Ship structural integrity

Transport and the Environment

University of Southampton

Ships are growing bigger in size. Operational demands impose high levels of structural loadings. Operational economics dictate that the payload to structural weight ratio should be high leading to requirements of weight minimisation. Thus this coupled action of higher loads and lighter, thinner structures leads to structures being subjected to higher stresses for larger portions of their operational lives. This has implications on the initiation of defects such as cracks in ship structures and their subsequent propagation. Ship owners and ship safety regulators have an obligation to examine ships for cracks and prescribe remedial action. The current philosophy is to accept no defects or cracks; that is, if a ship surveyor detects a crack then the instruction is to repair and rectify that defect regardless of its location and significance (potentially consuming resources and energy unnecessarily). There is a need to examine this philosophy in a fundamental manner and create a safe-ship approach based on rational examination of defects and their implications on ship structural integrity.

This project focuses on the role of fracture mechanics to underpin assessment of ship structural integrity. Numerical (FEA, BEA, meshless) methods will be developed and applied to assess critical strain energy release rates for stiffened plate structures with possible multiple cracks, perhaps using non-linear J-integral or equivalent approaches to account for plasticity. It is envisaged that parallel experimental modelling aided full field strain and stress measurements from different TSA, DIC and other techniques will help in both validating the numerical models as well as providing physical understanding of the fracture toughness characteristics of plated structures.  This project will be aligned with that sponsored by TWI.

This EngD project is being funded through Lloyd's Register sponsorship. More details here.

Enquiries:  engd@soton.ac.uk