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.Fluid Flow and Heat Transfer Over Staggered ꞌ+ꞌ Shaped Obstacles
http://jacm.scu.ac.ir/article_13989_0.html
The inclusion of complex obstacles within solar channels is the aim of our study. Two obstacles of the form ꞌ+ꞌ interlaced within a two-dimensional and rectangular channel are the subject of our study. Fluid is Newtonian, turbulent, non-compressible and has constant properties. The number of Reynolds varies from 12,000 to 32,000 with a constant temperature along the upper surface of the channel. The thermal and dynamic analysis of the channel's internal structure has been carefully processed. Different fields of speed and heat, with various profiles of frictions and heat exchange coefficients have been included in this research. Future work will involve more complex geometries and using nanofluids to assess the optimum conditions for heat transfer enhancements.Fri, 14 Dec 2018 20:30:00 +0100A New Adaptive Extended Kalman Filter for a Class of Nonlinear Systems
http://jacm.scu.ac.ir/article_14168_1889.html
This paper proposes a new adaptive extended Kalman filter (AEKF) for a class of nonlinear systems perturbed by noise which is not necessarily additive. The proposed filter is adaptive against the uncertainty in the process and measurement noise covariances. This is accomplished by deriving two recursive updating rules for the noise covariances, these rules are easy to implement and reduce the number of noise parameters that need to be tuned in the extended Kalman filter (EKF). Furthermore, the AEKF updates the noise covariances to enhance filter stability. Most importantly, in the worst case, the AEKF converges to the conventional EKF. The AEKF performance is determined based on the mean square error (MSE) performance measure and the stability is proven. The results illustrate that the proposed AEKF has a dramatic improved performance over the conventional EKF, the estimates are more stable with less noise.Tue, 31 Dec 2019 20:30:00 +0100Non-similar solutions of MHD mixed convection over an exponentially stretching surface: ...
http://jacm.scu.ac.ir/article_14133_0.html
In this paper, an analysis of MHD mixed convection over an exponentially stretchingsurface in the presence of a non-uniform heat source/sink and suction/injection is presented. Thegoverning boundary layer equations are transformed into a set of non-dimensional equations byusing a group of non-similar transformations. The resulting highly non-linear coupled partialdifferential equations are solved by using the implicit finite difference method combined with thequasilinearization technique. Numerical results for the velocity, temperature and concentrationprofiles, as well as the skin friction coefficient, wall heat transfer and mass transfer rates arecomputed and presented graphically for various parameters.Mon, 18 Feb 2019 20:30:00 +0100Sequential Implicit Numerical Scheme for Pollutant and Heat Transport in a Plane-Poiseuille Flow
http://jacm.scu.ac.ir/article_14258_1889.html
A sequential implicit numerical scheme is proposed for a system of partial differential equations defining the transport of heat and mass in the channel flow of a variable-viscosity fluid. By adopting the backward difference scheme for time derivative and the central difference scheme for the spatial derivatives, an implicit finite difference scheme is formulated. The variable-coefficient diffusive term in each equation is first expanded by differentiation. The next step of the sequential approach consists of providing a solution of the temperature and concentration, before providing a solution for the velocity. To verify the numerical scheme, the results are compared with those of a Matlab solver and a good agreement are found. We further conduct a numerical convergence analysis and found that the method is convergent. The numerical results are investigated against the model equations by studying the time evolution of the flow fields and found that the data, such as the boundary conditions, are perfectly verified. We then study the effects of the flow parameters on the flow fields. The results show that the Solutal and thermal Grashof numbers, as well as the pressure gradient parameter, increase the flow, while the Prandtl number and the pollutant injection parameter both decrease the flow. The conclusion of the study is that the sequential scheme has high numerical accuracy and convergent, while a change in the pollutant concentration leads to a small change in the flow velocity due to the opposing effects of viscosity and momentum source.Tue, 31 Dec 2019 20:30:00 +0100Analysis of Transient Rivlin-Ericksen Fluid and Irreversibility of Exothermic Reactive ...
http://jacm.scu.ac.ir/article_14202_1889.html
This study analyzes the unsteady Rivlin-Ericksen fluid and irreversibility of exponentially temperature dependent variable viscosity of hydromagnetic two-step exothermic chemical reactive flow along the channel axis with walls convective cooling. The non-Newtonian Hele-Shaw flow of Rivlin-Erickson fluid is driven by bimolecular chemical kinetic and unvarying pressure gradient. The reactive fluid is induced by periodic changes in magnetic field and time. The Newtons law of cooling is satisfied by the constant heat coolant convection exchange at the wall surfaces with the neighboring regime. The dimensionless non-Newtonian reactive fluid equations are numerically solved using a convergent and consistence semi-implicit finite difference technique which are confirmed stable. The response of the reactive fluid flow to variational increase in the values of some entrenched fluid parameters in the momentum and energy balance equations are obtained. A satisfying equations for the ratio of irreversibility, entropy generation and Bejan number are solved with the results presented graphically and discussed quantitatively. From the study, it was obtained that the thermal criticality conditions with the right combination of thermo-fluid parameters, the thermal runaway can be prevented. Also, the entropy generation can minimize at low dissipation rate and viscosity.Tue, 31 Dec 2019 20:30:00 +0100Buckling and Free Vibration Analysis of Fiber Metal-laminated Plates Resting on Partial Elastic ...
http://jacm.scu.ac.ir/article_14158_1889.html
This research presents, buckling and free vibration analysis of fiber metal-laminated (FML) plates on a total and partial elastic foundation using the generalized differential quadrature method (GDQM). The partial foundation consists of multi-section Winkler and Pasternak type elastic foundation. Taking into consideration the first-order shear deformation theory (FSDT), FML plate is modeled and its equations of motion and boundary conditions are derived using Hamilton's principle. The formulations include Heaviside function effects due to the nonhomogeneous foundation. The novelty of this study is considering the effects of partial foundation and in-plane loading, in addition to considering the various boundary conditions of FML plate. A computer program is written using the present formulation for calculating the natural frequencies and buckling loadings of composite plates without contacting with elastic foundation and composite plates resting on partial foundations. The validation is done by comparison of continuous element model with available results in the literature. The results show that the constant of total or partial spring, elastic foundation parameter, thickness ratio, frequency mode number and boundary conditions play an important role on the critical buckling load and natural frequency of the FML plate resting on partial foundation under in-plane force.Tue, 31 Dec 2019 20:30:00 +0100Melting Heat Transfer Analysis on Magnetohydrodynamics Buoyancy Convection in an Enclosure: A ...
http://jacm.scu.ac.ir/article_14492_1889.html
The roll of melting heat transfer on magnetohydrodynamic natural convection in a square enclosure with heating of bottom wall is examined numerically in this article. The dimensionless governing partial differential equations are transformed into vorticity and stream function formulation and then solved using the finite difference method (FDM). The effects of thermal Rayleigh number (Ra), melting parameter (M) and Hartmann number (Ha) are graphically illustrated. As melting parameter and Rayleigh number increase, the rate of fluid flow and temperature gradients also increase. And in the presence of magnetic field, the temperature gradient reduces and hence, the conduction mechanism is dominated for larger Ha. Greater heat transfer rate is observed in the case of uniform heating compared with non-uniform case. The average Nusselt number reduces with increasing magnetic parameter in the both cases of heating of bottom wall.Tue, 31 Dec 2019 20:30:00 +0100Nonlocal Elasticity Effect on Linear Vibration of Nano-circular Plate Using Adomian ...
http://jacm.scu.ac.ir/article_14265_1889.html
In this study, the small scale effect on the linear free-field vibration of a nano-circular plate has been investigated using nonlocal elasticity theory. The formulation is based on the classical theory and the linear strain in cylindrical coordinates. To take into account the small scale and the linear geometric effects, the governing differential equation based on the nonlocal elasticity theory was extracted from Hamilton principle while the inertial effect, as well as the shear stresses effect was ignored. Effect of nonlocal parameter is investigated by solving the governing equation using Adomian decomposition method (ADM) for the clamped and simply supported boundary conditions. By using this method, the first five axisymmetric natural frequencies and displacements of nano-circular plate are obtained one at a time and some numerical results are given to illustrate the influence of nonlocal parameters on the natural frequencies and displacements of the nano-circular plate. For the purpose of comparison, the linear equations were solved by the analytical method. Excellent agreements were observed between the two methods. This indicates that the latter method can be applied to seek the linear solution of nano-circular plates with high accuracy while simplifying the problem.Tue, 31 Dec 2019 20:30:00 +0100Exploration of the Significance of Autocatalytic Chemical Reaction and Cattaneo-Christov Heat ...
http://jacm.scu.ac.ir/article_14430_1889.html
During the homogeneous-heterogeneous autocatalytic chemical reaction in the dynamics of micropolar fluid, relaxation of heat transfer is inevitable; hence Cattaneo-Christov heat flux model is investigated in this report. In this study, radiative heat flux through an optically thick medium is treated as nonlinear due to the fact that thermal radiation at low heat energy is distinctly different from that of high heat energy, hence classical approach of using Taylor series for simplification is ignored and implicit differentiation is used leading to temperature parameter. Uniqueness of the present analysis is the consideration of cubic autocatalytic chemical reaction between the homogeneous bulk fluid and two species of catalyst at the wall. Application of similarity analysis enabled us to recast the flow equations into a set of coupled nonlinear ODEs. The resulting equations along with the appropriate conditions are solved computationally. Graphical illustrations of the effect of pertinent parameters on momentum, heat and mass boundary layers are presented and discussed. The concentration of the homogeneous bulk fluid with microstructures and catalyst at the surface decreases and increases with diffusion ratio, respectively. Buoyancy has a decreasing effect on temperature distribution.Tue, 31 Dec 2019 20:30:00 +0100Stress Redistribution Analysis of Piezomagnetic Rotating Thick-Walled Cylinder with ...
http://jacm.scu.ac.ir/article_14246_1889.html
In this article, the problem of time-dependent stress redistribution of a piezomagnetic rotating thick-walled cylinder under an axisymmetric hygro-thermo-magneto-electro-mechanical loading is analyzed analytically for the condition of plane strain. Using the constitutive equations, a differential equation is found in which there are creep strains. Primarily, eliminating creep strains, an analytical solution for the primitive electric and magnetic potential in addition to stresses is obtained. Then, creep strains are kept and creep stress rates are found by utilizing Norton’s law and Prandtl-Reuss equations for steady-state hygrothermal boundary condition. Lastly, the history of stresses and radial displacement as well as magnetic and potential fields during the time is obtained using an iterative method. In the numerical examples, the effect of angular velocity, hygrothermal loading and thermal and moisture concentration dependency of elastic constants is investigated comprehensively.Tue, 31 Dec 2019 20:30:00 +0100The Development and Application of the RCW Method for the Solution of the Blasius Problem
http://jacm.scu.ac.ir/article_14159_1889.html
In this research, a numerical algorithm is employed to investigate the classical Blasius equation which is the governing equation of boundary layer problem. The base of this algorithm is on the development of RCW (Rahmanzadeh-Cai-White) method. In fact, in the current work, an attempt is made to solve the Blasius equation by using the sum of Taylor and Fourier series. While, in the most common numerical methods, the answer is considered only as a Taylor series. It should be noted that in these algorithms which use Taylor expansion, the values of the truncation error are considerable. However, adding the Fourier series to the Taylor series leads to reduce the amount of the truncation error. Nevertheless, the results of this research show the RCW method has the ability to achieve the accuracy of analytical solution. Moreover, it is well illustrated that the accuracy of RCW method is higher than the Runge-Kutta one.Tue, 31 Dec 2019 20:30:00 +0100Upgrading the Seismic Capacity of Pile-Supported Wharfs Using Semi-Active Liquid Column Gas Damper
http://jacm.scu.ac.ir/article_14185_1889.html
One of the most important structures in the ports is the wharf. The most common one is the pile-supported wharf. This type of wharf is consisted of a number of piles and one deck which placed on the piles. In addition to the conventional loads that this structure should withstand, in seismic areas, pile-supported wharfs should have the necessary capacity and strength against seismic excitations. There are some approaches to increase the seismic capacity of the berth. One of these methods is to control the vibrations of the pile-supported wharf against earthquake loads using a damper. In this research, for the first time, a new semi-active damper called the semi active liquid column gas damper (SALCGD), was used to reduce the response of pile supported wharf under seismic loads. In the first step by applying different records of the earthquake, the most important parameter of this damper - the optimal opening ratio of the horizontal column- was obtained for this particular structure. In the following, the performances of this damper and its comparison with the tuned liquid column gas damper (TLCGD) were discussed. This study showed that the use of this semi-active damper (SALCGD) reduces the displacement of the pile-supported wharf by 35% and reduces the acceleration of the structure by 50% on average. In contrast, the passive damper (TLCGD) reduces the displacement of about 20 percent and the acceleration of about 30 percent. Therefore, it was observed that the semi-activation of the damper (SALCGD) had a significant improvement in its performance in controlling the vibrations of pile-supported wharf.Tue, 31 Dec 2019 20:30:00 +0100VISCOELASTIC MICROPOLAR CONVECTION FLOWS FROM AN INCLINED PLANE WITH NONLINEAR TEMPERATURE: ...
http://jacm.scu.ac.ir/article_14296_0.html
An analytical model is developed to study the viscoelastic micropolar fluid convection from an inclined plate as a simulation of electro-conductive polymer materials processing with nonlinear temperature. The Jeffery’s viscoelastic model is deployed to describe the non-Newtonian characteristics of the fluid and provides a good approximation for polymers. Micro-structural is one of the characteristics of non-Newtonian fluid that represents certain polymers, which constitutes a novelty of the present work. The normalized nonlinear boundary value problem is solved computationally with the Keller-Box implicit finite-difference technique. Extensive solutions for velocity, surface temperature, angular velocity, skin friction, heat transfer rate and wall couple stress are visualized numerically and graphically for various thermophysical parameters. Validation is conducted with earlier published work for the case of a vertical plate in the absence of viscous dissipation, chemical reaction and non-Newtonian effects. This particle study finds applications in different industries like reliable equipment design, nuclear plants, paint spray, thermal fabrication, water based gel solvents, polymeric manufacturing process, gas turbines and different propulsion devices.Sat, 11 May 2019 19:30:00 +0100THREE DIMENTIONAL CASSON - CARREAU NANO FLUID FLOW
http://jacm.scu.ac.ir/article_14411_0.html
The current work inquired the computational analysis of three dimensional Casson and Carreau nanofluid flow concerning the convective conditions. After using appropriate self-similarity functions, the flow equations are modified to nonlinear ODEs system. The solution to the modified system is evaluated by numerical technique. The significant results are to inquire the impacts of involving variables on flow characteristics. We have evaluated the outcomes to the friction factors. The outcomes to local Nusselt are evaluated. The outputs to Sherwood number are evaluated. Favourable comparison was performed with before available outcomes for correlating the present results. The achieved results are matched to solutions which are obtained by other researchers. The solution is presented for flow characteristics in the case of Casson and Carreau fluids. Velocities reduce for growing values of permeability and velocity slip parameters in case of Casson and Carreau nanofluids. Temperature field enhances with the hike in the estimations of thermohoresis parameter and the thermal Biot number in case of Casson and Carreau nanofluids. Enhancing values of velocity slip parameter results in decrease in the skin friction coefficients, rate of heat transfer and increase in the rate of mass transfer in case of Casson and Carreau nanofluids.Mon, 13 May 2019 19:30:00 +0100Nonlinear Bending Analysis of Functionally Graded Plates Using SQ4T Elements based on Twice ...
http://jacm.scu.ac.ir/article_14483_1889.html
This paper develops a computational model for nonlinear bending analysis of functionally graded (FG) plates using a four-node quadrilateral element SQ4T within the context of the first order shear deformation theory (FSDT). In particular, the construction of the nonlinear geometric equations are based on Total Lagrangian approach in which the motion at the present state compared with the initial state is considered to be large. Small strain-large displacement theory of von Kármán is used in nonlinear formulations of the quadrilateral element SQ4T with twice interpolation strategy (TIS). The solution of the nonlinear equilibrium equations is obtained by the iterative method of Newton-Raphson with the appropriate convergence criteria. The present numerical results are compared with the other numerical results available in the literature in order to demonstrate the effectiveness of the developed element. These results also contribute a better knowledge and understanding of nonlinear bending behaviors of these structures.Tue, 31 Dec 2019 20:30:00 +0100Prediction of Entrance Length for Magnetohydrodynamics Channels Flow Using Numerical simulation ...
http://jacm.scu.ac.ir/article_14420_0.html
This paper focuses on using the numerical finite volume method (FVM) and artificial neural network (ANN) in order to propose a correlation for computing the entrance length of laminar magnetohydrodynamics (MHD) channels flow. In the first step, for different values of the Reynolds (Re) and Hartmann (Ha) numbers (600Tue, 14 May 2019 19:30:00 +0100Numerical Analysis of Transient Heat Transfer in Radial Porous Moving Fin with Temperature ...
http://jacm.scu.ac.ir/article_14456_1889.html
In this article, a time dependent partial differential equation is used to model the nonlinear boundary value problem describing heat transfer through a radial porous moving fin with rectangular profile. The study is performed by applying a numerical solver in MATLAB (pdepe), which is a centered finite difference scheme. The thermal conductivity and fin surface emissivity are linearly dependent on temperature while the heat transfer coefficient is given by power law function of temperature. The effects of thermo-physical parameters, such as the Peclet number, surface emissivity coefficient, power index of heat transfer coefficient, convective-conductive parameter, radiative-conductive parameter and non-dimensional ambient temperature on temperature are studied.Tue, 31 Dec 2019 20:30:00 +0100Efficient solution of nonlinear Duffing oscillator
http://jacm.scu.ac.ir/article_14428_0.html
In this paper, the efficient multi-step differential transform method (EMsDTM) is applied in order to get accurate approximate solutions for strongly nonlinear Duffing oscillator. The main improvement of EMsDTM, which is to reduce the number of arithmetic operations, is thoroughly investigated and compared with the classic multi-step differential transform method (MsDTM). To illustrate the applicability and accuracy of the new method, six case studies of the free undamped and forced damped conditions are considered. The periodic response curves of both the MsDTM and EMsDTM methods are obtained and contrasted with the exact solution or the numerical solution Runge Kutta 4th order (RK4) method. This approach can be easily extended to other nonlinear systems and is therefore widely applicable in engineering and other sciences.Thu, 16 May 2019 19:30:00 +0100Analysis of High-order Approximations by Spectral Interpolation Applied to One- and ...
http://jacm.scu.ac.ir/article_14444_1889.html
The implementation of high-order (spectral) approximations associated with FEM is an approach to overcome the difficulties encountered in the numerical analysis of complex problems. This paper proposes the use of the spectral finite element method, originally developed for computational fluid dynamics problems, to achieve improved solutions for these types of problems. Here, the interpolation nodes are positioned in the zeros of orthogonal polynomials (Legendre, Lobatto, or Chebychev) or equally spaced nodal bases. A comparative study between the bases in the recovery of solutions to 1D and 2D elastostatic problems are performed. Examples are evaluated, and a significant improvement is observed when the SFEM, particularly the Lobatto approach, is used in comparison to the equidistant base interpolation.Tue, 31 Dec 2019 20:30:00 +0100A Hybrid Particle Swarm Optimization and Genetic Algorithm for truss structures with discrete ...
http://jacm.scu.ac.ir/article_14429_0.html
A new hybrid algorithm of Particle Swarm Optimization and Genetic Algorithm (PSOGA) is presented to get the optimum design of truss structures with discrete design variables. The objective function chosen in this paper is the total weight of the truss structure, which depends on upper and lower bounds in the form of stress and displacement limits. The Particle Swarm Optimization basically modeled the social behavior of birds on the basis of the fact that Individual birds exchange information about their position, velocity, fitness, and on the basis that the behavior of the flock is then influenced to increase the probability of migration to other regions with high fitness. One of the problems of PSO is that it is easily trapped at the local point due to its non-uniform movement. The present study uses the mutation, the random selection, and reproduction to reach the best genetic algorithm with the operators of natural genetics. Therefore, only identical chromosomes or particles can be converged. In other words, the PSO and GA algorithm goes from one point in the search space to another point, interacting with each other. In this way this helps them to find the optimum design by means of deterministic and probabilistic rules. The present study merged the two algorithms together in order to design several benchmark truss structures, and then the results of the new algorithm compared to those of other evolutionary optimization methods.Thu, 16 May 2019 19:30:00 +0100Modeling of Weld Bead Geometry Using Adaptive Neuro-Fuzzy Inference System (ANFIS) in Additive ...
http://jacm.scu.ac.ir/article_14504_1889.html
Additive Manufacturing describes the technologies that can produce a physical model out of a computer model with a layer-by-layer production process. Additive Manufacturing technologies, as compared to traditional manufacturing methods, have the high capability of manufacturing the complex components using minimum energy and minimum consumption. These technologies have brought about the possibility to make small pieces of raw materials in the shortest possible time without the need for a mold or tool. One of the technologies used to make pieces of the layer-by-layer process is the Gas Metal Arc Welding (GMAW). One of the basic steps in this method of making parts is the prediction of bead geometry in each pass of welding. In this study, taking into account the effective parameters on the geometry of weld bead, an empirical study has been done in this field. For this purpose, three parameters of voltage, welding speed and wire feeding rate are considered as effective parameters on the welding geometry of the process. Width and height of the bead are also determined by the parameters of the geometry of the weld according to the type and application of the research as output parameters are considered. In this paper, an adaptive neuro-fuzzy inference system (ANFIS) is used to create an adaptive model between input process data and parameters of weld bead geometry. The least squares mean error is used to evaluate the model. The predicted results by the model have a good correlation with the experimental data.Tue, 31 Dec 2019 20:30:00 +0100Entropy Generation of Variable Viscosity and Thermal Radiation on Magneto Nanofluid Flow with ...
http://jacm.scu.ac.ir/article_14243_1889.html
The present work illustrates the variable viscosity of dust nanofluid runs over a permeable stretched sheet with thermal radiation. The problem has been modelled mathematically introducing the mixed convective condition and magnetic effect. Additionally analysis of entropy generation and Bejan number provides the fine points of the flow. The of model equations are transformed into non-linear ordinary differential equations which are then transformed into linear form using the spectral quasi-linearization method (SQLM) for direct Taylor series expansions that can be applied to non-linear terms in order to linearize them. The spectral collocation approach is then applied to solve the resulting linearized system of equations. The validity of our model is established using relative entropy generation analysis. A convergence schematic was obtained graphically. Consequence of various parameters on flow features have been delivered via graphs. Some important findings reported in this study that entropy generation analysis have significant impact in controlling the rate of heat transfer in the boundary layer region. The paper acquires realistic numerical explanations for rapidly convergent solutions using the Spectral quasi-linearization method. Convergence of the numerical solutions was monitored using the convergence graph. The initial guess values are automatically satisfied the boundary conditions. The resulting equations are then integrated using the Spectral quasi-linearization methods. The influence of radiation, heat and mass parameters on the flow are made appropriately via graphs. The effects of varying certain physical parameters of interest are examined and presented.Tue, 31 Dec 2019 20:30:00 +0100Slip effects on Ohmic dissipative non-Newtonian fluid flow in the presence of aligned magnetic field
http://jacm.scu.ac.ir/article_14453_0.html
The present paper deals with the effects of Ohmic dissipative Casson fluid flow over a stretching sheet in the presence of aligned magnetic field. The present phenomenon also includes the interaction of thermal radiation and velocity slip. The governing boundary layer equations are transformed into a set of ordinary differential equations using the similarity transformations. The dimensionless velocity and temperature profiles are solved analytically using hypergeometric function and numerically by using fourth order Runge-Kutta method with shooting technique. It is noted that the increasing values of Eckert number increases the temperature profile and decreases the local Nusselt number.Mon, 20 May 2019 19:30:00 +0100A parameter uniform numerical scheme for singularly perturbed differential-difference equations ...
http://jacm.scu.ac.ir/article_14461_0.html
In this paper, we consider a second order singularly perturbed differential-difference equations with mixed delay and advance parameters. At first, we approximate the model problem by an upwind finite difference scheme on a Shishkin mesh. We know that the upwind scheme is stable and its solution is oscillation free, but it gives a lower order of accuracy. So, to increase the convergence, we propose a hybrid finite difference scheme, in which we use cubic spline difference method in the fine mesh regions and a midpoint upwind scheme in the coarse mesh regions. We establish a theoretical parameter uniform bound in the discrete maximum norm. To check the efficiency of the proposed methods, we consider test problems with delay, advance and the mixed parameters and the results are in agreement with our theoretical findings.Sun, 26 May 2019 19:30:00 +0100Implicit RBF meshless method for the solution of two-dimensional variable order fractional ...
http://jacm.scu.ac.ir/article_14509_0.html
At the present work, we consider the numerical solution of two dimensional variable order fractional cable (VOFC) equation using meshless collocation methods with thin plate spline radial basis functions. In the proposed methods, we first use two schemes of order for the time derivatives and then meshless approach is applied to the space component. Numerical results obtained from solving considered model on regular and irregular domains, demonstrate the accuracy and efficiency of the proposed schemes.Tue, 18 Jun 2019 19:30:00 +0100Finite element analysis of low velocity impact on carbon fibers/carbon nanotubes reinforced ...
http://jacm.scu.ac.ir/article_14510_0.html
An effort is made to gain insight on the effect of carbon nanotubes (CNTs) on the impact response of carbon fiber reinforced composites (CFRs) under low velocity impact. Certain amount of CNTs could lead improvements in mechanical properties of composites. In the present investigation, ABAQUS/Explicit finite element code (FEM) is employed to investigate various damages modes of nano composites including matrix cracking, fiber damage and delamination by employing Hashin’s criterion and cohesive zone modeling. The obtained results for 0, 0.5, 1, 2 and 4% CNTs demonstrated that by including CNTs in composite plates, damage could be reduced. However, adding further CNTs causes sudden reduction of impact tolerance capability of the composite plates, particularly, damage due to delamination.Wed, 19 Jun 2019 19:30:00 +0100Effect of Corrugated Baffles on the Flow and Thermal Fields in a Channel Heat Exchanger
http://jacm.scu.ac.ir/article_14531_0.html
The performance of corrugated baffles inserted in a rectangular channel heat exchanger is investigated. The fluid flows and thermal distribution are determined via numerical simulations. The working fluid has a shear thinning behavior. The influence of the baffle design is explored, we interest to the “wavy” shape. The corrugation angle of baffle (α) is changed from 0° (i.e. a straight baffle) to 45°. Also, the height (h) of the corrugated baffle is changed and three cases are considered, namely: h/H = 0.4, 0.5 and 0.6, where “H” is the channel height. In a comparison with the unbaffled channel, the overall performance factor has increased from 1.27 up to 1.53 when the corrugation angle is increased from 0° to 45°. Concerning the corrugation height, the predicted results allowed us to select the case h/H = 0.5 as the best configuration from the cases studied.Fri, 21 Jun 2019 19:30:00 +0100On the influence of riveting process parameters on fatigue life of riveted lap joint
http://jacm.scu.ac.ir/article_14533_0.html
Riveting is a common process to fasten structural parts in industries such as automotive and aircraft. In this paper, the influence of riveting process parameters, namely, riveting force, sheet thickness, friction coefficient and clearance fit are investigated on residual stress field and fatigue life of single riveted lap joint of AA2024 type. According to the effect of riveting induced residual stresses on fatigue life of riveted lap joint, these parameters are optimized to maximize the residual stress field. For this purpose, finite element simulations are performed for various combinations of the parameters according to Taguchi design of experiments. Afterwards, the parameter combination that maximize the residual stress field and also the most effective parameters are obtained. The joint with maximum residual stress field is considered to have a semi-elliptical crack emanating from the rivet hole as an initial defect. Stress intensity factors are calculated by implementing two approaches. First, formulation overview that considers the effect of residual stress field, geometry and secondary bending, and second, the finite element method. The fatigue life of the joint is estimated using the obtained stress intensity factors and Paris-Erdogan rule. Finally, good accordance is found between results of these two approaches.Sat, 22 Jun 2019 19:30:00 +0100EFFECT OF TOOL SHOULDER AND PIN CONE ANGLES IN FRICTION STIR WELDING USING NON-CIRCULAR TOOL PIN
http://jacm.scu.ac.ir/article_14534_0.html
In friction stir welding frictional heat is generated by the rotating tool, sliding over the stationary plate along the weld centre. Tool being the only source of heat producing member, its geometrical design influences the heat generation rate. In this present work, effects of variation in tool shoulder and tool pin taper angles on thermal history during joining are analysed. Tools with triangular and hexagonal tool pins are used to understand the influence of tool pin shape on process temperature. An analytical heat input model is developed for tools with non-circular tool pins and a comparative study is carried out between the hexagonal and triangular tool pins on temperature distribution using a three dimensional Matlab model. Proposed model is validated through experimental analysis. Apart from this, regression model based comparative study is carried out on the variation in temperature response to the change in tool pin shape, tool shoulder and tool pin taper angle.Sat, 22 Jun 2019 19:30:00 +0100On the six node hexagon elements for continuum topology optimisation of plates carrying in ...
http://jacm.scu.ac.ir/article_14535_0.html
The need of polygonal elements to represent the domain is gaining interest among structural engineers. The objective is to perform static analysis and topology optimization of a given continuum domain using the rational fraction type shape functions of six node first order hexagonal elements. In this paper, the main focus is to perform the Topology optimisation of two dimensional plate structures using Evolutionary swarm intelligence firefly algorithms and three dimensional shell structures using optimality criteria. The optimisation of plates carrying in plane loading is performed with minimum weight as objective. Two different types of shell structures are optimized using maximum strain energy as criteria. The optimal distribution of the material in the design domain obtained using six node hexagon elements is compared with the optimal distribution of material obtained using quadrilateral elements. A few problems from the literature have been solved and this study has proved that hexagon element gives better results over traditional quadrilateral elements.Sun, 23 Jun 2019 19:30:00 +0100Impact of blood vessel wall flexibility on the temperature and concentration dispersion
http://jacm.scu.ac.ir/article_14536_0.html
The analysis of solute and thermal dispersion in a pulsatile flow through the stenotic tapered blood vessel is presented. The present problem is an extension of the work done by Ramana et. al.[5], who considered the time invariant arterial wall. In the present model flexible nature of the arterial wall through the obstruction (called stenosis) is considered and is achieved with the help of the period trigonometric function. In the present study, the impact of the time dependent arterial wall on the blood flow dynamics is understood in detail. The rheology of the blood is modelled as a couple stress fluid. The proposed fluid model is the isothermal inclusion of temperature sensitive drug coated Titanium dioxide Nano-particles in the couple stress fluid for examining the concentration and temperature dispersion. The effects of the catheter and permeability of the stenosis are considered in the model. Care has been taken to model the thermo-physical properties of the fluid with immersed nanoparticle, e.g., and The modelled non-linear and coupled equations are solved by using the Homotopy Perturbation Method. The temperature and concentration dispersion effects are in the flexible stenotic arterial vessel under the pulsatile physiological pressure gradient is studied and reported in detail. The alterations in the axial velocity, resistance to the flow, and wall shear stress are studied and found out that the high intense vortex regions are identified in the stenotic region. The model has direct applications in pharmaceutical industry in design and developing the drug to treat stenotic conditions.Wed, 26 Jun 2019 19:30:00 +0100Mesoscopic Simulation Of Forced Convective Heat Transfer Of Carreau-Yasuda Fluid Flow Over An ...
http://jacm.scu.ac.ir/article_14545_0.html
In the current study, the Non-Newtonian flow pattern and heat transfer in an enclosure containing a tilted square are examined. In order to numerically simulate the problem, the mesoscopic lattice Boltzmann method is utilized. The Non-Newtonian Carreau-Yasuda model because of its capability to adequately handle the shear-thinning case is employed. The simulation results of flow and heat transfer have been successfully validated with the previous studies. Some engineering parameters such as Nusselt number, Drag coefficient, and Carreau number have been investigated in details. Considering the temperature-dependent viscosity, it is seen that with increasing the temperature-thinning index, the drag coefficient increases, but the Nusselt number decreases. By rotating the square obstacle, the results display that increasing the angle of deviation from zero to 45 degrees, increases both the drag coefficient and the Nusselt number. Also, the highest rate of heat transfer will occur at an angle of 45 degrees (diamond); however it has a negative impact on the Drag coefficient.Thu, 27 Jun 2019 19:30:00 +0100Exact solution for nonlinear local fractional partial differential equations
http://jacm.scu.ac.ir/article_14550_0.html
In this work, we extend the existing local fractional Sumudu decomposition method to solve the nonlinear local fractional partial differential equations. Then, we apply this new algorithm to resolve the nonlinear local fractional gas dynamics equation and nonlinear local fractional Klein-Gordon equation, so we get the desired the non-differentiable exact solutions. The steps to solve the examples and the results obtained, showed the flexibility of applying this algorithm, and therefore, can be applied to similar examples.Fri, 28 Jun 2019 19:30:00 +0100Sealing performance analysis of marine unbonded flexible pipe end fitting under pressure penetration
http://jacm.scu.ac.ir/article_14570_0.html
The sealing performance of end fittings is very important for offshore oil and gas pipelines. To investigate the sealing behavior of a ring-shaped wedge seal, global and local numerical models of the ring–pipe interaction have been developed based on the finite-element method. First, the sealing process of the ring under pressure is simulated. Second, a criterion for the penetration of fluid pressure is applied in these models to assess how the sealing capacity changes along the contact surface. Finally, the contact magnitude of interference and the shape of the sawtooth heaves on the sealing ring are predicted and compared. The results show an interesting concentration of von Mises stress in the sealing ring and also that the peak contact pressure appears in the sealing zone. However, the penetration of fluid pressure has obvious effects on the distributions of von Mises stress and contact pressure. The best sealing performance is when the axial displacement of the sealing ring is 1.4 mm and the contact magnitude of interference is 0.3 mm. Given the sawtooth heave of sealing ring, semicircular heave gives the better sealing capacity compared with trapezoidal heave.Mon, 01 Jul 2019 19:30:00 +0100Vibration Analysis of Different Types of Porous FG Conical Sandwich Shells in Various Thermal ...
http://jacm.scu.ac.ir/article_14572_0.html
For the first time, vibration behavior of different types of porous functionally graded (FG) conical sandwich shells are investigated based on a modified high order sandwich shells theory. First sandwich shell includes FG face sheets which cover a homogeneous core and the second one includes homogeneous face sheets and a FG core. Power law rule which modified by considering two types of porosity distributions is used to model the functionally graded materials. All materials are temperature dependent and uniform, linear and nonlinear temperature distributions are used to model the effect of the temperature variation in the sandwiches. Governing equations are obtained by the Hamilton's energy principle and solved by Galerkin method. To verify the results, they are compared with finite element method results obtained by Abaqus software and for special cases with the results in literatures.Wed, 03 Jul 2019 19:30:00 +0100Multivariate Jeffrey fluid flow past a vertical plate through porous medium
http://jacm.scu.ac.ir/article_14579_0.html
An analysis is suggested to study the impact of Hall currents in Jeffrey fluid which is chemically reactive through a porous medium limited by a semi-infinite vertical permeable plate within the existence of heat generation. An evenly distributed magnetic field turns vertically on the porous surface which absorbs the Jeffrey fluid with a changed suction velocity with time. The analytical expressions are solved by means of three terms harmonic and non-harmonic functions. Statistical calculations are carried out for the point of resultant outcomes which are shown graphically and the impacts of the parameters velocity, temperature and concentration are listed. In addition to this, the results of skin-friction coefficient ( ), Nusselt number (Nu) and Sherwood number (Sh) are taken in to consideration. It’s originated that the impact of the Hall parameter on the channel velocities and skin friction coefficient is subject to the estimation of the wall suction parameter.Tue, 09 Jul 2019 19:30:00 +0100Unsteady Hydromagnetic Flow of Eyring-Powell Nanofluid over an Inclined Permeable Stretching ...
http://jacm.scu.ac.ir/article_14580_0.html
Present analysis deals with an unsteady magnetohydrodynamic flow of Eyring-Powell nanofluid over an inclined permeable stretching sheet. Effects of thermal radiation, Joule heating and chemical reaction are considered. The effects of Brownian motion and thermophoresis on the flow over the permeable stretching sheet are discussed. Numerical and graphical results were obtained for the governing flow equations by using Runge-Kutta fourth order along with shooting technique. The influence of various parameters on flow variables have been examined in detail. The results reveal that the temperature of the fluid enhanced with increasing Brownian and thermophoresis parameters. The increase of fluid velocity with the local Grashof number and solutal Grashof number has been noticed. Further, the nanoparticles concentration decreased for given increase in Brownian motion and chemical reaction parameters while it is increased with an increase in thermophoresis parameter.Fri, 12 Jul 2019 19:30:00 +0100HEAT TRANSFER ANALYSIS OF NANOFLUID FLOW WITH POROUS MEDIUM THROUGH JEFFERY HAMEL ...
http://jacm.scu.ac.ir/article_14616_0.html
In this paper, flow and heat transfer of nanofluid through converging or diverging channel with porous medium is investigated. The fluid flows under the effect of magnetic field constantly through the channel. The diverging/converging channel fluid motion is modeled using the momentum and energy equations. Parametric influence of the nanofluid with porous medium through the non-parallel plates such as opening channel angle, Reynolds number and Darcy’s number are studied. It is observed from result that high Reynolds number enhances fluid viscosity, this decreases velocity. Similarly, heat transfer reduces at high Darcy’s number owing to decreased flow consequently internal friction reduces. Study results in comparison with similar studies obtained from literatures shows satisfactory conclusion.Mon, 22 Jul 2019 19:30:00 +0100Simple two variable refined theory for shear deformable isotropic rectangular beams
http://jacm.scu.ac.ir/article_14620_0.html
In this paper, a displacement-based, variationally consistent, two variable refined theory for shear deformable beams is presented. The beam is assumed to be of linearly elastic, homogeneous, isotropic material and has a uniform rectangular cross-section. In this theory, the beam axial displacement and beam transverse displacement consist of bending components and shearing components. The assumed displacement field of this theory is such that, bending components do not take part in the cross-sectional shearing force, and shearing components do not take part in the cross-sectional bending moment. This theory utilizes linear strain-displacement relations. The displacement functions give rise to the beam transverse shear strain (and hence to the beam transverse shear stress) which varies quadratically through the beam thickness, and maintains transverse shear stress free beam surface conditions. Hence the shear correction factor is not required. The Hamilton’s principle is utilized to derive governing differential equations and variationally consistent boundary conditions. This theory involves only two governing differential equations of fourth order. These governing equations are only inertially coupled for the case of dynamics and are decoupled for the case of statics. This theory is simple and has a strong resemblance with the Bernoulli-Euler beam theory. To demonstrate the efficacy of the present theory, illustrative examples pertaining to the static bending and free vibrations of shear deformable isotropic rectangular beams are presented.Fri, 26 Jul 2019 19:30:00 +0100Designing and Creating a Mouse Using Nature-Inspired Shapes
http://jacm.scu.ac.ir/article_14621_0.html
Human beings have always made their tools and instruments they need using patterns in nature. Mimicking the nature has become the foundation of a new science called biometrics. In the present article, several forms and levels in nature were used to design and create the mouse. The rivers are a good source for choosing the shape of a mouse with lots of stones abraded through the centuries and have smooth surfaces. In this research, a significant number of stones fitted to hand size were collected and then the best ones were scanned by an optical scanner. The point cloud model obtained was used to design and create the mouse and determine the geometric parameters of the mouse. After extracting the 3D model of the point cloud using a rapid prototyping technique with the Fused Deposition Modeling (FDM) method, some mouse models were designed for left-handed and right-handed people. Considering the results of the mouse evaluation by 30 people who provided with the mouse, it can be concluded that the mouse made enjoyed a high satisfactionSat, 27 Jul 2019 19:30:00 +0100A FEM Multiscale Homogenization Procedure using Nanoindentation for High Performance Concrete
http://jacm.scu.ac.ir/article_14634_0.html
This paper aims to develop a numerical multiscale homogenization method for prediction of elasto-viscoplastic properties of a high performance concrete (HPC). The homogenization procedure is separated into two-levels according to the microstructure of the HPC: the mortar or matrix level and the concrete level. The elasto-viscoplastic behavior of individual microstructural phases of the matrix are identified from nanoindentation data using an inverse identification method. The micromechanical results are then used as input parameters for numerical elasto-viscoplastic homogenization at microscale. The mortar level is analyzed with numerical homogenization by using the finite element simulation to predict the overall elasto-viscoplastic properties of HPC. The results are compared with macroscopic experimental and analytical results from the literature showing a good agreement.Mon, 29 Jul 2019 19:30:00 +0100Numerical simulation of unsteady flow toward a stretching/shrinking sheet in porous medium ...
http://jacm.scu.ac.ir/article_14641_0.html
The purpose of this study is to present simulation and numerical solutions to the unsteady flow and heat transfer near stagnation point over a stretching/shrinking sheet in porous medium filled with a hybrid nanofluid. Water (base fluid), nanoparticles of titania and copper were considered as a hybrid nanofluid. It is worth mentioning that evaluating the heat transfer enhancement due to the use of hybrid nanofluids has recently become the center of interest for many researchers. The coupled non-linear boundary-layer equations governing the flow and heat transfer are derived and reduced to a set of coupled non-dimensional equations using the appropriate transformations and then solved numerically as a nonlinear boundary value problem by bvp4c scheme from MATLAB. To validate the modeling of hybrid nanofluid and also numerical procedure, the value of the skin friction and the heat transfer rate for the limited cases of pure water, titania/water and copper/water is obtained and compared with previously reported results that demonstrate an excellent agreement. In the present investigation, the thermal characteristics of hybrid nanofluid are found to be higher in comparison to the base fluid and fluid containing single nanoparticles, respectively. It can be concluded that both skin friction coefficient and local Nusselt number enhance almost linearly with increasing the copper nanoparticle volume fraction (as second nanoparticle). Besides, the porosity and the magnetic effect amplify heat transfer rate, while the unsteadiness parameter has a reducing effect on heat transfer rate in problem conditions.Sat, 03 Aug 2019 19:30:00 +0100An analytical approach of nonlinear thermo-mechanical buckling of functionally graded ...
http://jacm.scu.ac.ir/article_14642_0.html
This paper deals an analytical approach to predict the nonlinear buckling behavior of functionally graded graphene-reinforced composite laminated cylindrical shells under axial compressive load surrounded by Pasternak’s elastic foundation in thermal environment. Piece-wise functionally graded graphene-reinforced composite layers are sorted with different types of graphene distribution. The governing equations are established by using the Donnell’s shell theory with von Kármán nonlinearity terms and three-term solution of deflection is chosen for modeling the uniform deflection of prebuckling state, linear and nonlinear deflection of postbuckling state. Galerkin method is applied to determine the critical axial compressive buckling load expression, postbuckling load-deflection and load-end shortening relations of shell. The effects of environment temperature, foundation, geometrical properties and graphene distribution on buckling behavior of shell are numerically evaluated.Mon, 05 Aug 2019 19:30:00 +0100Experimental investigation and optimizing geometrical characteristics and surface quality in ...
http://jacm.scu.ac.ir/article_14643_0.html
Purpose of this study is to investigate and optimize surface quality and geometrical characteristics in drilling process of AISI H13 steel, because they are critical items for precision manufacturing. After conducting the experiments, two regression models were developed to extensively evaluate the effect of drilling parameters on process outputs. After that, evolutionary multi-objective optimization algorithm was employed to find the optimal drilling conditions. Non-dominated Sorting Genetic Algorithm (NSGA-ІІ) was developed and regression functions were taken into account as objective functions of algorithm to simultaneously optimize the surface roughness and deviation of circularity. Results of optimization were successfully in agreement with experimental findings and finally the set of optimal drilling conditions was reported that can be selected by process engineer according to the priority and application. It was shown that, increase in Cutting speed and liquid coolant intensity decreases the surface quality, while higher depth of cut, tool Diameter and reed rate improve it. It was also found that tool diameter and depth of cut are the most effective input parameters on deviation of circularity. Finally, it can be concluded that, implemented approach in this research provide efficient method for other manufacturing processes to increase performance and reduction of production costs.Mon, 05 Aug 2019 19:30:00 +0100Multiple Solutions for Slip Effects on Dissipative Magneto-Nanofluid Transport Phenomena in ...
http://jacm.scu.ac.ir/article_14645_0.html
The present paper considers a numerical investigation of transport phenomena in electrically-conducting nanofluid flow within porous bed utilizing Buongiorno’s transport model and Runge-Kutta-Fehlberg fourth-fifth order method. Induced flow by non-isothermal stretching/shrinking sheet along with magnetic field impact, dissipation effect and slip conditions at the surface are also included. The numerical results show the existence of two branches of the solution for a selected range of the governing parameters. The physical significance of both branches of solutions is ensured by performing a stability analysis in which a linearized eigenvalue problem is solved. The multiple regression analysis with help of MALTAB LinearModel.fit package has also been conducted to estimate the dependency of the parameters on Nusselt number.Thu, 08 Aug 2019 19:30:00 +0100Emotional Learning Based Intelligent Controller for MIMO Peripheral Milling Process
http://jacm.scu.ac.ir/article_14664_0.html
During the milling process, one of the most important factors in reducing tool life expectancy and quality of workpiece is the chattering phenomenon due to self-excitation. The milling process is considered as a MIMO strongly coupled nonlinear plant with time delay terms in cutting forces. We stabilized the plant using two independent Emotional Learning-based Intelligent Controller (ELIC) in parallel. Control inputs are considered as forces Ux and Uy in two directions x and y, which are applied by the piezoelectrics. The ELIC consists of three elements; Critic, TSK controller and the learning element. The results of the ELIC have been compared with a Sliding Mode Controller (SMC). The simulation for the nominal plant shows better performance of the ELIC in IAE and ITSE values at least 86% in the x-direction and 79% in the y-direction. Similar simulation for an uncertain plant also shows an improvement of at least 89% in the x-direction and 97% in the y-direction.Wed, 14 Aug 2019 19:30:00 +0100Effect of coating materials on the fatigue behavior of hip implants: A three-dimensional finite ...
http://jacm.scu.ac.ir/article_14665_0.html
This study aimed to validate, using finite element analysis (FEA), the design concept by comparing the fatigue behavior of hip implant stems coated with composite (carbon/PEEK) and polymeric (PEEK) coating materials corresponding to different human activities: standing up, normal walking and climbing stairs under dynamic loadings to find out which of all these models have a better performance in the prosthesis-bone systems. A 3D finite element models of hip implants, femur, coating layers with polymeric (PEEK) and composite (carbon/PEEK) coating materials were created for FEA. The cyclic loads were applied on the prosthesis head. Fatigue life durations were calculated based on the Goodman mean-stress fatigue theory. The fatigue safety factor for the coated implant was increased more than 12.73% at least compared to the uncoated implant. The carbon/PEEK composite material with 0, +45, -45, and 90 degrees fiber orientation (configuration I) has the highest fatigue life and fatigue safety factor. The numerical result showed that the carbon/PEEK composite material (configuration I) seems to be a good solution to increase the values of fatigue safety factor of coating layers due to highest fatigue life and fatigue safety factor. It distributes the applied load and transfer it to the bone, reducing stress-shielding effects and prolong the bone-prosthesis system life span.Thu, 15 Aug 2019 19:30:00 +0100