فهرست مطالب

Mechanical Engineering Transactions - Volume:20 Issue:1, 2019
  • Volume:20 Issue:1, 2019
  • تاریخ انتشار: 1397/12/10
  • تعداد عناوین: 6
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  • Gbeminiyi Sobamowo *, Ahmed Yinusa Pages 5-45
    This paper presents an insight into the boundary layer of free convection and heat transfer of nanofluids over a vertical plate at very low and high Prandtl number. Suitable similarity variables are used to convert the governing systems of nonlinear partial differential equations of the flow and heat transfer to systems of nonlinear ordinary differential equations which are solved using multi-step differential transformation method. The approximate analytical solutions are verified with numerical solutions. From the parametric studies, it is observed that the velocity and temperature of the nanofluid decreases and increases, respectively as the Prandtl number and volume-fraction of the nanoparticles in the base fluid increase. Also, the decrease in velocity and increase in temperature are highest in lamina shaped nanoparticle followed by platelets, cylinder, bricks and sphere shaped nanoparticles, respectively. Using a common base fluid to all the nanoparticle type, it is observed that the decrease in velocity and increase in temperature are highest TiO2 followed by CuO, Al2O3 and SWCNTs nanoparticles, in that order. The present study will enhance the understanding of free convection boundary-layer problems.
    Keywords: free convection, Boundary Layer, Heat Transfer, nanofluid, Multi-step differential transformation method
  • Mohammad Talley, Ahmad Reza Khorshidvand * Pages 46-70
    In this study, free vibration of functionally graded rectangular plates for various types of boundary conditions has been presented . The properties of the plate are assumed as power- law form along the thickness direction , while poisson's ratio is kept constant. the linear vibration equations of functionally graded rectangular plates are derived based on first order shear deformation theory by using Hamilton's principles . The results are tabulated for a large range of plate aspect ratios. This appears to be the first thorough study by using Differential quadrature method and First order Shear Deformation Theory based that presents effects of boundary conditions , material , and geometrical parameters on natural frequencies of functionally graded rectangular plates . The numerical results on natural frequencies of the FG plate for combination of boundary conditions, volume fraction index, radii to thickness, and aspect ratio are presented and with existing results in the literature are compared.
    Keywords: Differential Quadrature Method, Free vibration, Functionally graded materials, rectangular plates
  • Koosha Arteshyar, Mohammad Monsour Mohieddin Ghomshei * Pages 71-93
    In this article, using generalized differential quadrature (GDQ) methods, free vibration of a thin annular plate coupled with two open circuit piezoelectric layers, is numerically studied based on the classical plate theory. The governing differential equations with respective boundary conditions are derived and transformed into a set of algebraic equations by implementing the GDQ rule, then solved as an eigenvalue problem to obtain the natural frequencies and mode shapes of the plate. Convergence of the solutions obtained for the natural frequencies is studied. Also, the present numerical model validated by comparing its numerical results with those reported in literature. Finally, parametric studies are carried out and the effects of a number of important parameters on the natural frequencies are investigated.
    Keywords: Free vibration, Piezoelectric, Annular plate, Differential Quadrature Method
  • Masoud Babaei, Kamran Asemi *, Pedram Safarpour Pages 94-112
    In this paper, static response and buckling analysis of functionally graded saturated porous beam resting on Winkler elastic foundation is investigated. The beam is modeled using higher-order shear deformation theory in conjunction with Biot constitutive law which has not been surveyed so far. Three different patterns are considered for porosity distribution along the thickness of the beam: 1) poro/nonlinear non-symmetric distribution, 2) poro/nonlinear symmetric distribution and 3) poro/monotonous distribution. To obtain the governing equations, geometric stiffness matrix concept and finite element method is used. The effect of various parameters such as: 1) Stiffness of elastic foundation 2) Slender ratio 3) Porosity coefficient 4) Skempton coefficient 5) Porosity distributions and 6) Different boundary conditions has been investigated to draw practical conclusions.
    Keywords: Saturated porous beam, Functionally graded, Third-order beam theory, Buckling, finite element method
  • M.M. Mahdavi, Heshmat Allah Haghighat * Pages 113-128
    In this paper, rod drawing process of strain-hardening materials is investigated by analytical, numerical and experimental methods. The classic upper bound solution, based on the assumption of perfect plasticity, has been extended to consider the work-hardening of the material during the drawing process. For a given process conditions and mechanical properties of the rod material, the power terms and the required drawing force are determined and optimized with respect to the die angle. The results afforded by this solution agree with data from finite element simulation, using the finite element code DEFORM 2D, and some experiments performed by the authors. It is shown that the drawing force and the optimum die angle are affected primarily by the work-hardening exponent. The amount of drawing force increases as work-hardening of material considers in the analytical solution and by increasing the work-hardening exponent, the drawing force and the optimum die angle are decreased. It is also shown that by increasing the work-hardening exponent of the rod material, the maximum possible reduction in area is increased.
    Keywords: Rod drawing, Work-hardening, Optimum die angle, experiment
  • Nabiollah Palangsavar *, Amir Reza Mamouri Pages 129-151
    Using hydraulic interconnected suspension (HIS) system to improve the stability of the vehicles is a matter of recent interest of many scholars. In this paper, application of this kind of suspension system and its impact on the stability of the vehicle are studied. The governing dynamic relations of the system are presented, using free body diagram, Newton-Euler motion equations, and relations related to the mass flow rate of fluid. By completing the design of the passive suspension system and the hydraulic interconnected suspension system and employing the half car model in the transverse direction with four degree of freedom, Matlab (Simulink) software is used to investigate and compare the body and wheel responses of the vehicle in exposure to road surface roughness. In the end, quaternion neural network controller has been used due to the obtained nonlinear equations in interaction of suspension system as well as the coupled differential equations. Using quaternion neural network controller, the results indicated that the stability of vehicle and ride comfort are increased and also more smooth responses are generated.
    Keywords: Quaternion Neural Network (QNN) Controller, Hydraulic Interconnected Suspension (HIS) System, Passive Suspension System, Vehicle Stability