2021-09-22T07:05:34Z
https://jcamech.ut.ac.ir/?_action=export&rf=summon&issue=10306
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
A wave-based computational method for free vibration and buckling analysis of rectangular Reddy nanoplates
Ali
Zargaripoor
Mansoor
Nikkhah bahrami
In this paper, the wave propagation method is combined with nonlocal elasticity theory to analyze the buckling and free vibration of rectangular Reddy nanoplate. Wave propagation is one of the powerful methods for analyzing the vibration and buckling of structures. It is assumed that the plate has two opposite edges simply supported while the other two edges may be simply supported or clamped. It is the first time that the wave propagation method is used for thick nanoplates. In this study, firstly the matrices of propagation and reflection are derived. Then, these matrices are combined to provide an exact method for obtaining the natural frequencies and critical buckling loads which can be useful for future studies. It is observed that obtained results of the wave propagation method are in good agreement with the obtained values by literature. At the end the obtained results are presented to evaluate the influence of different parameters such as nonlocal parameter, aspect ratio and thickness to length ratio of nanoplate.
Rectangular thick nanoplate
Propagation matrix
Reflection matrix
Vibration analysis
Buckling analysis
2020
12
01
253
274
https://jcamech.ut.ac.ir/article_66040_0f5f96ae165e7884f1a02b9d4c4812b7.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Energy cost minimization in an electric vehicle solar charging station via dynamic programming
Mohammad Reza
Hajidavalloo
Farzad
Ayatolah Zadeh Shirazi
Mohammad
Mahjoob
Environmental crisis and shortage of fossil fuels make Electric Vehicles (EVs) alternatives for conventional vehicles. With growing numbers of EVs, the coordinated charging is necessary to prevent problems such as large peaks and power losses for grid and to minimize charging costs of EVs for EV owners. Therefore, this paper proposes an optimal charging schedule based on Dynamic Programming (DP) to minimize the overall cost of charging EVs for consumers in a solar Charging Station (CS). The large state space that makes the use of general DP inefficient is handled by using modified DP. Also, due to the stochastic behavior of the PV production, four different cases accounting for four different weather conditions are considered. Simulations are done for each weather condition and potential cost savings for customers and benefits for the grid are investigated in comparison to uncontrolled charging in each case. Simulation results demonstrated a significant decrease in the total CS purchased power cost, indicating reduced costs for consumers. Also, the optimal charging schedule shifts the charging sequence of EVs from high demand hours to low demand hours, to keep a smooth load shape for the distribution grid.
Dynamic Programming
Solar charging station
Electric vehicles
Cost minimization
2020
12
01
275
280
https://jcamech.ut.ac.ir/article_74674_393d96f6e20787f988aceb312f29d6b1.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Parametric study of nonlinear buckling capacity of short cylinders with Hemispherical heads under hydrostatic pressure
Firooz
Ahmadi
Mohamad
Hoseini
This study investigates the buckling behavior of short cylindrical shells with hemi-spherical heads subjected to hydrostatic pressure. It is assumed that the length of the cylindrical part is smaller than or equal to its diameter while its material may be dif-ferent from that of hemispherical heads. Finite element analysis was used to seek out the effect of geometric parameters such as thickness, length, and volume of the tank on the ultimate buckling load. Results indicate that the buckling load is directly pro-portional with the thickness and inversely proportional with the volume of the vessel. A close examination of the buckling modes reveals that under uniform hydrostatic pressure, the cylindrical part undergoes the most critical deformation compared with its hemispherical heads. This behavior was observed for the two loading cases of (a), a hydrostatic pressure applied to the whole structure and (b), the hydrostatic pressure was only applied to the cylindrical part of the vessel.
nonlinear buckling
Shell of revolution
Hydrostatic pressure
Finite Element Analysis
2020
12
01
281
287
https://jcamech.ut.ac.ir/article_74864_919b7859cf0297306e624ce5fc26e1d8.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Mechanical properties of CNT reinforced nano-cellular polymeric nanocomposite foams
Mohammad
Babadi
Saeed
Momeni Bashusqeh
Mechanics of CNT-reinforced nano-cellular PMMA nanocomposites are investigated using coarse-grained molecular dynamics simulations. Firstly, static uniaxial stretching of bulk PMMA polymer is simulated and the results are compared with literature. Then, nano-cellular foams with different relative densities are constructed and subjected to static uniaxial stretching and obtained stress-strain curves are used to compute Young moduli and tensile strength of PMMA foams. Carbon nanotubes in various weight fractions and random orientations are then introduced into the constructed samples to investigate effect of reinforcement on mechanical properties of bulk and foam samples. Also dynamic compression experiment at high strain-rate is simulated in all of the samples to check effects of relative density and reinforcement on energy absorption capability and plateau stress. By plotting variation of lateral strain with respect to longitudinal strain, auxeticity of the foams at the early stage of loading was observed. It is shown that there are multiple distinct regimes in stress-strain curves obtained from simulation of compression due to densification of foams during compression. Both recoverable and unrecoverable energies per unit volume in all of the compression experiments are computed and it is shown that reinforcement of foams could result in a lighter structure with improved energy absorption.
Foam
Molecular Dynamics
Uniaxial stretching
Dynamic compression
2020
12
01
288
293
https://jcamech.ut.ac.ir/article_74865_cca7653f5dc058203b86db218597a598.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Comparison study between layered and functionally graded composite beams for static deflection and stress analyses
Okan
Kirlangiç
Şeref
Akbaş
The aim of this paper is to compare the static deflections and stress results of layered and functionally graded composite beams under static load. In the comparison study, the results obtained for a cantilever beam under point load. The Timoshenko beam and the Euler-Bernoulli beam theories are used in the beam model. The energy based Ritz method is used for the solution of the problem and algebraic polynomials are used with the trivial functions for the Ritz method. Two different materials are considered as layered and functionally graded distribution in a cantilever beam and their static deflections, stress distributions are compared under a point load at free end of the beam. For two different distributions, the formulations of Ritz method are obtained and solved numerically. In the numerical results, the effects of material distribution parameter, aspect ratio on the static deflections and stress distribution of functionally graded beams are obtained and compared with the results of the layered composite beam. Difference among of beam theories are compared for functionally graded and layered beams. Also, some comparison studies are performed in order to validate the using formulations.
Functionally Graded Material
Layered Composites
Beam
Ritz Method
Timoshenko Beam Theory
2020
12
01
294
301
https://jcamech.ut.ac.ir/article_75010_a3b826190050166dfcfd2a4ade792c9f.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Elzaki transform method for finding solutions to two-dimensional elasticity problems in polar coordinates formulated using Airy stress functions
Charles
Ike
In this paper, the Elzaki transform method is used for solving two-dimensional (2D) elasticity problems in plane polar coordinates. Airy stress function was used to express the stress compatibility equation as a biharmonic equation. Elzaki transform was applied with respect to the radial coordinate to a modified form of the stress compatibility equation, and the biharmonic equation simplified to a fourth order ordinary differential equation (ODE). The general solution for the Airy stress potential function in the Elzaki transform space was obtained by solving the ODE. By inversion, the general solution for the Airy stress potential function was obtained in the physical domain space variables in terms of four unknown integration constants. Normal stresses and shear stress fields were also determined for the general case of 2D elasticity problems. The Flamant problem was solved as a particular illustration of 2D elasticity problems. The stress boundary conditions and the requirement of equilibrium of the internal stress resultants and the external forces were used simultaneously to determine the four constants of integration. The Airy stress potential function and the normal and shear stress fields were thus completely determined. The principle of superposition was used to obtain the elasticity solutions for the stress fields in the elastic half plane due to strip load of infinite extent, and solutions for horizontal stresses on smooth rigid retaining walls due to strip loads and parallel line load of infinite extent acting on the elastic half plane.
Elzaki transform method
Airy stress potential function
stress compatibility equation
line load of infinite extent
elastic half plane
two dimensional elasticity problem
2020
12
01
302
310
https://jcamech.ut.ac.ir/article_75011_f6f0b3d9c814d755500501f72295f07c.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Analysis of the nonlinear axial vibrations of a cantilevered pipe conveying pulsating two-phase flow
Adeshina
Adegoke
Omowumi
Adewumi
Akin
Fashanu
Ayowole
Oyediran
The parametric resonance of the axial vibrations of a cantilever pipe conveying harmonically perturbed two-phase flow is investigated using the method of multiple scale perturbation. The nonlinear coupled and uncoupled planar dynamics of the pipe are examined for a scenario when the axial vibration is parametrically excited by the pulsating frequencies of the two phases conveyed by the pipe. Away from the internal resonance condition, the stability regions are determined analytically. The stability boundaries are found to reduce as the void fraction is increasing. With the amplitude of the harmonic velocity fluctuations of the phases taken as the control parameters, the presence of internal resonance condition results in the occurrence of both axial and transverse resonance peaks due to the transfer of energy between the planar directions. However, an increase in the void fraction is observed to reduce the amplitude of oscillations due to the increase in mass content in the pipe and which further dampens the motions of the pipe.
Axial Vibration
Parametric resonance
Void fraction
Two phase flow
Perturbation method
2020
12
01
311
322
https://jcamech.ut.ac.ir/article_75013_f161c054d38522a36bd41706090bb3db.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Influence of Magnetic Wire Positions on free convection of Fe3O4-Water nanofluid in a Square Enclosure Utilizing with MAC Algorithm
K
VENKATADRI
A
shobha
C
Venkata Lakshmi
V
Ramachandra Prasad
B. Md
Hidayathulla Khan
The augment of heat transfer and fluid of buoyancy-driven flow of Fe3O4-Water nanofluid in a square cavity under the influence of an external magnetic field is studied numerically. Cold temperature is applied on the side (vertical) walls and high temperature is imposed on the bottom wall while the top wall is kept at thermally insulated. The governing non-dimensional differential equations are solved using Marker and Cell (MAC) Algorithm. The developed MATLAB code is validated with previous literature and it gives good agreement. The effects of Rayleigh number Ra, Prandtl number Pr and Hartmann number Ha on the flow and heat transfer characteristics are analyzed. Results indicate that the temperature gradient is an increasing function of the buoyancy force. The heat transfer characteristics and flow behavior are presented in the form of streamlines and isotherms. The position of magnetic wire is played a vital role in controlling of heat transfer rate.
MAC Method
Magnetizable Fluid
magnetic sources
enclosure
Nanofluid
2020
12
01
323
331
https://jcamech.ut.ac.ir/article_75016_a3db981d3116c15ea7c1d00088b5e386.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Thermoelastic response of microbeams under a magnetic field rested on two-parameter viscoelastic foundation
Adam
Sidig
Ahmed
Abouelregal
Mechanical foundations and pavements design need a perfect prediction of the response of the material to reach a reliable and safe structure. This work deals with the thermoelastic response of microbeams rested on a two-parameter viscoelastic foundation due to a magnetic field in the context of the dual - phase lag thermoelasticity model. The solutions of the governing equations are attained using the Laplace transform method. The distributions of the deflection, temperature, the displacement and the flexure moment of the micro beam are numerically obtained and illustrated graphically. The effects of the magnetic field, Winkler and shear foundation parameters, the ramping time parameter and the models of thermoelasticity on the considered fields are concerned and discussed in details. For comparison purposes, the response of the micro beam and the dynamic deflection using the Bernoulli- Euler beam and thermoelasticity theories are compared with earlier investigated studies and magnificent agreements are detected.
Microbeams
Thermoelasticity
magnetic field
Pasternak foundation
Phase lags
2020
12
01
332
339
https://jcamech.ut.ac.ir/article_75014_f316e998e6c1ebdbeeb9a00c02515df9.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Size-dependent thermoelastic analysis of rotating nanodisks of variable thickness
Abbas
Barati
Mehdi
Mousavi Khoram
Mohammad
Shishesaz
Mohammad
Hosseini
This paper contains a strain gradient theory to capture size effects in rotating nanodisks of variable thickness under thermal and mechanical loading. Material properties of nanodisks have been taken homogeneous material. The strain gradient theory and the Hamilton’s principle are employed to derive the governing equations. Due to complexity of the governing differential equation and boundary conditions, numerical schemes are used to solve the problem. In the following, some numerical results are presented to show the influence of size effect on stress analysis of rotating nanodisks. Results show that the stresses of rotating nanodisks is strongly sensitive to the length scale material parameters.
Nanodisk
Strain gradient theory
Thermoelastic analysis
Angular Velocity
2020
12
01
340
360
https://jcamech.ut.ac.ir/article_74965_57a553106d9a9482af156bbf89d9ba7a.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Flexural behavior of porous functionally graded plates using a novel higher order theory
Sidda
Bathini
K.
Vijaya Kumar Reddy
In this paper, the flexural response of functionally graded plates with porosities is investigated using a novel higher order shear deformation theory, which considers the influence of thickness stretching. This theory fulfills the nullity conditions at the top and bottom of the plate for the transverse shear stresses, thus avoids the need of a shear correction factor. The effective material properties are computed through the rule of mixtures. The principle of virtual displacements is employed to derive the equilibrium equations. The Navier’s method is adopted to obtain the solutions in closed form for simply supported boundary conditions. The accuracy and consistency of the developed theory are established with numerical results of perfect and porous functionally graded plates available in the open literature. The dimensionless transverse displacements and stresses have been reported. The effect of even, uneven and logarithmically-uneven porosity distributions with different porosity volume fraction, gradation index, side-to thickness ratios and aspect ratios are studied. The numerical results show that, the increase of volume fraction of porosity increases the dimensionless transverse deflections and axial stresses, and decreases the transverse shear stresses. No variation of transverse shear stresses observed for a completely ceramic and metallic plate for all kinds of porosity models. The provided numerical results can be used to evaluate various plate theories and also to compare the results of other analytical methods and finite element methods.
Functionally Graded Plates
Porosities
Flexure
Rule of Mixtures
Navier’s method
2020
12
01
361
373
https://jcamech.ut.ac.ir/article_75288_0898a0f9ce064c0cc28402cd92893c3e.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Free vibration behavior of bi-directional functionally graded plates with porosities using a refined first order shear deformation theory
Sidda
Bathini
Vijaya Kumar Reddy
K
Chinna Ankanna
B
This paper proposes the refined first order shear deformation theory to investigate the free vibration behavior of bidirectional functionally graded porous plates. This theory satisfies the transverse shear stress free conditions at the top and bottom of the plate, thus avoids the need of a shear correction factor. The rule of mixtures is employed to compute the effective material properties and assumed to be graded in both x and z-directions. The equations of motion are derived by means of Lagrange equations to investigate the free vibration response. The displacement functions in axial and transverse directions are expressed in simple algebraic polynomial series form, including admissible functions which are used to fulfill the simply supported boundary conditions. The admissible functions are generated using Pascal’s triangle. The accuracy of the present theory is assessed with the numerical results and is confirmed by comparing with 3-D exact solutions and with other higher order theories. The influence of thickness ratios, aspect ratios, gradation indexes, type of porosity distribution and the volume fraction of porosity on the free vibration behavior of bi-directional FGPs are discussed in detail. The presented numerical results can be used as benchmark solutions to assess the various plate theories and compare with solutions obtained by other analytical and finite element methods. From the present work, it can be concluded that the present theory allows examining the vibration behavior of bidirectional porous FG plates manufactured in the sintering process.
Bidirectional Functionally graded plates
Porosities
Free Vibration
Rule of Mixtures
Lagrange Equations
2020
12
01
374
388
https://jcamech.ut.ac.ir/article_77372_6b33f3f9e443e450fe44626a0e9fda4e.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
A hybrid scheme of single relaxation time lattice Boltzmann and finite volume methods coupled with discrete ordinates method for combined natural convection and volumetric radiation in an enclosure
Rabiaa
soualmi
Abderrahmane
Benbrik
Denis
Lemonnier
Mohammed
Cherifi
Mohammed
Bouanani
This paper is focused on the application of hybrid Single relaxation time lattice Boltzmann and finite volume methods in conjunction with discrete ordinates method to simulate coupled natural convection and volumetric radiation in differentially heated enclosure, filled with an absorbing, emitting and non-scattering gray medium. In this work, the velocity and temperature fields are calculated using lattice Boltzmann and finite volume methods respectively, whereas the radiative term is computed by the discrete ordinates method. This study is carried out for Pr = 0.71, a Rayleigh number range of 103 ≤ Ra ≤ 106, an optical thickness with values 0 ≤ τ ≤ 100, a Planck number ranging in 0.001≤ Pl ≤ 100 and an aspect ratio varying between 0.5 ≤ Ar ≤ 2. Results are presented in terms of streamlines, isotherms, velocity profiles and average Nusselt number. Based on the obtained results, it can be concluded that the presence of volumetric radiation is noteworthy. Its effect, as a function of Rayleigh number and the radiative properties, yields significant changes on the behavior of streamlines and isotherms. In the taller enclosure, the increase of average total Nusselt number with increasing Rayleigh number is less significant than that in the case of the shallow enclosure.
Natural convection
volumetric radiation
single relaxation time lattice Boltzmann method
Aspect ratio
discrete ordinates method
2020
12
01
389
402
https://jcamech.ut.ac.ir/article_77373_cb4d1c401cd3821c546a284e364d220e.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
The axisymmetric computational study of a femoral component to analysis the effect of titanium alloy and diameter variation.
Ana Rita
Carreiras
Elza M. M.
Fonseca
Diana
Martins
Rui
Couto
This work presents a numerical approach in order to predict the influence of implant material stiffness in a femoral component design when submitted in compression. The implant success depends on the transferred load to the neighboring bone. The finite element method can be used to analysis the stress and strain distribution in the femoral component allowing to improve the implant selection. For this purpose, 2D axisymmetric computational models of an implant-cement-bone (Model 1), implant-bone (Model 2) and core implant-bone (Model 3) were constructed using the finite element method with ANSYS program. The finite element model was assumed a state of ideal osseointegration, where the cortical bone, cement and implant were assumed as perfectly bonded. Three different implant diameters were chosen and two materials considered, a typical titanium alloy and iso-elastic titanium alloy with low stiffness. The finite element analysis was carried out to calculate the von Mises stress, the shear stress and the strain energy density in all studied models. Also, an analytical procedure, based on the elastic stress theory and applied to composite materials for an axial load, was used to measure the load transferred to the bone. In all results, Model 3 with the vertical graded iso-elastic alloy in vicinity to the bone with high diameter has a good performance.
Stiffness
Bone
Numerical model
Load transferred to the bone
2020
12
01
403
410
https://jcamech.ut.ac.ir/article_77374_7403122450abef4b3bed681e87c07063.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Geometrically nonlinear analysis of axially functionally graded beams by using finite element method
Şeref
Akbaş
The aim of this paper is to investigate geometrically nonlinear static analysis of axially functionally graded cantilever beam subjected to transversal non follower load. The considered problem is solved by finite element method with total Lagrangian kinematic approach. The material properties of the beam vary along the longitudinal direction according to the power law function. The finite element model of the beam is considered in the three dimensional continuum approximation for an eight-node quadratic element. The geometrically nonlinear problem is solved by Newton-Raphson iteration method. In the numerical results, the effects of the material distribution on the geometrically nonlinear static displacements of the axially functionally graded beam are investigated. Also, the differences between of material distributions are investigated in geometrically analysis.
Axially Functionally Graded Beams
Geometrically nonlinear Analysis
finite element method
Total Lagrangian
2020
12
01
411
416
https://jcamech.ut.ac.ir/article_77577_2f1558340ebcf11ecc175c9f20e36922.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
A refined inverse hyperbolic shear deformation theory for bending analysis of functionally graded porous plates
Sidda
Bathini
Vijaya Kumar Reddy
K
The modern engineering structures require the advanced engineering materials to resist the high temperatures and to provide high stiffness. In particular the functionally graded porous materials (FGPMs) introduced are expected to have these desired properties, consequently eliminating local stress concentration and de-lamination. In the present paper, a new shear strains shape function is chosen to research the bending analysis of functionally graded plates (FGPs) with uneven symmetrical, uneven asymmetrical and even distributions of porosity. The material properties of uneven porosity distributions along the thickness of the FGPs vary with cosine function. The present theory includes the influence of thickness stretching. This theory also fulfills the nullity of the shear stresses in the transverse direction on the top and bottom of the plate, thus avoids the use of a shear correction factor. The virtual displacement principle is employed to develop the equilibrium equations for porous FGPs. The Navier’s method is used to obtain the solutions of porous FGPs for simply supported (SS) conditions. The accuracy of the developed theory is established with numerical results of perfect and porous FGPs available in the open source. The transverse displacements and stress results have been reported and studied for evenly, unevenly symmetrical and unevenly asymmetrical distributions with different porosity volume fraction (PVF), thickness ratios and aspect ratios. From the numerical results it is concluded that the type of porosity distribution needs to be considered as a key factor in the optimal design of the porous FGPs.
Functionally graded porous plates
Bending analysis
Rule of Mixtures
Porosity distribution
Porosity volume fraction
2020
12
01
417
431
https://jcamech.ut.ac.ir/article_77578_d01c84b3f1de16eacaf3c6bbeae42bb6.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Damped DQE Model Updating of a Three-Story Frame Using Experimental Data
Laleh
Fatahi
Shapour
Moradi
Ali
Hajnayeb
In this paper, following a two-stage methodology, the differential quadrature element (DQE) model of a three-story frame structure is updated for the vibration analysis. In the first stage, the mass and stiffness matrices are updated using the experimental natural frequencies. Then, having the updated mass and stiffness matrices, the structural damping matrix is updated to minimize the error between the experimental and numerical damping ratios. Note that two different damping models are used, including a diagonal matrix with unknown diagonal elements and a general damping model. Since the structural joints of the frames are not completely rigid in practice, several parameters are used to model the flexibility of these joints. The optimum values of the material and geometrical design parameters are obtained by updating the DQE model using the experimental modal parameters obtained through modal testing. Considering the robustness of the evolutionary optimization algorithms in the model updating practice, a combination of particle swarm optimization and artificial bee colony algorithm, that benefits from the advantages of both approaches, is utilized. By updating the DQE model, the effectiveness of the evolutionary optimization algorithms, especially in a high-dimensional optimization problem, e.g., finding the optimum general damping matrix, is studied. The results show that, considering the geometrical lengths of the frame as the design parameters, the natural frequencies of the updated model match better with the experimental ones. In addition, using the general damping matrix, the errors of the damping ratios significantly are decreased.
DIFFERENTIAL QUADRATURE ELEMENT METHOD
Evolutionary Optimization Algorithms
Damped Model Updating
Mechanical Vibrations
Frames
2020
12
01
432
442
https://jcamech.ut.ac.ir/article_77710_b6d7ffdfbcc07c9f0fa4b45731cc3438.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
On the buckling analysis of functionally graded sandwich beams using a unified beam theory
Atteshamuddin
Sayyad
Yuwaraj
Ghugal
In this paper, a unified beam theory is developed and applied to study the buckling response of two types of functionally graded sandwich beams. In the first type (Type A), the sandwich beam has a hardcore whereas in the second type (Type B), the sandwich beam has a softcore. In both the type of beams, face sheets are made up of functionally graded material. The material properties of face sheets are varied through the thickness according to the power-law distribution. A unified beam theory developed in the present study uses polynomial and non-polynomial type shape functions in-terms of thickness coordinate to account for the effect of shear deformation. The present theory is built upon classical beam theory and shows a realistic variation of transverse shear stresses through the thickness of the beam. The governing equations are deduced based on the principle of virtual work. Analytical solutions for simply supported sandwich beams subjected to axial force are presented. The critical buckling load factors of two types of FG sandwich beams are investigated. The numerical results are obtained for various power law coefficients and face-core-face thickness ratios. The validity of the present theory is proved by comparing the present results with various available solutions in the literature.
A unified beam theory
Shear deformation
FG sandwich beam
Softcore and hardcore
Critical buckling load factors
2020
12
01
443
453
https://jcamech.ut.ac.ir/article_78065_f5f1a4707f1583a600e3de17a5122e1f.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
A genetic algorithm-based approach for numerical solution of droplet status after Coulomb fission using the energy
Mohamad Hamed
Hekmat
Morteza
Rahmanpour
Mahnaz
Mahmoudi
Saleh
Saharkhiz
As a droplet moves, due to evaporation at the surface, the droplet size is gradually reduced. Due to decreasing the size of the droplets moving in the spray core, the surface charges become closer and the repulsive force between the charges increases. When the Coulombic force overcomes the surface tension force (Rayleigh instability) the droplet breaks into smaller droplets (Coulomb fission). The present study predicts droplet Coulomb fission and droplets trajectories of steady spray plume in a monodisperse Electrohydrodynamics (EHD) spray within a Lagrangian framework. Droplet fission is simulated based on the principle of minimum free energy using the Genetic Algorithm (GA) and droplet trajectories are predicted using the Lagrangian single-droplet dynamic tracking method. The numerical model is validated by comparing the model predictions with the experimental and previous modeling results. In the current method, an optimization method for minimizing the energy in the minimum energy principle is utilized to avoid any simplifying assumptions, such as number of sibling droplets and charge distribution on their surfaces which may affect the physics of the problem. According to the process of the present solutions and results, it is clearly seen that the developed method has sufficient accuracy and precision.
Genetic Algorithm
Droplet
Coulomb fission
Rayleigh limit
energy conservation method
2020
12
01
454
463
https://jcamech.ut.ac.ir/article_78637_d9bb43bd01524a67ca6b555e3234125d.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Kinetics of swelling of cylindrical functionally graded temperature-responsive hydrogels
amir hossein
namdar
Cylindrical hydrogels have a wide variety of applications in microfluidics; for example, they serve as micro-valves, micro-mixers, and micro-lenses. The main advantages of them can be mentioned as their autonomous functionality due to their responses to environmental stimuli and simple geometry. Furthermore, functionally graded hydrogels have recently found applications in hydrogel actuators. Therefore, in this work, the kinetics of swelling, shrinking, and force generation of cylindrical functionally graded temperature-responsive hydrogels are investigated. Kinetics of cylindrical structure is investigated analytically by developing a mathematical model based on available constitutive models of large deformation of hydrogels. The cross-link density of the hydrogel polymeric network varies along the radius of the cylinder linearly. In order to analyze the structure's behavior, the temperature is changed, and the response time of the structures with different distribution of cross-link density is investigated. In addition, to investigate the realistic actuators' performance, the cylindrical hydrogel is located inside a hollow cylinder, and the pressure of the hydrogel, which puts on the cylinder, is investigated. The results show that manipulation of cross-link density influences the response time of the cylindrical hydrogel; hence, it is a useful tool to manage the overall performance of cylindrical actuators.
Temperature-responsive hydrogel
Kinetics of swelling
analytical study
micro-mixer
2020
12
01
464
471
https://jcamech.ut.ac.ir/article_78638_186e78e6afb24db5a9e398f4b9f30485.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Pull-in behaviors of micro-beam made of bidirectional functionally grade materials based on modified couple stress theory
Esmail
Zarezadeh
Ali
Shirpay
In this paper, pull-in behavior of cantilever micro/nano beams made of bi directional functionally graded materials (BDFGM) with small scale effects under electrostatic force is investigated. Couple stress theory is employed to study the influence of small-scale on pull-in behavior. The material properties except Poisson’s ratio obey the arbitrary function in the thickness and length direction. The approximate analytical solutions for the pull-in voltage and pull-in displacement of the microbeams are derived using the Galerkin method. Comparison between the results of present work with other article for pull-in behavior of a microbeams made of isotropic material reveals the accuracy of this study. Numerical results explored the effects of material length scale parameter, inhomogeneity constant, gap distance and dimensionless thickness.
pull-in
couple stress
Bi directional functionally graded materials
Size effect
Galerkin
2020
12
01
472
481
https://jcamech.ut.ac.ir/article_78641_0346b968d32523ced5fbfcd1dd7399a4.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Investigation of the effect of angle beam transducer parameters on the lamb wave field in the three–layer plate by normal mode expansion method
Pezhman
Taghipour Birgani
The effect of angle beam transducer parameters such as wedge angle and width transducer on the Lamb wave field generated in the elastic-viscoelastic three-layer plate has been investigated using normal mode expansion method. At first, the propagation of Lamb wave in the three-layer plate has been investigated using global matrix method, and all the modes that are propagated in the three-layer plate have been specified. Then, the optimum parameters of angle beam transducer have been obtained to generate a mode with minimum attenuation at a specific frequency. In addition to this mode, other modes are also generated in the three-layer plate, but this mode has maximum energy in the three-layer plate. The results indicate that the energy contribution of the mode with minimum attenuation at a specific frequency is 99.9% of the total energy and this mode has the highest energy contribution.
Angle Beam Transducer
Three-Layer Plate
Attenuation
Lamb Wave
Normal Mode Expansion
2020
12
01
482
485
https://jcamech.ut.ac.ir/article_78642_d6c83a88baeff2b1e9f2a7e677f0b4a2.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Mechanical behavior analysis of a clamped-clamped micro-beam with stepped viscoelastic layer under electrostatic excitation
maryam
ghalenoei
Mehdi
Zamanian
Behnam
Firouzi
seyed ali asghar
hosseini
In this study, static deflection, natural frequency and nonlinear vibration in bi-layer clamped-clamped microbeam are investigated. In this configuration, the second layer is the viscoelastic layer which covers a part of the microbeam length. This model is the main element of many chemical microsensors. The governing equations of motion for the system are obtained by Lagrange method and discretized using the assumed mode method. The non-uniform micro-beam modes shape are used as the comparison function in the assumed mode method. Initially, considering the DC voltage, system static response and natural frequency around the static position are obtained. Then, considering the AC voltage, the dynamic response around the dynamic position is calculated by both analytical (perturbation method) and numerical methods (Rung-kutta) and compared for validation purposes. The effect of different geometrical parameters of the viscoelastic layer on the static and dynamic behaviors of the system is also analyzed. The results indicate that the dimensions and location of the viscoelastic layer significantly affect the static and dynamic behavior of the system. Therefore, by using this property and considering the application of microsensors, their behaviors can be made efficient. For sensors operating based on resonance frequency shift, the optimum shift of frequency state can be obtained by varying the dimensions and position of the viscoelastic layer. Moreover, time of response can be optimized when the system is operating based on changes in the capacity of a capacitor. The results also represent that convergence in the assumed mode method used in this paper is feasible even using a single mode, whereas in previous works and using the Galerkin method, convergence was fulfilled in the presence of 3 modes.
MEMS
Viscoelastic
microbeam
Galerkin
2020
12
01
486
497
https://jcamech.ut.ac.ir/article_78643_b95d1b03cbade8513ce383140959e8b5.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Are reported methods for synthesizing nanoparticles and microparticles by magnetic stirrer reproducible?
Narges
Mahmoodi
Jafar
Ai
Zahra
Hassannejad
Somayeh
Ebrahimi-Barough
Elham
Hasanzadeh
Amin
Hadi
Houra
Nekounam
Vafa
Rahimi-Movaghar
One of the most common tools for fabricating different drug-loaded polymeric particles is magnetic stirrer, a widely-used tool in nano-based drug delivery systems. Typically, the revolutions per minute (rpm) or G-Force of the stirrer are reported in related literature, while other parameters generate less attention and must be better understood. Reporting the rpm or G-Force is likely insufficient for producing the same vortex flow intensity and mono-dispersity as having a reliable and reproducible nanoparticle and microparticle synthesis method. We speculate that the magnetic stirrer bar’s length and diameter, and the size of the cylindrical container, affect the qualities of nanoparticles and microparticles. Given the importance of these particle characteristics in the field of nanomedicine, understanding these details would improve reporting method reliability. These data are currently missing in most related papers and must be reported. The purpose of our study is to highlight the importance of these underestimated parameters (magnetic bar’s length, diameter, and the size of the cylindrical container) and the impact on the reproducibility of particle synthesis methods using a magnetic stirrer.
Vortex Flow
Nanomedicine
Magnetic bar
Liquid height
Mono-dispersity
2020
12
01
498
500
https://jcamech.ut.ac.ir/article_78644_b01c3894b07381d28f467988019f0c25.pdf
Journal of Computational Applied Mechanics
J Appl. Comput. Appl. Mech.
2423-6713
2423-6713
2020
51
2
Review of the application and mechanism of surface enhanced raman spectroscopy (sers) as biosensor for the study of biological and chemical analyzes
Vahid
Eskandari
Amin
Hadi
Raman spectroscopy is an important method for the identification of molecules that is widely used to determine the chemical and structural properties of various materials. Many materials have special Raman spectra so that this phenomenon can it has become an effective tool for studying the structural and chemical properties of molecules. Since Raman spectroscopy can provide accurate information on the chemical and structural properties of biological compounds, this method is used in the field of science. Vital and especially in biological and medical studies is rapidly expanding. Raman is inherently weak and sometimes masked by noise and fluorescence. As a result, the study of low-concentration molecules is not feasible and the need to amplify the Raman scattering signal is clearly felt. . One of the efficient methods for studying low and even single molecular concentrations is the Surface Enhanced Raman Scattering (SERS) method. It uses gold, silver, copper and noble metal nanoparticles to enhance the Raman scattering signal. . SERS has been rapidly expanding over the past four decades, as applications for recognition in the fields of chemistry, materials sciences, biochemistry and biosciences are rapidly expanding. Advances in the manufacture of SERS-based biosensors are a major breakthrough in the detection of biological materials in which the electromagnetic field (effect) molecule is affected by the external field, this larger substitute field due to electromagnetic resonance near the metal surface is formed. Mechanisms of electromagnetic field (field effect) amplifiers mainly contribute to the development of SERS, which includes the study of detection performance, direct and indirect fabrication methods for the identification of biological and chemical analytes, Applications of biosensors, amplifiers, and SERS-based biosensor structures to detect biomolecules are briefly described.
Surface Enhanced Raman Spectroscopy (SERS)
Biological Nano-Sensor
Biological analytes
Chemicals
Metal Nanoparticles
2020
12
01
501
509
https://jcamech.ut.ac.ir/article_77543_0bd43a9e5746f24716f9b657ac47c9b8.pdf