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RISS 인기검색어
- 검색키워드
- 저자 : A. Alipour (검색결과 4 건)
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A. Alipour,M. H. Korayem,D. Younesian 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.5
In this paper, a new strategy for providing tensile force to suppress the transverse vibration of a micro-beam is introduced. This axial tensile force is supplied by a specific fluid flow called "magnetohydrodynamics" (MHD), which flows in a micro-pump, and then the fluid enters the micro-beam. The micro-beam is vibrated by an oscillating external force acting at its base. Therefore, a fluid structure interaction problem arises. The pressure of the fluid is increased due to the Lorentz force appears in the micro pump, and is directed by the channel towards the micro-beam and suppress the vibration of the micro-beam. It was observed that when the magnetic field rises from 0.25 Tesla to 0.5 Tesla, the amplitude of the micro-beam fluctuations will decrease from 13 6 10 m - ´ to 13 3 10 m - ´ . Assuming a laminar and incompressible flow, the finite volume method (FVM) is used to solve the governing equations. In the design of the micropump, the parameters studied are the value of the magnetic field, the amount of voltage applied to the micro-pump, the external force oscillation amplitude and the Reynolds number, and the effect of each parameter on the fluid and micro-beam behavior. The results show that with increasing fluid pressure in the micro-pump, the micro-beam vibration is suppressed. In addition, the pressure of the fluid along the micro-beam remains constant at 0.1 percent.
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R. Alipour,A. Farokhi Nejad,S. Izman 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5
The application of dual phase steels (DPS) such as DP600 in the form of thin-walled structure in automotive components is being continuouslyincreased as vehicle designers utilize modern steel grades and low weight structures to improve structural performance, makeautomotive light and reinforce crash performance. Preventing cost enhancement of broad investigations in this area can be gained byusing computers in structural analysis in order to substitute lots of experiments with finite element analysis (FEA). Nevertheless, it necessitatesto be certified that selected method including element type and solution methodology is capable of predicting real condition. Inthis paper, numerical and experimental studies are done to specify the effect of element type selection and solution methodology on theresults of finite element analysis in order to investigate the energy absorption behavior of a DP600 thin-walled structure with three differentgeometries under a low impact loading. The outcomes indicated the combination of implicit method and solid elements is in betteragreement with the experiments. In addition, using a combination of shell element types with implicit method reduces the time of simulationremarkably, although the error of results compared to the experiments increased to some extent.
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Numerical Analysis of the Nonlinear Performance of Concentrically Braced Frames Under Cyclic Loading
M. Alipour,A. A. Aghakouchak 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.3
Concentrically braced frames (CBFs) are widely used as lateral-load resisting system in steel structures. This study examines the effects of different parameters especially those associated with connections, on the behavior of CBFs. A single bay, singlestory frame is used to evaluate the interaction between structural members. Nonlinear analyses using a detailed inelastic finiteelement model (FEM) are carried out to study the behavior of frames subjected to cyclic loading. Models are designed based on seismic codes and analyzed to evaluate the performance of both SCBFs and OCBFs. The equivalent plastic strain concept is used to determine the ductility capacity and to predict fracture and failure in these models. Results show that the seismic performance of CBFs, which are designed according to current provisions can be improved by configuring the details of gusset plate connections in a way that inelastic demands are balanced in middle of brace and gusset plate corners.
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M. H. Korayem,A. Alipour,D. Younesian 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.9
In this paper, vibration suppression of a micro-beam covered by a piezoelectric layer is studied. The micro-beam is modeled with the specific attention to its application in AFM. The AFM micro-beam is a cantilever one which is stimulated close to its natural frequency by applying a harmonic voltage to the piezoelectric layer. The beam is an Euler-Bernoulli beam which abbeys Kelvin-Voigt model. Using such model supplies the comparison between elastic and viscoelastic beams; and one of the most important properties of viscoelastic materials, damping effect can readily be investigated. The pump provides an axial load with the result that it suppresses the vibrations. First, the vibration equations are extracted using Lagrangian and extended Hamiltonian method in vertical, longitudinal, as well as torsional directions and are discretized by exploiting the Galerkin mode summation approach. The discretized time-domain equations are solved by the aid of the Runge-Kutta method. The viscoelastic beam is compared with the elastic one, and the effects of damping ratio on vibration responses are presented. Additionally, the effects of micro-pump load, excitation voltage, and initial twist angle are investigated on the amplitude of vibration and natural frequency of system. It is observed that viscoelasticity of beam and axial load of the pump reduce vibrations and provide uniform time-domain responses without beatings.
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