Isfahan University of Thechnology
Computational Methods in Engineering
2228-7698
2423-5741
39
2
2021
2
1
Numerical Simulation of Particle Separation in the Fluid Flow in a Microchannel Including Spiral and Acoustic Regions
1
21
FA
F.
Shabani
Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
M.
Saghafian
saghafian@cc.iut.ac.ir
D.
Saeidi
Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
F.
F. Momennasab
Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
10.47176/jcme.39.2.0571
Particulate separation has many applications in medicine, biology and industry. In this research, the separation of polystyrene particles with a diameter of 10, 20 and 30 μm in the fluid flow of a microchannel is investigated. The microchannel consists of a spiral region and a straight region under the influence of acoustic waves. In the spiral region, the particles under hydrodynamic effects undergo the initial separation; then the particles enter the straight region of the microchannel, and the final separation of the particles is done by the force generated and exerted through the acoustic waves. The effects of acoustic frequency and the number of spiral region loops on separation are investigated. The results show that for measured dimensions and parameters, at 1 MHz acoustic wave, when the number of loops is 2 for the spiral region, the particles at the end of the path are in a suitable position for separation. In addition, the results show that the separation of particles with this hybrid system is better than that done by the simple methods, and the separation rate can be as high as 100%
Acoustic wave, Spiral microchannel, Particle separation, Microfluidics
http://jcme.iut.ac.ir/article-1-784-en.html
http://jcme.iut.ac.ir/article-1-784-en.pdf
Isfahan University of Thechnology
Computational Methods in Engineering
2228-7698
2423-5741
39
2
2021
2
1
Design of a Constrained Nonlinear Controller using Firefly Algorithm for Active Suspension System
23
44
FA
Z.
Z. Ahangari Sisi
Faculty of Mechanical Engineering, Sahand University of Technology, Tabriz, Iran
M.
Mirzaei
Faculty of Mechanical Engineering, Sahand University of Technology, Tabriz, Iran
Mirzaei@sut.ac.ir
S.
Rafatnia
Faculty of Mechanical Engineering, Sahand University of Technology, Tabriz, Iran
B.
Alizadeh
Faculty of Basic Science, Sahand University of Technology, Tabriz, Iran
10.47176/jcme.39.2.7461
Active vehicle suspension system is designed to increase the ride comfort and road holding of vehicles. Due to limitations in the external force produced by actuator, the design problem encounters the constraint on the control input. In this paper, a novel nonlinear controller with the input constraint is designed for the active suspension system. In the proposed method, at first, a constrained multi-objective optimization problem is defined. In this problem, a performance index is defined as a weighted combination of the predicted responses of the nonlinear suspension system and control input. Then, this problem is solved by the modified firefly optimization algorithm to find the constrained optimal control input. To evaluate the performance of the proposed method, the results of the unconstrained and constrained controllers are provided and discussed for various road excitations. The results show a remarkable increase in the ride comfort with the limited force, while other suspension outputs including the suspension travel and tire deflection being in the acceptable ranges. In addition, these controllers are compared with Sliding Mode Control (SMC) and Nonlinear Model Predictive Control (NMPC) in the presence of model uncertainty.
Active suspension system, Nonlinear control, Constrained optimal control, Input constraint, Firefly algorithm
http://jcme.iut.ac.ir/article-1-788-en.html
http://jcme.iut.ac.ir/article-1-788-en.pdf
Isfahan University of Thechnology
Computational Methods in Engineering
2228-7698
2423-5741
39
2
2021
2
1
A New Recursive Formulation for the Mixed Redundancy Strategy in Reliability Optimization Problems
45
58
FA
M.
Abouei Ardakan
Department of Industrial Engineering, Faculty of Engineering, Kharazmi University, Tehran, Iran
mabouei2001@gmail.com
S.
Talkhabi
Department of Industrial Engineering, Faculty of Engineering, Kharazmi University, Tehran, Iran
10.47176/jcme.39.2.7471
One of the common approaches for improving the reliability of a specific system is to use parallel redundant components in subsystems. This approach, which is known as the redundancy allocation problem (RAP), includes the simultaneous selection of the component type and its level for each subsystem in order to maximize the system reliability.Traditionally, there are two redundancy strategies, namely active and standby, for the redundant components. Recently, a new powerful strategy called mixed strategy has been developed. It has been proved that the mixed strategy has a better performance when compared to both previous strategies. The main issue in utilizing the mixed strategy is its complicated formulation and sophisticated calculations, leading to a time-consuming procedure for solving the problems. Hence, in this paper, a new formulation based on the recursive approach is introduced to ease the calculation of the mixed strategy. In the new formulation, the complex double integral calculations are removed and the calculation times is reduced. The proposed recursive formulation provides a general statement for the mixed strategy formula which is not changed by altering the number of components in each subsystem. This flexibility and stability in the formula can be very important, especially for large scale cases. In order to evaluate the new approach and to compare its performances with the previous formulation, a benchmark problem with 14 subsystems is considered and the results of the two formulation are compared with each other.
Reliability optimization, Redundancy allocation problem, Mixed strategy, Recursive functions
http://jcme.iut.ac.ir/article-1-789-en.html
http://jcme.iut.ac.ir/article-1-789-en.pdf
Isfahan University of Thechnology
Computational Methods in Engineering
2228-7698
2423-5741
39
2
2021
2
1
The Nonlinear Bending Analysis for Circular Nano Plates Based on Modified Coupled Stress and Three- Dimensional Elasticity Theories
59
72
FA
Z.
Barouei
Department of Mechanical Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran
M.
Jabbarzadeh
Department of Mechanical Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran
jabbarzadeh@mshdiau.ac.ir
10.47176/jcme.39.2.7491
In this paper, the nonlinear bending analysis for annular circular nano plates is conducted based on the modified coupled stress and three-dimensional elasticity theories. For this purpose, the equilibrium equations, considering nonlinear strain terms, are calculated using the least energy potential method and solved by the numerical semi-analytical polynomial method. According to the previous works, there have been no studies calculating all boundary conditions numerically based on three-dimensional elasticity. Typically, the research done on three-dimensional elasticity is either finite element or only for a simply-supported boundary condition. In this research, for the first time, the nonlinear analysis of bending is calculated with the help of three-dimensional elasticity for a variety of boundary conditions. Also, with the help of the modified couple stress theory, the results on the nano-scale scale have been studied. In the following, while validating the results, we investigate the changes in the scale parameter for the types of boundary conditions, the effect of changing the parameter of scale in different thicknesses, and the impact of the parameter of scale on the linear and nonlinear results.
Nonlinear bending, Circular Nano plates, Three-dimensional elasticity theory, Modified coupled stress, Semi-analytical polynomial method
http://jcme.iut.ac.ir/article-1-790-en.html
http://jcme.iut.ac.ir/article-1-790-en.pdf
Isfahan University of Thechnology
Computational Methods in Engineering
2228-7698
2423-5741
39
2
2021
2
1
Buckling Analysis of Variable Stiffness Composite Laminates by Semi-Analytical Finite Strip Method
73
95
FA
R.
Keshavarzi
Civil Engineering Department, Faculty of Engineering, Yasouj University, Yasouj, Iran.
Sh.
Hatami
Civil Engineering Department, Faculty of Engineering, Yasouj University, Yasouj, Iran.
hatami@yu.ac.ir
Sh.
Hashemi
Civil Engineering Department, Faculty of Engineering, Yasouj University, Yasouj, Iran.
10.47176/jcme.39.2.4912
Plates made of laminated composite materials with variable stiffness can have wide applications in various branches of engineering due to such advantages as high strength /stiffness to weight ratio. In these composites, curved fibers are used to reinforce each lamina instead of the straight fibers. In this paper, the application of finite strip method for the buckling analysis of moderately thick composite plates with variable stiffness is investigated. For buckling analysis, a semi-analytical finite strip method based on the first-order shear deformation theory is employed. In this method, all displacements are presumed by the appropriate harmonic shape functions in the longitudinal direction and polynomial interpolation functions in the transverse direction. The minimum potential energy method has been used to develop the stability formulations. This analysis examines the effect of using curved fibers instead of straight fibers on the laminate composites. The critical loads obtained from this analysis are compared with those of other researchers and the efficiency and accuracy of the developed finite strip method are confirmed. Comparison of the analysis results of these plates shows that changing the slope of the fibers can lead to a significant change in the buckling response. Also, increasing the number of the terms of shape functions in the longitudinal direction has a significant effect on the convergence to the desired results.
Buckling, Laminated composite, Variable stiffness, Finite strip method, First-order shear deformation theory.
http://jcme.iut.ac.ir/article-1-805-en.html
http://jcme.iut.ac.ir/article-1-805-en.pdf
Isfahan University of Thechnology
Computational Methods in Engineering
2228-7698
2423-5741
39
2
2021
2
1
Estimation of the Stress Intensity Factors for Surface Cracks in Spherical Electrode Particles Subject to Phase Separation
97
117
FA
S.
Esmizadeh
Department of Civil Engineering, University of Isfahan, Isfahan, Iran.
H.
Haftbaradaran
Department of Civil Engineering, University of Isfahan, Isfahan, Iran.
h.haftbaradaran@eng.ui.ac.ir
F.
Mossaiby
Department of Civil Engineering, University of Isfahan, Isfahan, Iran.
10.47176/jcme.39.2.7851
Experiments have frequently shown that phase separation in lithium-ion battery electrodes could lead to the formation of mechanical defects, hence causing capacity fading. The purpose of the present work has been to examine stress intensity factors for pre-existing surface cracks in spherical electrode particles during electrochemical deintercalation cycling using both analytical and numerical methods. To this end, we make use of a phase field model to examine the time-dependent evolution of the concentration and stress profiles in a phase separating spherical electrode particles. By using a geometrical approximation scheme proposed in the literature, stress intensity factors at the deepest point of the pre-existing surface cracks of semi-elliptical geometry are calculated with the aid of the well-established weight function method of fracture mechanics. By taking advantage of a sharp-interphase core-shell model, an analytical solution for the maximum stress intensity factors arising at the deepest point of the surface cracks during a complete deintercalation half-cycle is also developed. Numerical results for evolution of the concentration profile and the distribution of the hoop stresses in the particle are presented; further, the stress intensity factors found numerically based on the phase field model are compared with those predicted by the analytical core-shell model. The results of the numerical model suggest that the maximum stress intensity factor could significantly vary with changes in the surface flux, increasing potentially by a factor of two within the range of parameters considered here, when the concentration difference between the two phases is decreased.
Lithium ion battery, Phase separation, Phase field modeling, Fracture mechanics.
http://jcme.iut.ac.ir/article-1-810-en.html
http://jcme.iut.ac.ir/article-1-810-en.pdf
Isfahan University of Thechnology
Computational Methods in Engineering
2228-7698
2423-5741
39
2
2021
2
1
Solution of Harmonic Problems with Weak Singularities Using Equilibrated Basis Functions in Finite Element Method
119
146
FA
O.
Bateniparvar
Department of Civil Engineering, Isfahan University of Technology, Isfahan, Iran.
N.
Noormohammadi
Department of Civil Engineering, Isfahan University of Technology, Isfahan, Iran.
Noormohammadi@iut.ac.ir
A. M.
Salehi
Department of Civil Engineering, Isfahan University of Technology, Isfahan, Iran.
10.47176/jcme.39.2.6242
In this paper, Equilibrated Singular Basis Functions (EqSBFs) are implemented in the framework of the Finite Element Method (FEM), which can approximately satisfy the harmonic PDE in homogeneous and heterogeneous media. EqSBFs are able to automatically reproduce the terms consistent with the singularity order in the vicinity of the singular point. The newly made bases are used as the complimentary enriching part along with the polynomial bases of the FEM to construct a new set of shape functions in the elements adjacent to the singular point. It will be shown that the use of the combined bases leads to the quality improvement of the solution function as well as its derivatives, especially in the vicinity of the singularity.
Singularity, Harmonic, Equilibrated basis functions, Finite Element Method.
http://jcme.iut.ac.ir/article-1-828-en.html
http://jcme.iut.ac.ir/article-1-828-en.pdf