Fluid–structure interaction of Brezina arch dam: 3D modal analysis

2015 ◽  
Vol 84 ◽  
pp. 19-28 ◽  
Author(s):  
Tahar Berrabah Amina ◽  
Belharizi Mohamed ◽  
Laulusa André ◽  
Bekkouche Abdelmalek
Keyword(s):  
Modal Analysis ◽  
Fluid Structure Interaction ◽  
Arch Dam ◽  
Fluid Structure ◽  
Structure Interaction

A Homogenization Method for the Modal Analysis of a Nuclear Reactor With Fluid-Structure Interaction

2006 ◽  
Author(s):  
Jean-Franc¸ois Sigrist ◽  
Daniel Broc
Keyword(s):  
Modal Analysis ◽  
Nuclear Reactor ◽  
Mass Operator ◽  
Fluid Structure Interaction ◽  
Homogenization Method ◽  
Theoretical Point ◽  
Element Discretization ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Internal Structures

The present paper exposes a homogenization method developed in order to perform the modal analysis of a nuclear reactor with fluid-structure interaction effects. The homogenization approach is used in order to take into account the presence of internal structures within the pressure vessel. A homogenization method is proposed in order to perform a numerical calculation of the frequencies and modal masses for the eigenmodes of the coupled fluid-structure problem. The technique allows the use of a simplified fluid-structure model that takes into account the presence of internal structures: the theory bases are first recalled, leading to a new formulation of the fluid-structure coupled problem. The finite element discretization of the coupled formulation leads to the modification of the classical fluid-structure interaction operators. The consistency of the formulation is established from a theoretical point of view by evaluating the total mass of the coupled system with the fluid and structure mass operator, and the modified added mass operator. The method is tested and validated on a 2D case (two concentric cylinders with periodical rigid inclusions within the annular space) and applied on the industrial case. A complete modal analysis (calculation of frequencies and modal masses) is performed on a simplified geometry of a nuclear reactor with and without internal structures. Numerical results are then compared and discussed, and the influence of the internal structures on the fluid-structure coupled phenomenon is highlighted.

Modal Analysis of Fluid-Structure Interaction in a Bent Pipeline

2016 ◽  
Author(s):  
Gudrun Mikota ◽  
Rainer Haas ◽  
Evgeny Lukachev
Keyword(s):  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Coupling Effect ◽  
Fluid Structure Interaction ◽  
Interaction Model ◽  
Coupling Mechanism ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Resonance Coupling ◽  
Measured Frequency Response

Fluid-structure interaction in a bent pipeline is investigated by modal methods. Measured frequency response functions between flow rate excitation and pressure response indicate a coupling effect near the third pipeline resonance. Using modal coordinates for the hydraulic and the mechanical subsystems, a two-degrees-of-freedom study of resonance coupling is carried out. An experimental modal analysis of the coupled hydraulic-mechanical system confirms the predicted resonance splitting; it illustrates the coupling mechanism and shows the relevant mechanical part. An analytical fluid-structure interaction model succeeds in reproducing the measured coupling effect. This model is also used for modification prediction; it demonstrates that an appropriate assembly of mass and damping on the pipeline can help to reduce hydraulic resonance amplitudes.

scholarly journals A Fluid-Structure Interaction Model for Dam-Water Systems: Analytical Study and Application to Seismic Behavior

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Ricardo Faria ◽  
Sérgio Oliveira ◽  
Ana L. Silvestre
Keyword(s):  
Fluid Structure Interaction ◽  
Fluid Pressure ◽  
Interaction Model ◽  
Arch Dam ◽  
Energy Estimates ◽  
Space Representation ◽  
Discrete Problem ◽  
Order Problem ◽  
Fluid Structure ◽  
Structure Interaction

We consider a dam-water system modeled as a fluid-structure interaction, specifically, a coupled hyperbolic second-order problem, formulated in terms of the displacement of the structure and the fluid pressure. Firstly, we investigate the well posedness of the corresponding variational formulation using Galerkin approximations, energy estimates, and mollification. Then, we apply the finite element method along with the state-space representation of the discrete problem in order to perform a 3D numerical simulation of Cabril arch dam (Zêzere river, Portugal). The numerical model is validated by comparison with available experimental data from a monitoring vibration system installed in Cabril dam.

Importance of Enclosed Gas for Modal Analysis of Space Inflatable Structure

2014 ◽  
Vol 1016 ◽  
pp. 244-248
Author(s):  
Fei Liu ◽  
Wei Liang He
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Fluid Structure Interaction ◽  
Mode Shapes ◽  
Follower Load ◽  
Nonlinear Finite Element Method ◽  
Load Effect ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Structure Research

The stress distribution and modal characteristics of a space inflatable torus is investigated using the nonlinear finite element method. This paper focused on the effect of enclosed air on the modal analysis of the torus, including the effect of follower pressure load and the effect of the interaction between the enclosed air and the torus structure. Research shows that follower pressure stiffness significantly reduces the natural frequencies and changes mode shapes order. The fluid-structure interaction obviously reduces the natural frequencies, and the in-plane translation mode is observed. Follower pressure stiffness has no effect on the in-plane translation mode. Fluid-structure interaction decreases the natural frequencies of the modal considering the follower load effect, but it does not change mode shapes order. The effect of enclosed gas seriously reduces the natural frequencies, changes mode shapes order, and produces the in-plane translation mode.

scholarly journals Soil-fluid-structure interaction applied to the Oued Taht dam (taking into account the membrane effect).

2018 ◽  
Vol 149 ◽  
pp. 02037
Author(s):  
Krenich Nasreddine ◽  
Tahar Berrrabah Amina ◽  
Houmadi Youcef ◽  
Belharizi Mohamed ◽  
Mehdeli Mohamed ◽  
...  
Keyword(s):  
Soil Structure ◽  
Fluid Structure Interaction ◽  
Arch Dam ◽  
Soil Structure Interaction ◽  
Constant Thickness ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Membrane Effect ◽  
Interaction Modeling ◽  
Interaction Phenomenon

The objective of this work is to analyze the dynamic behavior (modal behavior) of the "Oued Taht" arch dam located at MASCARA, taking into consideration the effect of soil-fluid-structure interaction. The finite element code "Ansys" was chosen for the dynamic modeling of the dam that is the subject of this study. Three hypotheses were used for soil-structure interaction modeling; model with embedded base which corresponds to the case where the phenomenon of interactions soil-structure is neglected, model with ground of foundation without mass which consists in taking into account the kinematic component of interaction soil structure and neglecting the inertial component and the model with foundation soil with mass where the two components of soil-structure interaction are taken into account. For the fluid, the model of added masses (equivalent to the westergaard approach) using the SURF element available in the Ansys code library was used. A comparison between the different models of the "Oued Taht" dam was made; it has been found that the taking into account of the soil-fluid-structure interaction phenomenon modifies the period of the system and that the modeling of the dam with and without fluid gives a very important difference of the periods. The results obtained were compared with those of the "Brezina" dam, which is a gravity dam located in BAYADH. The work has shown that the periods of the "Oued Taht" dam with soil-fluid-structure interaction modeling are very out of phase with the periods without fluid modeling (taking into account only the soilstructure interaction phenomenon). which is not the case for the Brezina dam where the periods for the two models are getting closer. The periods between the two models mentioned before are close to the dam of Brézina because the latter is a dam which participates much more by its own weight than by its vault (thickness of the vault varies between 36.3 m at the base and 5m in crest) which is the opposite for the dam "Oued Taht" which participates by its vault (constant thickness of 7 m) thus the membrane effect is present, which is translated by the shift of the periods between the empty case and the filled case.

Fluid-Structure Interaction Effects Modeling for the Modal Analysis of a Nuclear Pressure Vessel

2006 ◽  
Vol 129 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Jean-François Sigrist ◽  
Daniel Broc ◽  
Christian Lainé
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Pressure Vessel ◽  
Nuclear Reactor ◽  
Fluid Structure Interaction ◽  
Added Mass ◽  
Interaction Effects ◽  
Element Discretization ◽  
Fluid Structure ◽  
Structure Interaction

The present paper deals with the modal analysis of a nuclear reactor with fluid-structure interaction effects. The proposed study aims at describing various fluid-structure interaction effects using several numerical approaches. The modeling lies on a classical finite element discretization of the coupled fluid-structure equation, enabling the description of added mass and added stiffness effects. A specific procedure is developed in order to model the presence of internal structures within the nuclear reactor, based on periodical homogenization techniques. The numerical model of the nuclear pressure vessel is developed in a finite element code in which the homogenization method is implemented. The proposed methodology enables a convenient analysis from the engineering point of view and gives an example of the fluid-structure interaction effects, which are expected on an industrial structure. The modal analysis of the nuclear pressure vessel is then performed and highlights of the relative importance of FSI effects for the industrial case are evaluated: the analysis shows that added mass effects and confinement effects are of paramount importance in comparison to added stiffness effects.

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