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plates--structural-components
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A comprehensive thermo-economic analysis, optimization and ranking of different microturbine plate-fin recuperators designs employing similar and dissimilar fins on hot and cold sides with NSGA-II algorithm and DEA model
, Article Applied Thermal Engineering ; Volume 130 , February , 2018 , Pages 1090-1104 ; 13594311 (ISSN) ; Sadeghi, S ; Khanjarpanah, H ; Haghshenas Gorgani, H ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
This study aims to perform a comprehensive thermo-economic analysis, optimization and ranking of cross and counter-flow plate-fin recuperators employing rectangular, triangular, offset strip and louver fins. The analysis is mainly conducted for two recuperator structures: (i) fins’ configurations on both hot and cold sides are the same; (ii) fins on hot side and cold side are dissimilar in configuration. Considering effective practical optimization constraints and design parameters, Non-dominated Sorting Genetic Algorithm (NSGA-II) is used to maximize the recuperator effectiveness and minimize its total cost, simultaneously. Pareto-optimal fronts are presented to specify the desirable...
Evaluation of PR steel frame connection with torsional plate and its optimal placement
, Article Scientia Iranica ; Volume 25, Issue 3A , 2018 , Pages 1025-1038 ; 10263098 (ISSN) ; Estekanchi, H.E ; Yekrangnia, M ; Sharif University of Technology
Sharif University of Technology
2018
Abstract
Characteristics of connections in steel moment-resisting frames are of utmost importance in determining the seismic performance of these structural systems. The results of several previous experimental studies have indicated that Partially Restrained (PR) connections possess excellent properties, which make them a reliable substitution for Fully Restrained (FR) connections. These properties include needing less base shear, being more economic, and, in many cases, being able to absorb more energy. In this study, the behavior of two proposed PR connections with torsional plate is studied through finite element simulations. The results of the numerical studies regarding initial stiffness and...
Structural analysis of stiffened FGM thick walled cylinders by application of a new cylindrical super element
, Article World Academy of Science, Engineering and Technology ; Volume 58 , 2009 , Pages 116-121 ; 2010376X (ISSN) ; Ahmadian, M. T ; Sharif University of Technology
2009
Abstract
Structural behavior of ring stiffened thick walled cylinders made of functionally graded materials (FGMs) is investigated in this paper. Functionally graded materials are inhomogeneous composites which are usually made from a mixture of metal and ceramic. The gradient compositional variation of the constituents from one surface to the other provides an elegant solution to the problem of high transverse shear stresses that are induced when two dissimilar materials with large differences in material properties are bonded. FGM formation of the cylinder is modeled by power-law exponent and the variation of characteristics is supposed to be in radial direction. A finite element formulation is...
Post-buckling optimization of two-dimensional functionally graded porous beams
, Article International Journal of Mechanics and Materials in Design ; Volume 15, Issue 4 , 2019 , Pages 801-815 ; 15691713 (ISSN) ; Arghavani, J ; Maboudi, G ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In the present study, an attempt is made to present the governing equations on the post-buckling of two-dimensional (2D) FGP beams and propose appropriate optimization procedure to achieve optimal post-buckling behavior and mass. To this end, Timoshenko beam theory, Von-Karman nonlinear relations, virtual work principle, and generalized differential quadrature method are considered to derive and solve governing equations and associated boundary condition (Hinged–Hinged) for an unknown 2D porosity distribution. Proposed method is validated using the papers in the literature. The optimization procedure including defining porosity distributions (interpolations), post-buckling function and...
Combining pole placement and online empirical mode decomposition methods to adaptive active control of structural vibration
, Article Journal of Vibration and Acoustics, Transactions of the ASME ; Volume 141, Issue 4 , 2019 ; 10489002 (ISSN) ; Hosseini Kordkheili, S. A ; Navazi, H. M ; Bahai, H ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2019
Abstract
Using a combination of the pole placement and online empirical mode decomposition (EMD) methods, a new algorithm is proposed for adaptive active control of structural vibration. The EMD method is a time-frequency domain analysis method that can be used for nonstationary and nonlinear problems. Combining the EMD method and Hilbert transform, which is called Hilbert-Huang transform, achieves a method that can be implemented to extract instantaneous properties of signals such as structural response dominant instantaneous frequencies. In the proposed algorithm, these estimated instantaneous properties are utilized to improve the pole-placement method as an adaptive active control technique. The...
Numerical simulation of drag reduction in microgrooved substrates using lattice-boltzmann method
, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 141, Issue 7 , 2019 ; 00982202 (ISSN) ; Moosavi, A ; Etemadi, A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2019
Abstract
We study drag reduction of a uniform flow over a flat surface due to a series of rectangular microgrooves created on the surface. The results reveal that making grooves on the surface usually leads to the generation of secondary vortices inside the grooves that, in turn, decreases the friction drag force and increases the pressure drag force. By increasing the thickness of the grooves to the thickness of the obstacle, the pressure drag increases due to the enhancement of the generated vortices and the occurrence of separation phenomenon and the friction drag reduces due to a decrease of the velocity gradient on the surface. In addition, by increasing the grooves depth ratio, the pressure...
Energy harvesting from plate using magnetic shape memory alloys
, Article Proceedings of the 6th RSI International Conference on Robotics and Mechatronics, IcRoM 2018, 23 October 2018 through 25 October 2018 ; 2019 , Pages 229-235 ; 9781728101279 (ISBN) ; Naderi, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Ferromagnetic shape memory alloys (FSMA) are new class of smart material and have been investigated for sensor and actuator and energy harvester applications.this paper presents the basis for a novel pressure sensor based on ferromagnetic shape memory alloys. Underlying mechanism for sensing applications is martensitic reorientation accompanied by a chang of magnetization of plate. When this alloy, is exposed in an external magnetic field or stress, has change of magnetization in result.the change in the magnetization of the alloy in accordance with the Faraday induction law, in the wires of the coil leads to the induction voltage. In this paper, a phenomenological constitutive structural...
Optimized design of adaptable vibrations suppressors in semi-active control of circular plate vibrations
, Article Scientia Iranica ; Volume 26, Issue 3B , 2019 , Pages 1358-1377 ; 10263098 (ISSN) ; Moradi, H ; Vossoughi, G. R ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
Due to flexibility of thin plates, high-amplitude vibrations are observed when they are subjected to severe dynamic loads. Because of the extensive application of circular plates in industry, attenuating the undesired vibrations is of foremost importance. In this paper, Adaptable Vibration Suppressors (AVSs) as a semi-active control approach were utilized to suppress the vibrations in a free circular plate under the concentrative harmonic excitation. Using mode summation method, the mathematical model of the hybrid system including the plate and an arbitrary number of vibration suppressors was analyzed. By developing a complex multiple-loop algorithm, optimum values for the parameters of...
Optimized design of adaptable vibrations suppressors in semi-active control of circular plate vibrations
, Article Scientia Iranica ; Volume 26, Issue 3B , 2019 , Pages 1358-1377 ; 10263098 (ISSN) ; Moradi, H ; Vossoughi, G. R ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
Due to flexibility of thin plates, high-amplitude vibrations are observed when they are subjected to severe dynamic loads. Because of the extensive application of circular plates in industry, attenuating the undesired vibrations is of foremost importance. In this paper, Adaptable Vibration Suppressors (AVSs) as a semi-active control approach were utilized to suppress the vibrations in a free circular plate under the concentrative harmonic excitation. Using mode summation method, the mathematical model of the hybrid system including the plate and an arbitrary number of vibration suppressors was analyzed. By developing a complex multiple-loop algorithm, optimum values for the parameters of...
Hydrodynamic damping enhancement by implementing a novel combined rigid-elastic heave plate
, Article Journal of Marine Science and Technology (Japan) ; 2020 ; Behzad, M ; Thiagarajan, K ; Sharif University of Technology
Springer
2020
Abstract
Heave plates are structural components used for reducing the vibrations caused by environmental forces on marine and offshore structures by changing the hydrodynamic properties. The fact that the added mass increase via heave plates does not always lead to the structural response reduction underscores the role of damping in maintaining the vibration amplitude within allowable limits. In the present experimental study, a novel combined rigid-elastic design is used to improve the damping through the velocity increase in the elastic part and added mass creation in the central rigid part. The desired percentage of total added mass and damping can be adjusted by changing the rigid-to-elastic...
Time-varying structural reliability assessment method: Application to fiber reinforced composites under repeated impact loading
, Article Composite Structures ; 2020 ; Pourtakdoust, S. H ; Crawford, B. J ; Seethalerc, R ; Milani, A. S ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Reliability evaluations play a significant role in engineering applications to ensure the serviceability and safety of advanced structures such as those made of composites. Here, a dynamic reliability evaluation analysis based on the probability density evolution Method (PDEM) has been adapted to assess the reliability of composite structures under uncertainties within the material properties and the external loadings. A Back-Propagation Neural Network approach is employed to identify the system's nonlinear structural response, which is often the case under large deformations. To exemplify, a split Hopkinson pressure bar system was employed to mimic the mechanical behavior of a...
Study of emi-based damage type identification in a cracked metallic specimen repaired by a composite patch
, Article Russian Journal of Nondestructive Testing ; Volume 56, Issue 6 , 2020 , Pages 540-548 ; Ghasemi, R ; Mohammadi, B ; Sharif University of Technology
Pleiades Publishing
2020
Abstract
Abstract: Using adhesively bonded composite patch repairs has been increased in various industries to improve the structural integrity of cracked metallic structures in recent decades. Monitoring of crack propagation and composite patch debonding, as two dominant failure mechanisms in this repair technique, plays a significant role in the integrity assessment of the component. This research conducts an experimental investigation on the simultaneous monitoring of these two failure mechanisms in a cracked metallic specimen repaired by a composite patch. For this purpose, the electromechanical impedance method was used to evaluate the feasibility of recognizing the type of damage at any phase...
Free vibration of joined cylindrical–hemispherical FGM shells
, Article Archive of Applied Mechanics ; Volume 90, Issue 10 , 2020 , Pages 2185-2199 ; Kiani, Y ; Bagheri, N ; Eslami, M. R ; Sharif University of Technology
Springer
2020
Abstract
Free vibration response of a joined shell system including cylindrical and spherical shells is analyzed in this research. It is assumed that the system of joined shell is made from a functionally graded material (FGM). Properties of the shells are assumed to be graded through the thickness. Both shells are unified in thickness. To capture the effects of through-the-thickness shear deformations and rotary inertias, first-order shear deformation theory of shells is used. The Donnell type of kinematic assumptions is adopted to establish the general equations of motion and the associated boundary and continuity conditions with the aid of Hamilton’s principle. The resulting system of equations is...
Three-dimensional stress analysis of structures in instability conditions using nonlinear displacement-based and hybrid-mixed quadrilaterals based on SaS formulation
, Article International Journal of Non-Linear Mechanics ; Volume 126 , 2020 ; Kulikov, G. M ; Plotnikova, S. V ; Kouchakzadeh, M. A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this paper, the three-dimensional (3D) stress analysis of plate-type structures in instability conditions is presented. The displacement-based and hybrid-mixed four-node quadrilateral elements are developed taking the advantages of the sampling surfaces (SaS) method. The SaS formulation is based on considering inside the plate N not equally spaced SaS parallel to the middle surface to specify the displacements of these surfaces as primary plate unknowns. The displacements, strains and stresses are assumed to be distributed through the thickness using Lagrange polynomials of degree N–1 that lead to a well-set higher-order plate theory. The locations of SaS are based on the use of Chebyshev...
Buckling and vibration analysis of FG-CNTRC plate subjected to thermo-mechanical load based on higher order shear deformation theory
, Article Mechanics Based Design of Structures and Machines ; 2020 ; Karbon, M ; Eyvazian, A ; Jung, D. W ; Habibi, M ; Safarpour, M ; Sharif University of Technology
Taylor and Francis Inc
2020
Abstract
In the present study, based on 12-unknown higher order shear deformation theory (HSDT), buckling and vibration analysis of FG-CNTRC rectangular plate are investigated for various types of temperature distribution and boundary conditions. Implementing Hamilton’s principle, the equations of motion are derived and solved by adopting the Navier solution for the simply supported boundary conditions and DQM method for other boundary conditions. Validation is carried out by comparing the numerical results with those obtained in the open literature. Also, a detailed parametric analysis is carried out to illuminate the influence of different system parameters such as CNT distributions, CNT volume...
Effect of mode shape switching on the loss factor of sandwich cylinders
, Article AIAA Journal ; Volume 58, Issue 8 , August , 2020 , Pages 3577-3592 ; Asgari, M ; Haddadpour, H ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2020
Abstract
Damping characteristics of three-layered sandwich cylindrical shells with the focus on mode switching phenomenon are investigated in the present study. All layers of the sandwich cylinder are formulated based on the first-order shear deformation theory. Considering the von Karman strain displacement relations, the nonlinear equations of motion are derived through Hamilton’s principle. By separating the displacement components into previbration and vibration states and substituting in the obtained nonlinear equations of motion, the previbration equilibrium equations and vibration equations of motion are obtained. The acquired equations are solved by applying the generalized differential...
Block shear failure in welded gusset plates under combined loading
, Article Journal of Constructional Steel Research ; Volume 170 , July , 2020 ; Ghaderi Garekani, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Block shear failure in the base metal of welded steel connections is a potential failure mode affecting many steel structures. However, there are only a few studies on the block shear failure of welded connections under combined shear and axial loading. Combined loading is defined as a simultaneous loading parallel and perpendicular to the weld lines (or an inclined loading) in the plane of the connecting plate. In this research, a nonlinear finite element model is used to study the effect of connection geometry and weld group configuration on the block shear strength of welded connections under combined loading. In current design standards, the block shear failure planes are assumed to...
A general multi-scale modeling framework for two-phase simulation of multi-stream plate-fin heat exchangers
, Article International Journal of Heat and Mass Transfer ; Volume 156 , 2020 ; Saidi, M. H ; Hannani, S. K ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Compact heat exchangers are among the vital components used in various industries. In this study, a general framework has been developed with a multi-scale point of view for three-dimensional simulation of multi-stream plate-fin heat exchangers. The most important features in the MSPFHEs simulation, such as phase change phenomena, multi-component mixtures, multiple streams, transversal, lateral and longitudinal conduction, non-uniformity of inlet flow, variable fluid properties, and heat leakage are simultaneously considered in this model. The modular form of the model structure has facilitated layer-by-layer simulation of cross flow heat exchangers as well as parallel flow ones. Our model...
Frequency characteristics of FG-GPLRC viscoelastic thick annular plate with the aid of GDQM
, Article Thin-Walled Structures ; Volume 150 , 2020 ; Ghabussi, A ; Ebrahimi, F ; Habibi, M ; Safarpour, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This is the first research on the free vibration analysis of functionally graded graphene platelets reinforced composite (FG-GPLRC) viscoelastic annular plate resting on the visco-Pasternak foundation and subjected to the nonlinear temperature gradient and mechanical loading within the framework of higher-order shear deformation theory (HSDT). Hamilton's principle is employed to establish governing equations within the framework of HSDT. In this paper, viscoelastic properties are modeled according to Kelvin-Voigt viscoelasticity. The deflection as the function of time can be solved by the fourth-order Runge-Kutta numerical method. Generalized differential quadrature method (GDQM) is applied...
On the nonlinear dynamics of a multi-scale hybrid nanocomposite disk
, Article Engineering with Computers ; 2020 ; Ebrahimi, F ; Habibi, M ; Safarpour, H ; Sharif University of Technology
Springer
2020
Abstract
This is the first research on the nonlinear frequency analysis of a multi-scale hybrid nanocomposite (MHC) disk (MHCD) resting on an elastic foundation subjected to nonlinear temperature gradient and mechanical loading is investigated. The matrix material is reinforced with carbon nanotubes (CNTs) or carbon fibers (CF) at the nano- or macroscale, respectively. We present a modified Halpin–Tsai model to predict the effective properties of the MHCD. The displacement–strain of nonlinear vibration of multi-scale laminated disk via third-order shear deformation theory (TSDT) and using Von Karman nonlinear shell theory is obtained. Hamilton’s principle is employed to establish the governing...