Dynamics of ship collisions

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Matusiak, Jerzy, Prof.
dc.contributor.author Tabri, Kristjan
dc.date.accessioned 2012-08-24T07:41:29Z
dc.date.available 2012-08-24T07:41:29Z
dc.date.issued 2010
dc.identifier.isbn 978-952-248-273-0 (electronic)
dc.identifier.isbn 978-952-248-272-3 (printed) #8195;
dc.identifier.issn 1795-4584
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/4736
dc.description.abstract The thesis studies ship collisions computationally and experimentally on large and model scales. On the basis of the experimental observations a 3D simulation model is proposed that couples the motions of the ships to the contact force, and considers all the major hydromechanical forces that act on colliding ships. Additionally, the effects of sloshing and the dynamic bending of the hull girder are investigated and implemented into the simulation model. Large-scale experiments were analysed in order to get a deeper insight into the collision dynamics. On the basis of the large-scale experiments a model-scale test setup is designed using the Froude's scaling law. There, the emphasis was laid on the external dynamics and the structural response, properly scaled from the large-scale test, was modelled using homogeneous foam in the side structure of the struck ship model. It is shown that the model-scale experiments illustrated the large-scale tests both qualitatively and quantitatively. A wide range of symmetric, both with and without sloshing, and non-symmetric collision scenarios are studied on a model scale. The experimental findings are exploited in the development of a coupled collision simulation model. The model is formulated in three-dimensional space, and the contact force between the colliding ships considers both the normal and frictional components. A discrete mechanical model for sloshing is implemented into this time-domain model. This linear sloshing model describes the fluid in partially filled tanks with a single rigid mass and with a number of oscillating mass elements that interact with the ship structure through springs and dampers. The dynamic bending of the ship hull girder is included by modelling it as an Euler-Bernoulli beam. Both the experiments and the simulations emphasised the importance of the coupling between the motions and the contact force. It was especially obvious in the case of non-symmetric collisions and in the experiments with sloshing. The penetration paths calculated with the developed time-domain simulation model agreed well with those from the experiments. The total deformation energy was predicted with a deviation of about 10%. The hydrodynamic radiation forces acting on colliding ships proved to have a strong influence on the energy distribution as at the end of the contact they accounted for up to 25% of the total available energy. However, if the interest is in the maximum deformation, the approach with the hydrodynamic damping ignored yields an error of about 5% in the deformation energy. The results of the large- and model-scale experiments with partially filled liquid tanks emphasised the importance of sloshing for collision dynamics. The structural deformation energy in the tests with sloshing was only about 70%-80% of that in similar collision tests without sloshing. The simulation method with the linear sloshing model overestimated the deformation energy by up to 10% for low filling levels of water, but in the case of medium filling levels the predictions agreed amazingly well. en
dc.format.extent Verkkokirja (3617 KB, 50 s.)
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Aalto-yliopiston teknillinen korkeakoulu en
dc.relation.ispartofseries TKK dissertations, 213 en
dc.relation.haspart [Publication 1]: Kristjan Tabri, Joep Broekhuijsen, Jerzy Matusiak, and Petri Varsta. 2009. Analytical modelling of ship collision based on full-scale experiments. Marine Structures, volume 22, number 1, pages 42-61. © 2008 Elsevier Science. By permission. en
dc.relation.haspart [Publication 2]: Kristjan Tabri, Jukka Määttänen, and Janne Ranta. 2008. Model-scale experiments of symmetric ship collisions. Journal of Marine Science and Technology, volume 13, number 1, pages 71-84. © 2008 The Japan Society of Naval Architects and Ocean Engineers (JASNAOE). By permission. en
dc.relation.haspart [Publication 3]: Kristjan Tabri, Petri Varsta, and Jerzy Matusiak. 2010. Numerical and experimental motion simulations of nonsymmetric ship collisions. Journal of Marine Science and Technology, volume 15, number 1, pages 87-101. © 2009 The Japan Society of Naval Architects and Ocean Engineers (JASNAOE). By permission. en
dc.relation.haspart [Publication 4]: Kristjan Tabri, Jerzy Matusiak, and Petri Varsta. 2009. Sloshing interaction in ship collisions—An experimental and numerical study. Ocean Engineering, volume 36, numbers 17-18, pages 1366-1376. © 2009 Elsevier Science. By permission. en
dc.subject.other Marine engineering
dc.subject.other Mechanical engineering
dc.title Dynamics of ship collisions en
dc.type G5 Artikkeliväitöskirja fi
dc.contributor.school Aalto-yliopiston teknillinen korkeakoulu fi
dc.contributor.department Sovelletun mekaniikan laitos fi
dc.contributor.department Department of Applied Mechanics en
dc.subject.keyword ship collisions en
dc.subject.keyword model-scale experiments en
dc.subject.keyword large-scale experiments en
dc.subject.keyword water sloshing en
dc.identifier.urn URN:ISBN:978-952-248-273-0
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.supervisor Varsta, Petri, Prof.

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