Interactive evolutionary concept exploration in preliminary ship design

Preliminary ship design (or early stage design in US terminology) is the very first step in designing a new ship. In this stage ship designers attempt to find an affordable balance of the future owner's (customer or operator) ambitions and operational needs. This balance is then translated into more tangible design requirements. However, the search for such a balance and the accompanying design requirements is not a trivial task. Ships, and service vessels in particular, are considered as some of the largest, most complex, moving man-made structures which often need to operate for extended periods of time in a hostile environment. Not surprisingly, the preliminary design of such ships is also inherently complex. The search for a balanced design solution benefits from early insight into the complex interrelations and interactions between the design requirements, the accompanying solutions, and their performances and cost. Insight which is often gained by generating and studying numerous design alternatives with varying requirements, performances, and costs, in a broad and investigatory phase of preliminary design called concept exploration. However, the complexity of ships and the design problem also challenge concept exploration.Ship Design, Production and Operation

Towards a novel design perspective for system vulnerability using a Markov chain

In order to investigate to which extent naval ships can execute their operational scenario after damage, an early stage assessment of the vulnerability of distributed systems needs to be carried out. Such assessments are currently mostly done by evaluating the performance of predefined concepts. However, such an approach does not necessarily lead to the most desirable solution, since solutions outside the scope of the designer’s preconceived ideas or experience are inherently hard to investigate. This paper therefore proposes several steps towards an approach that enables a vulnerability assessment that is independent of predefined concepts. This is done by incorporating several additions to an existing system vulnerability approach developed by the authors, using a Markov chain. With this approach there is no longer a need for modelling individual hits or damage scenarios. Whereas the approach has previously been shown in concept, this paper introduces three improvements that contribute to the applicability of the approach: 1)it is scaled up in order to model a larger number of compartments and distributed systems, 2) the hit probabilities for different compartments can be adjusted, and 3) it is shown how the availability of main ship functions can be derived from the availability of individual connections. A test case that compares two powering concepts (conventional and full electric powering) of a notional Oceangoing Patrol Vessel (OPV) is provided to illustrate the principles behind the improvements. From the results the two main contributions of this paper can be obtained: 1)the possibility to assess the system vulnerability for different levels of required residual capacity at different impact levels, and 2) and the quantitative nature of the results, aiding ship designers and naval staff with understanding the consequences of various concepts on the system vulnerability.Ship Design, Production and Operation

Interactive Multi-Constrained System-To-Compartment Allocation To Support Real-Time Collaborative Complex Ship Layout Design Decision-Making

The development of concept designs during early warship design stages is essential to inform stakeholder dialogues on technical feasibility, affordability, and risk. One of the key aspects of warship concept designs is the layout of systems in the overall arrangement. The adoption of real-time design processes, such as concurrent design, require naval architects to use layout design tools in a more dynamic setting than during traditional design review session-based design processes. This paper investigates how ship layout design tools can be used in a real-time manner. It does so by considering the arrangement problem of allocating systems to compartments, subject to available and required area, global system position preferences, and preferred relative system positions. An existing ship layout design tool, WARGEAR, is extended to consider global and relative system constraints, and is integrated in a proposed method for the allocation of systems to compartments. Furthermore, a novel two-item correlation metric is developed to support designers in the analysis of the, typically large, design space. The metric can be used to identify conflicts and trade-offs between design parameters, as well as promising combinations of design parameters. Two case studies (8 and 89 systems respectively) are used to demonstrate and evaluate the proposed method. Based on these case studies, the calculation time or accuracy of the allocation method does not seem to be the main issue for collaborative design decision-making. Indeed, most effort is required for the analysis of the generated concept designs. Since this is not a problem as such, the real-time use of automated design tools to evaluate the impact of proposed design changes seems to be a promising way to enhance the effectiveness of collaborative ship layout design sessions.Ship Design, Production and Operation

On-The-Fly Design Rationale to Support Real-Time Collaborative Naval Ship Layout Design

This paper presents a new design rationale methodology to support collaborative design decision-making during early stage complex ship design. The nature of collaborative design is described and the need and key challenges of design rationale capturing and reuse are identified.Subsequently, the methodology is developed to overcome these key challenges. A primary characteristic of the methodology is it’s integration with design tools to reduce intrusiveness and enhance usefulness during collaborative design sessions. Finally, a case study was used to demonstrate the usefulness of the developed design rationale ontology, a critical step in providing designers an improved capability to capture and reuse design rationale during collaborative design decisionmaking.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Ship Design, Production and Operation

Assessing complex failure scenarios of on-board distributed systems using a Markov chain

Vulnerability reduction is an important topic during the design of naval ships because they are designed to operate in hostile environments and because their on-board distributed systems are becoming increasingly complex. The vulnerability needs to be addressed in the early design stages already, in order to prevent expensive or time-consuming modifications in later, more detailed design stages. However, most existing methods for assessing the vulnerability are better suited for more detailed design stages. Furthermore, existing methods often rely on pre-defined damage scenarios, while damage–or system failure in general–may also occur in ways that were not expected beforehand. This paper proposes a method that addresses these gaps. This is done by incorporating several additions to an existing vulnerability method that has been developed by the authors, using a Markov chain. With this method, there is no longer a need for modelling individual hits or failure scenarios. The additions are illustrated by two test cases. In the first one, a notional Ocean-going Patrol Vessel is considered, and damage is related to physical locations in the ship. The second test case considers a chilled water distribution system in more detail, with failures modelled independent from the physical architecture. The quantitative nature of the results provide an indication of the generic, overall vulnerability of the distributed systems, which is meant to be used in the early design stages for identifying trade-offs and prioritising capabilities.Ship Design, Production and OperationsMarine and Transport Technolog

Development and experimental testing of a collaborative design rationale method for early-stage ship layout design

Design rationale is a promising way of capturing design decisions and considerations for later retrieval and traceability to improve collaborative design decision-making. To achieve these perceived benefits for early-stage complex ship design, this paper first elaborates on the development of a proof-of-concept design rationale method. The method aims to aid ship designers in the continuous capturing and reuse of design rationale during the collaborative concept design process. Second, the setup and results of an experiment conducted with marine design students and with experts are discussed. This experiment shows how the developed design rationale method benefits collaborative design decision-making such that it leads to improved insight into design issues across the design team during a single design session.Ship Design, Production and Operation

A case study into an automated detailed layout generation approach in early stage naval ship design

The Defence Materiel Organisation (DMO) of the Netherlands Ministry of Defence identified that detailing warship layouts to space level of detail during the concept definition design phase is a complex and time consuming process. Currently it can take up to 150 man hours to complete a feasible general arrangement plan (GAP).Yet, these GAPs are crucial for balancing requirements and budget with technical feasible designs. Insufficient consideration of spatial details during concept definition increases the probability that sizing and integration issues will emerge later in the design process.This paper discusses the first steps undertaken to integrate a new layout generation tool, called WARGEAR (WARship GEneral ARrangement), into the DMO ship design process. WARGEAR is able to semi-automatically generate feasible and balanced detailed layouts in a matter of minutes, thus providing almost real-time feedback and design insight to naval architects. In this paper the issues of tool validation and user acceptance are addressed via a realistic warship design test case and a presentation of the test case results to a larger group of naval architects and senior management at the DMO respectively.The test case showed that WARGEAR is able to generate detailed layouts that compare well to GAPs manually generated by naval architects. The attendees at the presentation were generally positive, but also provided valuable feedback for further development of the WARGEAR tool and methodology. This shows the potential of WARGEAR to increase the speed of detailed layout generation to a matter of minutes and to improve the early stage design process by providing early insight into detailed layouts and their design drivers.Ship Design, Production and Operation

Design space exploration for on-board energy distribution systems: A new case study

This paper demonstrates the usefulness of an automatic topology generator that uses genetic algorithm techniques to generate many alternative system designs and in doing so enables design space exploration for on-board energy distribution systems. This will provide better insight in the relation between design requirements (e.g. budget), system design solutions and important perfor-mance characteristics like ship survivability in early design stages. The basic idea is to apply proven techniques as used for ship configuration (i.e. hull and layout design) to the design of “ship service systems”. The case study will consist of multiple, interconnected systems on board an Ocean-going Patrol Vessel that distribute electric power, chilled water and mechanical (propulsion) power.Ship Design, Production and Operation

IMDC State of the Art Report: Design for Layout

Marine & Transport TechnologyMechanical, Maritime and Materials Engineerin

WARGEAR: ‘Real time’ generation of detailed layout plans of surface warships during early stage design

Generating detailed warship layouts is crucial to check technical feasibility and performance consistent with emergent requirement elucidation during early stage design. However, generating feasible detailed layouts is a complex and time consuming task. Even today, detailed layout plans are often manually drawn using CAD software, taking up to 150 work hours to complete a single feasible layout plan, as found by the Netherlands Defence Materiel Organisation (DMO). As a result, the number of layout variations that can be generated and analysed is limited. This typically means that further detailed layout generation is postponed, increasing the risk of costly sizing and integration issues later in the design process. Therefore, a method that enables rapid insight into layout sizing issues is required. This paper elaborates on the mathematical working mechanisms of the WARship GEneral ARrangement (WARGEAR) tool, that has been developed to support naval architects in detailing ship arrangements to space level in a matter of minutes. Contributions are: (1) a probabilistic staircase placement algorithm, (2) a network-based approach combined with probabilistic selection for allocation of spaces to compartments, (3) the use of cross-correlation to quickly arrange spaces, and (4) a ‘carving’-based approach to ensure connectivity. A representative WARGEAR application case study is presented. This test shows how WARGEAR is able to confirm the feasibility of future warship arrangements at a high level of detail within minutes.Ship Design, Production and Operation