Fluid Structure Interactions Research Group

FSI Away Day 2012

Damage Assessment Tool for Marine Structures

Adam Sobey – ajs502@soton.ac.uk – Faculty of Engineering and the EnvironmentMoD\Lloyd’s Register Centre of Excellence in Marine Structures

Fluid Structure Interactions Research Group

Motivation

Damage Assessment Tool Framework

Collaboration

Methodology

Aims and Objectives

Each year ships sustain damage through collisions, groundings and other reasons but relatively few are lost. During emergencies where the vessel remains afloat the safety of the crew and cargo are put into danger. It is therefore key that advice is based on accurate modelling. Current assessment tools have ensured safety but are conservative. The ability to rapidly model the damage in an emergency scenario will lead to savings in cost and reduce the environmental impact of these occurrences.

The aim of the project is to develop an improved methodology for damaged ship assessment and design. This aim will be completed through a number of objectives:

• Develop methodologies to aid each stage of the damage scenario• Determine the applicability of each framework• Investigate the use of FEA within damage scenarios• Investigate the use of CFD and potential flow within damage scenarios• Validate the modelling of these tools• Investigate the use of faster tools against experiments or more computationally expensive techniques• Model damage situations

Conclusions

The project is developing research in the area of damaged structural analysis. This research has been split into four main stages of a vessels life:

1. Design– Vessels are analysed for damage tolerance which is then optimised.

2. First 48 hrs Emergency Response – At this stage little is known about the damage that has occurred. Information is scarce and crews and emergency response must react quickly to secure the safety of the crew and cargo. There is limited time for modelling but advice must be accurate.

3. Recovery of the Vessel – This stage can last for a period of a couple of weeks. More knowledge is known about the vessel and decisions are being made about whether to tug the boat to safety, the cheapest and most environmentally friendly option, to ferry it home or to scrap it, the least desirable option. Rapid modelling techniques will allow the investigation of a number of “what if” scenarios.

4. Partial damage of the structure – It is possible that the damage that occurs may not penetrate the structure but may lead to total failure through use. This is common in composite materials.

These areas all rely on the use of response surfaces as metamodels to represent more complex modelling. This allows a rapid yet accurate analysis of the damaged structure. The tool relies on a hydrodynamic response surface that will feed into a structural response surface determining the probability of a total failure.

The project is split between the University of Southampton and University College London. In total 7 PhDs have worked or are working on the project covering areas of hydrodynamics, both experimentally and through modelling, structural analysis of steel and damage tolerance of composite materials.

Diagram Key:- Modelling currently under way

- Modelling Completed and

validated

- Input Data

- Potential areas of work

- Outputs

Damage to ship hulls represents a threat to the safety of crews and cargo and can lead to environmental and economic impacts. Current levels of structural modelling represent methods that have ensured safety but are conservative in how they assess the collapse of damaged structures. This research combines a number of specialist areas to develop models that are rapid enough to be used in emergency response but are more accurate than those currently in use.