• Title/Summary/Keyword: Vibration-Based

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Structural Vibration Control for Broadband Noise Attenuation in Enclosures

  • Krishnaswamy Kailash;Rajamani Rajesh;Woo Jong Jin;Cho Young Man
    • Journal of Mechanical Science and Technology
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    • v.19 no.7
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    • pp.1414-1423
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    • 2005

  • This paper develops and evaluates several strategies for structural vibration control with the objective of attenuating broadband noise inside a rectangular enclosure. The strategies evaluated include model-independent collocated control, model-based feedback control and a new 'modal-estimate' feedback strategy. Collocated control requires no knowledge of model parameters and enjoys the advantage of robustness. However, effective broadband noise attenuation with colocated control requires a large number of sensor-actuator pairs. Model-based con-trollers, on the other hand, can be theoretically effective even with the use of a single actuator. However, they suffer from a lack of robustness and are unsuitable from a practical point of view for broadband structural vibration applications where the dynamic models are of large order and poorly known. A new control strategy is developed based on attenuating a few structural vibration modes that have the best coupling with the enclosure acoustics. Broadband attenuation of these important modes can be achieved using a single actuator, a limited number of accelerometers and limited knowledge of a few modal functions. Simulation results are presented to demonstrate the effectiveness of the developed strategy.

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Degradation analysis of horizontal steam generator tube bundles through crack growth due to two-phase flow induced vibration

  • Amir Hossein Kamalinia;Ataollah Rabiee
    • Nuclear Engineering and Technology
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    • v.55 no.12
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    • pp.4561-4569
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    • 2023

  • A correct understanding of vibration-based degradation is crucial from the standpoint of maintenance for Steam Generators (SG) as crucial mechanical equipment in nuclear power plants. This study has established a novel approach to developing a model for investigating tube bundle degradation according to crack growth caused by two-phase Flow-Induced Vibration (FIV). An important step in the approach is to calculate the two-phase flow field parameters between the SG tube bundles in various zones using the porous media model to determine the velocity and vapor volume fraction. Afterward, to determine the vibration properties of the tube bundles, the Fluid-Solid Interaction (FSI) analysis is performed in eighteen thermal-hydraulic zones. Tube bundle degradation based on crack growth using the sixteen most probable initial cracks and within each SG thermal-hydraulic zone is performed to calculate useful lifetime. Large Eddy Simulation (LES) model, Paris law, and Wiener process model are considered to model the turbulent crossflow around the tube bundles, simulation of elliptical crack growth due to the vibration characteristics, and estimation of SG tube bundles degradation, respectively. The analysis shows that the tube deforms most noticeably in the zone with the highest velocity. As a result, cracks propagate more quickly in the tube with a higher height. In all simulations based on different initial crack sizes, it was observed that zone 16 experiences the greatest deformation and, subsequently, the fastest degradation, with a velocity and vapor volume fraction of 0.5 m/s and 0.4, respectively.

  • https://doi.org/10.1016/j.net.2023.08.035 인용 PDF

The Analysis of Eigenvalue Problems of Timoshenko Beams Using Curvature-based Beam Elements (곡률 보요소에 의한 Timoshenko 보의 고유치 문제 해석)

  • 양승용;이재관;신효철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.11
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    • pp.2694-2703
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    • 1993

  • In the vibration analysis of Timoshenko beams by the finite element method, it is necessary to use a large number of elements or higher-order elements in modeling thin beams. This is because the overestimated stiffness matrix due to the shear locking phenomenon when lower-order displacement-based elements are used yields poor eigensolutions. As a result, the total number of degrees of freedom becomes critical in view of computational efficiency. In this paper, the curvature-based formulation is applied to the vibration problem. It is shown that the curvaturebased beam elements are free of shear locking and very efficient in the vibration analysis.

  • https://doi.org/10.22634/KSME.1993.17.11.2694 인용 PDF

The construction of second generation wavelet-based multivariable finite elements for multiscale analysis of beam problems

  • Wang, Youming;Wu, Qing;Wang, Wenqing
    • Structural Engineering and Mechanics
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    • v.50 no.5
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    • pp.679-695
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    • 2014

  • A design method of second generation wavelet (SGW)-based multivariable finite elements is proposed for static and vibration beam analysis. An important property of SGWs is that they can be custom designed by selecting appropriate lifting coefficients depending on the application. The SGW-based multivariable finite element equations of static and vibration analysis of beam problems with two and three kinds of variables are derived based on the generalized variational principles. Compared to classical finite element method (FEM), the second generation wavelet-based multivariable finite element method (SGW-MFEM) combines the advantages of high approximation performance of the SGW method and independent solution of field functions of the MFEM. A multiscale algorithm for SGW-MFEM is presented to solve structural engineering problems. Numerical examples demonstrate the proposed method is a flexible and accurate method in static and vibration beam analysis.

  • https://doi.org/10.12989/sem.2014.50.5.679 인용 KSCI