Least Cost Optimization of Large Passenger Vessels

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 ▲]

Integration of a Bottom-Up Production Cost Model in LBR-5 Optimization Tool

in Conference on Computer Applications and Information Technology in the Maritime Industries (COMPIT) (2007, April)

The LBR-5 software allows the optimization of ship structures following different objectives as the highest inertia, least weight and/or least cost. The interest of European shipyards to optimize the ship ... [more ▼]

The LBR-5 software allows the optimization of ship structures following different objectives as the highest inertia, least weight and/or least cost. The interest of European shipyards to optimize the ship structure is basically related to the production cost and mainly to the labor cost. In order to increase the quality of cost estimation, a bottom-up module has been developed by University of Liege in partnership with AKERYARDS France. This module has been validated on different types of ships (LNG, Cruise Vessels, Fast Ferry) and integrated in the LBR-5 optimization process. The bottom-up cost module has two important goals. The first one is to estimate accurately the labor cost of a given ship structure taking into account the production breakdown, the block splitting sequence and all the individual operations required by the fabrication process. The second one is to compute properly the sensitivities of the design objective (construction cost) related to the design variables (scantlings). The paper also presents the results of a validation test on a large passenger vessel. The effect of the bottom-up cost module on the optimal scantling and on the cost gain is highlighted through a comparison with the results obtained using a basic cost module. [less ▲]

Assessment of Ultimate Bending Moment of Ships from a Reliability Point of View, Using Independent Perturbations Method

in Network for Integrating Structural Safety, Risk and Reliability (ASRANet) (2006, July)

This paper presents a method to asses hull girder ultimate bending moment distribution, taking into account parameters uncertainty. This method is a part of a research activity carried out at University ... [more ▼]

This paper presents a method to asses hull girder ultimate bending moment distribution, taking into account parameters uncertainty. This method is a part of a research activity carried out at University of Liege. The method is able to compute four statistical moments of ultimate strength distribution: average, standard deviation, skewness and kurtosis. Geometry parameters, material parameters and initial imperfections (initial deflections and residual stresses) are considered as random variables and a distribution is associated to each of them. Ultimate bending moment algorithm is a progressive collapse analysis based on Smith method and associated with the load-end shortening model proposed by Bureau Veritas and Joint Bulker Project Rules (JBP). In order to perform a reliability analysis, this algorithm is coupled with independent perturbations method. The advantage is a lower number of simulations compared to the standard Monte-Carlo procedure and a good use of the initial information that is available. The paper contains also a comparative analysis between the presented method and a linear sensitivity analysis performed by the ISSC 2000 “Ultimate Strength” committee for a VLCC structure. [less ▲]

An Analytical Cost Assessment Module for the Detailed Design Stage

in Conference on Computer Applications and Information Technology in the Maritime Industries (COMPIT) (2006, May)

The main goal of the project is to implement a “real time” and automatic cost assessment model of the ship hull construction, which integrates the design criteria and production parameters. The presented ... [more ▼]

The main goal of the project is to implement a “real time” and automatic cost assessment model of the ship hull construction, which integrates the design criteria and production parameters. The presented method for short-term cost assessment promises to increase the productivity. Nowadays, cost assessment is a key task of an integrated ship design. The various methods to estimate the production cost differs with the required information (input data). The less information is needed, the earlier this method can be used in the design process. The more information is used, the better we can assess the differences between design alternatives. This means: − At the basic design stage: validate the budget and give a reliable bidding price, − At the detailed design stage:, plan the deadlines and establish the production schedule, − At the scheduling production stage: distribute the workload between the various production workshops and assess the productivity. A first prototype of cost assessment module reaches the validation stage at the Alstom Marine St Nazaire shipyard (Chantiers de l’Atlantique) within the framework of the European project InterSHIP which has partly financed the study. In the future, cost assessment will become increasing important. It is proposed to assist/help the designers by a “real time” follow-up of the cost, starting at the earliest conceptual design stage up to the latest detailed design stage. The development such a cost assessment tool requires considering simultaneously the design criteria and the production parameters. Designers will consequently be able to choose the least expensive options at each step of the design procedure (earlier is of course better). [less ▲]

Least Construction Cost of FSO Offshore Structures and LNG Gas Carriers

in ISOPE, The fifteenth International Offshore and Polar Engineering Conference, Seoul (2005, June 19)

In this paper, scantling optimization a FSO offshore structure and a medium size capacity LNG gas carrier are presented. Optmization is based on the LBR5 least cost optimization package. Main originality ... [more ▼]

In this paper, scantling optimization a FSO offshore structure and a medium size capacity LNG gas carrier are presented. Optmization is based on the LBR5 least cost optimization package. Main originality and advantage is to combine the minimization of the construction cost with the preliminary design stage. The optimum scantling (least cost) is determined at the earliest design stage, this means before the signature of the contract. Cost savings of 5 to 10% are currently recorded. Relevant information on the methodology and applications to a FSO unit and a LNG carrier are presented in the paper. [less ▲]

Modelling, Simulation and Optimization of a Shipbuilding Workshop

in COMPIT'2005 -Conference on Computer Applications and Information Technology in the Maritime Industries, Hamburg (2005, May)

Cost Assessment in Ship Production

in RINA (2005)

Développement et mise au point d’une boucle d’étalonnage pour vanne de régulation en vue d’une future accréditation

Master's dissertation (2002)

This project for the graduation of Mechanical Engineer has been realised in the Laboratory for Hydraulic Research of the Ministry of Equipment and Transport of Belgium. It consisted of the design and the ... [more ▼]

This project for the graduation of Mechanical Engineer has been realised in the Laboratory for Hydraulic Research of the Ministry of Equipment and Transport of Belgium. It consisted of the design and the realisation of a test bench for hydraulic control valves in preparation for qualified calibration (ISO 17025). Enventually measurement of actual flow characteristics will allow to optimise the use of valves in piping systems. The work has been done in several phases: design, study of metrology, study of standards, implementation and finally preliminary tests and results. The dimensioning of the test bench led to the drawings and draughts of all pipe sections and of the rejection canal (valves with diameter from 100 to 300 mm). The prssure drop has also been evaluated over the whole system. Concerning methodology, measuring techniques were identified, sensors and their signal handling units have been chosen and dimensioned: weirs, pressure sensor, torque meter and electromagnetic flow meter. With the aim to prepare the future qualification of the test bench, existing standards were identified and studied. Their recommendations have been applied where possible. Finally the test bench has been constructed, which has been a rich experience because of the many unexpected problems related to technique as well as to methodology. Preliminary test results for the calibration of a butterfly valve are promising. Nevertheless there is still some work to do before calibration can be qualified. Anyhow the data already collected and the many observations done during these tests were a good opportunity to analyse technological problems and standardisation. So this as a whole results in a data package which can be the base for future projects. [less ▲]