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A Fuzzy Metric for Assessing the Producibility of Straightening in Early Design Caprace, Jean-David ; ; Losseau, Nicolas et al in The 14th International Conference on Computer Applications in Shipbuilding (ICCAS) (2009, September 01) Since several years, the large shipyards use more and more thin plates to build up stiffened panels in order to decrease the structural weight. The major problem relating to the utilization of thin plates ... [more ▼] Since several years, the large shipyards use more and more thin plates to build up stiffened panels in order to decrease the structural weight. The major problem relating to the utilization of thin plates is the occurrence of welding distortions that have to be eliminated for esthetical and service reasons. This straightening operation involves significant costs and it seems thus important to characterize its economical impact on the global hull fabrication. This paper presents a way to minimize cost in shipbuilding industry by the implementation of a producibility fuzzy metric in order to obtain a better knowledge of the straightening process. Attention has been focused on the definition of fuzzy rules by experts but also on the optimisation of the decision surface to reduce the error compared to actual measurement points. [less ▲] Detailed reference viewed: 104 (16 ULg)Space Allocation Optimization Applied to Lower Hulls’ Production of Semi-Submersible Platforms Caprace, Jean-David ; ; Losseau, Nicolas et al in COMPIT'09 (2009, May 10) This paper presents a part of new developments included inside a holistic optimisation strategy during the design cycle of ships. The first part of the paper describes an algorithm to maximize the number ... [more ▼] This paper presents a part of new developments included inside a holistic optimisation strategy during the design cycle of ships. The first part of the paper describes an algorithm to maximize the number of ship blocks and ship sections to produce in workshops during a certain time window. A tool was developed in order to support planners to improve the space utilization and workshop productivity. Thanks to this software, the scheduling is now done more efficiently and above all it takes less time. The second part of the paper describes a recent development of an algorithm able to generate a feasible blocks erection sequence starting from the blocks splitting definition. The idea is to integrate this module as a new functionality inside simulation software in order to take into account blocks sequence during the elaboration of the optimised production strategy. The two developments were validated on the lower hull of a semi-submersible platform coming from a new Brazilian shipyard. [less ▲] Detailed reference viewed: 111 (14 ULg)A Data Mining Analysis to evaluate the additional workloads caused by welding distortions Losseau, Nicolas ; Caprace, Jean-David ; et al in MARSTRUCT'09 (2009, March) This paper presents a way to minimize cost in shipbuilding industry by using the results of a data mining analysis aiming to improve the cost knowledge of the additional operations caused by welding ... [more ▼] This paper presents a way to minimize cost in shipbuilding industry by using the results of a data mining analysis aiming to improve the cost knowledge of the additional operations caused by welding distortions. This statistical analysis had the scope to establish assessment formulas of the supplementary workloads in function of scantlings and welding distortions. Those formulas can be useful to evaluate the profitability of new welding devices and can improve the research in the following domains: production simulation, cost assessment of ship hull, structure optimization, design for production, etc. [less ▲] Detailed reference viewed: 97 (15 ULg)OptiView − A Powerful and Flexible Decision Tool Optimising Space Allocation in Shipyard Workshops Caprace, Jean-David ; Bair, Frédéric ; Losseau, Nicolas et al in Conference on Computer Applications and Information Technology in the Maritime Industries (COMPIT) (2008, May) This 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 ... [more ▼] This 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. [less ▲] Detailed reference viewed: 129 (36 ULg)Estimation of Welding Distortions and Straightening Workload Through a Data Mining Analysis Losseau, Nicolas ; Caprace, Jean-David ; et al in Design, Fabrication and Economy of Welded Structures (DFE) (2008, April) This paper will present a way to minimize cost in shipbuilding industry by using the results of a data mining analysis aiming to improve the cost knowledge of the straightening process. This statistical ... [more ▼] This paper will present a way to minimize cost in shipbuilding industry by using the results of a data mining analysis aiming to improve the cost knowledge of the straightening process. This statistical analysis was based on production data from a shipyard and has the scope to establish an assessment formula of the straightening workload. An intermediate step of the analysis was to estimate the welding distortions appearing in stiffened panels. Those generated formulae are useful to improve the research in the following domains: production simulation, cost assessment of ship hull, structure optimization, design for production, etc. [less ▲] Detailed reference viewed: 132 (9 ULg)Multicriterion Scantling Optimization of the Midship Section of a Passenger Vessel considering IACS Requirements ; Caprace, Jean-David ; Losseau, Nicolas et al in The 10th International Symposium on Practical Design of Ships and Other Floating Structures (PRADS) (2007, October) In the scantling design of a passenger ship, minimum production cost, minimum weight and maximum moment of inertia (stiffness) are conflicting objectives. For that purpose, recent improvements were made ... [more ▼] In the scantling design of a passenger ship, minimum production cost, minimum weight and maximum moment of inertia (stiffness) are conflicting objectives. For that purpose, recent improvements were made to the LBR-5 software (French acronym of “Stiffened Panels Software”, version 5.0) to optimize the scantling of ship sections by considering production cost, weight and moment of inertia in the optimization objective function. Moreover, IACS requirements regarding bending, shearing and buckling strength are currently available in LBR-5. Until now, only raw scantling optimizations were performed with LBR-5. Thanks to new developments using heuristics, it is now possible to realize discrete optimization so that a standardized and “ready to use” set of optimum scantlings can be obtained. [less ▲] Detailed reference viewed: 337 (50 ULg)Least Cost Optimization of Large Passenger Vessels ; Caprace, Jean-David ; Losseau, Nicolas et al in Ships & Offshore Structures (2007), 2 The LBR-5 software allows optimizing ship structures according to objectives of higher inertia, less weight and/or lower cost. This last criterion offers the choice between two approaches of calculation ... [more ▼] The LBR-5 software allows optimizing ship structures according to objectives of higher inertia, less weight and/or lower cost. This last criterion offers the choice between two approaches of calculation. The first approach is based on a simplified assessment of the cost in which the total cost is described by rather simple analytical functions which bring into play on the one hand the design variables and on the other hand empirical parameters. In the second approach, the calculation of the cost is based on data specific to the shipyard. The material cost is analyzed according to the first approach while the cost of the labor considers each relevant operation of the ship building with respect to the LBR-5 model. A survey of all the tasks was carried out at Aker Yards France, and a thorough study made it possible to develop assessment tools of the labor cost for each operation as functions of the design variables. Plate straightening operations are also considered in this analysis. This paper presents a cost-based optimization study carried out on a large passenger ship structure with more than 600 design variables, by the use of the detailed approach for the cost calculation. The structural model has been formulated on the basis of technical documentation prepared by Aker Yards France. The loads and strength criteria applied on the model are considered according to classification society rules (Bureau Veritas). Results and conclusions of the study are presented. [less ▲] Detailed reference viewed: 158 (15 ULg)A Data Mining Analysis Applied to a Straightening Process Database Caprace, Jean-David ; Losseau, Nicolas ; et al in Conference on Computer Applications and Information Technology in the Maritime Industries (COMPIT) (2007, April) The paper presents the results of a data mining analysis aiming to improve the cost knowledge of the labour intensive straightening process. The data mining approach yields a formula linking the ... [more ▼] The paper presents the results of a data mining analysis aiming to improve the cost knowledge of the labour intensive straightening process. The data mining approach yields 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. [less ▲] Detailed reference viewed: 90 (27 ULg)Minimization of Production Cost by use of an Automatic Cost Assessment Method and Simulation Caprace, Jean-David ; Bair, Frédéric ; Losseau, Nicolas et al in The Euro-Asia Maritime Network (EAMARNET) (2007, January) This 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 ... [more ▼] This 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. [less ▲] Detailed reference viewed: 110 (23 ULg) |
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