Early Structural Assessment and Optimisation of Passenger Ships

peer reviewedA multi-criteria optimisation of a passenger ship is conducted in this paper. Minimum production cost and minimum steel weight are the both objective studied. Moreover the study answers to the following question: "From when will the higher costs of high tensile steel should be offset by a gain of steel weight?". For a passenger ship, a significant reduction of the steel weight, for a controlled raise of the gravity centre, should lead either to a reduction of fuel consumption either to an additional deck, which for a ship owner means a faster return on investment. Pareto frontiers are obtained and results are validated by classification rules

Tools for early design stage: presentation of LBR-5 Software

peer reviewedLBR-5 is a tool for early design stage. Taking into account numerous kinds of constraints – structural, geometrical, etc. – an optimum scantling can quickly been found. In the framework of IMPROVE European project many new modules have been implemented to increase the quality of the optimised scantling. Mainly 6 major changes have been brought: implementation of a sloshing module, a fatigue module, a multi-structure module, a multi-materials module, a life cycle cost module and finally a vibration module. Tests to validate these modules have been carried out on the three ships studied in the IMPROVE project: a LNG, a Chemical Tanker and a ROPAX

Developments of Tools Focused on Production Simulation to Improve Productivity in Shipyards’ Workshops

The goal of the thesis is to develop tools for improving shipbuilding workshops’ productivity. These tools have been tested on workshops of Aker Yards France shipyard, in Saint-Nazaire.The main chapter concerns the modelling of a workshop with the discrete-event simulation methodology. Production simulation is strongly used in some fields – as automobile industry – but is less used in shipbuilding. Indeed, the difficulty is that almost each piece to produce is unique. The objective is to show the importance of production simulation for such workshops. The modelled workshop is linked to a genetic algorithm to improve its productivity by optimizing its production sequence.Secondly a tool of creation and optimization of PERT networks has been created. The tool contains a graphical interface to easily handle networks and an optimization algorithm. This last one can minimize total cost of any project for a given total time. The tool has been linked to the modelled workshop. Consequently we get a PERT diagram of the workshop that can highlight critical activities.Finally, the last chapter explains the development of a tool to solve space allocation problems. Indeed space is often a critical point in many shipyards. Thanks to a user-friendly interface, the developed tool facilitates scheduling of these workshops. Furthermore it contains an optimization algorithm based on a heuristic approach to automate the planning process.In conclusion a set of efficient tools has been carried out with concrete applications on real workshops./L’objectif de la thèse est de développer une série d’outils qui permettent d’optimiser la production d’ateliers de construction navale. Ces outils sont testés sur des ateliers du Chantier Naval Aker Yards France à Saint-Nazaire.Le chapitre principal traite de la modélisation d’un atelier – dit de PréPréFabrication – sur le principe de la simulation de production à évènements discrets. La simulation de production est fortement utilisée dans certains domaines – industrie automobile par exemple – mais encore peu souvent en construction navale. En effet, la difficulté réside dans la diversité des pièces à produire. L’objectif est de démontrer l’intérêt de la simulation de production même dans ces ateliers où pratiquement chaque pièce à construire est unique. L’atelier modélisé a été couplé avec un algorithme génétique pour améliorer sa productivité en optimisant la séquence de production.En second lieu, un outil de création et d’optimisation des réseaux PERT a été créé. L’outil contient une interface graphique permettant une manipulation aisée des réseaux et un algorithme d’optimisation. Ce dernier permet de minimiser le coût de réalisation d’un projet pour un temps total fixé. En étant couplé avec le logiciel de simulation développé, une création automatique du diagramme PERT de l’atelier est créée, permettant de mettre clairement en évidence ses activités critiques.Finalement, le dernier chapitre de la thèse porte sur la création d’un logiciel permettant de résoudre les problèmes de gestion de surface et de planification rencontrés dans certains chantiers. En effet, l’espace au sol est un élément critique pour beaucoup d’ateliers de construction navale. Le logiciel développé, grâce à une interface conviviale et pratique, permet de faciliter grandement la planification. De plus, il contient un algorithme d’optimisation basé sur des heuristiques afin d’automatiser le processus de planification.En conclusion, un ensemble d’outils efficaces a été généré, avec des applications concrètes sur des ateliers réels

Minimization of Production Cost by use of an Automatic Cost Assessment Method and Simulation

peer reviewedThis paper will present different ways to minimize cost in shipbuilding industry. Amongst them we have the production simulation methods, the cost assessment methods and the optimization methods. Nowadays, cost assessment is a key task of an integrated ship design. The various methods to estimate the production cost differ with the known information (input data). The less information is detailed, the earlier a method can be used in the design process. The more information is used, the better we can assess the differences between design alternatives. The methods presented here and the “design for production” concept promise to increase the productivity trough the following points: a more accurate cost estimation, an improvement in the deadlines planning and the production schedule, a progress in distribution of the workload between the various production workshops, a better knowledge of the individual costs that will permit to reduce the global cost. In order to illustrate our work, we present in this paper three methods to decrease the global cost of a ship

Panama Lock Gate optimisation – using LBR5 software

Research report to reduce the weight of the Panama lock gates - using LBR5 optimisatio

Optimization of monopile offshore wind structures

peer reviewedABSTRACT: As industrialization is essential for large-scale offshore wind deployment, a computerized methodology to optimize the scantling of monopile steel structures has been developed using a genetic alg rithm. The objective functions of this tool are minimization of the structure weight and production costs. The constraints implemented are mainly related to structural stability under extreme loads, resonance check of the wind turbine support and fatigue strength at welded connections between shells and stiffeners. This optimiz tion should be invoked at the preliminary stage of the offshore project in order to assess the impacts of the structure design on the fabrication and installation costs

OptiView − A Powerful and Flexible Decision Tool Optimising Space Allocation in Shipyard Workshops

peer reviewedThis paper presents new developments to maximize the number of ship blocks and ship sections produced in various workshops of shipyards during a certain time window. The visualization tool OptiView® was developed to support users to improve the space utilization and workshop productivity. The software is coupled with a heuristic optimisation solver. The paper describes the approach to the space allocation problem and gives three application examples

A Data Mining Analysis Applied to a Straightening Process Database

peer reviewedThe complexity of modern manufacturing processes in a highly competitive environment forces the manufacturers to invest massively in automation and monitoring systems. The large data flows from these new installations are sources of valuable and hidden knowledge that is so far hardly used. Data mining methods through integrated data analysis tools give a solution to this situation, allowing easy retrieval of knowledge starting from a data base. This is also a unique opportunity to learn faster about the process and to detect hidden and complex relationships between parameters involved. Within this framework we have decided to apply this data analysis method to the straightening process in shipbuilding. We refer to Caprace et al. (2007) for additional illustrations. In shipbuilding, the assembly of elements by welding involves temperature gradients within the ma- terial. These cause deformations which sometimes have to be reduced to obtain an acceptable surface flatness. The straightening process to eliminate these distortions for esthetical or functional reasons is labour intensive. Estimating the straightening impact on the production workload is interesting in the context of production simulation, cost assessment of ship hull, structure optimization, design for production, etc. To reach these objectives, the idea was to elaborate, through a data mining approach, a formula linking the straightening cost to the sections scantlings (plate thickness, dimension and inter-distance of longitudinal stiffeners, dimension and inter-distance of transversal frames) and to other section characteristics. This paper describes each stage of the methodology: data description, analysis of data quality, data exploration and finally choice of discriminatory attributes and the generation of the data-driven models.InterSHI