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SPS Papers, Authors & Abstracts

The SNAME Annual Meeting will feature the offical release of dozens of technical papers and over 40 hours of cutting-edge technical presentations.   Among these will be the presentations and papers associated with the Ship Production Symposium of the National Shipbuilding Research Program.   

Paper and presentation abstracts are available below.  Attendees can review the current drafts through the 2010 Annual Meeting Library.   See the Schedule Page for information on paper presentations and links to the papers.

P01 The Technical Practices of Compressed Natural Gas Fueled Ship
Xu-dong Yang

On July 6, 2009, the world first commercial single compressed natural gas (CNG) fueled ship, M.V. NP Jenjosh, which is first one of 12 contracted vessels built in Dajiang and Hongyu shipyards located in Wuhu city of Anhui Province, P.R. China and classed to China Classification Society (CCS), is delivered to the owner, Jenjosh Group based in Thailand. In this paper, we will make some technical discussions during the class plans review of the subject vessels, including: hull technical practices, machinery & electrical technical practices. And in the final, we have make a conclusion and looked forward to the future practice of the CNG fueled ship.

P03 Pipe Weld Sequencing to Maximize Mechanized Welding (POSTER)
Christopher B. Ligetti and Daniel A. Finke

Shipyards are continually developing and implementing mechanization and automation technologies to reduce fabrication time, improve welding productivity, and maintain quality. This is particularly evident in pipe welding, where mechanized welding equipment is increasingly used in the fabrication of both small and large diameter pipe assemblies.

This paper describes a methodology developed to determine the optimal fit/weld sequence for joining several pieces of pipe and fittings into a pipe assembly. The objective of the methodology is to maximize the utilization of mechanized pipe welding equipment, including horizontal welding machines and portable, orbital welding equipment. The problem is constrained by pipe and fitting diameter, material, weight, and the ability to fixture the part.

The methodology is comprised of an algorithm that generates optimal sequences using a detailed set of business rules and physical constraints resultant of the equipment geometry and pipe assemblies. In addition, the methodology contains an efficient collision detection routine that analyzes potential interferences with the pipe assembly and the weld equipment. A small example problem is presented to demonstrate the methodology.

In addition, a real world problem is solved using the algorithm, and the results are compared to the manual planning method traditionally employed in the shipbuilding industry. Results show that the sequencing methodology has potential to reduce the cost of pipe fabrication in the shipbuilding industry.

P04 Construction Visualization Modeling
Christopher B. Ligetti, Daniel A. Finke, Jim Bean

This paper discusses the development of a software tool that utilizes light-weight versions of 3D digital product models and detailed module construction and erection schedules to visually validate and modify the erection sequence. The tool enables planners to quickly and easily modify the schedule to improve the sequence during the planning phase, where planners with limited knowledge of the predecessor/successor relationships can visually determine erection sequence conflicts. In addition, the Erection Visualization Tool (EVT) provides a means for communicating module status and aids decision making throughout the erection process to avoid excess construction costs and ensure on time delivery of ships.

P05 Weight Optimization of a Submarine Pressure Hull
N. S. Barner

This presentation documents the use of simulation management software to perform a weight optimization for submergence loading on a submarine pressure hull, varying geometry and thicknesses. The objective of the project is to improve the cycle time required to perform a full-ship analysis, which allows Electric Boat to find an optimized design earlier in the design process.

P08 Improved Methods for the Generation of Full-Scale Simulation/Analysis Models
A. Boday and Stewart Moore

Large full-ship engineering analyses and simulations are performed today in various disciplines. Such analysis models are almost always "hand-crafted" by skilled and experienced analysts. There is a need to improve upon the time, cost, and skill mix required to create such large-scale ship models. In order to perform a full ship computational analysis, the engineering analyst must have or create an analysis-ready model. Following current work practices, a computer-aided design (CAD) database of the vessel is created, primarily for design disclosure and manufacturing rather than for analysis. Consequently, the model may not be suitable or easily modified to create an analysis-ready model. Several thousand man hours are required to obtain data and prepare a model that is usable for analyses. Furthermore, solely expanding use of modeling and simulation tools, without accompanying changes in the model generation approach, will not deliver significant savings. Model generation is a complex effort and often is the major cost of full ship analysis.

The authors present a summary of several National Shipbuilding Research Program (NSRP) efforts which support ship design and analysis automation from the early concept to the detailed stages. These unique approaches focus on supporting multilevel modeling fidelity within a flexible design environment at the earliest stages of ship concept formulation by implementing a more computer-aided engineering (CAE) centric approach, in which data is captured at the beginning of the ship design cycle, thus having the most cost effective impact as ship design progresses through the ship’s lifecycle.

P09 Development of Distortion Modeling Methods for Large Welded Structures
Y. P. Yang, H. Castner, and N. Kapustka

Two distortion modeling methods, mapping plastic strain and lump-pass modeling, were developed and validated for predicting distortion on large welded structures to reduce the computation time. The mapping plastic-strain method requires two kinds of models, local models and a global model. The local models are analyzed to predict plastic strains and the global model is analyzed by mapping the plastic strains to prediction distortions. The lump-pass modeling method includes two kinds of analyses: a thermal analysis and a thermomechanical analysis. The thermal analysis is conducted to predict temperature history. The thermomechanical analysis is performed to predict distortion by inputting the predicted temperature history.

P10 An Integrated Logistics Environment for an Effective Shipbuilding & Supporting Enterprise
Burton Gischner

Over the past several years the ISE Projects under NSRP have been developing and prototyping tools to enable an Integrated Shipbuilding Environment (ISE). A current NSRP project is continuing those efforts with a special emphasis on creating an environment to facilitate data exchange and interoperability throughout the entire life cycle of the ship. This natural transition brings project focus on creating a standards-based Integrated Logistics Environment (ILE).

NSRP has led the way in developing standards and prototyping tools to facilitate product model exchange between shipyards and the Navy throughout the life cycle of the ship. In conjunction with the Navy Product Data Initiative (NPDI) effort, a Ship Common Information Model (SCIM) was defined to specify the information that must be migrated between IPDE environments throughout the life cycle of the ship.

A current NSRP Project for an Integrated Logistics Environment (ILE) is evaluating and validating the SCIM models that have been developed, as well as completing the SCIM document for several additional disciplines. This paper and presentation will discuss the results, accomplishments, and plans for the ILE Project.

P13 Aluminum Applications to Naval Ship Design and Shipbuilding
Thomas Lamb and Nathaniel Beavers

In earlier papers, the authors conducted an analysis of the difference in acquisition and total-life cycle costs of steel and aluminum equivalent naval ship designs. This paper is slightly different in that it focuses on the expanding application of aluminum for ship's structure first and then uses the specific applications to naval ships as an example of the potential aluminum advantages. The example shows that in comparing aluminum ships to steel ships a simple replacement of aluminum for steel does not take all the advantages into account and it is clear from the example that the structural material must be taken into consideration in the initial and following development of the design of an aluminum ship. It also introduces the notion that breakthroughs in aluminum technology and manufacturing methods are quickly closing the stated difference in aluminum versus steel ship acquisition cost.

P14 Development of a Low Cost Virtual Welding Training System
Ken Fast and Jerry Jones

Manual welding continues to be a primary process in shipbuilding. Training new welders is a significant expense for shipbuilders. In order to reduce the cost of training welders a virtual welding system is being developed. As a result of lessons learned from the development of previous virtual welding systems, the goal of this effort is to create a very low cost end product. The system would be intended for training in shipyards, technical colleges, and vocational schools. A prototype virtual welder has been created that takes advantage of existing weld monitoring software and recent advances in sensor technology. The system includes a welding torch, optical tracking, helmet-based display, and realistic welding simulation, all running on a standard PC platform. Technical details of the system's design and development are presented, along with plans for user testing and evaluation, and potential future commercial production.

P20 SPS Overlay: 23500 sq.ft RoRo Main Deck Plating Renewal, 30 days off-hire
James E. Bond, Armin Reindl, David Potts, Greg Wiggins, and Gerard Stevenson

The plating of the main deck of the ropax ferry PRINCESS OF ACADIA (1971) was renewed during the month of March 2010 using Sandwich Plate System (SPS) Overlay. In comparison to conventional repair methods the processes used reduced costs and the out of service time making the deck renewal on the elderly ship viable. The SPS Overlay was installed afloat at the ferry terminal whereas a conventional renewal would have required drydocking the ship. This paper describes the project execution details, the steps involved in applying the SPS Overlay and summarizes the post project impact on the ship’s operational characteristics including passenger impact and future maintainability. SPS Overlay is the conversion of a stiffened plate into a composite plate structure with stiffeners. In the project presented, the existing deck plating is utilized as the bottom faceplate in the newly formed composite deck plating comprising a new steel top plate separated from and fully bonded to the bottom faceplate by a polyurethane elastomer core material. The conversion to an SPS composite deck structure is performed quickly, does not disrupt existing structure, services or insulation and allows other work to be performed in parallel.

P24 Alternatives for Joining Stainless Steel to Reduce Cr(VI) Emissions and Occupational Exposures
K.P. Paulson, J.Wang, N. Topham, C.Y. Wu, B.T. Alexandrov, John C. Lippold and O.S. Es-said

Welding stainless steels generates hazardous air pollutants. Two technologies have been developed to reduce these HAPs. The first, Tetramethylsilane is added to the welding shield gas, and welding proceeds as normal. Reactive oxygen species are consumed and the resulting metal fume particles are encapsulated. In the second technique, new chromium-free welding consumables are introduced nearly eliminating Cr(VI) in the welding fume.

P26 Safety Considerations Applicable to Shipboard Electrical Installations
Dennis K. Neitzel

This paper provides insight into the electrical safety considerations, specifically as it relates to medium-voltage electrical systems and equipment for shipboard application, for the electricians and engineers who operate and maintain them, frequently under adverse and dangerous conditions.

P27 Implementation of Process Oriented Visual Planning Methods and Techniques
P.D. Cahill and E. Atkins

The Process Oriented Visual Planner (POV Planner) project combines commercial off the shelf visualization software (Navisworks®) with a resource constrained simulation based planning and forecasting tool (WorkSim®). The concept was developed and prototyped at Todd Pacific Shipyards during the construction of a 64 car ferry for Washington State Ferries. POV Planner allows the production planners to access and manipulate the product model without impacting the engineered design, extract information pertinent to planning, and perform both what-if
analyses and process duration calculations while applying a variety of personnel and facilities resource constraints.

P28 Mechanical Bending Process and Application for a Large Curved Shell Plate by Division Multi Point Forming
S. Y. Hwang and J. H. Lee, C. Ryu

Curved hull plates of marine vessels have been fabricated by skilled workers using line heating or flame bending method. Recently in Korean shipyards, mechanical bending such as multi-point press forming or die-less forming has been tried to replace the flame bending since the mechanical bending is more efficient than the flame bending. This paper discusses a multiple point pressing machine composed of a pair of reconfigurable punches in order to achieve the rapid forming of curved hull plates and presents how forming information is obtained from the given design surface.

Although the mechanical forming can be efficient in the metal forming, springback after pressing is a phenomenon which must be carefully considered when uantifying the process variables. If the springback is not accurately controlled, the fabricated shell plate cannot meet assembly tolerance. In this study, the proper stroke of each punch is determined by an iterative process of sequential pressing and springback compensation from an unfolded flat shape to its given design surface. It is finally aimed to develop an integrated system that can automatically perform the springback compensation process and calculate strokes of punches of the double sides’ reconfigurable multiple-press machine. The deformation is numerically simulated by elastic-plastic FEA and springback compensation adjusts the offset of pressing punches from the deformation results and the design surface. For the practical application, a software configuration has been implemented to automatically calculate the strokes of pressing punches for the division multi-point forming work from the given design surface of a curved shell plate. The present study also provides several experiments of real forming processed by the suggested process.

P29 On-demand virtual mentoring to accelerate cross-training and multi-skill training (POSTER)
Michael Paley, Diane Miller, Eileen Entin, Gilbert Mizrahi and Michael Therrien

KEEL (Knowledge and Experiences of Expert Labor) is a virtual, on-demand training and mentoring system for the shipbuilding industry. KEEL enables experienced workers to record video stories that convey their wisdom and techniques. A knowledge repository and retrieval component links the stories to training materials, enabling convenient access by users.

P33 Composites Design for Large Vessels: An Imperative for 3D and Collaboration (POSTER)
Greg Albrechtsen

The use of composite materials in naval architecture and marine engineering is a relatively recent phenomenon. Once limited to smaller vessels such as pleasure yachts and small commercial fishing boats, advancements in technology including 3D and collaborative design tools built specifically for composites have enabled the introduction of these strong, lightweight and corrosion-resistant materials for large vessels as well. The complexities involved with using composites parts -- versus metals such as steel or aluminum -- call for a unique set of knowledge and tools. For example, when working with metal, designers must only decide on the shape of the part and how the metal will be cut and assembled. Working with composites means actually designing unique material with characteristics optimal for its intended use, and then deciding how to shape and assemble it. Because of this intricate process, collaboration between design, analysis and manufacturing teams and tools is imperative to deliver a superior product on time and on budget. Traditional composites design solutions address the design, analysis and manufacturing processes of composites parts separately, without collaboration. This makes for a slow, tedious and strictly sequential process that involves one team actually working at any given time, while two teams are just waiting for the project to land on their desk.

To avoid this, the goal is to integrate the work environment and provide unique collaboration capabilities for designers to work in a functional context where they can get accurate, real-time feedback from simulation and manufacturing teams, and vice versa. By doing so, these teams will gain the ability to anticipate problems so they can be avoided early in the design cycle.

This presentation will describe the benefits of embracing a collaborative design, analysis, and manufacturing environment specific to composites and the advantages they can bring to even more areas of a ship, including hulls, floor and wall panels, decks and bulkheads, ducting systems, oil and waste water tanks, sonar domes, piping, pumps, valves and superstructures. In a collaborative environment users from each domain can share their ideas, results, and processes seamlessly to shorten the development lifecycle and result in a superior product.

P37 Development and Qualification of Laser Ablation for Naval Coating Removal (POSTER)
E. Oller, M. Klingenberg, J. Valencia, K. Reasbeck, T. Blair and G. Price

Concurrent Technologies Corporation, through the Navy Metalworking Center, is investigating laser ablation processes to remove coating systems from steel in shipbuilding and repair applications. Laser ablation may be an economical alternative to current processes used to remove paint systems, glass reinforced plastic (GRP), and rust from submarine shafts or small areas of structural steel. For these applications, coating removal by laser ablation is not only environmentally friendly, but can also significantly reduce task duration and the amount of waste generated. Laser ablation can be performed safely in the shop or shipboard with simple precautions in place. This presentation will describe the technology being developed to remove common coatings from shipbuilding steel and submarine shafts. In addition, the effects of the laser ablation on the characteristics of the steel surface and subsequent coating adhesion will be discussed. This work will also describe the NAVSEA approved qualification program, the environmental and safety impacts, and the cost benefit analysis for implementing laser ablation.

P38 Advanced Mold Design Technolgoy of the LCS Waterjet (WJ) Entry Edge Casting Assisted by Flow, Solidification and Stress Modeling (POSTER)
Laurentiu Nastac and John Romanelli

In order to reduce cost, increase performance and ensure quality, this Navy Metalworking Center (NMC) project utilized an advanced casting simulation-based optimization approach to assist in the improvement of the mold design of LCS Waterjet (WJ) entry edge components. This approach helped to minimize mold filling and solidification related defects (misruns, coldshuts, shrinkage and porosity and hot tears), as well as post-solidification related defects (hot and cold cracks, distortion and residual stresses). The results of this optimization were used to more readily achieve first time quality on the geometrically challenging WJ components.

NMC performed the simulation work to improve the rigging system (gating and risering) design and to assist ExOne/Prometal Company in the mold design of these WJ castings. The melt chemical composition and the thermo-physical and mechanical properties of ASTM A 757 C1Q steel material as a function of temperature were used in the simulation study. To accomplish this work, NMC used the commercial Control Volume Method (CVM)-based Nova Flow and SolidTM and the Finite Element Method (FEM)-based NovaStressTM software packages. These casting analysis tools were previously extensively validated by CTC to optimize the rigging systems of geometrically complex cast parts made from a large variety of casting alloys including super-alloys, Ti, steel, Al bronze, Monel, and Mg alloys.

From this simulation study, NMC established that it is indeed feasible to produce the LCS WJ casting components using the specified material and ExOne/Prometal advanced molding processing technology. NMC also determined that the main factors that influence the integrity and mechanical properties of these complex castings, and therefore, their quality, are the melt chemistry, the foundry practice and the solidification characteristics. Several additional improvements were made on the mold rig design of all WJ components under the existing foundry practice to further minimize the amount of shrinkage, porosities, and deformation, as well as the tendency for hot tearing and cracking. Prototype castings were manufactured and successfully passed NDT inspection. The actual results of radiography were compared with the predicted shrinkage and microporosity.