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Faculté des Sciences appliquées
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Bending Vibration Analysis of Pipes and Shafts Arranged in Fluid Filled Tubular Spaces Using FEM

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Edessa, Desta Milkessa ULiège
Promotor(s) : Kaeding, Patrick ; Bronsart, Robert ; Holtmann, Michael
Date of defense : 2012 • Permalink : http://hdl.handle.net/2268.2/6090
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Title : Bending Vibration Analysis of Pipes and Shafts Arranged in Fluid Filled Tubular Spaces Using FEM
Author : Edessa, Desta Milkessa ULiège
Date of defense  : 2012
Advisor(s) : Kaeding, Patrick 
Bronsart, Robert 
Holtmann, Michael 
Committee's member(s) : Taczala, Maciej 
Language : English
Number of pages : 102
Keywords : [en] Fluid cylindrical structure interaction, bending vibration, added mass, natural frequency, modal analaysis, harmonic analysis
Discipline(s) : Engineering, computing & technology > Civil engineering
Target public : Researchers
Professionals of domain
Student
Institution(s) : Université de Liège, Liège, Belgique
Degree: Master de spécialisation en construction navale
Faculty: Master thesis of the Faculté des Sciences appliquées

Abstract

[en] The interaction between fluid and cylindrical structures has been received extensive research
focus over the past decades, and an enormous effort has been paid to investigate various
aspects of this complex multi-physics phenomenon. This is not surprising at all since circular
cylindrical shells and shafts are one of the most commonly used construction members in a
wide variety of engineering structures.
An important step in vibration analysis of fluid-cylindrical structures interaction is the
evaluation of their vibration modal characteristics, such as natural frequencies, mode shapes,
and added mass. This modal information plays a key role in the design and vibration
suppression of these structures when subjected to dynamic excitations. This thesis aims to
investigate the bending vibration characteristics of two engineering problems namely, first:
shaft surrounded by fluid (oil) confined concentrically by outer cylindrical tube and immersed
in infinite fluid (e.g., stern tube) and second: cylindrical pipe filled with fluid and confined in
cylindrical fluid medium (sea water), confined concentrically by cylindrical outer tube
surrounded by infinite fluid (e.g., Overboard discharge line).
The study has been divided into two as PART-1, bending vibration analysis of stern tube both
2D and 3D acoustic fluid structure finite element model with ANSYS has been employed, and
PART-2 bending vibration of an overboard discharge line arranged in a tabular caisson partly
filled with sea water has been analyzed with 3D acoustic fluid structure finite element
analysis.
To validate the acoustic fluid structure interaction vibration analysis using finite element
(ANSYS), a well calculated fluid cylindrical structure interaction problems such as, bending
vibration of shaft inside infinite fluid, bending vibration of shaft inside fluid filled rigid
tabular space have been re-analyzed using ANSYS and validated with available theoretical
results. Using the same trend further complicated arrangements (stern tube, Overboard
discharge line) vibration characteristics, added mass coefficients have been analyzed using
acoustic fluid structure interaction finite element model (ANSYS). Furthermore mesh
adaptation and parametric study has been determined for PART-1 and the corresponding
empirical formula to determine added mass of shaft and tube for stern tube has been suggested
over specific dimensions. The analysis has been also examined with different density of fluids
and found that added mass much depend on fluid density. For PART-2, bending vibration
characteristic of system parts have been analyzed before proceeding to the whole system,
which helps to know individual vibration characteristic and the assembled system vibration
characteristic has been studied including the effect of ballast water level change.
Harmonically forced vibration analysis has been also performed and result reveal that due to
transmission of vibration via fluid, both shaft and tube vibrate together at their resonance
frequencies and same characteristic has been observed for PART-2 as well.
The investigation of vibration characteristic, added mass, added mass coefficient, mesh
adaptation, and parametric studies of the mentioned fluid cylindrical structure interaction has
vital role in design and vibration suppression of the system.


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  • Edessa, Desta Milkessa ULiège Université de Liège - ULiège >

Promotor(s)

Committee's member(s)

  • Taczala, Maciej
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