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Seyed Mojtaba Hozhabrossadati - One of the best experts on this subject based on the ideXlab platform.

  • Vibration suppression of a double-beam System by a two-degree-of-freedom Mass-Spring System
    Smart Structures and Systems, 2018
    Co-Authors: Mohammad Rezaiee-pajand, Ahmad Aftabi Sani, Seyed Mojtaba Hozhabrossadati
    Abstract:

    This paper investigates the free vibration analysis of double-beam System coupled by a two-degree-of-freedom Mass-Spring System. In order to generalize the model, the main beams are assumed to be elastically restrained against translation and rotation at one end and free at the other. Furthermore, the Mass-Spring System is elastically connected to the beams at adjustable positions by means of four translational and rotational springs. The governing differential equations of the beams and the Mass-Spring System are derived and analytically solved by using the Fourier transform method. Moreover, as a second way, a finite element solution is derived. The frequency parameters and mode shapes of some diverse cases are obtained using both methods. Comparison of obtained results by two methods shows the accuracy of both solutions. The influence of System parameters on the free vibration response of the studied mechanical System is examined.

  • Free Vibration Analysis of a Six-degree-of-freedom Mass-Spring System Suitable for Dynamic Vibration Absorbing of Space Frames
    International Journal of Engineering, 2016
    Co-Authors: Mohammad Rezaiee-pajand, Ahmad Aftabi Sani, Seyed Mojtaba Hozhabrossadati
    Abstract:

    This study is concentrated on the natural frequencies and mode shapes of a simple three-member space frame coupled with a dynamic vibration absorber. The dynamic vibration absorber is modeled as a six-degree-of-freedom Mass-Spring System. For the first time, the free vibration of an elastic structure with a six-degree-of-freedom Mass-Spring System is found. Each member of the space frame has uniform mechanical and geometrical properties, but these may differ from one member to another. The exact result of this complex problem is obtained via analytical scheme and finite element method. All effects of the axial and torsional deformations and also in- and out-of-plane bending are taken into account. This formulation includes eighteen differential equations along with thirty six boundary and compatibility conditions. Comparison of the results by both approaches mentioned above, illustrates the accuracy of our solutions. Findings are useful benchmarks for the natural frequencies and mode shapes of the space frame coupled with a dynamic vibration absorber.

  • Exact solution for free vibration of elastically restrained cantilever non-uniform beams joined by a Mass-Spring System at the free end
    The IES Journal Part A: Civil & Structural Engineering, 2015
    Co-Authors: Seyed Mojtaba Hozhabrossadati
    Abstract:

    This article focuses on the free vibration analysis of a non-uniform cantilever beam with an attached Mass-Spring System at the free end. One end of the beam is elastically restrained against rotation and translation. The height of the beam is assumed constant but the width of the beam exponentially varies. The governing differential equations of the beam, which is a partial differential equation with variable coefficients, and that of the Mass-Spring System, which is an ordinary differential equation, are found. The exact solution of the problem is then obtained using the pertinent boundary conditions. The eigenvalues and eigenfunctions of the problem which are frequencies and mode shapes of the System are derived for various properties of the System such as stiffness of springs and attached mass. Some limiting cases with available results in the literature are analyzed. The comparison of the proposed results and the reference results shows the accuracy of the solution.

  • A closed-form study on the free vibration of a grid joined by a Mass-Spring System
    Journal of Vibration and Control, 2014
    Co-Authors: Seyed Mojtaba Hozhabrossadati, Ahmad Aftabi Sani, Masood Mofid
    Abstract:

    This paper deals with the coupling flexural-torsional vibration analysis of a grid formed by two members. A Mass-Spring System is attached to the grid at the intersecting joint. The members of the grid are assumed to resist torsion as well as bending and shear. Moreover, the mechanical and geometrical properties of each member are different. In order to analyze the problem, a closed-form solution is obtained. In doing so, the governing differential equations of the System along with the pertinent boundary and compatibility conditions of the System are introduced. Then, the frequency parameters of the mechanical System under study are derived and given for the first five modes of vibration. Furthermore, some diagrams of the mode shapes of the grid are plotted. A finite element program is also written to verify the results. The results obtained from these two methods are in good agreement and the accuracy of our results is confirmed.

  • Free vibration analysis of a beam with an intermediate sliding connection joined by a Mass-Spring System:
    Journal of Vibration and Control, 2014
    Co-Authors: Seyed Mojtaba Hozhabrossadati, Ahmad Aftabi Sani, Masood Mofid
    Abstract:

    In the free vibration analysis of beams, the inclusion of an intermediate sliding connection with an attached Mass-Spring System has not been yet treated. The present paper studies the free vibrations of uniform Euler-Bernoulli beams with an intermediate sliding connection and joined by a Mass-Spring System. Two different types of beams are considered. The Type 1 is attached with a single-degree-of-freedom Mass-Spring System and the Type 2 is attached with a two-degree-of-freedom Mass-Spring System. The ends of both beams are elastically restrained against rotation and translation. First, the eigenvalue problems including differential equations and boundary conditions are introduced. Then, the frequency equation of beam could be found. The roots of this frequency equation, i.e., frequency parameters, for several cases along with mode shapes are presented. Some special cases for the sake of verification are thoroughly investigated.

T. Sugie - One of the best experts on this subject based on the ideXlab platform.

  • Controller design of 2 Mass-Spring System via LMI
    Proceedings of 35th IEEE Conference on Decision and Control, 1
    Co-Authors: Kenichi Hamamoto, T. Sugie
    Abstract:

    This paper gives a controller design method of 2 Mass-Spring System which satisfies the given H/sub /spl infin// control performance and pole assignment in the prescribed region in the presence of physical parameter perturbations. The method uses linear matrix inequalities. In addition, its effectiveness is demonstrated by experiments.

  • Controller design of two-Mass-Spring System based on BMI optimization
    Proceedings of 35th IEEE Conference on Decision and Control, 1
    Co-Authors: Michihiro Kawanishi, T. Yada, T. Sugie
    Abstract:

    This paper gives a design example of multipurpose controllers for two-Mass-Spring Systems based on BMI optimization technique. The obtained controller achieves (a) tracking with zero steady-state error, (b) pole placement in a prescribed region, and (c) optimal H/sub /spl infin// performance, simultaneously in the presence of physical parameter uncertainties. In addition, its effectiveness is demonstrated via simulations and experiments.

Qingping Sun - One of the best experts on this subject based on the ideXlab platform.

  • Analytical solution of a Mass-Spring System containing shape memory alloys : Effects of nonlinearity and hysteresis
    International Journal of Solids and Structures, 2019
    Co-Authors: Mingzhao Zhuo, Minglu Xia, Qingping Sun
    Abstract:

    Abstract Nonlinear dynamics of vibration Systems containing NiTi shape memory alloy (SMA) bars has long been obscured by the lack of an analytical solution, like the analytical solution for duffing equation. The problem results from the nonlinear and hysteretic restoring force of the SMA bar. Here we use a piecewise linear hysteretic model to describe the force-displacement relation of the SMA bar and use the averaging method to solve the equation of motion. We thus obtain an approximate analytical solution of the steady-state response of an SMA Mass-Spring System. The analytical solution can describe both stable and unstable behaviors of the vibration System and therefore offer a comprehensive understanding of the nonlinear responses. It is shown that the phase transition induced softening nonlinearity bends the frequency response curve (FRC) to the left, while the subsequent rehardening of martensite further bends the FRC to the right, leading to multi-valued regions and jump phenomena. The hysteresis is found to have little influence on the bending but it can significantly suppress the response amplitude. Comparison of the analytical results with experimental data validates the piecewise linear hysteretic model and the analytical solutions. This work provides a theoretical tool for design and vibration control of SMA Mass-Spring Systems.

Masood Mofid - One of the best experts on this subject based on the ideXlab platform.

  • A closed-form study on the free vibration of a grid joined by a Mass-Spring System
    Journal of Vibration and Control, 2014
    Co-Authors: Seyed Mojtaba Hozhabrossadati, Ahmad Aftabi Sani, Masood Mofid
    Abstract:

    This paper deals with the coupling flexural-torsional vibration analysis of a grid formed by two members. A Mass-Spring System is attached to the grid at the intersecting joint. The members of the grid are assumed to resist torsion as well as bending and shear. Moreover, the mechanical and geometrical properties of each member are different. In order to analyze the problem, a closed-form solution is obtained. In doing so, the governing differential equations of the System along with the pertinent boundary and compatibility conditions of the System are introduced. Then, the frequency parameters of the mechanical System under study are derived and given for the first five modes of vibration. Furthermore, some diagrams of the mode shapes of the grid are plotted. A finite element program is also written to verify the results. The results obtained from these two methods are in good agreement and the accuracy of our results is confirmed.

  • Free vibration analysis of a beam with an intermediate sliding connection joined by a Mass-Spring System:
    Journal of Vibration and Control, 2014
    Co-Authors: Seyed Mojtaba Hozhabrossadati, Ahmad Aftabi Sani, Masood Mofid
    Abstract:

    In the free vibration analysis of beams, the inclusion of an intermediate sliding connection with an attached Mass-Spring System has not been yet treated. The present paper studies the free vibrations of uniform Euler-Bernoulli beams with an intermediate sliding connection and joined by a Mass-Spring System. Two different types of beams are considered. The Type 1 is attached with a single-degree-of-freedom Mass-Spring System and the Type 2 is attached with a two-degree-of-freedom Mass-Spring System. The ends of both beams are elastically restrained against rotation and translation. First, the eigenvalue problems including differential equations and boundary conditions are introduced. Then, the frequency equation of beam could be found. The roots of this frequency equation, i.e., frequency parameters, for several cases along with mode shapes are presented. Some special cases for the sake of verification are thoroughly investigated.

Ahmad Aftabi Sani - One of the best experts on this subject based on the ideXlab platform.

  • Vibration suppression of a double-beam System by a two-degree-of-freedom Mass-Spring System
    Smart Structures and Systems, 2018
    Co-Authors: Mohammad Rezaiee-pajand, Ahmad Aftabi Sani, Seyed Mojtaba Hozhabrossadati
    Abstract:

    This paper investigates the free vibration analysis of double-beam System coupled by a two-degree-of-freedom Mass-Spring System. In order to generalize the model, the main beams are assumed to be elastically restrained against translation and rotation at one end and free at the other. Furthermore, the Mass-Spring System is elastically connected to the beams at adjustable positions by means of four translational and rotational springs. The governing differential equations of the beams and the Mass-Spring System are derived and analytically solved by using the Fourier transform method. Moreover, as a second way, a finite element solution is derived. The frequency parameters and mode shapes of some diverse cases are obtained using both methods. Comparison of obtained results by two methods shows the accuracy of both solutions. The influence of System parameters on the free vibration response of the studied mechanical System is examined.

  • Free Vibration Analysis of a Six-degree-of-freedom Mass-Spring System Suitable for Dynamic Vibration Absorbing of Space Frames
    International Journal of Engineering, 2016
    Co-Authors: Mohammad Rezaiee-pajand, Ahmad Aftabi Sani, Seyed Mojtaba Hozhabrossadati
    Abstract:

    This study is concentrated on the natural frequencies and mode shapes of a simple three-member space frame coupled with a dynamic vibration absorber. The dynamic vibration absorber is modeled as a six-degree-of-freedom Mass-Spring System. For the first time, the free vibration of an elastic structure with a six-degree-of-freedom Mass-Spring System is found. Each member of the space frame has uniform mechanical and geometrical properties, but these may differ from one member to another. The exact result of this complex problem is obtained via analytical scheme and finite element method. All effects of the axial and torsional deformations and also in- and out-of-plane bending are taken into account. This formulation includes eighteen differential equations along with thirty six boundary and compatibility conditions. Comparison of the results by both approaches mentioned above, illustrates the accuracy of our solutions. Findings are useful benchmarks for the natural frequencies and mode shapes of the space frame coupled with a dynamic vibration absorber.

  • A closed-form study on the free vibration of a grid joined by a Mass-Spring System
    Journal of Vibration and Control, 2014
    Co-Authors: Seyed Mojtaba Hozhabrossadati, Ahmad Aftabi Sani, Masood Mofid
    Abstract:

    This paper deals with the coupling flexural-torsional vibration analysis of a grid formed by two members. A Mass-Spring System is attached to the grid at the intersecting joint. The members of the grid are assumed to resist torsion as well as bending and shear. Moreover, the mechanical and geometrical properties of each member are different. In order to analyze the problem, a closed-form solution is obtained. In doing so, the governing differential equations of the System along with the pertinent boundary and compatibility conditions of the System are introduced. Then, the frequency parameters of the mechanical System under study are derived and given for the first five modes of vibration. Furthermore, some diagrams of the mode shapes of the grid are plotted. A finite element program is also written to verify the results. The results obtained from these two methods are in good agreement and the accuracy of our results is confirmed.

  • Free vibration analysis of a beam with an intermediate sliding connection joined by a Mass-Spring System:
    Journal of Vibration and Control, 2014
    Co-Authors: Seyed Mojtaba Hozhabrossadati, Ahmad Aftabi Sani, Masood Mofid
    Abstract:

    In the free vibration analysis of beams, the inclusion of an intermediate sliding connection with an attached Mass-Spring System has not been yet treated. The present paper studies the free vibrations of uniform Euler-Bernoulli beams with an intermediate sliding connection and joined by a Mass-Spring System. Two different types of beams are considered. The Type 1 is attached with a single-degree-of-freedom Mass-Spring System and the Type 2 is attached with a two-degree-of-freedom Mass-Spring System. The ends of both beams are elastically restrained against rotation and translation. First, the eigenvalue problems including differential equations and boundary conditions are introduced. Then, the frequency equation of beam could be found. The roots of this frequency equation, i.e., frequency parameters, for several cases along with mode shapes are presented. Some special cases for the sake of verification are thoroughly investigated.