Papers by Mostafa Talebitooti
Thin-walled structures, May 1, 2024
Mechanics Based Design of Structures and Machines
هدیکچ تاعبرم لضافت شور کمک هب ،قیقحت نیا رد ) DQM ( یطورخم لپوک هتسوپ دازآ تاشاعترا لیلحت هب هدش ... more هدیکچ تاعبرم لضافت شور کمک هب ،قیقحت نیا رد ) DQM ( یطورخم لپوک هتسوپ دازآ تاشاعترا لیلحت هب هدش هتخادرپ یچیودناس یطورخم قیقحت نیا رد هدش یسررب یطورخم هتسوپ هسدنه .تسا ، صقان تروص هب تسا فلتخم هدام عون راهچ ،لنپ چیودناس هتسه . یلپ نوتکرتارتا ) PEEK ( تانبرک یلپ ، ) PC ( ، یلپ نلیپورپ دماج ) SPP ( و لپ موف ی مآ ی د لااب یلاگچ اب ) HDPF ( هیلا و زا یجراخ و یلخاد ياه لدم .تسا هدش رظن رد موینیمولآ سنج لوا هبترم یشرب لکش رییغت يروئت کمک هب یضایر يزاس ) FSDT ( تلاداعم و ماجنا هتسوپ رسود رد يزرم طیارش هب طوبرم تلاداعم ،هتسوپ تاشاعترا رب مکاح تکرح تلاداعم .تسا هدش جارختسا نوتلیمه شور کمک هب تکرح شور کمک هب ،هتسوپ ود لاصتا لحم رد یگتسویپ طرش هب طوبرم تلاداعم و DQ هژیو رادقم هلئسم هطبار و هدش يزاس هتسسگ جارختسا و هجیتن رد نآ ، فلتخم يزرم طیارش رثا و هتسه سنج ،طورخم سار هیواز ،تماخض ،لوط رییغت رثا .تسا هدش هبساحم یعیبط سناکرف هسیاقم ،یجنسرابتعا روظنم هب .تسا هدیدرگ یسررب یعیبط سناکرف يور و قیقحت تایبدا رد دوجوم جیاتن و هدمآ تسدب جیاتن نایم يا مرن نینچمه سوکابآ رازفا ) Abaqus ( .تسا هتفرگ تروص
Original Research Paper Received 03 August 2015 Accepted 01 November 2015 Available Online 05 Dec... more Original Research Paper Received 03 August 2015 Accepted 01 November 2015 Available Online 05 December 2015 The objective of this investigation is to present a semi-analytical method for studying the buckling of the moderately thick composite conical shells under axial compressive load. In order to derive the equilibrium equations of the conical shell, first order shear deformation shell theory is used. The equilibrium equations are derived by applying the principle of minimum potential energy to the energy function that they are, in the type of partial differential equations. In the following, the partial differential equations are transformed to algebraic type by using Galerkin and differential quadrature methods and then the standard eigenvalue equation is formed and critical buckling load is calculated. Also, to validate the results obtained in this study, comparisons are made with outcomes of previous literature and the results of Abaqus finite element software. Analyzing the r...
In the present work, study of the vibration of a functionally graded (FG) cylindrical shell made ... more In the present work, study of the vibration of a functionally graded (FG) cylindrical shell made up of stainless steel, zirconia, and nickel is presented. Free vibration analysis is presented for FG cylindrical shells with simply supported-simply supported and clamped–clamped boundary condition based on temperature independent material properties. The equations of motion are derived by Hamilton’s principle. Material properties assume to be graded in the thickness direction according to a simple power law distribution in terms of the volume fraction of the constituents. Effects of boundary conditions and volume fractions (power law exponent) on the natural frequencies of the FG cylindrical shell are studied. Frequency characteristics of the FG shell are found to be similar to those of isotropic cylindrical shells. Furthermore, natural frequencies of these shells are observed to be dependent on the constituent volume fractions and boundary conditions. Strain displacement relations fro...
Smart Materials and Structures, 2019
Vibration of a rotating functionally graded carbon nanotube-reinforced sandwich composite beam wa... more Vibration of a rotating functionally graded carbon nanotube-reinforced sandwich composite beam was controlled using two magnetostrictive actuator layers. A closed-loop velocity proportional feedback control approach was employed to mitigate the vibration amplitude. The Timoshenko beam theory (TBT) as well as the Hamilton's principle were used to derive the equations of motion. The differential quadrature method was implemented to solve the governing equations. Some convergence and comparison studies were performed to assess the stability and accuracy of results. The effects of distribution type and volume fraction of the carbon nanotubes (CNTs) and angular velocity on vibration suppression of different modes of the sandwich beam were investigated. Overshoot response of the rotating sandwich beam was significantly affected by the volume fraction and distribution type of CNTs.
Journal of Sandwich Structures & Materials, 2019
This paper reports on the numerical results that are performed with a freely vibrating magnetorhe... more This paper reports on the numerical results that are performed with a freely vibrating magnetorheological elastomer sandwich beams reinforced by carbon nanotubes, exposed to an angular velocity and a magnetic field. The shear deformable beam model of the Timoshenko is employed to model the top and bottom functionally graded carbon nanotube reinforced (FGCNTR) layers, whereas a linear viscoelastic behavior is considered for the magnetorheological elastomer core layer. Using the Hamilton principle as well as a differential quadrature method, the natural frequencies and corresponding loss factors are derived. Convergence study and comparison results with the literature show a high stability and accuracy of the present approach. Enhancement of angular velocity causes a significant increasing and decreasing trends for the natural frequencies and loss factors, respectively. Observations reveal that there is an optimum value for the magnetic field intensity in which the loss factor is the ...
Journal of Intelligent Material Systems and Structures, 2019
Vibration suppression of a carbon nanotube–reinforced sandwich beam with magnetorheological fluid... more Vibration suppression of a carbon nanotube–reinforced sandwich beam with magnetorheological fluid core is numerically investigated by employing the differential quadrature method. The beam has functionally graded carbon nanotube–reinforced composite base and constraining layers while its core layer is made of magnetorheological fluid. Four different types of distribution of carbon nanotubes along the thickness direction are considered. The extended rule of mixture is used to explain the effective material properties of the base and constraining layers of the beam. The equations of motion and corresponding boundary conditions are derived by applying Hamilton’s principle, and then these coupled differential equations are transformed into a set of algebraic equation applying the differential quadrature method. Natural frequencies and loss factors are extracted and compared with those available in literature. Convergence study has been performed to verify stability of the method. Effect...
Archive of Applied Mechanics, 2016
This paper focuses on the buckling analysis of composite sandwich conical shells subjected to a u... more This paper focuses on the buckling analysis of composite sandwich conical shells subjected to a uniform external lateral pressure based on the first-order shear deformation theory. Approximate analytical solutions are assumed to satisfy fully clamped boundary conditions and then Fourier decomposition and Galerkin method is applied to achieve closed-form relations of buckling loads. The closed analytical formula for the critical pressure has been verified by comparison with the finite-element solutions and a special case where the angle of the conical shell approaches zero, that is, a cylindrical shell. Based on this formula buckling analyses of sandwich conical shells with different types of core materials have been accomplished. The outcomes are achieved considering the effects of half-vertex cone angle, core thickness and indicating applicability, accuracy, and stability of the present method.
Mechanics of Composite Materials, 2014
ABSTRACT This paper focuses on an analysis of free vibration of thick rotating stiffened composit... more ABSTRACT This paper focuses on an analysis of free vibration of thick rotating stiffened composite cylindrical shells with different boundary conditions. The analysis is performed on the basis of a three-dimensional theory by using the layerwise-differential quadrature method (LW-DQM). The equations of motion are derived employing Hamilton’s principle. In order to accurately allow for the thickness effects, a layerwise theory is used to discretize the equations of motion and related boundary conditions through the thickness of the shells. Then, the equations of motion and the boundary conditions are transformed into a set of algebraic equations by using the DQM in the longitudinal direction. This study demonstrates the applicability, accuracy, stability, and fast rate of convergence of the present method in free vibration analyses of rotating stiffened cylindrical shells. The presented results are compared with those of other shell theories obtained by conventional methods and with a special case where the number of stiffeners approaches zero, i.e., an nonstiffened cylindrical shell, and excellent agreements are achieved. Finally, some new results are presented, which can be used as benchmark solutions for future investigations.
Latin American Journal of Solids and Structures, 2013
This paper presents effects of boundary conditions and axial loading on frequency characteristics... more This paper presents effects of boundary conditions and axial loading on frequency characteristics of rotating laminated conical shells with meridional and circumferential stiffeners, i.e., stringers and rings, using Generalized Differential Quadrature Method (GDQM). Hamilton's principle is applied when the stiffeners are treated as discrete elements. The conical shells are stiffened at uniform intervals and it is assumed that the stiffeners have similar material and geometric properties. Equations of motion as well as equations of the boundary condition are transformed into a set of algebraic equations by applying the GDQM. Obtained results discuss the effects of parameters such as rotating velocities, depth to width ratios of the stiffeners, number of stiffeners, cone angles, and boundary conditions on natural frequency of the shell. The results will then be compared with those of other published works particularly with a non-stiffened conical shell and a special case where angle of the stiffened conical shell approaches zero, i.e. a stiffened cylindrical shell. In addition, another comparison is made with present FE method for a non-rotating stiffened conical shell. These comparisons confirm reliability of the present work as a measure to approximate solutions to the problem of rotating stiffened conical shells.
Journal of Mechanics, 2010
Free vibration analysis of rotating composite laminated conical shells with different boundary co... more Free vibration analysis of rotating composite laminated conical shells with different boundary conditions using the generalized differential quadrature method (GDQM), is investigated. Equations of motion are derived based on Love's first approximation theory by taking the effects of initial hoop tension and the centrifugal and Coriolis acceleration due to rotation and initial uniform pressure load into account. Then, the equations of motion as well as the boundary condition equations are transformed into a set of algebraic equation applying the GDQM. The results are obtained for the frequency characteristics of different orthotropic parameters, rotating velocities, cone angles and boundary conditions. The presented results are compared with those available in the literature and good agreements are achieved.
Archive of Applied Mechanics, 2009
In this paper, an analytical solution for the free vibration of rotating composite conical shells... more In this paper, an analytical solution for the free vibration of rotating composite conical shells with axial stiffeners (stringers) and circumferential stiffener (rings), is presented using an energy-based approach. Ritz method is applied while stiffeners are treated as discrete elements. The conical shells are stiffened with uniform interval and it is assumed that the stiffeners have the same material and
Archive of Applied Mechanics, 2012
This paper focuses on the free vibration analysis of thick, rotating laminated composite conical ... more This paper focuses on the free vibration analysis of thick, rotating laminated composite conical shells with different boundary conditions based on the three-dimensional theory, using the layerwise differential quadrature method (LW-DQM). The equations of motion are derived applying the Hamilton's principle. In order to accurately account for the thickness effects, the layerwise theory is used to discretize the equations of motion and the related boundary conditions through the thickness of the shells. Then, the equations of motion as well as the boundary condition equations are transformed into a set of algebraic equation applying the DQM in the meridional direction. This study demonstrates the applicability, accuracy, stability and the fast rate of convergence of the present method, for free vibration analyses of rotating thick laminated conical shells. The presented results are compared with those of other shell theories obtained using conventional methods and a special case where the angle of the conical shell approaches zero, that is, a cylindrical shell and excellent agreements are achieved.
Thin-walled tubes are widely used to absorb energy in road accidents. In this paper, a novel circ... more Thin-walled tubes are widely used to absorb energy in road accidents. In this paper, a novel circumferentially corrugated tubes with a tangential circular profile is studied. The LS-Dyna finite element code is used to evaluate the crashworthiness. In order to verify the models and the solution method, the results are compared with the experimental results. These studies show that the simulation correctly predicts the behavior of the structure. These profiles are investigated under quasi-static, axial, lateral and oblique loads. Then, the results are compared with the results of the conventional square, circular and cellular square tubes. The results indicate that the present profiles under simultaneous axial and lateral loads, compared with the conventional cellular square tubes, increase the specific energy absorption and the crush force efficiency parameter by 26% and 10%, respectively. In addition, the results show that use of cross blades inside the corrugated profiles prevents ...
Journal of Thermal Stresses, 2013
ABSTRACT In this article, an approximate solution using differential quadrature method is present... more ABSTRACT In this article, an approximate solution using differential quadrature method is presented to investigate the effects of thermo-mechanical loads and stiffeners on the natural frequency and critical speed of stiffened rotating functionally graded cylindrical shells. Transverse shear deformation and rotary inertia, based on first-order shear deformation shell theory (FSDT), are taken into consideration. The equations of motion are derived by the Hamilton's principle while the stiffeners are treated as discrete elements. Material properties are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fraction of the constituents. The temperature field is assumed to be varied in the thickness direction. The equations of motion as well as the boundary condition equations are transformed into a set of algebraic equations applying the DQM. The results obtained include the relationship between frequency characteristics of different power-law index, rotating velocities, thermal loading and amplitude of axial load. To validate the present analysis, the comparison is made with a number of particular cases in literature. Excellent agreement is observed and a new range of results are presented for stiffened rotating FG cylindrical shell under thermo-mechanical loads which can be used as a benchmark to approximate solutions.
Journal of Vibration and Control, 2021
This article is provided to investigate the free vibrational behaviors accompanied by buckling ch... more This article is provided to investigate the free vibrational behaviors accompanied by buckling characteristics of carbon nanotube-reinforced conical shells via the Haar wavelet technique. For a bet...
An optimal design of internal pressurized stiffened conical shell is investigated using the genet... more An optimal design of internal pressurized stiffened conical shell is investigated using the genetic algorithm (GA) to minimize the structural weight and to prevent various types of stress and buckling failures. Axial compressive load is applied to the shell. Five stress and buckling failures as constraints are taken into account. Using the discrete elements method as well as the energy method, global buckling load and stress field in the stiffened shell are obtained. The stiffeners include rings and stringers. Seven design variables including shell thickness, number of rings and stringers, stiffeners width and height are considered. In addition, the upper and lower practical bounds are applied for the design variables. Finally, a graphical software package named as Optimal Sizer is developed to help the designers. © 2017 IAU, Arak Branch. All rights reserved.
Composite Structures, 2021
In this paper, frequency behavior of the joined conical-conical panels is investigated while the ... more In this paper, frequency behavior of the joined conical-conical panels is investigated while the structures are reinforced with uniform or functionally graded (FG) embedment of carbon nanotubes (CNTs). To consider both rotary inertia and in-plane effects, the formulation is developed upon FSDT considerations. By means of Hamilton’s principle the dynamic equations for two cones are derived. To attach two individual panels accurately, continuity conditions is performed at the junctions to satisfy the compatibility of displacements and stress resultants. After imposing simply supported boundary conditions at the straight edges, the set of governing equations are discretized meridionally on the basis of generalized differential quadrature (GDQ) technique. The proposed discretization approach is applicable for arbitrary boundary types imposed on the two curved edges at the initiating and terminating points of the structure. The validation of results is primarily assessed via some compari...
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Papers by Mostafa Talebitooti