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Tools for Ultra Large Container Ships

Periodic Report Summary 3 - TULCS (Tools for ultra-large container ships)

Project context and objectives:

The increase in world trade has largely contributed to the explosion in sea traffic. As a result, the market demand is leading to ultra-large container ships (ULCS), which have a capacity up to 14 000 TEU with length up to 400 m, without changes of the operational requirements (speed around 27 knots). The particular structural design of the container ships, leads to open mid-ship sections, resulting in increased sensitivity to torsional and horizontal bending loads which is much more complex to model numerically. At the same time, due to their large dimensions, the ULCS become much 'softer' and their structural natural frequencies become significantly lower so that the global hydroelastic structural responses (springing and whipping) can become a critical issue in the ship design and should be properly modelled by the simulation tools.

On the other hand, it appears that the existing simulation tools do not provide the definite answer to all these design issues and there is a clear need for their improvement.

The particular importance of whipping and the insufficient knowledge in its modelling is clearly reflected in the recent 'Marine accident investigation branch' (MAIB) report, following the loss of the MSC Napoli container ship:
'It is likely that the hull of MSC Napoli was subjected to additional load due to whipping'. '... it is apparent that whipping effect is currently very difficult to reliably calculate or model'. 'In view of the potential increase in wave loading due to whipping effect, further research is required to ensure that the effect is adequately accounted for in ship design and structural analyses, and that sufficient allowance is made for the effect when determining design margins'.

The final goal of the present project is to deliver clearly validated design tools and guidelines, capable of analysing all hydro-structure interaction problems relevant to ULCS. One additional objective is the identification of the further research needs for these topics.

Project results:

First reporting period

During the first reporting period (first 20 months of the project), the project was successfully oriented toward the main objectives. The project consortium was consolidated with the important associated partner which is the world biggest shipyard Hyundai Heavy Industry (HHI) from Korea. This fact gave the additional practical value to the project showing the high interest on the subjects which are considered.

During the first phase, all the main tasks of the project were well identified, scope of work clearly defined and the main part of the developments started.

Second reporting period

In the second phase, the work was continued and the overall progress was in line with the objectives. However, due to the numerous technical difficulties some delay was encountered and the project extension of 6 months was requested and granted by the European Union (EU). Thanks to that the project continued rather smoothly and there was no risk to not achieve the initial objectives.

In particular, all the model test campaigns were successfully performed and the useful databases for validation of the numerical tools were produced. In that respect, it is important to mention that the test matrix for hydroelastic model of Rigoletto container vessel was significantly extended thanks to cooperation with another EU EXTREME SEAS project. The main part of the analysis of the model test results was finished and the comparisons with numerical tools were well advanced. In addition to the complex model tests campaign on Rigoletto, which was performed by Cehipar, an additional model test campaign, which was devoted to slamming impact problems, was also performed by ECM. This campaign showed to be very useful for validation of the slamming modules which are the critical part of the whole physical problem.

The full-scale measurements on Rigoletto continued without major problems. The data collection progressed smoothly and the exploitation plan which was agreed in between the partners was followed. Fortunately, for the project, and unfortunately for the ship crew, some heavy weather conditions were encountered during few voyages. These time traces were very useful for validation of the numerical procedures and tools.

On the numerical side, most of the developments were successfully finalised. That was true both for hydrodynamic, structural and hydrostructural tools. The first verifications were already performed and the different numerical tools were used independently as stand-alone codes. The overall integration in the final TULCS tool progressed well.

The dissemination activities were also successful (publications, conferences, workshop on springing and whipping ...) and the TULCS project was clearly identified within the shipbuilding community worldwide.

Third reporting period

The last phase of the project was mainly dedicated to two main tasks:

(a) finalisation and validation of different software;
(b) exploitation and dissemination.

Both tasks were successfully finalised.

Different parts of software are now operational and integrated into the final TULCS tool which allows for an easy application in practice.

During the third reporting period the following dissemination actions were undertaken:

(1) The project website which was built during the first phase of the project was continuously updated.
(2) More than 40 additional scientific publications related to TULCS were published at the specialised conferences and scientific journals which makes the total number of publications close to 80.
(3) Second International Workshops on Springing and Whipping (IWSWS) was successfully organised at 8 - 10 November. Similar to the first IWSWS it was extremely well attended by worldwide experts.
(4) Project manager gave more than 10 invited lectures all over the world. All these lectures were related to the issues treated in TULCS project.
(5) Thanks to the developments and cooperation in TULCS project four new separate projects were initiated. All these projects continue to investigate the issues along the lines recommended by TULCS.

Potential impact:

The main final objective of the project was to increase the safety and security of sea transport by container ships. This was done by proper analysis of all the aspects of ULCS particular structural design.

The end products of the project are the dedicated numerical tools and guidance for their use within the dedicated design methodology. Specific accent was put to the validation of the tools and that is why an important part of the project concerned the experimental and full scale measurements. The so called direct approach design methodology was proposed around these tools in order to have more rational design procedure as compared to the classical rule procedures of classification societies. This direct approach is judged to be necessary because the actual size of ULCS often exceed the size commonly covered by the rules. This new methodology was proposed to the community through the different means. In particular, the project results were communicated to the IACS partners and the importance of the necessity for more precise evaluation of the hydrodynamic loading and ship structural response was highlighted. A dedicated project team (PT56) was created within IACS and the work was started with the objective of finalisation by the end of 2014. On the other side, thanks to the TULCS project, Bureau Veritas issued new guidance note on springing and whipping of container ships and the new class notation WHISP. This guidance note is already used in cooperation with the shipyards for the new projects of ULCSs.

In addition, four new projects treating the similar issues were initiated thanks to theoutcmes of the TULCS project.

It is also important to note that, even if the project is specifically oriented to ULCS the results of the project might be used for other ship types too. Indeed, the methodologies and the tools are only slightly dependent on the ship type and can be applied, with small modifications, to any ship type and also to the floating off shore platforms.

Project website: http://www.fsb.hr/tulcs