The University of Southampton

SESS6071 Marine Structures in Fluids

Module Overview

This module provides the fundamental aspects of advanced concepts associated with structural integrity and fluid-structure interactions for ships and ship like floating offshore vessels such as FPSO and FLNG, hitherto referred to as floating vessels. There are two assignments which integrate the structure and fluids and support understanding of the concepts taught through applications to real floating vessels.

Aims and Objectives

Module Aims

• Provide the student with an advanced knowledge base and understanding of the dynamic behaviour of a rigid or flexible floating vessels in regular waves and random seas. • Provide a background to advanced topics of interest to maritime structural designers with particular emphasis on the safety and integrity of floating vessels.

Learning Outcomes

Knowledge and Understanding

Having successfully completed this module, you will be able to demonstrate knowledge and understanding of:

  • The potential applicability of fatigue, fracture, and fluid structure interactions to the structural design of floating vessels,
  • The concepts and potential application of rational structural design procedures.
  • Safety aspects in structural design.
  • The concepts in long-term structural performance including fatigue and fracture aspects.
  • The fundamentals in fluid-structure interactions, through seakeeping and hydroelasticity methods
  • Deterministic and statistical measures to assess wave loading, floating vessel behaviour in different sea states and to compare performance between ships.
  • The dynamic behaviour of differing floating vessel types through synthesis of concepts into engineering application and design.
  • Analysis, critical assessment and the nuances of dynamics in relation to floating vessel design and operation.


Part A; lectures on: Fluid-Structure Interactions • Introduction to hydroelasticity theory. • Dynamics of flexible beamlike structure in vacuo. • Principal modes and natural frequencies. • Hydroelastic approach to still water problem. • Hydrodynamics of regular waves • Strip theory, boundary value problems. • Fluid actions in equilibrium axes. • Hydrodynamic coefficients • Generalized equation of motion in seaway. • Responses (bodily motions -seakeeping, distortions, bending moments, stresses) in waves. • Random seas and responses in random seas. • Criteria for comparing floating vessel forms - slamming, deck wetness, etc.. Part B; lectures on: Structural Integrity • The rational structural design of floating vessels: - Levels of structural design processes - Limit state design including ultimate and fatigue limits and load effects • Fatigue of floating vessel structures: - Basic concepts of fatigue, fatigue damage mechanisms, S-N methodology, local strain methodology - Life time load determination, wave induced loads, stochastic combination of loads - Load effect determination, FEA approaches and choices of elements, meshing, structural details - Fatigue assessments, voyage simulation behaviour, long term fatigue damage • Fracture modelling in ship and offshore structures: - Fundamental concepts - energy-based and stress intensity based approaches - LEFM, modes of crack extension, useful K solutions, fracture testing, life modelling - EPFM, CTOD, J integral and crack growth resistance curve The integrations of Parts A and B will take place through two group assignments, with contributions and support from staff at Lloyd’s Register. Wave-induced Loads Assignment; where the students perform predict wave-induced loads on a real ship using quasi-static and fully coupled dynamics (hydroelasticity) analyses and design a flexible model for experimentation. Ship Fatigue Life Assignment; where the students analyse stress records (measured or predicted) of a real ship in order to predict the fatigue life of a structural detail.

Learning and Teaching

Teaching and learning methods

Teaching methods include • Lectures • Tutorials/seminars focussed on the two assignments Learning activities include • Directed reading/independent learning • Example sheets for problem solving exercises • Report-writing for the 2 group assignments • Application of structures and fluid-structure interactions related knowledge to real floating vessels through the two assignments • Use of commercial and academic software to perform the two assignments

Completion of assessment task35
Wider reading or practice8
Preparation for scheduled sessions4
Follow-up work27
Total study time150

Resources & Reading list

Blackboard. Resources and reading list: Available on blackboard



MethodPercentage contribution
Assignment 15%
Assignment 15%
Examination  (120 minutes) 70%


MethodPercentage contribution
Examination  (120 minutes) 100%

Repeat Information

Repeat type: Internal & External

Linked modules

Pre-requisites: SESS2015 Hydrodynamics And Seakeeping 2016-17, FEEG2005 Materials And Structures 2016-17

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