Trans RINA, Vol 153, Part A1, Intl J Maritime Eng, Jan-Mar 2011


4.6 INVESTIGATIONS INTO EARLY STAGE INCORPORATION OF SIMULATION TOOLS


Due to the architectural dimension of the DBB based concept studies, a further set of initial design studies can now be contemplated. These studies address a wider range of issues than the traditional naval architectural topics. Thus issues like Design for Production [31], fire simulation [32], heat distribution [33], vulnerability [34] and personnel movement [35] can be modelled and simulated in early stage ship concept studies to see how new ship concepts and future requirements could be affected by issues traditionally not addressable in the concept phase. Of all the topics investigated by the DRC the one that has been considered in most detail, as a case study in the integration of simulation tools in initial design, has been that of personnel movement. While there remain considerable challenges to be tackled, to ensure that the ship design definitions and simulation derived data are kept to a level that is commensurate with rapid trade off needs at the concept stage, it is clear that the Requirement


Elucidation dialogue display can of both be


improved and more stakeholders directly involved in it by integrating such tools into concept design. Thus Figure 11 shows a typical


personnel


movement simulation results for a scenario of personnel movement on a frigate. Such a design representation could then assist in early design decisions on ship layout and complementing numbers. These simulation-based investigations, when combined with a DBB approach to concept


design studies, importantly add a further


dimension to the Requirement Elucidation process. They enable the ship designer to investigate aspects previously only considered, if at all, much later in a design and even then, typically, well after ship construction has commenced. Current practice means late investigations are


unlikely to substantially influence the major


requirements and design decisions, whereas the DBB approach can facilitate early effective consideration.


4.7 INITIAL CONCLUSIONS ON CONCEPT STUDIES


The range of concept studies briefly outlined in the previous sub-sections enable some conclusions to be drawn, in


Requirements Elucidation, with regard to the comparison between the


providing the traditional


concept sizing


design input process


ship to (see


Figure 4) and the architecturally based DBB approach (see Table 2). Firstly, there is a wide range of studies possible at the early stages of ship design and that range is increasing, due in part to the insights possible with an integrated architectural approach. Secondly, given the decisions that are made at the early (concept) phase are the most crucial, it is necessary that they be made with as good an exploration, as is possible and appropriate, of what might be the crucial issues. Traditionally, for the ubiquitous naval


combatant, these issues have been “payload” dominated, that is to say they are focused on Next, it is the key phase in the whole design process


where the major decisions are made. Design has been characterised as decision-making in its entirety but, as indicated by Figure


3, the crucial decisions for the


overall ship design process are made at the very front of the process. Many of these are often not appreciated by the two key players in the initial design phase – the requirement owner (usually the naval staff) and the concept ship designer. This lack of awareness of the extent of the crucial decisions being made can narrow down the


options for consideration and arbitrarily


5. THE NATURE OF THE CONCEPT DESIGN PROCESS FOR NAVAL VESSELS


From the above consideration of the process at the initial (concept) phase of ship design, there are seen to be five highly interrelated aspects. These then characterise this fundamentally different part of the process of designing such physically large and complex systems as naval vessels.


Firstly, the process is that of a wicked problem, as first coined by Rittel and Webber [7]. Unlike the downstream process, which is of a highly convergent nature and seen to be “pealing off the layers of an onion” to reveal more physical detail to gain technical assurance together with providing sufficient detail to manufacture the eventual ship, this phase consists of working out what is really wanted and what can be afforded (see Figure 2). It is characterised by starting with a (or even better several) blank sheet of paper to gain insight, in the form suggested by the first “bubble” of Figure 2.


the major combat system sub-systems and specific equipment items. To a degree the traditional sizing process


reflected that, however more technically


significant to the naval architect, in particular, has been the dichotomy of achieving adequate ship stability with minimum hydrodynamic resistance at full speed. This is a clear indication, even before any of the wider design issues opened up by the integrated architectural synthesis approach are


addressed, S5 issues that such issues largely


determine the overall ship design. Such “style” related aspects, rather than just the combat system, are often the drivers on ship size and its proportion of overall cost. Thus the


Strength, and Style [36]) need to be addressed in the concept


phase Requirement


through the dialogue Elucidation


process.


(Speed, Stability, Seakeeping, that


is the Aside from


demolishing the false vision of “Platform vs Payload”, which the Requirement Engineering misapprehension has fostered, this more whole ship vision also emphasises the importance of tackling the Style aspects, as part of the concept process. This now possible given the tools and techniques as is shown by some of the above architecturally driven design studies, where the results can be used to reassess putative requirements (see Figure 3).


A-36


©2011: The Royal Institution of Naval Architects


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