Numerical and experimental studies of nonlinear wave loads of ships

Dissertation

Timo Kukkanen

Research output: ThesisDissertationMonograph

Abstract

Extreme wave loads have to be defined in the ultimate strength assessment of ship structures. Nonlinearities in extreme wave loads can be significant in high waves. Numerical and experimental studies of nonlinear wave loads are presented in this work. A nonlinear time domain method has been developed and the fundamentals of the method are given. The method is based on the source formulation expressed by means of the transient three-dimensional Green function. The exact body boundary condition is satisfied on the instantaneous floating position of the body. The free surface boundary condition is linear. The time derivative of the velocity potential in Bernoulli's equation is solved with a similar source formulation to that of the perturbation velocity potential. The verification of the method is presented for a hemisphere and cones. Wigley hull forms are used to validate the calculation method in regular head waves and calm water. Model tests of a roll-on roll-off passenger ship with a flat bottom stern have been carried out. Model test results of ship motions, vertical shear forces and bending moments in regular and irregular head waves and calm water are given. The nonlinearities in ship motions and hull girder loads are investigated using the calculation method and the model test results. The nonlinearities in the hull girder loads have been found to be significant. The calculation method is used to predict rigid hull girder loads for the model test ship. It is shown that the time domain calculation method can be applied to ship-wave interaction problems to predict the nonlinear wave loads.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Matusiak, Jerzy, Supervisor, External person
Award date26 Oct 2012
Place of PublicationEspoo
Publisher
Print ISBNs978-951-38-7932-7
Electronic ISBNs978-951-38-7933-4
Publication statusPublished - 2012
MoE publication typeG4 Doctoral dissertation (monograph)

Fingerprint

Ships
Boundary conditions
Bending moments
Green's function
Cones
Water
Derivatives

Keywords

  • wave loads
  • nonlinear loads
  • numerical methods
  • model tests
  • ship strength

Cite this

Kukkanen, T. (2012). Numerical and experimental studies of nonlinear wave loads of ships: Dissertation. Espoo: VTT Technical Research Centre of Finland.
Kukkanen, Timo. / Numerical and experimental studies of nonlinear wave loads of ships : Dissertation. Espoo : VTT Technical Research Centre of Finland, 2012. 226 p.
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abstract = "Extreme wave loads have to be defined in the ultimate strength assessment of ship structures. Nonlinearities in extreme wave loads can be significant in high waves. Numerical and experimental studies of nonlinear wave loads are presented in this work. A nonlinear time domain method has been developed and the fundamentals of the method are given. The method is based on the source formulation expressed by means of the transient three-dimensional Green function. The exact body boundary condition is satisfied on the instantaneous floating position of the body. The free surface boundary condition is linear. The time derivative of the velocity potential in Bernoulli's equation is solved with a similar source formulation to that of the perturbation velocity potential. The verification of the method is presented for a hemisphere and cones. Wigley hull forms are used to validate the calculation method in regular head waves and calm water. Model tests of a roll-on roll-off passenger ship with a flat bottom stern have been carried out. Model test results of ship motions, vertical shear forces and bending moments in regular and irregular head waves and calm water are given. The nonlinearities in ship motions and hull girder loads are investigated using the calculation method and the model test results. The nonlinearities in the hull girder loads have been found to be significant. The calculation method is used to predict rigid hull girder loads for the model test ship. It is shown that the time domain calculation method can be applied to ship-wave interaction problems to predict the nonlinear wave loads.",
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author = "Timo Kukkanen",
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year = "2012",
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Kukkanen, T 2012, 'Numerical and experimental studies of nonlinear wave loads of ships: Dissertation', Doctor Degree, Aalto University, Espoo.

Numerical and experimental studies of nonlinear wave loads of ships : Dissertation. / Kukkanen, Timo.

Espoo : VTT Technical Research Centre of Finland, 2012. 226 p.

Research output: ThesisDissertationMonograph

TY - THES

T1 - Numerical and experimental studies of nonlinear wave loads of ships

T2 - Dissertation

AU - Kukkanen, Timo

N1 - Project code: 78189

PY - 2012

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N2 - Extreme wave loads have to be defined in the ultimate strength assessment of ship structures. Nonlinearities in extreme wave loads can be significant in high waves. Numerical and experimental studies of nonlinear wave loads are presented in this work. A nonlinear time domain method has been developed and the fundamentals of the method are given. The method is based on the source formulation expressed by means of the transient three-dimensional Green function. The exact body boundary condition is satisfied on the instantaneous floating position of the body. The free surface boundary condition is linear. The time derivative of the velocity potential in Bernoulli's equation is solved with a similar source formulation to that of the perturbation velocity potential. The verification of the method is presented for a hemisphere and cones. Wigley hull forms are used to validate the calculation method in regular head waves and calm water. Model tests of a roll-on roll-off passenger ship with a flat bottom stern have been carried out. Model test results of ship motions, vertical shear forces and bending moments in regular and irregular head waves and calm water are given. The nonlinearities in ship motions and hull girder loads are investigated using the calculation method and the model test results. The nonlinearities in the hull girder loads have been found to be significant. The calculation method is used to predict rigid hull girder loads for the model test ship. It is shown that the time domain calculation method can be applied to ship-wave interaction problems to predict the nonlinear wave loads.

AB - Extreme wave loads have to be defined in the ultimate strength assessment of ship structures. Nonlinearities in extreme wave loads can be significant in high waves. Numerical and experimental studies of nonlinear wave loads are presented in this work. A nonlinear time domain method has been developed and the fundamentals of the method are given. The method is based on the source formulation expressed by means of the transient three-dimensional Green function. The exact body boundary condition is satisfied on the instantaneous floating position of the body. The free surface boundary condition is linear. The time derivative of the velocity potential in Bernoulli's equation is solved with a similar source formulation to that of the perturbation velocity potential. The verification of the method is presented for a hemisphere and cones. Wigley hull forms are used to validate the calculation method in regular head waves and calm water. Model tests of a roll-on roll-off passenger ship with a flat bottom stern have been carried out. Model test results of ship motions, vertical shear forces and bending moments in regular and irregular head waves and calm water are given. The nonlinearities in ship motions and hull girder loads are investigated using the calculation method and the model test results. The nonlinearities in the hull girder loads have been found to be significant. The calculation method is used to predict rigid hull girder loads for the model test ship. It is shown that the time domain calculation method can be applied to ship-wave interaction problems to predict the nonlinear wave loads.

KW - wave loads

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KW - numerical methods

KW - model tests

KW - ship strength

M3 - Dissertation

SN - 978-951-38-7932-7

T3 - VTT Science

PB - VTT Technical Research Centre of Finland

CY - Espoo

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Kukkanen T. Numerical and experimental studies of nonlinear wave loads of ships: Dissertation. Espoo: VTT Technical Research Centre of Finland, 2012. 226 p.