Search for: moving-oscillators
M.Sc. Thesis Sharif University of Technology ; Vafaei, Abolhassan
Vibration of a stationary structure excited by another structure moving on the surface of the stationary Structure is very common in engineering, such as vibration of bridges or railway track under travelling vehicles. In the simplest case, the moving structure maybe modeled as a constant load or a mass or an oscillator, in this case the moving mass is attached to the structure either by a spring or by a mass-spring assembly.The model of a moving mass brings some improvements to the model of the moving load where there is no inertia effect. However, the relative displacement between the moving structures and the beam cannot be considered in the moving mass model. A more appropriate model in...
Dynamics of a laminated composite beam on pasternak-viscoelastic foundation subjected to a moving oscillator, Article JVC/Journal of Vibration and Control ; Volume 14, Issue 6 , 2008 , Pages 807-830 ; 10775463 (ISSN) ; Jafari Talookolaei, R. A ; Esmailzadeh, E ; Sharif University of Technology
Dynamic behavior of a laminated composite beam (LCB) supported by a generalized Pasternak-type viscoelastic foundation, subjected to a moving two-degree-of-freedom (DOFs) oscillator with a constant axial velocity is studied. Analytical solution using the Galerkin method is sought and the couplings of the bending-tension, shear-tension, and bending-twist with the Poisson effect are considered. The possible separation of the moving oscillator from LCB during the course of motion is investigated by monitoring the contact force between the oscillator and LCB. The effects of the non-rigid foundation, oscillator parameters, and the load speed on the separation are also studied. It is found that...
Article Shock and Vibration ; Volume 20, Issue 1 , 2013 , Pages 79-96 ; 10709622 (ISSN) ; Ahmadian, M. T ; Jafari Talookolaei, R. A ; Sharif University of Technology
This paper presents the dynamic response of a delaminated composite beam under the action of a moving oscillating mass. In this analysis the Poisson's effect is considered for the first time. Moreover, the effects of rotary inertia and shear deformation are incorporated. In our modeling linear springs are used between delaminated surfaces to simulate the dynamic interaction between sub-beams. To solve the governing differential equations of motion using modal expansion series, eigen-solution technique is used to obtain the natural frequencies and their corresponding mode shapes necessary for forced vibration analysis. The obtained results for the free and forced vibrations of beams are...
Article Journal of Composite Materials ; Volume 46, Issue 22 , 2012 , Pages 2863-2877 ; 00219983 (ISSN) ; Kargarnovin, M. H ; Ahmadian, M. T ; Sharif University of Technology
The dynamic response of a delaminated composite beam under the motion of an oscillatory mass moving with a constant velocity has been studied. The delaminated composite beam is modeled as four interconnected sub-beams using the delamination limits as their boundaries. The constrained model is used to model the delamination region. The continuity and equilibrium conditions are forced to be satisfied between the adjoining beams. A set of derived governing differential equations along with those obtained by imposing boundary conditions are simultaneously solved in a closed form manner. The results for the response of the delaminated beam were compared with those of the intact beam. Furthermore,...
Dynamic responses of a rectangular plate under motion of an oscillator using a semi-analytical method, Article JVC/Journal of Vibration and Control ; Volume 17, Issue 9 , 2011 , Pages 1310-1324 ; 10775463 (ISSN) ; Kargarnovin, M. H ; Ghahremani, A. R ; Sharif University of Technology
A semi-analytical method is presented to calculate the dynamic responses of a rectangular plate due to a moving oscillator. In previous analytical solutions of the moving oscillator problem, the elastic distributed structure has usually been modeled by an elastic beam structure. This restrictive assumption is removed in this study by assuming a general plate as two-dimensional elastic distributed structure. The method can be applied for any arbitrary path on the plate. A combination of the Fourier and Laplace transformation as well as the convolution theorem is used to solve the governing differential equations of the problem. A modified integration technique is then presented to solve the...
Investigation of Moving Oscillator’s Critical Speed on Single-Span Bridge with Roadway Roughness by FEM, M.Sc. Thesis Sharif University of Technology ; Vafai, Abolhassan ; Mofid, Masoud
In this research the critical speed of a moving oscillator on a single-span bridge with different support (boundary) conditions and by considering the presence of road surface roughness surface with finite element perspective is studied. Due to the fact that passing a moving load on top of the beam causes increased maximum stress and deformations in beam compared to static situation, therefore in reputable codes for bridge design such as AASHTO a dynamic amplification factor is used for designing bridge components. Moving oscillator is a more precise model compared to moving mass for modeling vehicles and the suspension system is modeled as a spring and damper and the moving mass is...
Vibration of Circular and Annular Plates Resting on Pasternak Foundation with a Variable Modulus, Subjected to a Moving Mass, M.Sc. Thesis Sharif University of Technology ; Mofid, Massood ; Foyouzat, Mohammad Ali
This thesis aims to study the dynamic behavior of circular and annular plates. First, free vibration of the plate, resting on a Pasternak foundation with a variable subgrade modulus, by using the infinite power series method is presented. The proposed method applies to various boundary conditions with no restriction. A comprehensive study is carried out to investigate the effects of the different parameters on the behavior of the plate. The obtained results demonstrate that the Pasternak foundation has a significant influence on the natural frequencies and greatly increases them. Secondly, the dynamic response of thin and moderately thick plates subjected to a moving load is considered. In...
Article ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 11 November 2011 through 17 November 2011 ; Volume 7, Issue PARTS A AND B , November , 2011 , Pages 863-870 ; 9780791854938 (ISBN) ; Kargarnovin, M. H ; Jafari Talookolaei, R. A ; Sharif University of Technology
This paper deals with the dynamic analysis of a delaminated composite beam under the action of moving oscillatory mass. The beam is analyzed as four interconnected sub-beams using the delamination limits as their boundaries. The constrained model is used to model the delamination region. The continuity and equilibrium conditions are satisfied between the adjoining beams. The beam response variation due to the delamination with respect to the intact beam has been investigated. Furthermore, the possible separation of the moving oscillator from the beam during the course of the motion is investigated by monitoring the contact force between the oscillator and the beam. The effect of the...
Article Mechanics Based Design of Structures and Machines ; Volume 40, Issue 2 , Apr , 2012 , Pages 218-240 ; 15397734 (ISSN) ; Ahmadian, M. T ; Jafari-Talookolaei, R. A ; Sharif University of Technology
This paper presents dynamic response of a delaminated composite beam under the action of moving oscillatory mass. The Poisson's effect, shear deformation and rotary inertia have been considered in this analysis. We have used the constrained mode model to simulate the behavior between the delaminated surfaces. Based on this model, eigen-solution technique is used to obtain the natural frequencies and their corresponding mode shapes for the delaminated beam. Then, the forced response is determined by employing the modal series expansion technique. The obtained results for the free and forced vibrations of beams are verified against reported similar results in the literature. Moreover, the...
Dynamic analysis of a functionally graded simply supported Euler-Bernoulli beam subjected to a moving oscillator, Article Acta Mechanica ; Volume 224, Issue 2 , 2013 , Pages 425-446 ; 00015970 (ISSN) ; Kargarnovin, M. H ; Gharini, M ; Sharif University of Technology
The dynamic behavior of a functionally graded (FG) simply supported Euler-Bernoulli beam subjected to a moving oscillator has been investigated in this paper. The Young's modulus and the mass density of the FG beam vary continuously in the thickness direction according to the power-law model. The system of equations of motion is derived by using Hamilton's principle. By employing Petrov-Galerkin method, the system of fourth-order partial differential equations of motion has been reduced to a system of second-order ordinary differential equations. The resulting equations are solved using Runge-Kutta numerical scheme. In this study, the effect of the various parameters such as power-law...