فهرس المقالات Variable thickness

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  1 - Stagnation-point flow of a viscous fluid towards a stretching surface with variable thickness and thermal ‎radiation‎
  B. C. Prasanna ‎Kumara ‎‎G. K‎. ‎ ‎Ramesh‎ A. J. Chamkha‎ B. J. ‎Gireesha‎‎
  ‎In the present analysis‎, ‎we study the boundary layer flow of an incompressible viscous fluid near the two-dimensional stagnation-point flow over a stretching surface‎. ‎The effects of variable thickness and radiation are also taken into account an أکثر

  ‎In the present analysis‎, ‎we study the boundary layer flow of an incompressible viscous fluid near the two-dimensional stagnation-point flow over a stretching surface‎. ‎The effects of variable thickness and radiation are also taken into account and assumed that the sheet is non-flat‎. ‎Using suitable transformations‎, ‎the governing partial differential equations are first converted to ordinary one and then solved numerically by fourth and fifth order Runge-Kutta-Fehlberg method with shooting technique‎. ‎The influence of the various interesting parameters on the flow and heat transfer is analyzed and discussed through graphs in detail‎. ‎Comparison of the present results with known numerical results is shown and a good agreement is observed‎. ‎It is found that boundary layer is formed when $\lambda > 1 $‎. ‎On the other hand‎, ‎an inverted boundary layer is formed when $\lambda < 1 $‎.‎ تفاصيل المقالة
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  2 - Thermo-Elastic and Time-Dependent Creep Evolution Behaviour of Ferritic Steel Rotating Disks using Theta Projection Concept
  H. Daghigh V. Daghigh
  In this article, thermo-elastic and creep evolution behaviour of ferritic steel rotating disks with variable thickness are investigated. Four thickness profiles of uniform, convex, concave and linear are considered for the disk geometry. The material creep constitutive أکثر

  In this article, thermo-elastic and creep evolution behaviour of ferritic steel rotating disks with variable thickness are investigated. Four thickness profiles of uniform, convex, concave and linear are considered for the disk geometry. The material creep constitutive model is defined by the Θ projection concept, based on the experimental results existing in the literature. Loading applied is due to the inertial body force caused by the rotation and a constant temperature field throughout the disk. To achieve history of stresses and displacements, a numerical procedure using finite difference and Prandtl-Reuss relations is used. Stress and deformation histories are calculated using successive elastic solution method. In order to verify the solution approach, both composite and aluminum rotating disks were taken into account and the thermo-elastic and time-dependent creep behaviours for composite as well as the former for aluminum were obtained. Results from the current study were found to be in very good agreement with those available from literature in the area. It was shown that convex thickness profile disks display the least creep displacement, creep effective and circumferential stresses. Additionally, constant and concave thickness profiles were positively correlated with time while for linear and convex ones, it was found to have an inverse trend. تفاصيل المقالة
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  3 - Nonlinear Investigation of Magnetic Influence on Dynamic Behaviour of Non-Homogeneous Varying Thickness Circular Plates Resting on Elastic Foundations
  S.A Salawu G.M Sobamowo O.M Sadiq
  10.22034/jsm.2021.1912143.1650
  In this work, a nonlinear investigation of non-homogeneous varying thickness circular plates resting on elastic foundations under the influence of the magnetic fieldis investigated. The non-homogeneity of the circular plates’ material is presumed to occur due to l أکثر

  In this work, a nonlinear investigation of non-homogeneous varying thickness circular plates resting on elastic foundations under the influence of the magnetic fieldis investigated. The non-homogeneity of the circular plates’ material is presumed to occur due to linear and parabolic changes in Young’s modulus likewise the density along the radial direction in a unique manner. The geometric Von Kármán equations are used in modelling the governing differential equations. The transverse deflection is approximated using an assumed single term mode shape while the central deflection in form of Duffing’s equation is obtained using the Galerkin method. Subsequently, the semi-analytical solutions are provided using the Optimal Homotopy Asymptotic Method (OHAM), the analytical solutions are used for parametric investigation. The results in this work are in good harmony with past results in the literature. From the results, it is realized that the nonlinear frequency of the circular plate increases with an increase in the linear elastic foundation. Also, the results showed that clamped edge and simply supported edge condition produced the same hardening nonlinearity. However, varying taper and non-homogeneity lower the nonlinear frequency ratio. Also, maximum deflection occurs when excitation force is zero, and attenuation of deflection is observed due to the presence of a magnetic field, varying thickness, homogeneity, and elastic foundation. It is anticipated that the discoveries from this research will boost the design of structures subjected to vibration. تفاصيل المقالة
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  4 - Elastic Buckling of Moderately Thick Homogeneous Circular Plates of Variable Thickness
  S.K Jalali M.H Naei
  In this study, the buckling response of homogeneous circular plates with variable thickness subjected to radial compression based on the first-order shear deformation plate theory in conjunction with von-Karman nonlinear strain-displacement relations is investigated. Fu أکثر

  In this study, the buckling response of homogeneous circular plates with variable thickness subjected to radial compression based on the first-order shear deformation plate theory in conjunction with von-Karman nonlinear strain-displacement relations is investigated. Furthermore, optimal thickness distribution over the plate with respect to buckling is presented. In order to determine the distribution of the prebuckling load along the radius, the membrane equation is solved using the shooting method. Subsequently, employing the pseudospectral method that makes use of Chebyshev polynomials, the stability equations are solved. The influence of the boundary conditions, the thickness variation profile and aspect ratio on the buckling behavior is examined. The comparison shows that the results derived, using the current method, compare very well with those available in the literature. تفاصيل المقالة
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  5 - Stress Analysis of Rotating Thick Truncated Conical Shells with Variable Thickness under Mechanical and Thermal Loads
  M Jabbari M Zamani Nejad M Ghannad
  In this paper, thermo-elastic analysis of a rotating thick truncated conical shell subjected to the temperature gradient, internal pressure and external pressure is presented. Given the existence of shear stress in the conical shell due to thickness change along the axi أکثر

  In this paper, thermo-elastic analysis of a rotating thick truncated conical shell subjected to the temperature gradient, internal pressure and external pressure is presented. Given the existence of shear stress in the conical shell due to thickness change along the axial direction, the governing equations are obtained based on first-order shear deformation theory (FSDT). These equations are solved by using multi-layer method (MLM). The model has been verified with the results of finite element method (FEM). Finally, some numerical results are presented to study the effects of thermal and mechanical loading, geometry parameters of truncated conical shell. تفاصيل المقالة
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  6 - Thermal Stability of Thin Rectangular Plates with Variable Thickness Made of Functionally Graded Materials
  M Pouladvand
  In this research, thermal buckling of thin rectangular plate made of Functionally Graded Materials (FGMs) with linear varying thickness is considered. Material properties are assumed to be graded in the thickness direction according to a simple power law distribution in أکثر

  In this research, thermal buckling of thin rectangular plate made of Functionally Graded Materials (FGMs) with linear varying thickness is considered. Material properties are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The supporting condition of all edges of such a plate is simply supported. The equilibrium and stability equations of a FGM rectangular plate (FGRP) under thermal loads derived based on classical plate theory (CPT) via variational formulation, and are used to determine the pre-buckling forces and the governing differential equation of the plate. The buckling analysis of a functionally graded plate is conducted using; the uniform temperature rise, having temperature gradient through-the-thickness, and linear temperature variation in the thickness and closed-form solutions are obtained. The buckling load is defined in a weighted residual approach. In a special case the obtained results are compared by the results of functionally graded plates with uniform thickness. The influences of the plate thickness variation and the edge ratio on the critical loads are investigated. Finally, different plots indicating the variation of buckling load vs. different gradient exponent k, different geometries and loading conditions were obtained. تفاصيل المقالة
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  7 - A Power Series Solution for Free Vibration of Variable Thickness Mindlin Circular Plates with Two-Directional Material Heterogeneity and Elastic Foundations
  M.M Alipour M Shariyat
  In the present paper, a semi-analytical solution is presented for free vibration analysis of circular plates with complex combinations of the geometric parameters, edge-conditions, material heterogeneity, and elastic foundation coefficients. The presented solution cover أکثر

  In the present paper, a semi-analytical solution is presented for free vibration analysis of circular plates with complex combinations of the geometric parameters, edge-conditions, material heterogeneity, and elastic foundation coefficients. The presented solution covers many engineering applications. The plate is assumed to have a variable thickness and made of a heterogeneous material whose properties vary in both radial and transverse directions. While the edge is simply-supported, clamped, or free; the bottom surface of the plate is resting on a two-parameter (Winkler-Pasternak) elastic foundation. A comprehensive sensitivity analysis including evaluating effects of various parameters is carries out. Mindlin theory is employed for derivation of the governing equations whereas the differential transform method is used to solve the resulted equations. In this regard, both the in-plane and rotary inertia are considered. Results show that degradations caused by a group of the factors (e.g., the geometric parameters) in the global behavior of the structure may be compensated by another group of factors of different nature (e.g, the material heterogeneity parameters). Moreover, employing the elastic foundation leads to higher natural frequencies and postponing the resonances. تفاصيل المقالة
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  8 - Evaluation of Buckling and Post Buckling of Variable Thickness Shell Subjected to External Hydrostatic Pressure
  A.R Ghasemi M.H Hajmohammad
  Buckling and post buckling of cylindrical shells under hydrostatic pressure is regarded as important issue in structure of submarines. These cylindrical shells have variable thickness due to construction process which effected by pressure of buckling and its destruction أکثر

  Buckling and post buckling of cylindrical shells under hydrostatic pressure is regarded as important issue in structure of submarines. These cylindrical shells have variable thickness due to construction process which effected by pressure of buckling and its destruction. In this paper, effects of changing thickness on buckling and destruction pressure under external hydrostatic pressure of a shell are studied. Results of buckling pressure of cylindrical shell have been obtained with theoretical relations and finite element method. Then, using machining process a sample of cylindrical shell with variable thickness has been produced. Buckling pressure and post buckling of the constructed sample have been obtained with the reservoir under closed-ended hydrostatic pressure. Changes of the test sample size have been considered with closed-ended testing apparatuses which are used for new evaluation of buckling. In this research, results of the pressure have been obtained in terms of the volume change. At the end, results of the finite element method have been compared with results of the analytical solutions and experimental data. Results show that the shell with variable thickness has buckling pressure close to shell bucking pressure with mean thickness. تفاصيل المقالة
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  9 - Free Vibration Analysis of Non-Uniform Circular Nanoplate
  M Zarei M Ghalami-Choobar G.H Rahimi G.R Faghani
  In this paper, axisymmetric free vibration analysis of a circular Nano-plate having variable thickness was studied. The variation in thickness of plate was considered as a linearly in radial direction. Nonlocal elasticity theory was utilized to take into account size-de أکثر

  In this paper, axisymmetric free vibration analysis of a circular Nano-plate having variable thickness was studied. The variation in thickness of plate was considered as a linearly in radial direction. Nonlocal elasticity theory was utilized to take into account size-dependent effects. Ritz functions was utilized to obtain the frequency equations for simply supported and clamped boundary. To verify accuracy of Ritz method, differential transform method (DTM) also used to drive the size dependent natural frequencies of circular nano-plates. The validity of solutions was performed by comparing present results with those of the literature for both classical plate and nano plate. Effect of nonlocal parameter, mode number and taper parameter on the natural frequency are investigated. Results showed that taper parameter has significant effect on the non-dimensional frequency and its effects on the clamped boundary condition is more than simply support. تفاصيل المقالة
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  10 - Stress analysis of non-linearly variable thickness rotating disk in gas turbine engine using hyper-geometric method
  Behrooz Shahriari Nedasadat Seddighi
  In this paper, the numerical and exact analytical calculation of elastic strains and stresses in gas turbine engine rotating disk with variable thickness, subjected to temperature gradient are presented. Galerkin method is applied to solve any kind of profiles with arbi أکثر

  In this paper, the numerical and exact analytical calculation of elastic strains and stresses in gas turbine engine rotating disk with variable thickness, subjected to temperature gradient are presented. Galerkin method is applied to solve any kind of profiles with arbitrary thickness, temperature and density functions while the other numerical and analytical methods used in previous works, are applied to profiles with certain thickness functions. Therefore, a comprehensive approach that takes all the circumstances into account was used in an attempt to fill this gap. To verify the numerical method, a few examples of rotating disks with non-linear variable thicknesses were solved using the analytical method as a reference method and their results were compared with numerical solution. A good agreement between numerical and analytical solutions was observed. In the analytical part, a new method to convert equilibrium equation of rotating disks to hyper-geometric differential equation was provided and then it was solved. Using hyper-geometric method is the main novelty of this research. The distributions of radial displacement and stresses were obtained and an appropriate comparisons and discussions were made at the same environmental conditions. تفاصيل المقالة
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  11 - Investigation on Buckling of Orthotropic Circular and Annular Plates of Continuously Variable Thickness by Optimized Ritz Method
  فاطمه فرهت نیا آرش گل شاه
  This paper investigates symmetrical buckling of orthotropic circular and annular plates of continuous variable thickness. Uniform compression loading is applied at the plate outer boundary. Thickness varies linearly along radial direction. Inner edge is free, while oute أکثر

  This paper investigates symmetrical buckling of orthotropic circular and annular plates of continuous variable thickness. Uniform compression loading is applied at the plate outer boundary. Thickness varies linearly along radial direction. Inner edge is free, while outer edge has different boundary conditions: clamped, simply and elastically restraint against rotation. The optimized RayLeigh-Ritz method is applied for buckling analysis. In this method, a polynomial function that is based on static deformation of orthotropic circular plates in bending is used. Also, byemploying an exponential parameter in deformation function, eigenvalue is minimized in respect to that parameter. The advantage of this procedure is simplicity in comparison with other methods, while whole algorithm for solution can be coded for computer programming. The effect of variation of radius, thickness, different boundary conditions, ratio of radial Young Modulus to circumferential one, ratio of outer radius to inner one in annular plates on critical buckling coefficient are investigated. The obtained results show that in plate with identical thickness, increasing of outer radius decreases the critical buckling coefficient. In addition increasing of thickness of the plates results in increase of critical buckling coefficient. تفاصيل المقالة