In shipbuilding, outfitting is the process of installing non-structural components, like equipment, pipes, cables, ducts, etc., which can run through several structural compartments. Pre-outfitting is defined as outfitting activities that take place before hull erection, thus during panel, section and block assembly. The outfitting process is characterized by interferences between yard and many subcontractors, disturbances by unexpected delays, and technological constraints concerning the installation of main propulsion machinery. Scheduling of this process is therefore quite complex and a difficult topic to research. According to extensive literature study, there have been some relevant paper published more than twenty years ago[1],[2],[3],although since then the topic has not received much attention.. Traditionally, the initial outfitting process planning is generated largely manually by experts with the help of computer software, like Microsoft Project and Primavera. These tools allow some limited plan checking and evaluation. As soon as special simulation tools, for example based on eM-Plant or, Arena, are fully developed, plans can be tested, analyzed and optimized in a more accurate way. Even though the digitalization of downstream work is being developed, the initial plan depends greatly on experts. They have to be trained and then gain their expertise from practice. It generally takes over five years for someone to acquire sufficient expertise in a particular area[4]. Furthermore, the knowledge the experts gained by their years of experience may be lost, due to retirement and personnel quitting the company. Hence, it is indispensable to make such tacit knowledge explicit through models. It means that in order to optimize the facilities, maximize the production efficiency and minimize the building time, it is necessary to develop a system to automatically generate plans for outfitting processes, which can also support the simulation models afterwards for verification purposes. The research discussed in this paper looks into the possibilities to automatically generate an outfitting sequence and planning, based on two approaches. The first approach is an analytical approach, where the focus lies on the most convenient installation sequence on a system or compartment level. This sequence considers all relations between activities within one system and with activities of other systems, and relations within one compartment and its adjacent compartments. Then a mathematical approach is discussed. Physical constraints between the pipes, ducts, cable trays, etc. are introduced and represented. A model is made to generate an installation sequence of these components in one compartment.
Titanium creates value through its attributes - light weight, corrosion immunities, strength, environmentally non-toxic, performance & proven durability providing benefits of reduced fuel consumption, greater payloads/storage, reduced maintenance, labor & weight while eliminating needs for material replacement, coatings & paints. The paper outlines these attributes, benefits and specific Marine applications.
In February 2007, NSRP awarded the project entitled “Design for Producibility (DFP) for Mid-Tiered Shipyards,” a collaborative research project which included Bollinger, Atlantic Marine, and Todd Pacific Shipyards. The purpose of the project was to incorporate DFP methodologies into the ship design process for each of the participating midtiered shipyards to enable simplification of the ship design process and vessel construction requirements. This paper will provide an understanding of the process used to develop the shipyard-specific DFP information. The paper will also provide a quantification and appreciation of the resulting cost benefits associated with the implementation of DFP principles at each of the participating shipyards. New construction programs in each of the shipyards enabled real-time metrics to be captured, illustrating the achievement of cost reduction opportunities resulting from DFP implementation.
The Office of Naval Research recognizing the importance of education, specifically science and mathematics, embarked nearly a decade ago on their National Naval Responsibility for Naval Engineering program. Since then, academia, industry, and SNAME have increased their individual and collaborative efforts towards reaching out to students in an effort to share the excitement and opportunities available within the marine industry. Recently, in this vein, the Northrop Grumman Shipbuilding Apprentice School Chapter of the Hampton Roads SNAME chapter held a “Boat Design Competition” exposing over 240 high school students from 10 school districts (30 teams from 18 different high schools) to the excitement and knowledge needed to prepare design, construction and engineering packages using guidelines, lectures, and tutorial videos prepared by Apprentices and veteran Naval Architects. This was the first time high school students had the opportunity to compete in a head-to-head competition to design, construct, and operate the best boat relative to a number of prescribed requirements. The program also served to educate Apprentices in leadership, project management, research methods, brainstorming, naval architecture and systems engineering as well as establish a nurturing relationship between student chapter and veteran SNAME members which continues today.
The hull job shop in a shipyard is a typical flexible manufacturing system (FMS), the flexibility and efficiency of which largely depends on the level of FMS scheduling. In this paper, the Object-Oriented Colored Petri Net (OOCPN) is used to build the FMS model for the hull job shop. A four-step modeling method of FMS has been developed to successfully simulate the scheduling of the hull job shop.
Oxygen cutting is a reliable and efficient process in shipbuilding. This study applies thermal elastoplastic analysis, using finite element techniques, to analyze the thermomechanical behavior and evaluate the residual stresses in oxygen cutting. A model for the temperature distribution during cutting and stress distribution in the workpiece are presented. The presented finite element model is capable of predicting the interface temperature and stress distribution during cutting and their influences in the workpiece. A noncontact temperature method—infrared radiation (IR) was used for surface temperature measurement. The residual stresses at the surface of the workpiece were measured by impact-indentation measurement. The results of finite element analysis were compared with experimental results to confirm the accuracy of the method. The numerical results are in good agreement with the experimental ones.
Vessel dry docking takes place on a large number of occasions during a ship's life. During dry docking, vessels may be repaired or inspected, either in relation to specific rule (statutory) requirements or in order to gain an overall view of the condition of the vessel. Dry docking can represent a considerable amount of time as they involve the inspection, overhaul, and, where necessary, the modification of existing equipment. Time and cost are two factors that, generally, play a significant role in the planning and controlling of dry docking. Faster completion will, probably, generate additional costs, but can also create additional revenues as ships can enter markets early. In this paper, the Goal Programming (GP) formulation is applied to the drydocking survey carried out on the vessel "Campeo´ n." With the aim to balance time and cost, we establish three objectives, that is, to limit: the crashing costs, the time to undertake the dry docking, and the daily costs incurred by the vessel during the dry docking.
An automatic line-heating process for the double-curved shell plates is introduced. This process contains four subprocesses: calculating the heating information based on shell development and analysis of primary technological parameters, which is named as prediction system of heating information; heating the plate by an automated line-heating machine according to the calculated heating information; measuring and inspecting the plate surface to determine whether it matches the designed surface; and calculating the reheating information for the deformed plate and reheating the plate automatically until the designed shape is achieved. Therefore, an iterative loop system of an automated line-heating process can be developed based on the integration of these four components.
Though many methods are applied to solve the combinatorial optimization problem, there are many cases in which the solution cannot be solved in practical computation time, even if the computer becomes more advanced. Recently the "ant colony optimization method (ACO)" has been proposed as one of the meta-heuristic method. This research tried the ACO in ship production field. Firstly, the ACO was applied and verified for the traveling salesman problem (TSP) to obtain the shortest path in many cities, as a representative combinatorial optimization problem. Next, based on the result, the ACO was applied to the problem in search of the optimum torch movement of a welding robot for the assembly of ship hull structure, and of a NC plasma cutting machine of steel plate. As a result, it was confirmed that the ACO is effective to solve the optimum path of machines.
One of the most disturbing aspects in structural assembly is welding distortion. These deformations adversely affect the subsequent fit-up and alignment of the adjacent panels. The extent of distortion depends on welding parameters, plate thickness, thermophysical properties of plate material, structural restraints, and welding sequence. Because welding is a fully transient phenomenon, its numerical analysis is highly time consuming, and hence analysis of full-size ship structural panels is simply not feasible using conventional finite element (FE) analysis. The computational time depends on number of elements, type of analysis, number of load steps, and computer configuration. Actual simulation of welding, that is, transient elastoplastic thermomechanical analysis is computationally highly time consumable. In the present study, two different modeling approaches for welding distortion prediction are presented that show a drastic reduction in computational time. Finally, comparative studies are made among the transient elastoplastic thermomechanical analysis and two different equivalent techniques, that is, inherent strain method and transient cooling phase analysis for prediction of welding distortions of a stiffened plate panel.
Friction stir welding, a comparatively new joining technique, is mainly used for welding aluminum alloys. In the present work, an attempt has been made to study the effect of weld parameters of friction stir welding of marine grade 5083 aluminum alloy. Several test runs were conducted to assess the effects of tool rotating speed and tool traverse speed on the microstructure and mechanical properties of the welded joint. It was observed that the tool traverse speed has a significant effect on the end properties of the welded joint. Grain refinement was observed in the thermomechanically affected zone (TMAZ), which led to improved mechanical properties of the welded joint. However, an increase in welding speed keeping rotational speed constant led to deterioration of mechanical properties. The study strongly indicates a possibility of achieving a superior welded joint in marine grade 5083 aluminum alloy with adequate selection of process parameters.
Automated line heating systems have been developed based on stand-alone operation with no consideration of the extensibility and maintainability. In the line heating shop, many of the line heating works are performed simultaneously; therefore, a collaborative and simultaneous automated line heating system is needed. In order to develop such a new line heating system, the current line heating process was analyzed, and then a distributed and automated process was determined, and the parts to be distributed and automated were identified to propose a distributed and automated line heating system based on modularization and network. Information and data flow from production design to robot control have been analyzed and integrated in the system. The system has two main processes: the calculation of the line heating information and execution of a working unit without calculation. A prototype of the system has been developed to study the feasibility of the system. Tests were carried out by using real production design data of a middle-sized Korean shipyard.
This paper describes a logical method for the design and certification of adhesively-bonded composite to steel joints for the marine industry. Normally certification is based on documented service at sea. Since these joints have not been previously deployed at sea, no data on their performance exists. Using an integrated combination of mechanical property evaluation and finite element modeling, the load bearing capacity of a joint can be compared to the anticipated seaway loads. Calculated factors of safety for the sandwich design used here show that the joint has adequate strength to maintain structural integrity even after severe environmental exposure.
This paper presents an analysis of the ship purchasing process and suggests to shipbuilders a methodology to identify the attractiveness of different markets in terms of location. Two analyses are carried out to identify if there is any correlation between exporting country and buyer size (e.g., are Korean exports focused on large clients?) and if the location of the production influences the purchasing decision of the ship buyer. We created a purchasing preference index (PPI) that can be computed for each type of ship and each builder-buyer country pair, and the PPI distribution over several countries is used to evaluate the entry potential for each country which, made up from market size, defines a simple market attractiveness measure. Further analysis is performed aiming to investigate company-level characteristics, such as the size of the players and loyalty in the relationship builder-buyer.
Recently, global shipbuilding companies have been increasing their productivity or expanding their shipyards to accommodate a large amount of orders. However, few studies have been carried out on shipyard layout designs. This research presents a simulation-based shipyard layout design framework to resolve the problems of the shipyard layout design. The shipyard layout design framework was developed on the basis of the systems engineering method. The disciplined systems engineering technique was guided by ISO/IEC 15288 during the planning phase of the shipyard layout design framework development. This framework suggests how to achieve an efficient and effective shipyard layout design that can satisfy the stakeholder of the layout design process. Furthermore, a method is recommended for how the proposed shipyard layout should be verified and validated using a computer simulation. It is expected that the framework will contribute not only to the improvement of the existing shipyard layout design but also to the construction of the new shipyard or ship-yard advancement.
In this paper, models to support the decision-making process for the design of a new shipyard are presented. The first model provides a way of globally assessing the effects various product mixes have on the effectiveness of a yard layout. The second, more detailed model is used to verify the rough results and analyze the effects of fluctuations in the product mix.
This paper presents a procedure for estimating the man-hours (MH) required for building ships and offshore platforms. Information gained from building completely different types of products may be used. The procedure is suitable for the bidding phase. The procedure makes it possible to investigate changes in estimated MH caused by changes in the fabrication process or design or effectiveness in the workshop. Sensitivity analysis of estimated MH may be used for evaluation of investments or as a basis for reduction of MH in bidding. Part I of the paper is the theoretical basis of the procedure. Part II is an implementation in building of a hull. This method for estimation of MH is implemented for building of load-bearing structures. Estimation can take place quickly, and sensitivity to changes in fabrication methods, design, and effectiveness in the workshop is visible. Examples of graphical representation of fabrication data for five disciplines are presented.
Operational flexibility is a powerful but complex strategy that is increasingly used in manufacturing and service industries. We introduce operational flexibility to ship production as a method to alleviate the effects of delays that ultimately create issues such as high cost, high variability in production workload, ineffective production control, and resultant low facility use. Our emphasis is on how incorporating a flexible curved block job shop can, with appropriate control/scheduling, increase the efficiency and timeliness of the block assembly process for both flat and curved blocks and enhance the robustness of the shipbuilding system. We formulate a stochastic model of our approach, as a flexible controlled queuing network in particular, and we provide a simulation test bed to quantify the value of this flexibility.
During the module division planning process, various factors such as shipyard facilities, ship structure, outfitting, material availability, and so forth must be considered simultaneously. At the early design stage, detailed information on these factors or constraints might not be certain. This uncertainty makes the generation of optimum module division plan difficult. In this paper, a system is proposed for module division planning considering the uncertainties in the information at the early design stages. Module division planning is defined as the process of selection of the best module division seam locations. Module division plans are evaluated and ranked based on the locations of seams in each pattern and also the properties of modules in each the pattern. Various factors affecting module division planning and their uncertainties are also considered. Based on the evaluation, some of the "preferable" module division plans can be selected. The system is developed based on graph theory and fuzzy logic.
Shipyards are increasingly responsible for the life cycle support of ships, including maintenance and logistics data over the life of the ship. Hence, it has become important for shipyards to efficiently integrate acquisition product model data with the lifecycle support product model data. The use of Integrated Data Environments (IDE) for Navy ship programs has fostered the integration of design, logistics, and production information for the ship. However, it has not been possible to exchange this integrated data set; rather, different data is typically transferred at different times often resulting in inconsistency. The Product Life Cycle Support (PLCS) STEP standard (ISO 10303-239) for logistics data and life cycle support provides the capability to exchange logistics data linked back to design data. The standard was developed and has been implemented by the aerospace and defense industry. The ISE-6 project demonstrated the feasibility of using the PLCS standard for naval shipbuilding. This approach should also enable interoperability of life cycle data with other defense programs. The ISE-6 team mapped naval shipbuilding requirements into PLCS, while preserving compatibility with existing PLCS implementations. A unique feature was the automated mapping via template expansion and identification. The ISE-6 team conducted a demonstration of this capability, exchanging data between two Integrated Data Environments (IDE) and a Knowledge Management tool, which was used to modify and update the data for the receiving IDE. During the next phase of the project, the ISE-6 team will be investigating interoperability using the S1000D Specification for the procurement and production of technical publications.
