فهرس المقالات Flexible core

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  1 - Free Vibration Analysis of Multi-Layer Rectangular Plate with Two Magneto-Rheological Fluid Layers and a Flexible Core
  M Shekarzadeh M.M Najafizadeh P Yousefi A. R Nezamabadi K Khorshidi
  10.22034/jsm.2019.1877385.1487
  In the present article, the free vibration analysis of a multi-layer rectangular plate with two magneto-rheological (MR) fluid layers and a flexible core is investigated based on exponential shear deformation theory for the first time. In exponential shear deformation t أکثر

  In the present article, the free vibration analysis of a multi-layer rectangular plate with two magneto-rheological (MR) fluid layers and a flexible core is investigated based on exponential shear deformation theory for the first time. In exponential shear deformation theory, exponential functions are used in terms of thickness coordinate to include the effect of transverse shear deformation and rotary inertia. The displacement of the flexible core is modeled using Frostig’s second order model which contains a polynomial with unknown coefficients. MR fluids viscosity can be varied by changing the magnetic field intensity. Therefore, they have the capability to change the stiffness and damping of a structure. The governing equations of motion have been derived using Hamilton`s principle. The Navier technique is employed to solve derived equations. To validate the accuracy of the derived equations, the results in a specific case are compared with available results in the literature, and a good agreement will be observed. Then, the effect of variation of some parameters such as magnetic field intensity, core thickness to panel thickness ratio and MR layer thickness to panel thickness ratio on natural frequency of the sandwich panel is investigated. تفاصيل المقالة
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  2 - Vibration Behavior of Thick Sandwich Composite Beam with Flexible Core Resting on Incompressible Fluid Foundation
  M Khosravi S Jafari Mehrabadi K Malekzadeh Fard
  10.22034/jsm.2021.1938490.1715
  In this research, free flexural vibration of a thick sandwich composite beam that is made up of two composite face sheets and a flexible foam-made core based on a fluid is investigated. Governing equations for the sandwich beam were extracted using a higher-order theory أکثر

  In this research, free flexural vibration of a thick sandwich composite beam that is made up of two composite face sheets and a flexible foam-made core based on a fluid is investigated. Governing equations for the sandwich beam were extracted using a higher-order theory. The face sheets were modeled using the first-order shear deformation theory (FSDT). In the analysis of the multilayer sandwich composite beam, the layers and the core in the middle were assumed to be well attached to one another, and continuous strain functions at the layer interfaces were assumed. Moreover, displacements were assumed to be small, so that the analyses could be performed in linear elastic region with simply supported boundary condition for the beam. Equations of motion of the beam were extracted using energy equations and Hamilton’s principle. Continuing with the research, effects of changing different parameters were evaluated; these included core thickness to total thickness ratio, beam length to total thickness ration, face sheet material, fluid density, and fluid height. The results showed that the presence of the liquid tend to lower the natural frequency of the structure. Our investigations further indicated that the natural frequency follows an increasing trend with decreasing the fluid density. تفاصيل المقالة
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  3 - Buckling and Free Vibrations of a Magneto-Electro-Elastic Sandwich Panel with Flexible Core
  H Talebi Amanieh S.A Seyed Roknizadeh A Reza
  10.22034/jsm.2020.1900703.1594
  This paper presents the buckling and out-of-plane free vibration response of a sandwich panel with flexible core for the different boundary condition. In the desired configuration of the sandwich panel, the top and bottom plates are made of magneto-electro-elastic (MEE) أکثر

  This paper presents the buckling and out-of-plane free vibration response of a sandwich panel with flexible core for the different boundary condition. In the desired configuration of the sandwich panel, the top and bottom plates are made of magneto-electro-elastic (MEE) plates. Moreover, the in-plane electric and magnetic potential fields are neglected for the derivation of the required relations. The sandwich structure is subjected to axial force in both longitudinal and transverse directions; in addition, and the top and bottom plates are exposed to electric and magnetic fields. The governing equations of motion for MEE sandwich panel with a flexible core are derived based on the first-order shear deformation theory by neglecting the displacement of the mid-plate and using the Hamilton’s principle. Furthermore, the derived partial differential equations (PDEs) are solved. According to the obtained numerical results, the core thickness, variation of electric field, variation of magnetic field and plate length are introduced as the most influential parameters on the free vibration response of the panel as well as the critical force of buckling. As one of the results, the electric potential is inversely related to the natural frequency and buckling load, so that with increasing the electric potential, the natural frequency and critical load of the structure is also increased.Moreover, the magnetic potential is directly related to the natural frequency and buckling load of the system, and increasing trends of natural frequency and critical load are observed by increasing the magnetic potential. تفاصيل المقالة
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  4 - Free Vibration of Sandwich Panels with Smart Magneto-Rheological Layers and Flexible Cores
  G Payganeh K Malekzadeh H Malek-Mohammadi
  This is the first study on the free vibrational behavior of sandwich panels with flexible core in the presence of smart sheets of oil which is capable of the excitation of magnetic field. In order to model the core, the improved high order theory of sandwich sheets was أکثر

  This is the first study on the free vibrational behavior of sandwich panels with flexible core in the presence of smart sheets of oil which is capable of the excitation of magnetic field. In order to model the core, the improved high order theory of sandwich sheets was used by a polynomial with unknown coefficients first degree shear theory was used for the sheets. The derived equations based on Hamilton principle with simple support boundary condition for upper and lower sheets were solved using Navier technique. Accuracy and precision of the theory were investigated by comparing the results of this study with those of analytical and numerical works. In the conclusion section, effect of the intensity of magnetic field and other physical parameters including ratio of sheet's length to width, ratio of sheet's length to thickness, ratio of core thickness to sheet's overall thickness, and ratio of oil layer thickness to sheet's overall thickness on natural frequency was investigated. تفاصيل المقالة
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  5 - Free Vibration and Buckling Analysis of Sandwich Panels with Flexible Cores Using an Improved Higher Order Theory
  K Malekzadeh Fard H Malek-Mohammadi
  In this paper, the behavior of free vibrations and buckling of the sandwich panel with a flexible core was investigated using a new improved ‎high-order sandwich panel theory. In this theory, equations of motion were formulated based on shear stresses in the core. F أکثر

  In this paper, the behavior of free vibrations and buckling of the sandwich panel with a flexible core was investigated using a new improved ‎high-order sandwich panel theory. In this theory, equations of motion were formulated based on shear stresses in the core. First-order shear deformation theory was ‎applied for the procedures. In this theory, for the first time, incompatibility problem of velocity and acceleration field existing in Frostig's ‎first theory was solved using a simple analytical method. The main advantage of this theory is its simplicity and less number of equations than the ‎second method of Frostig's high-order theory. To extract dynamic equations of the core, three-dimensional elasticity theory was utilized. ‎Also, to extract the dynamic equations governing the whole system, Hamilton's principle was used. In the analysis of free vibrations, the ‎panel underwent primary pressure plate forces. Results demonstrated that, as plate pre-loads got closer to the critical buckling loads, the natural frequency of the panel tended zero. The results obtained from the present theory were in good correspondence with the ‎results of the most recent papers. تفاصيل المقالة
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  6 - Free vibration analysisof soft-core composite-faced sandwich plates using three-dimensional finite element method
  Mohammad Mahdi Kheirikhah Hasan Aghabarati Pooneh Khosravi
  In this paper, natural frequencies of the sandwich plates with soft flexible core and composite face sheets are obtained. Three-Dimensional (3D) finite element method (FEM) is used for constructing and analyzing of the sandwich plates to obtain their natural frequencies أکثر

  In this paper, natural frequencies of the sandwich plates with soft flexible core and composite face sheets are obtained. Three-Dimensional (3D) finite element method (FEM) is used for constructing and analyzing of the sandwich plates to obtain their natural frequencies. Continuity conditions for transverse shear stresses at the interfaces as well as transverse flexibility and transverse normal strain and stress of the core are considered.The effects of plate dimensions such as aspect ratio and thickness ratio are studied. Also, different boundary conditions such as all edges clamped (CCCC), all edges simply supported (SSSS) and combined boundary conditions including (CFCF)are applied to the sandwich plates. Comparison of the present results in special case with those of the accurate plate theories confirms the accuracy of the proposedmodel. تفاصيل المقالة