bluuebunny/crossref_metadata_2025 huggingface dataset:
Applicability of High Speed Craft and High Speed Naval Craft Classification Rules to Current Mission Requirements
Authors: Curry Robert , Ashe Glenn , Novak Derek S.
Published: January 2021

The paper describes the content of and background to the development of the Guide for Building and Classing High Speed Naval Craft. It explains the role of ABS and the Naval Administration in the design and classification process. Focusing on the hull requirements, it discusses some of the important design load parameters, acceptance criteria, and the reasons for the similarities and differences between standards for naval craft and commercial craft. It concludes with a brief description of the machinery requirements.
Experimental Verification of Distortion Analysis of Welded Stiffeners
Authors: Deo M. V. , Michaleris P.
Published: January 2021

This paper presents an experimental verification for the predictive distortion analysis approach proposed in Michaleris & DeBicarri (1996,1997) and Vanli & Michaleris (2001) for welded T-type stiffeners. The predictive technique employing the decoupled 2-D and 3-D approach is used for the prediction of buckling distortion and the magnitude of bowing distortion. Two-dimensional thermo-mechanical welding process simulations are performed to determine the residual stress. The critical buckling stress along with the buckling mode are computed in 3-D eigenvalue analyses. Large deformation analyses are carried out to predict the magnitude of bowing distortion. Experimental validation of the prediction is carried out in the lab. Welding experiments are carried out using welding conditions identical to those used in the FEA model. The computational results are then verified with experimental observations
Prediction of Plate Bending by High-Frequency Induction Heating
Authors: Jang Chang-Doo , Kim Ho-Kyung , Ha Yun-Sok
Published: January 2021

In this study, we developed an analysis method of plate forming by induction heating and verified the effectiveness of the present method through a series of experiments. The phenomena of induction heating is a 3-D transient problem coupled with electromagnetic, heat transfer, and elastoplastic large-deformation analyses. To solve the problem, we suggest a proper model and an integrated system. Using the present analysis model, we can estimate the plate deformation in heating without experiments and simulate the plate bending process of induction heating. A series of induction heating experiments was carried out with various heating conditions such as plate thickness, heat speed, and input power. We measured the transient thermal distribution and final configuration of the plates, and acquired useful data to identify the characteristics of the high-frequency induction heating and for comparison with the analysis results.
Strategic Outsourcing: A Process for Shipbuilders
Authors: Phelps Thomas A. , Fleischer Mitchell , Lamb Thomas , DeGraw Kevin
Published: January 2021

A comprehensive process for making outsourcing decisions at shipyards was developed through a pilot project at Northrop Grumman Newport News. The process steps begin with carefully defining the product family and continue through capturing the manufacturing processes and costs, determining the requirements the product family or process must meet, comparing appropriate suppliers, and, ultimately, determining whether to outsource the candidate work. Throughout, examples from the pilot outsourcing analyses are used to illustrate the approach.
Methodology Used to Calculate Naval Compensated Gross Tonnage Factors
Authors: Craggs John , Bloor Damien , Tanner Brian , Bullen Hamish
Published: January 2021

Internationally accepted compensation factors exist for the main commercial ship types, but as yet there are no reliable factors for some unusual ship types or naval vessels. There have been at least two attempts to develop factors for U.S. naval vessels, but at present there is no agreement regarding the validity of the proposed factors. The aim of this paper is to outline the methodology developed to determine compensated gross tonnage (CGT) factors for U.K. naval vessels. This ongoing area of work, instigated and funded by the U.K. Ministry of Defence (MoD) and carried out by First Marine International, has been undertaken in partnership with leading U.K. and European shipbuilders. Three different methods have been used to calculate factors for a Type 23 frigate and an auxiliary oiler replenishment vessel. There was a good correlation between the factors derived by each method, giving the researchers a high degree of confidence in the principal weight-based methodology. The derivation of naval CGT factors and the subsequent analysis will assist MoD to estimate construction budgets, improve acquisition strategies, and quickly assess the implications of changes on unit procurement costs. U.K. naval shipbuilders will benefit from the ability to benchmark themselves against other naval and commercial shipbuilders and assess opportunities for performance improvement. The paper also discusses disparities in productivity between naval and commercial shipbuilders. It puts forward the view that fundamental differences between the two sectors will mean naval shipbuilders will inherently exhibit a lower level of productivity than commercial yards of similar technology.
Development of an Enterprise Supply Chain Model for Naval Warship Construction
Authors: Wallen Rex , Wilson Veasey
Published: January 2021

This paper presents issues critical to the development and successful implementation of computer simulation models for ship component manufacturing within a naval shipyard environment. More specifically, it addresses the need for a supply chain approach to developing simulation models for use as a management tool. The problem domain is the naval shipbuilding industry, which is different from industries associated with traditional manufacturing. Due to the tremendous number of components associated with naval warship construction and the extreme length of the build cycle, managing such an enterprise presents a formidable challenge. As Northrop Grumman Newport News strives to be a lean enterprise, managers will need new tools to address the lean initiatives of the many shops and construction areas within their domain. In this paper, it is suggested that the application of computer simulation using a component supply chain approach could provide management with a powerful tool to improve efficiency. A three-phased approach for the development of an enterprise supply chain model is presented. In the first phase, individual simulation models are developed for manufacturing and material support functions. The second phase addresses the linking of the models into small model networks. In the third phase, additional models are developed and more sophisticated networking strategies are utilized.
How to Identify and Remove the Barriers for a Successful Lean Implementation
Authors: Boyer Michael , Sovilla Lisa
Published: January 2021

This article discusses the issues with moving forward with lean manufacturing or learn repair. Once there is executive awareness and an understanding of the basic principles with significant momentum, there is knowledge and experience that may ensure your path of success. What are the barriers or obstacles to implementation, and what are the realities? Companies are differentiated by their various personalities, characteristics, and pools of knowledge, skills, and abilities. The barriers to change and reasons for failure among them, however, are very similar. The typical obstacles are underestimating the cultural and managerial impacts, the illusion of progress, conflicting measures, believing the excuse list, not remaining principle based, and using lean as a set of tools rather than a way of doing business. The countermeasures include embedding the lean principles in strategy, recognizing the realities of change, focusing efforts and getting immediate results, and assessing, acknowledging, and resolving cultural and managerial constraints.
Shop-Floor Automation and Market Strategy in Japanese Shipbuilding
Authors: Koenig Philip C. , Narita Hitoshi , Baba Koichi
Published: January 2021

Effective development and implementation of shop-floor automation is one of the keys to continued Japanese shipbuilding competitiveness. Manufacturing technology is implemented to serve a market strategy, and in many heavy industries (e.g., the manufacture of automobiles and commercial transport airplanes) heavily mechanized production processes are correlated with an exclusive dependence on repeat production. In the case of the Japanese shipbuilding industry, however, extensive automation has not had this result. Instead, shipbuilding automation in Japan is generally designed to support a variety of products, including comparatively simple ship types plus certain kinds of high-value products. Although high-value markets are pursued, the ability to build simpler ship types in a cost-effective manner cannot be abandoned lightly, due to the need to maintain capacity utilization. This position contrasts with that of some European shipyards, which have decided to specialize in high-value special products, such as cruise ships, ferries, and so forth. In this paper, specific cases of automation development and implementation in Japan are reviewed, and we discuss how these types of automation support a two-pronged market strategy.
Friction Stir Welding of HSLA-65 Steel for Shipbuilding
Authors: Konkol Paul J. , Mathers James A. , Johnson Richard , Pickens Joseph R.
Published: January 2021

HSLA-65 (ASTM A945) is a new structural steel of interest to the Navy shipbuilding community. The feasibility of joining the alloy by the friction stir welding (FSW) process was assessed. Single-pass weldments in 6.4-mm plates and two-pass weldments in 12.7-mm plates were successfully made. The FS weldments were evaluated by performing transverse tensile and bend tests; hardness, Charpy V-notch toughness, and salt spray corrosion testing; and metallographic evaluations. The weldments exhibited satisfactory transverse weld tensile strength, ductility, Charpy Vnotch toughness, and hardness. Visual examination revealed no difference in salt spray corrosion rates between the stir zone, the heat-affected zone, and the parent material. The results indicate that FSW does indeed have potential for joining ferrous alloys in shipbuilding, which should promote further efforts in this area.
Pulsed Semiconductor Diode Lasers as an Environmentally Efficient and Affordable Decoating Method for Shipbuilding and Ship Maintenance
Authors: Lancaster Frederick A.
Published: January 2021

Coating removal during new ship construction or ship maintenance has traditionally posed environmental and production issues. Coating removal results in a large amount of waste, and other trades cannot work in or near areas where coating removal operations are going on. Hydroblasting, an environmentally friendly method, has significantly decreased in recent years; it cannot be used on interior compartments. The dilemma has been to find a surface-preparation method that is effective yet environmentally acceptable and one that can work on the outer hull as well as on the inside compartments. Further, a method is needed to remove coatings from the new "soft" substrates. Laser devolved over the years from expensive CO2 and Nd:YAG lasers to the recent innovation of using affordable semiconductor diode lasers for coatings removal. Semiconductor diode laser decoating is a nonintrusive, nonkinetic energy process that has successfully removed coatings from a variety of substrates, such as composites, fiberglass, metal, and plastics, in a controlled manner, layer by layer, without damage, leaving the surface ready for immediate repainting. The process is very rapid (up to 400 sq ft per hour), 6 to 10 times faster on average than the present manual hand-sanding methods, and involves a minimal increase in temperature, because the energy is mostly absorbed and utilized in coating decomposition (i.e., instant pyrolization and evaporation). The only waste associated with this process is the ablated coating that is vacuumed from the surface and captured in particle filters, approximately one-third of the amount of coating originally on the surface. Diode lasers are compact, durable for shipbuilding and repair industry use, and present low operating costs. Due to delays in receiving test panels from Navy and commercial ship sources, this paper will highlight data from tests of removal of coatings similar to military epoxy/polyurethane coatings from thin-skin metallic, composite, and fiberglass structures, radome material, and for removing powder coatings. Pulsed high-energy diode laser decoating technology is now commercially and economically available for ship corrosion control and maintenance, can reduce the overall environmental impact of decoating, and can increase productivity of all the ship trades.
Removal of Tributyltin in Shipyard Waters: Characterization and Treatment to Meet Low Parts per Trillion Levels
Authors: Schafran Gary C. , Prasad R. , Thorn F. H. , Ewing R. Michael , Soles J.
Published: January 2021

Removal of tributyltin (TBT) from shipyard waters has been conducted in Virginia shipyards for over 2.5 years and has resulted in a 99% reduction of TBT discharged to coastal-estuarine waters. This has been achieved by conventional coagulation clarification for particulate TBT removal and removal of dissolved TBT using activated carbon. Although advances have been made in the understanding of TBT removal under various treatment conditions, TBT removal with the existing full-scale treatment plant to levels that would comply with a 50 parts per trillion (pptr) discharge limit are not possible. Results from study efforts that are currently ongoing suggest that the 50 pptr limit might be reached using ultraviolet irradiation or ozonation and that both processes would be substantially improved with the addition of hydrogen peroxide to promote hydroxyl radical formation.
Development of Dimensional Variation Simulation and Analysis Tool for the Shipbuilding Industry
Authors: Spicknall Mark H. , Kumar Ramesh
Published: January 2021

The paper discusses the progress to date of the Office of Naval Research-supported development of a dimensional variation simulation and analysis tool for the shipbuilding industry. The paper describes needs identification, specification and software development, functionality enhancements, industry feedback to date, and future development and commercialization plans.
Group Technology Through “People Modules?: A Case History
Authors: Turner Jody , Wharton Rick , Barry Christopher D.
Published: January 2021

Group technology, advanced outfit, and worker incentivization are commonly regarded as critical to improved productivity in shipbuilding. The authors present a case history that clearly demonstrates the importance of these techniques. The authors discuss the initial problems encountered during production of the 49-ft boat, utility, stern loading (49 BUSL); development of the solutions; their detailed implementation; and their effects in productivity improvements. They suggest how these techniques can be implemented and improved in other applications, including those involving more conventional modular construction.
Numerical Method for Design Margin Selection
Authors: Meyer Jan , Whitcomb Clifford A.
Published: January 2021

Design margins on speed or weight growth, to name just two, are used to ensure performance of a ship design given uncertainties in the design models or the production process. Although facing a high probability of meeting all performance requirements is very desirable, this assurance also comes at a price. When designers have the choice to set multiple margins, which all have some interacting effect on the vessel's performance, the problem of choosing a profit-maximizing margin combination becomes nontrivial. Using a mathematical model of the design process in conjunction with a Monte Carlo simulation, this paper demonstrates how the theoretical approach to margin selection presented in Meyer and Whitcomb (2004) can be applied. From the theory the profit-maximizing margin combination can be found where the Pareto frontier in the construction cost versus expected penalty graph touches the highest iso-profit line. The results from the numerical simulation show that such a Pareto frontier does form and a good (close to optimal) margin selection can be selected. Furthermore, limiting the risk level for failing to meet the performance requirements appears to have only a small negative effect on profit. Finally, a Bayesian approach is suggested, when insufficient data are available for meaningful statistics.
Evaluation of Surface Preparation Alternatives for Abrasive Blast Cleaning in Ship Repairing
Authors: Andronikos G. , Labrakis D. , Kaliampakos D.
Published: January 2021

Nowadays, the major argument against the use of dry abrasive blast cleaning focuses on its poor environmental compliance. The research work presented herein was the first of the kind ever to be conducted in Greece, and included the comparative examination of a number of alternative surface preparation methods and abrasives, on the basis of an integrated evaluation procedure. The results produced are in favor of the "best method for the job" approach, and advanced environmental protection has been taken into primary consideration.
Knowledge-Driven Production and Qualification: Key Factors for Sustainable Productivity
Authors: Brodda Joachim
Published: January 2021

Shipyards in recent years continuously invested in high-technology system solutions for engineering, design, construction, and other areas of ship production. These innovations dramatically changed the working process with substantial impact on the workforce, especially on the requirements on skills for individual employees. As a consequence, the level of low-skill employment is constantly decreasing in shipbuilding, and the shipbuilding industry increasingly faces the difficulty of finding skilled and suitable personnel. This gap must be overcome through suitable qualification and training of the existing workforce in close connection to the innovation measures. The challenge must be taken seriously by the individual shipyards and the industry sector as a whole. The full exploitation of knowledge-driven production in terms of productivity improvements and cost savings very much depends on targeted structural and organizational measures of the shipyards. This paper discusses results of a strategic study performed in Germany based on discussions with four shipyards that have worked within the context of knowledge-driven production and qualification in shipbuilding. The study includes an evaluation of so-called "soft skills" and recommendations for targeted measures in the shipbuilding industry. In brief, the analysis has shown that the success of technical innovation depends on the people involved, especially when system integration is a key issue. A structural change in the demand profile for all employees toward a broader shipbuilding competence can be seen. This is characterized by demands for higher individual competency in information and communication (technical and social); knowledge of systems, contexts, the overall process, and integration of functions; and project management and leadership. The relative significance of these skills is increasing in relation to technical skills, which of course have to be of high standards. This trend can be verified through a trend toward more outsourcing and automation, which become feasible and manageable through knowledge-driven technologies. Strategic tasks and qualification needs derived from that situation provide a real challenge to the successful management of shipyards in industrialized countries. Shipyards are differently prepared for that, often within the context of their experiences in knowledge-driven production technologies. The paper proposes a portfolio for the classification shipyards in levels of high technology implemented and level of "soft skills" achieved, allowing a justification of the right transition policy. Finally, the paper gives some recommendations for individual and industry wide measures, which may provide some guidance for suitable future activities in this field.
Thermomechanical Analysis of Plates Undergoing Line Heating Using Pseudolinear Equivalent Constant Rigidity System
Authors: Adak Malabika , Mandal N. R.
Published: January 2021

Line-heating technique involves application of controlled thermal cycles. In developing the technique of line heating, which is nonlinear and involves plastic deformation of the medium at high temperature varying in both time and space, analytical solutions turned out to be inadequate. At the same time conventional numerical techniques proved to be highly time consuming and thereby prohibitively expensive in real life situations. In this investigation, the initial nonlinear problem with modulus varying with temperature was transformed into a pseudolinear equivalent system of constant rigidity that was solved by applying linear analysis. The analysis procedure presented in this work and the results thus obtained hold great promise for analyzing the complicated thermal elastic-plastic problems as encountered in line-heating process.
Some Notes on the Influence of Manufacturing on the Fatigue Life of Welded Aluminum Marine Structures
Authors: Kecsmar J. , Shenoi R. A.
Published: January 2021

Designers are constantly looking for ways to reduce the structure weight to lower the overall displacement and hence the cost of fast ferries and other high-speed vessels. The easiest option for the designer is to choose a lightweight material. Aluminum has become the adopted choice of material for high-speed vessels owing to its high strength to weight characteristics. Unlike steel, aluminum is more prone to fatigue cracking and has no fatigue limit. In order to minimize weight, the designer will make use of finite element methods to optimize the scantlings and perform fatigue checks against established codes. This can lead to a structure that has the empirical margins of safety reduced owing to the accuracy of mathematical modeling. However, what is often overlooked is the effect the manufacturing process has on the fatigue life of the fabricated structure. This aspect is excluded from the designer's fatigue calculations, which assist in reducing the scantlings. Currently, there is no guidance for fatigue life reduction for the designer that establishes good and bad workshop practice, other than experience, or the implications of basic shipyard fabrication. It is shown that whereas strain-hardened alloys improve mechanical strength, they reduce ductility. This has consequences when forming the hull plate by potentially introducing crack like flaws into the alloy matrix if the plater overrolls the plate. If there is misalignment or there is too much gap between the plates, the weld will create localized stress concentrations. If the welder has poor joint preparation or gas shielding, porosity can be introduced into the weld. Porosity has a significant effect on the fatigue life of the weldment. This paper brings together a collection of data on such issues that the designer needs to be aware of to prevent an unwanted fatigue failure in the fabrication process.
Laser Welding Process: A Research Project on Quality Assurance and Control
Authors: Manzon Luciano
Published: January 2021

For the industrial adoption of laser welding technology, it is important that the yards achieve full control of the process and that they and the classification societies reach a level of confidence in the technology to permit a reduced level of quality controls after the welds have been performed. This would lead to a practicable and easier implementation of the technology in the industrial field. This is the approach that two EU yards, Odense Steel Shipyard and Fincantieri, had in mind while developing, with the partnership of important EU research institutes and classification societies, the EU-supported research project Shipbuilding Laser Welds: An Integrated System for Assurance and Control of Quality (SHILWACQ). The author, who was the coordinator of the project, explains, from the point of view of an end user shipyard, how this approach was implemented following two main research lines:the quality assurance line, focusing on the "defect avoidance" criterion and the "defect acceptance" (fitness for purpose) criterion;the quality control line, concentrating on the on-line process monitoring and automated not-destructive-test inspection systems. The CO2 laser welding technology for small/medium-thickness steel hull components is addressed. The article explains the activity development and the scientific results achieved by the two research lines, as well as how these results have been tested and validated in the industrial environment.
Cooperative Design by Using Intelligent Electronic Supplier Catalogs in the Maritime Industry
Authors: Ahlers Reinhard
Published: January 2021

Make-to-order manufacturers, such as the manufacturers related to the maritime industry, are more and more following the worldwide trend toward further outsourcing of processes and services to benefit from a better specialization, lead time reduction, and better cost performance of smaller and self-responsible companies. This trend requires the optimization of supply chain management with respect to interorganizational information management. Especially in the shipbuilding industry, supply chains are characterized by project orientation (new supplier structures are required for each ship type), the high number of suppliers (more than 60% of a containership consists of supplier parts), and heterogeneous structure of cooperation partners (subcontractor, component supplier, material supplier, engineering offices, etc.), which all together leads to different requirements and a limited cooperation duration. In many cases the expense for both sites (customers and suppliers) for organizing the cooperation is extremely high in relation to the duration of the cooperation. Because of the temporary nature and the heterogeneous portfolio of maritime supply chains, the management mechanisms applied need to be flexible, standardized, and easy to reconfigure. An open communication infrastructure, agreed upon data exchange standards, and harmonized workflows are vital success parameters for maritime supply chains. The European research and development project Dynamic Interorganisational Co-operative Networks for the Maritime Industry (DYCONET) has been established to define and develop an open communication infrastructure that can be managed also by small and medium enterprises. One important part of the infrastructure is intelligent electronic supplier catalogs. The pilot implementations of the catalogs for complex valves have shown advantages for all partners of the maritime supply chain. The developed intelligent catalog modules are based on international standards, which enables easy extension to other product groups. The DYCONET architecture is the step from centralized internet portals to distributed cooperative design networks.
Advanced Joining Techniques in European Shipbuilding
Authors: Roland Frank , Manzon Luciano , Kujala Pentti , Brede Markus , Weitzenbock Jan
Published: January 2021

Joining processes are an important key factor for the competitiveness of European shipbuilders. They not only represent a significant portion of the total man hour consumption in hull production and outfitting, but due to heat distortions they also have a significant impact on nonproductive work operations, such as straightening and fitting. Those operations can interfere with on-board outfitting and increase lead time and construction cost. In addition to their contribution to shipyard productivity, joining techniques have a significant impact on material properties and thus on product performance and quality. Those factors become increasingly important for complex structures using comparatively thin and high-strength materials. Considering the importance of efficient joining, European shipbuilders in the past decade have invested significant efforts to develop new joining techniques, such as laser welding, adhesive bonding, and mechanical joining. Based on research results, practical industrial applications have been developed recently. After reviewing the impact of joining processes on competitiveness, the article will summarize a number of past and ongoing research projects with special focus on design methods, process and equipment development, fatigue strength of joints, quality assurance, and approval. It will then present a number of recent applications of new joining techniques in European shipyards. Finally, open problems and future research needs will be briefly discussed. The article is based on a joint effort of leading European experts and will focus on laser and laser hybrid welding, adhesive bonding, and mechanical joining
Integrating Manufacturing and Life Cycle Information Into the Product Model
Authors: Oetter Rolf , Barry Christopher D. , DeCan Lawrence A. , Sorensen Paul F.
Published: January 2021

The power of the integrated product model can be extended well beyond the mere definition of geometry, and this extension offers significant benefits to shipbuilders. The nature of computer-aided design/manufacturing (CAD/CAM) data allows use of arbitrarily extensible linked databases, which can contain any other information that might be useful for manufacture, production engineering, procurement, and even maintenance and operation of the ship throughout its life cycle.
Connector Architecture for Computer-Assisted Design and Manufacturing Systems
Authors: Staebler Reinhard M. , Miller Bryan J. , Rakow Paul J. , Koch Thomas
Published: January 2021

Flexible integration concepts for computer-assisted design (CAD) and manufacturing (CAM) systems have been identified as a key to let shipyards select and implement best-in-class software components for their CAD and CAM operations. Current implementations are dominated by bilateral links based on proprietary data exchange formats and are too complex to upgrade parts of a CAD/CAM infrastructure without negative impacts on the other parts. This paper describes the ongoing development of a connector architecture for CAD and CAM systems in shipbuilding. The architecture decouples CAD and CAM systems on the basis of a flexible integration technology, utilizing XML data exchange, lightweight directory access protocol (LDAP), and message-based communication. An enterprise reference model describing all relevant shipbuilding business objects forms the basis for the integration. So-called adapters connect the various CAD and CAM systems to the architecture. An automatic nesting solution is presented as a sample business solution in the connector architecture environment.
A Method for Automatic Nesting of Ship Plates
Authors: Vitória J. , Guedes Soares C.
Published: January 2021

This work describes a method that provides an automatic nesting method and an optional simple interactive nesting tool for final adjustments. This approach has been incorporated in a system that has been developed for small shipyards and has been connected with a Standard for the Exchange of Product Model Data (STEP) interface that produces the data in a neutral format. In this paper a review is provided of methods for plate nesting and the method adopted is described. Examples of applications are given demonstrating the performance of the system with academic examples and with realistic examples with ships parts. It is demonstrated that a good performance is achieved.
Evaluation and Management of the Cost and Risk of Weld Deformations in Modular Ship Construction
Authors: Asok Kumar Ajay , Aoyama Kazuhiro
Published: January 2021

The weld deformations of construction blocks are a major problem affecting productivity and quality in modular ship construction. Therefore, proper evaluation and management of the weld deformations is necessary. In this paper, a system that predicts the cost and risk associated with weld deformations is proposed. Using this system, for different block division plans, the designer can calculate the weld deformations of each block, deformation variation with the variation in weld parameters for different assembly sequences, rework cost due to deformations, and the variation of rework cost. Based on this evaluation, the designer can select the best module division plan and construction plan by minimizing the cost and risk of rework due to weld deformations.
The One Shipyard in Practice: Implementation of a Second-Tier Common Parts Catalog
Authors: David Patrick , Cahill Patrick , Roberts Patrick
Published: January 2021

This paper presents the methodology for the realization of a Common Parts Catalog (CPC) system for second-tier shipyards. Applying current principles in data management and conceptualization, a relational system is employed whereby the previously unstructured and haphazard approach to material management and parts definition is broken down to a meaningful and systematic taxonomic structure. The current majority of second-tier shipyards employ antiquated and/or bulky control systems for tracking and monitoring parts within each shipyard's own cataloging systems. This has led to a spate of data that are often duplicated needlessly, as well as leaving the most current state of the catalogs in such disarray as to be almost indecipherable in some instances. For these reasons, parts catalogs have often had to be "reinvented" as they are needed. Unfortunately, the process was often not undertaken with either a full understanding of database management and creation or with any meaningful level of standardization in the data. Given the latest advances in computing technology and the decreasing cost of associated hardware to utilize these technologies, a means of standardizing and organizing a shipyard's parts catalog has become a crucial step in the further development of the industry as a whole. From the extremely outdated method of parts tracking and cataloging on paper, to the latest available computer hardware and relational databases, the CPC aims to alleviate the shipyards of the tasks involved with maintaining a disparate collection of data used currently as a parts cataloging system and to replace it with a highly organized and flexible data structure to store and manage parts and materials. The National Shipbuilding Research Program's (NSRP) Integrated Shipbuilding Environment (ISE) project standardized and classified the methods of catalog construction and administration such that needless replication and unwieldy catalog size have all but been eliminated. These same ISE type Common Parts Catalog standards and procedures are now being adopted by second-tier shipyards in an attempt to better utilize resources available, streamline the process of cataloging parts and material, and facilitate direct interaction among shipyards' (both first and second-tier) catalog systems.
Optimization of Steel Plate Cutting Sequence Using the Tabu Search Method
Authors: Okumoto Yasuhisa , Iseki Ryutaro
Published: January 2021

This study concerns the cutting scheduling of steel plates by numerically controlled (NC) machines in shipyards. The combinatorial optimization of the cutting sequence to minimize the idle time of machines has been examined for processing many plates by multiple cutting machines. As an algorithm of the optimization, the tabu search method, which is a kind of metaheuristic technique and has been widely applied recently for such optimization problems, was adopted. The procedure was programmed on a personal computer, and calculations were carried out for test data as well as field data. It was confirmed that the idle time to wait for the next process decreased remarkably compared with the initial planned sequence, and the tabu search method was a simple and effective method to solve combinatorial problems.
Curvature Analysis Method for Ship-Hull Plate Forming
Authors: Xuebiao Zhang , Zhuoshang Ji , Yujun Liu
Published: January 2021

Ship-hull plate forming by line heating requires hard and skillful labor. Initially, the plate is curved in one direction by rolling. Then, the curved plate is transported to the line-heating workshop to obtain the required shrinkage. However, this two-step forming leads to a series of problems. This paper presents a method to change the two-step forming into line-heating forming by using curvature analysis. The principal curvatures of the formed plate can be calculated directly from the offset data. The principal curvature distribution provides information on the deformation distribution and the heating lines. Heating along a line will result in a uniform bending angular deformation. A numerical method to determine the heating lines to produce the required bending angle is presented. This kind of heating line does not require adjustment of parameters in line heating. It would benefit temperature control and facilitate plate forming automatically.
The Establishment and Management of a Production Data Exchange Group
Authors: Morea Gregory F.
Published: January 2021

The design and construction of any marine vessel designed on a computer-assisted design (CAD) system, from a nuclear aircraft carrier to the smallest work boat, requires the interaction of many electronic databases, all of which must be continually updated for the work to proceed. The exchange of this information, especially geometry, in digital format is accomplished using many different tools and techniques. Much has been presented to the marine community about the tools used, such as the Initial Graphics Exchange Specification (IGES) and the Standard for the Exchange of Product Model Data (STEP), and how these tools might be used for exchanges in the future, but little has been presented on how production data exchanges actually occur. At Electric Boat, current submarine programs cannot wait for future data transfer solutions. Design and construction data must be exchanged among various activities, internal and external, with such volume as to make manual reentry of data an unrealistic solution. Because of the complexities associated with the electronic exchange of these data, the General Dynamics (GD) Marine organization of Electric Boat has a dedicated group that both performs production data exchanges and researches and implements new methods of electronic transfer. This paper discusses the rationale for and the formation of the data exchange group at Electric Boat, along with its place within GD Marine. It then presents an overview of the tools used by the group and how production transfers occur, both routine and unique. Notable transfers provide examples of how the group works to solve transfer problems. Importantly, this paper shows how many of the exchange standards developed for the marine industry actually work in production. Special emphasis will be placed on the exchange of solid models in a day-to-day environment. The paper concludes with a look at the future of production data exchanges for Electric Boat and the larger marine industry.
New Automated Tandem Process for Agile Fillet Welding of Ship Structures
Authors: Dierksheide J. , Harwig D. , Evans N. , Kvidahl L.
Published: January 2021

New ship designs are calling for complex, lightweight panels made of thinner steel (as thin as 3 mm) for weight and structure optimization. For stiffener welding on ship panels, thin steel demands small, precision fillet welds in order to reduce panel distortion and improve downstream processes. The existing panel welding systems in most shipyards use flux-cored arc welding with mechanical seam tracking and cannot cope with the complexity and precision required. Tandem gas metal arc welding (T-GMAW) has shown an increase in deposition rate of up to three times that of single-electrode GMAW while offering process robustness. However, when T-GMAW was combined with through-the-arc (TTA) seam tracking by weaving, the travel speed was limited to 1 m/min (40 in./min) and the minimum fillet weld size was 5 mm. Rotating electrode (RE) GMAW utilizes TTA seam tracking by rotating the contact tip and electrode around a small diameter at 10 to 100 Hz. This method results in capabilities to seam track while making welds as small as 2 mm at travel speeds as high as 2.5 m/min (100 in./min). RE-GMAW is also a robust process with enhanced bead shape characteristics ideal for horizontal fillet welds. However, because RE-GMAW is a single-electrode process, it cannot match the deposition rates of T-GMAW. This project developed rotating lead tandem (RLT) GMAW, which is a new process that offers deposition rates comparable to T-GMAW with the seam-tracking capability of RE-GMAW. An objective was to develop the preferred torch setup and electrode conditions that provide a complete range of fillet weld sizes for agile processing of ship structures. Procedures were developed for 3-, 4-, 6-, and 8-mm fillet welds with RLT-GMAW using the ARCWISE (EWI, Columbus, OH) procedure development method on a seam-tracking T-joint test. Process robustness was assessed by evaluating fusion quality, leg size, convexity, process stability, and spatter susceptibility. A preferred torch setup was determined that met the project objective. RLT-GMAW was shown to offer deposition rates that were near or equal to standard tandem GMAW, especially on smaller 3and 4-mm fillets. While offering high deposition rates, it also demonstrated high-resolution seam tracking at travel speeds up of 2.3 m/min on 3-mm fillets.
Comparison of Measured Deck Buckling to Finite Element Analysis Predictions
Authors: Hand Steven D. , Clark James F. F. , Bond Bryan A.
Published: January 2021

A noncontact, remote measurement technology is coupled with finite element analysis (FEA) techniques to provide a real-time comparison of actual versus theoretical distortions of a ship's deck under load. These comparisons are generated using coherent laser radar scanning techniques with surfacing inspection software. The deck is measured in a "no load" condition and then remeasured while varying hogging and sagging loads are applied. The point cloud measurements are taken at micron level accuracies and can be directly related to the predicted FEA distortions. This effort and its results are described in this paper.
Digital Manufacturing of Pipe Unit Assembly
Authors: Okumoto Yasuhisa , Hiyoku Kentaro
Published: January 2021

This paper introduces an outline of digital manufacturing in shipbuilding and results of its application, with the aim of modernizing ship manufacturing, following the introduction of a shipbuilding computer-integrated manufacturing (CIM) system. The pipe unit assembly in a shipyard was taken up as an example, because the assembly work has depended on personal experience of skilled workers and has not been generalized and digitized. As a result of the work analysis in the job site, it was found that even veteran assembly workers often use the drawing to image the final assembly unit. Hence, the assembly simulation program was developed and a PC was introduced in the job site in order to assemble the pipe unit in accordance with the computer simulation on the display. The method was effectively tested and verified in the job site. In addition, a wearable computer system was applied in a pipe shop to check the purchased parts and to allot them to the pallets. These applications were confirmed as an effective digital manufacturing system.
A Robust Approach to Jobshop Scheduling Problems in the Marine Environment
Authors: Dalton J. A. , McGregor J. I. , Sen P. , Kenevissi F.
Published: January 2021

In industry the scheduling of large made-to-order products, such as submarines or ships, is typically implemented using precise time intervals. As a result of this, schedules rarely if ever reflect reality, and this can make the task of managing large projects difficult and potentially costly. Not surprisingly, robustness is a desired property of a schedule, bringing with it a greater stability with less uncertainty. In addressing these problems, this paper first describes a practical job shop model that is then extended to allow the inclusion of imprecise durations. By implementing this methodology on an industrial case study, a submarine pressure hull, a means of gauging and providing greater robustness of scheduling is determined. This investigation into robustness also shows that improvements can be made by optimizing pessimistic duration times in contrast to the common practice of using optimistic times.
Mapping of Shell Plates of Double Curvature Into Plane Surfaces
Authors: Branco J. N. Rodrigues , Soares C. Guedes
Published: January 2021

A solution for mapping of shell plates of double curvature into plane surfaces is presented. As in most cases in which the equation of the surface of a compound-curved shell plate is unknown, the mapping of the surface of such a plate is done to a so-called "associated surface," which is specified in three dimensions and can substitute for the previous one within the shipbuilding tolerances. This solution allows a plane peripheral contour of one of these shell plates to be built according to the forming process chosen. It also allows the calculation of the parameters involved instead of the traditional trial and error method.
Study on Production-Oriented Design for the Capesize Bulk Carrier: Using Transverse Reinforced Double-Bottom Pipe Duct
Authors: Hsu Shou-Hsiung (Vincent) , Wu Jong-Shyong
Published: January 2021

Cutting total man-hours is one of the most effective ways of reducing costs in a shipyard and, in general, designing structures with fewer pieces will achieve the goal of reducing man-hours. The Capesize bulk carrier, due to requirements for access, ballast capacity, and double-bottom height, always has a pipe duct in the center part of the double bottom. Comparison between two existing Capesize bulk carriers reveals that one may eliminate more than 1,800 structural pieces (about 2.6% of the total number of ship pieces) if the conventional longitudinal reinforced pipe duct is replaced by a transverse reinforced one. Further, from the finite element analysis (FEA) results using the SafeHull computer package of the American Bureau of Shipping (ABS), it has been found that the vertical deflection and stress concentration of the double bottom are improved and some of the thicker plates can be removed if the transverse reinforced pipe duct is used. Therefore, the overall steel weight for the Capesize bulk carrier using the transverse reinforced pipe duct was found to be less than that using the longitudinal reinforced pipe duct.
Particulate Matter Emissions and Emission Factors for Specialty Sand Used in Dry Abrasive Blasting
Authors: Kura Bhaskar , Kambham Kalpalatha , Sangameswaran Sivaramakrishnan , Silvadasan Xavier
Published: January 2021

Sand is being replaced with alternative materials in abrasive blasting because of the adverse health effects of silica emissions from the process. However, many industries still use sand due to its low cost and abundant occurrence in nature. This paper presents the effect of blast pressure and feed rate on particulate matter (PM) emission factors and optimum process conditions that can minimize PM emissions in dry abrasive blasting using specialty sand.