longitudinal rectangular fin. From the results, it shows that the fin temperature distribution, the total heat transfer, and the fin efficiency are significantly affected by the thermo-geometric parameters of the fin. The results obtained in this analysis serve as basis for comparison of any other method of analysis of the problem and they also provide platform for improvement in the design of fin in heat transfer equipment.Wed, 15 Feb 2017 20:30:00 +0100Modified U-Slot Stacked Microstrip Patch Antenna for Ultra Wideband Applications in S Band, C ...
http://jacm.scu.ac.ir/article_12638_0.html
U-slot microstrip patch antennas were originally developed for bandwidth broadening applications. This paper presents a transmission line fed modify U-slot stacked rectangular microstrip patchantenna for Ultra Wide Band (UWB) communications, modified antenna have U cut loaded with parallel slit and corner slots and is printed on a dielectric substrate of FR4 with relative permittivity (εr)of 4.4, thickness of 1.59 mm & tangent loss of 0.025. The results show that the proposed antenna achieves an impedance bandwidth of 11.5 GHz (2.1 – 13.65 GHz) with Return Loss < (-10)dB. This antenna can be employed for ultra wideband applications in S Band, C Band & X Band. The proposed patch antenna is designed and simulated using IE3D 14.0 software. Simulation results are presented interms of Resonant Frequency, Return Loss, VSWR, Impedance Bandwidth and Impedance Matching.Wed, 31 May 2017 19:30:00 +0100Haar Wavelet Collocation Method for Thermal Analysis of Porous Fin with Temperature-dependent ...
http://jacm.scu.ac.ir/article_12702_0.html
In this study, the thermal performance analysis of porous fin with temperature-dependent thermal conductivity and internal heat generation is carried out using Haar wavelet collocation method. The effects of various parameters on the thermal characteristics of the porous fin are investigated. It is found that as the porosity increases, the rate of heat transfer from the fin increases and the thermal performance of the porous fin increases. The numerical solutions by the Haar wavelet collocation method are in good agreement with the standard numerical solutions.Tue, 14 Mar 2017 20:30:00 +0100Thermal-Hydraulics analysis of pressurized water reactor core by using single heated channel model
http://jacm.scu.ac.ir/article_12706_0.html
Thermal hydraulics of nuclear reactor as a basis of reactor safety has a very important role in reactor design and control. The thermal-hydraulic analysis provides input data to the reactor-physics analysis, whereas the latter gives information about the distribution of heat sources, which is needed to perform the thermal-hydraulic analysis. In this study single heated channel model as a very fast model for predicting thermal hydraulics behavior of pressurized water reactor core has been developed. For verifying the results of this model we used RELAP5 code as US nuclear regulatory approved thermal hydraulics code. The results of developed single heated channel model have been checked with RELAP5 results for WWER-1000. This comparison shows the capability of single heated channel model for predicting thermal hydraulics behavior of reactor core.Fri, 17 Mar 2017 20:30:00 +0100Using the Matrix Method to Compute the Degrees of Freedom of Mechanisms
http://jacm.scu.ac.ir/article_12712_0.html
In this paper, some definitions and traditional formulas for calculating the mobility of mechanisms are represented, e.g. Grubler formula, Somov - Malyshev formula, and Buchsbaum - Freudenstei. It is discussed that there are certain cases in which they are too ambiguous and incorrect to use. However, a matrix method is suggested based on the rank of the Jacobian of the mechanism instead and its application is investigated. It is shown that the matrix method will definitely lead to a correct answer, however, it is lengthy and consums more computational effort. It is shown that in the cases the traditional formulas give a wrong answer, the matrix method gives the correct mobility. To compare the methods, several examples are given including the four bar planar linkage, the augmented four bar linkage, University of Maryland manipulator, Cartesian parallel manipulator (CPM), delta robot, orthoglide robot, and H4 parallel robot.Sun, 19 Mar 2017 20:30:00 +0100Effect of variable thermal expansion coefficient and nanofluid properties on steady natural ...
http://jacm.scu.ac.ir/article_12714_0.html
Steady state natural convection are numerically investigated in an enclosure using variable thermal conductivity, viscosity and thermal expansion coefficient of Al2O3–water nanofluid. Study has been conducted for a wide range of Rayleigh numbers (103≤ Ra ≤ 106), concentrations of nanoparticles (0% ≤ Φ ≤ 7%), enclosure aspect ratios (0.5 ≤ AR ≤ 2) and temperature differences between the cold and the hot walls (1≤ ∆T≤ 30). The main idea in this study is about the effect of temperature on natural convection pattern of nanofluid by changing nanoparticles concentration. Also changing thermal expansion coefficient with temperature is considerd in this study which will have significant effects on natural convection and has not been considerd before. In low Rayleigh numbers (Ra= 103) and for cavities with AR≥1, the pattern shown in the average Nusselt number versus volume fraction of nanoparticles diagram deteriorates by increasing ∆T.Thu, 23 Mar 2017 19:30:00 +0100Vibration and Static Analysis of Functionally Graded Porous Plates
http://jacm.scu.ac.ir/article_12716_0.html
This paper deals with free vibration and static bending of a simply supported functionally graded (FG) plate with porosity effect. Material properties of the plate change in position-dependent. Governing equations of the FG plate is obtained by using the Hamilton’s principle within First-order shear deformation plate theory. In the solution of the problem, the Navier solution is used. In this paper, the effects of the porosity and material distribution parameters on the static and vibration responses of the FG plate are presented and discussed.Sun, 26 Mar 2017 19:30:00 +0100VOC level control by ventilation improvement of Flexography printing room Using CFD modeling
http://jacm.scu.ac.ir/article_12721_0.html
Using Computational Fluid Dynamics (CFD) technique, dispersion contours and exposure rate of Flexographic printing workers to VOCs to in a printing department is evaluated. Firstly, VOCs distribution in the printing room due to the existing ventilation system determined. In the followings, 4 scenarios for lowering VOCs concentration and its exposure rate to workers are analyzed. Structured mesh of the printing room model is created for OpenFOAM CFD code package. CFD, K-ε turbulence and mixture model is used for solving the concentration of the VOCs. Possible number and positions of ventilation fans and windows in 4 scenarios are modelled and analyzed. Concentration distributions of ethylene glycol (MEG) as a representative of VOCs are determined for all scenarios. The results show that with the existing ventilation, concentration of MEG at breathing height is 1×10-5 mg/m3 and is higher than the standard permissible level.Mon, 03 Apr 2017 19:30:00 +0100Investigations on the ultrasonic assistance In the tube hydroforming process
http://jacm.scu.ac.ir/article_12738_0.html
The purpose of introducing ultrasonic vibrations in tube hydroforming process is to create more formability by obtaining a lower corner radius, improving thickness distribution of the wall and to provide good tribological conditions at the tube and die interface. Vibrations imposed on the die, creatre alternating gaps which improve the formability in tube hydroforming process in the presence of ultrasonic vibrations. Therefore, we attempted to understand the processing mechanism of the ultrasonic tube hydroforming in the square die using finite element method. Abaqus software was used in these simulations and die considered deformable.Tue, 04 Apr 2017 19:30:00 +0100The effect of small scale on the vibrational behavior of single-walled carbon nanotubes with a ...
http://jacm.scu.ac.ir/article_12740_0.html
In this paper, free and forced vibration of simply-supported Single-walled carbon nanotube under the moving nanoparticle by considering nonlocal cylindrical shell model is investigated. To validate the theoretical results, modal analysis of nanotube is conducted using ANSYS commercial software. Excellent agreement is exhibited between the results of two different methods. Furthermore, the dynamic response of SWCNT under moving nanoparticle is also studied. It is assumed that the nanoparticle travels along the center of nanotube with constant velocity and the van der Waals force between CNT and particle is taken into account. The dynamic response of the SWCNT under the influence of C60 particle obtained using dynamic Green’s function and modal expansion. The obtained results show that the nonlocal scale effect decreases the natural frequency and dynamic displacement of the CNT.Wed, 05 Apr 2017 19:30:00 +0100FLOW AND HEAT TRANSFER ANALYSIS OF SODIUM ALGINATE CONVEYING COPPER NANOPARTICLES BETWEEN TWO ...
http://jacm.scu.ac.ir/article_12773_0.html
The steady incompressible flow of a non-Newtonian sodium alginate (SA) fluid conveying copper nanoparticles (Cu) flowing past two vertical parallel plates is considered in this paper, using the homotopy perturbation analytical scheme to solve the coupled nonlinear ordinary equations arising from the mechanics of fluid. The developed analytical solutions are used to investigate the effect of fluid flow and heat transfer parameters such as nanoparticle concentration, non-Newtonian parameter and viscosity variation parameter. Obtained analytical results when compared to existing works in literature are in satisfactory agreements. Also results obtained from this paper can be used to further the study of the behavior of sodium alginate in applications such as food processing, chemical and pharmaceutical industries.Thu, 20 Apr 2017 19:30:00 +0100Analytical prediction for buckling of nanoplate subjected to nonuniform compression based on ...
http://jacm.scu.ac.ir/article_12806_0.html
In the present work, buckling analysis of rectangular nanoplate under biaxial nonuniform compression using modified couple stress continuum theory with various boundary conditions has been considered. The simplified first order shear deformation theory (S-FSDT) has been employed and the governing differential equations have been obtained using Hamilton’s principle. An analytical approach was applying to obtain exact results with various boundary conditions. Due to the fact that there are not any researches about buckling of nanoplates based on S-FSDT including couple stress effect, so, obtained results have been compared with the molecular dynamic simulation and FSDT papers which uses Eringen nonlocal elasticity theory. In the end, results have been presented by change in some parameters, such as; aspect ratio, effect of various nonuniform loads and length scale parameter changes.Thu, 04 May 2017 19:30:00 +0100The Finite Element Analysis for CFST Columns under Blast Loading
http://jacm.scu.ac.ir/article_12816_0.html
Concrete-filled steel columns have been extensively used in the world due to having all suitable characteristics of concrete and steel, more ductility, increasing concrete confinement using steel wall, large energy-absorption capacity and appropriate fire behavior. In the present paper, concrete-filled steel square columns have been simulated under the influence of blast load using ABAQUS software. The responses will be compared for scaled distances based on the distance to source and weight of the explosive material. As a result, it can be seen that although concrete deformation has been restricted using steel tube, the inner layer of concrete has been seriously damaged and column displacement is decreased by increasing scaled distance. We also concluded that concrete-filled steel columns have high ductility and blast resistance.Sun, 07 May 2017 19:30:00 +0100Bending, Buckling and Vibration of a Functionally Graded Porous Beam Using Finite Elements
http://jacm.scu.ac.ir/article_12817_0.html
This paper presents the effect of porosity on mechanical behaviors of power distribution functionally graded beam. The Euler-Bernoulli beam is assumed to describe the kinematic relations and constitutive equations. Because of technical problems and particle size shapes and micro-voids are created during the fabrication, which should be taken into consideration. Two porosity models are proposed. The first model describes properties in explicit form as linear functions of the porosity parameter. The second is a modified model which presents porosity and Young’s modulus in an implicit form, where the density is assumed as a function of the porosity parameter and Young’s modulus as a ratio of mass with porosity to the mass without porosity. The modified proposed model is more applicable than the first model. The finite element model is developed to solve the problem. Numerical results are presented to show the effects of porosity on mechanical behaviors of FG beams.Sun, 07 May 2017 19:30:00 +0100Buckling analysis of micro sandwich plate with nano coating using modified couple stress theory
http://jacm.scu.ac.ir/article_12863_0.html
Present work investigates buckling of thick sandwich plate under biaxial nonuniform compression using modified couple stress theory with various boundary conditions. For this purpose, the top and bottom faces are orthotropic graphene sheets and for central core the isotropic soft materials have been investigated. The simplified first order shear deformation theory (S-FSDT) has been employed and the governing differential equations are obtained using Hamilton’s principle and considering the Von-Karman’s nonlinear strains. An analytical approach was applying to obtain exact results with different boundary conditions. Due to the fact that there are not any researches in stability of micro/nano sandwich plates based on S-FSDT including couple stress effect, so, obtained results have been compared with the FSDT papers which uses Eringen nonlocal elasticity.Tue, 16 May 2017 19:30:00 +0100Experimental Investigation on Radial Ball Bearing Parameters using Taguchi Method
http://jacm.scu.ac.ir/article_12993_0.html
In this work characteristics of various Ball Bearing parameters are studied under different loads and rotational speeds. By using Dimensional Analysis (DA) dimensionless parameters are computed which provides solution for group of parameters. This analysis can be accomplished by using Buckingham π-theorem. DA leads to reduction of the number of independent parameters involved in a problem. These independent parameters get expressed as dimensionless groups. These dimensionless groups are always ratios of important physical quantities involved in the problem of interest. In modeling and experimentation, its main function is to reduce the amount of independent variables, to simplify the solution and generalize the results. It becomes an effective method, especially if a complete mathematical model of the investigated process is not known. The present work also attempts the application of Buckingham π-theorem to find the influencing parameter π5 by using Taguchi Method.Thu, 15 Jun 2017 19:30:00 +0100Ritz method application to bending, buckling and vibration analyzes of Timoshenko beams via ...
http://jacm.scu.ac.ir/article_13028_0.html
Bending, buckling and vibration behaviors of nonlocal Timoshenko beams are investigated in this research using a variational approach. At first, governing equations of nonlocal Timoshenko beams are obtained and then weak form of these equations is outlined in this paper. Ritz technique is selected to investigate the behavior of nonlocal beams with arbitrary boundary conditions along them. To find the equilibrium equations of bending, buckling and vibration of these structures, an analytical procedure is followed. In order to verify the proposed formulation, the results for nonlocal Timoshenko beams with four classical boundary conditions are computed and compared, wherever possible. Since the Ritz technique can efficiently model the nano-sized structures with arbitrary boundary conditions, two types of beams with general boundary conditions are selected and new results are obtained.Fri, 23 Jun 2017 19:30:00 +0100