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RISS 인기검색어
- 검색키워드
- 저자 : Mehdi Zamanian (검색결과 3 건)
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Mehdi Zamanian,Reza Kolahchi,Mahmood Rabani Bidgoli 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.24 No.1
The use of nanotechnology materials and applications in the construction industry should be considered for enhancing material properties. However, the nonlinear buckling of an embedded straight concrete columns reinforced with silicon dioxide (SiO2) nanoparticles is investigated in the present study. The column is simulated mathematically with Euler-Bernoulli and Timoshenko beam models. Agglomeration effects and the characteristics of the equivalent composite are determined using Mori-Tanaka approach. The foundation around the column is simulated with spring and shear layer. The governing equations are derived using energy method and Hamilton\'s principal. Differential quadrature method (DQM) is used in order to obtain the buckling load of structure. The influences of volume percent of SiO2 nanoparticles, geometrical parameters and agglomeration on the buckling of column are investigated. Numerical results indicate that considering agglomeration effects leads to decrease in buckling load of structure.
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Vortex induced vibration analysis of a cylinder mounted on a flexible rod
Mehdi Zamanian,Luigi Garibaldi 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.6
In this study, vortex induced vibrations of a cylinder mounted on a flexible rod are analyzed. This simple configuration represents the key element of new conception bladeless wind turbine (Whitlock 2015). In this study the structure oscillations equation coupled to the wake oscillation equation for this configuration are solved using analytical perturbation method, for the first time. An analytical expression that predicts the lock-in phenomena range of wind speed is derived. The discretized equations of motion are also solved using RKF45 numerical method. The equations of motion are discretized by Galerkin method. Free vibration mode shape of the structure taking into account the discontinuity of the cross section are used as comparison function. Numerical results are compared to the analytical results, and they show a satisfying agreement. The effect of system parameters on the oscillations of structure and wake as well as on the lock-in domain are presented. Moreover, it is shown that the values of wind speed triggering the start and the stop of the lock-in phenomenon, for increasing wind speed are different from those values obtained during the reverse process, i.e., when the wind speed decreases.
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Improving performance of piezoelectric energy harvester under electrostatic actuation using cavity
Delalat, Kourosh,Zamanian, Mehdi,Firouzi, Behnam Techno-Press 2021 Coupled systems mechanics Vol.10 No.5
This study aims to investigate the effect of cavity on electric energy harvesting from cantilever beam vibrations under electrostatic actuation. Electrostatic actuation is created by a layer of radioisotope materials that is placed on the opposite side of the beam emitting electrons. When the beam is charged, the electrostatic force is generated between the beam and the opposite plate and pulls the beam towards itself. After the beam strikes the radioisotope, it is electrically discharged and then released. The piezoelectric layer converts the released microbeam vibration into electricity. The equations of motion coupled with the electrical effects of the piezoelectric layer are extracted using Hamilton's principle and Gauss's law. The equations are discretized by Galerkin method. The exact mode shape of the cantilever beam with the piezoelectric layer is employed as the comparison function. By identifying the relations governing the system, the output voltage and consequently the amount of harvested electrical energy are obtained using various parameters such as thickness and position of the cavity and system electrical resistance. The results indicates that creating cavity has a significant effect on the energy harvesting.
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