SHIP PRODUCTION COMMITTEEFACILITIES AND ENVIRONMENTAL EFFECTSSURFACE PREPARATION AND COATINGSDESIGN/PRODUCTION INTEGRATIONHUMAN RESOURCE INNOVATIONMARINE INDUSTRY STANDARDSWELDINGINDUSTRIAL ENGINEERINGEDUCATION AND TRAINING

THE NATIONALSHIPBUILDINGRESEARCHPROGRAM

August 1990NSRP 0320

1990 Ship Production Symposium

Paper No. 5A-1:Modeling and Transfer of ProductModel Digital Data for the DDG 51Class Destroyer Program

U.S. DEPARTMENT OF THE NAVYCARDEROCK DIVISION,NAVAL SURFACE WARFARE CENTER

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THE SOCIETY OF NAVAL ARCHITECTS AND MARINE ENGINEERS601 Pavonia Avenue, Jersey City, NJ 07306

Paper presented at the NSRP 1990 Ship Production Symposium,Pfister Hotel. Milwaukee, Wisconsin. August 21-24,1990

Modeling and Transfer Of Product Model Digital 5A-1Data for the DDG 51 Class Destroyer ProgramCDR William R. Schmidt, USN, Department of the Navy, Washington, DC, James R. VanderSchaaf, Visitor, Bath Iron Works Corporation, Bath, ME, Richard V. Shields Ill, Visitor, Pascagoula,MSINTRODUCTION DDG 51 in 3D CAD. However, the

necessary resources and capabilitiesdid not exist to successfully completethe plan and BIW reverted to manualdesign. To support the transition ofDDG 51 design to CAD it was necessaryto create or acquire the following:

Computer Aided Design andComputer Aided Manufacturing (CAD/CAM)technologies offer significantbenefits in the design, construction,and life cycle support of today'scomplex Navy ships. CAD provides thecapability to create three dimensional(3D) product models which canrealistically represent geometry andassociated design data of the shipprior to construction. Building of acomputer model of the ship prior toconstruction reduces interferences andimproves design accuracy andcompleteness. The 3D computer modelsconsist of geometry and associateddesign data for components andsystems, and provide a tool to designand evaluate form, fit, and function.Efforts such as interference detectionand resolution, simulatedwalk-throughs, change-impact analysis,and improved production sequenceplanning can be conducted concurrentlywith design development. Detaildesign drawings, manufacturingsketches and Numerical Control (NC)instructions can be developed andextracted directly from the designdatabase. This reduces duplication ofdata, saves time, and lowers costs -for both the construction of the shipand the life cycle maintenancefunctions that follow. The mostsignificant benefits of 3D CAD/CAMmethodologies as applied to complexNavy surface combatants are improveddesign and manufacturing accuracy andconsistency, which in turn result insavings in production time and cost.On the U.S. Navy's ARLEIGH BURKE (DDG51) Class AEGIS Destroyer program,CAD/CAM technology is beingimplemented to take full advantage ofthese savings.

BACKGROUND

Computer Aided Design is arapidly developing technology in theshipbuilding industry. In 1985 BathIron Works (BIW) and Gibbs and Coxplanned to execute detailed design for

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• Processes - adequately pilotedand tested methods.

. Software - the necessaryapplication computer programsand relational databasemanagement software.

. Hardware - the requireddistributed and integratedwork stations with sufficientprocessing speed.

. Trained personnel

Since the beginning of theprogram, Bath Iron Works (lead yard) ,Gibbs and Cox, and IngallsShipbuilding (follow yard) have builttheir CAD capabilities to the pointthat their combined resources havemade it feasible to model the ship.Based on this capability the AEGISDestroyer Program initiated a projectto move DDG 51 to a CAD based design.

The project objectives are toallow construction of ships in twoyards from a single design; to improvethe movement of construction databetween the shipyards; and to create adigital information base for lifecycle support.

The project required theachievement of two tasks, transferringthe existing paper design into CAD andcreating the capability to transferintelligent 3D product models.

This paper addresses thespecifics of the parallel efforts inCAD modeling and Digital Data Transfer(DDT) implemented by the AEGISDestroyer Program. The paper coversbackground information, taskobjectives, problems encountered andtheir resolution, current status andfuture plans. This project representsa significant cooperative effort

between the U.S. Navy's AEGISDestroyer Program, BIW, Ingalls, Gibbsand Cox, and GeneralElectric/Government ElectronicsServices Division.

PRODUCT DATA MODELING

Approach

The Program Manager in the AEGISDestroyer Division (PMS 400D)initiated a project to translate thepaper design information into 3D CADproduct models in a phased programover a 36 month period. The productmodel consists of all informationnecessary to define the detail designfor manufacture. The product modelswill be used to generate fabricationand installation drawings,supplemental drawings, NC informationand templates. The 3D CAD models willalso be available for use in thecontract and detail design stages offuture flights of the DDG 51 Class.

The CAD modeling effort isintended to create a database tosupport construction. The 3D designmodels will be used to check and clearinterferences and, after validationagainst the manual design control matsand issued construction paper, willreplace the paper design control matsas the design basis for the class.Accomplishing the actual modelingrequires the resources of bothshipbuilders and the Class CombatSystems Engineering Agent, GeneralElectric (GESD). There are seventy-seven Design Zones in the ship and aplan was laid out for concurrent workon an initial subset of twenty-sixzones. These twenty-six zones wereselected because they are the mostcomplex and represent the largestinitial payoff.

The AEGIS Destroyer Programtasked Bath Iron Works and Gibbs & Coxwith modeling eleven Combat Systemszones including the Combat InformationCenter (CIC), Radio Central, and thePilot House. General Electric wastasked to provide the combat systemcomponents as library parts to betransferred to Bath and used directlyin the models. Ingalls Shipbuildingwas tasked with modeling the fifteenzones comprising the auxiliary andmain machinery spaces. Both modelingefforts are shown in Figure 1. Modelcontent and library part standardswere developed concurrent with thiswork to insure the resulting. modelswould meet the needs of bothshipbuilders and the Navy. Theoverall 3D Modeling Process is shownin Figure 2. A graphical depiction ofthe steps involved in the replacementof manual drawings with CAD drawings

is shown in Figure 3. Bath Iron Worksas lead yard is tasked to process theresulting models to replace theexisting paper design control mats.The approach depends on the ability toeffectively transfer 3D product modelinformation between the shipbuilders.

Needs and Capabilities

In all design and manufacturingenvironments, there is a pressing needto improve the quality, usability,timeliness and accessibility ofengineering, design, and productiondata. This is especially true withinthe shipbuilding industry. Navysurface combatants are very complex,have long procurement cycles, incursignificant design changes, and havelong maintenance and overhaullife-cycle requirements.

Introduction of 3D CAD into thedesign and construction process asearly as possible minimizes theduplication of information. For theexisting DDG 51 design the appropriatepoint of transition to CAD is theDesign Control Mat (DCM). The DCMrepresents the culmination of thecomposite design process, and marksthe starting point for preparation ofconstruction products. The DCM isalso the document used to incorporatedesign changes.

A primary benefit of 3D CAD isthe availability of accurate andconsistent data for Computer AidedManufacturing (CAM). The definitionof CAM in this context is allmanufacturing data used by Production,not just limited to the classicaldefinition of Numerical Control (NC)data. Realization of the fullpotential that CAM offers inproduction requires that allconstruction information originatefrom the same 3D CAD database. Thisinformation includes: drawings andmaterial lists; NC tapes; templates;and jigs and fixtures. CAD can alsoprovide additional information such asimproved production sequence planninggraphics, which are not practicalotherwise.

3D product models, within thecontext of CAD/CAM, include definitionof:

• Object type (e.g. components,fittings, pumps, valves,cableways, etc.)

. Detail, clearance andmaintenance geometry

• Location• Orientation• Connectivity information• Catalog (material)

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. Instance identification(specific occurrence of thepart)

. Revision identification(latest change to the part)

Additional information such aszone, discipline, and system is alsostored within each model. This datais sufficient to control the designconfiguration, and may be integratedwith other material or productionsystems. For example, this data maybe tied to a material catalog throughthe catalog number, and, to materialmanagement systems through theinstance identifier (unique piece orpart number identifier) and catalognumber. The CAD product model is thenthe central source of materialidentification for quantity, type, andfabrication and installation data.Additional material data fordefinition of work packages,construction stage and sequence, shopfloor control, and inter-trade routing(e.g. the production bill ofmaterial) should supplement the CADengineering/design bill of material ona separate but linked MaterialManagement System.

Utilizing well-defined processesand standards, CAD linked withengineering data management toolsoffers the opportunity to integratethe entire shipbuilding process.Product models, tied to a relationaldatabase which defines the materialincorporated in a design, provide:the basis to drive the yard detailmaterial ordering system: input to theNavy supply support system; and inputfor technical publications andtraining. In like fashion, a relationaldatabase, which defines processinformation associated with theinstallation of each component, feedsthe materials control system and theproduction planning system. Aseparate but integrated file tracksall the drawings associated with anymodel and flags them for revision whenchanges are made to the model.

To support engineering efforts ofthe shipbuilding process, the use ofComputer Aided Engineering (CAE) isbeing developed. As engineeringchanges are introduced in the classand revised ship support systems arerequired, the use of analysis programswhich operate directly with the CADdata greatly enhance the systemengineering function. Controlled useof the CAD database insures theanalysis matches the actual systemconfiguration. Development of on-lineengineering analysis tools offers theopportunity to improve both the

quality and the efficiency of thedesign engineering process.

The implementation of theseCAD/CAM technologies has started, butremaining work is formidable. Whilethe use of 3D CAD may not make theindividual designer more efficient,the resulting data used to drive theentire production process makes theCAD system a powerful tool.

Development of capabilities likethese is critical to achieving thequality improvements and cost savingsneeded to make continued productimprovement possible and affordable.The AEGIS Destroyer Program isadvancing the development of thesecapabilities and their introductioninto the program.

shin Life Cycle Support

Ship configuration information indigital form offers advantages forlife cycle support since the productmodel data can be transferredelectronically to support activitiessuch as the planning yard, the U.SNavy Supply System, and the variousin-service engineering agents.Improvements can be made in: theprocess of overhaul and repairplanning (installation sequence);maintaining a more accurate andup-to-date configuration; andproviding more accurate fabricationand installation drawing and materialinformation at time of repair oroverhaul. The DDG 51 CAD modelingprogram provides the initial digitalinformation, while the Digital DataTransfer program establishes the basicstandards for content and format toaccommodate the information transfer.

Model Construction Benefits

The process of building modelshas demonstrated many of the benefitsCAD offers. Model construction isaccomplished by assembling all theconstruction drawings and open changenotices to establish a dated baseline.Pipe, ventilation, and electricalmodels are built for each ship workbreakdown structure (SWBS) for thezone. Very large or complicatedmodels may be subdivided into port,center, and starboard segments. Inthe case of Combat Systems and hulloutfitting, models are segregated byoverhead or deck within the zone.Both the fabrication and installationdrawings are used to construct themodel.

This has proven to be anexcellent consistency check betweenthe fabrication drawing and theinstallation drawing. Discrepancies

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are reported to the lead shipyard,which has responsibility formaintaining drawings. Corrections aremade to manufacturing aides beforemanhours and material are spent onunusable fabrications. The resultingsavings to the program have offset thecost of the modeling effort.

Model Processing Benefits

Once the individual distributedsystems models have been constructedfor a zone, they are merged forinterference checking. Eachinterference is analyzed as being aproblem interference or an acceptableinterference. In certain cases,collisions (two objects or surfacesoccupying the same space) are reportedas interferences but may beacceptable. A watertight penetrationof a pipe through a bulkhead is anexample of an acceptable interference.Once the reported interference isclassified as to its acceptability, aCAD generated sketch is created thatreflects those considered to be aproblem. If detailing formanufacturing aids is in process, theproblem is reported to the detailinggroup for resolution prior to issuingthe aids and drawing to manufacturing.

Post-Design Information

A major impact the modelingeffort has on manufacturing will bethe reduction of interferences. Shipconstruction schedules require manyparts of the design to take placesimultaneously. This leads to thepossibility of pipes, ventilationducts, and/or wireways being routedinto the same location and interferingwith equipment. While the compositesor design mats worked toward theelimination of these occurrences, someundetected interferences still manageto slip into the manufacturingprocess. It is widely accepted thatthe elimination of interferences andtheir corresponding costs is a majorbenefit from 3D modeling during thedesign and manufacturing processes.

Another major benefit of CADmodeling is the ability to extractdata to satisfy the manufacturingcriteria of the specific yard. Thesecriteria tend to be determined by theequipments in a specific yard and howthese equipments are used. Extractionof Numerical Control (N/C) data can,when properly formatted, drive burningor bending machines. After beingentered into the product model andchecked, data is programmaticallyextracted.

Another feature is the ability toextract specific task-oriented

drawings where the craftsman receivesonly that information required toperform his job. The craftsman doesnot have to work from a large,complicated and cluttered designdrawing. Figures 4, 5, 6, and 7 areexamples of the types of drawings andbills of material that can beextracted from a product model.Projected cost benefits from otheruses of this data have been identifiedand efforts are underway to developtheir capabilities. These includeuses such as simulated walk-throughand change impact analysis.

Planning can clearly benefit fromaccess to this information. Bytesting "what-if" scenarios, size andsequence of installation can beoptimized while viewing the actualdata in three dimensions. Further,different views can be utilized torepresent the configuration of theship as it is being manufacturedrather than the configuration it willultimately assume. Many fabricationor installation drawings may beplotted in an inverted position thatenables a craftsman to view hisproduct as it appears to him.Drawings showing downstream work willshow the product flipped to a shiporientation for final integration withother ship components.

costs

This project has required asignificant investment in personnel,hardware, training and processes.While the AEGIS Destroyer Program hascarried the majority of the costs,each participating organization hashad to dedicate management resourcesand make a corporate commitment toimplement new technology. The effectsof this project will permeate througheach organization and in someinstances fundamentally change methodsof operation. The challenge is tomanage the changing methodology andCAD based ship construction.

Status

Actual 3D modeling and drawingdevelopment work is well underway witheighteen (18) zones completed by bothshipbuilders and the majority of thelibrary parts completed by GeneralElectric and BIW. Model transfer fromIngalls to Bath is in process, and theAEGIS Destroyer Program has taskedboth shipyards to create constructionproducts from their models. Extensivework remains to be done to integratemodels as they are built and totransition to 3D CAD-based design bothwithin each yard and between the yardsfor the DDG 51 Class, but the

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achievements thus far leave no doubtof future success.

OUTFITTING DATA TRANSFER PLAN

Background

Transfer of the product modelsand use by both shipbuilders, combatsystems design agent and the Navy isrequired to achieve the full benefitof using CAD. Each yard uses CADsystems for outfitting and structuraldefinition which are different withinand between the yards. Bath IronWorks uses Computervision for outfitand AUTOKON for structure; IngallsShipbuilding utilizes Calma for outfitand SPADES for structure. In order toutilize these combined resources, itwas necessary to develop a means oftranslating digital data between theirproprietary and incompatible dataformats.

Objective

The AEGIS Destroyer Program'soverall objective in this effort is toimplement a two-way transfer of Outfitproduct models between the BIWComputervision (CV) System and theIngalls calma System, as illustratedin Figure a. Both BIW and Ingalls hadpreviously developed the capability totransfer structural models from theirrespective structural to outfitsystems.

Overall Approach

The AEGIS Destroyer Programtasked BIW and Ingalls to develop amutually agreed-upon plan of action.In order to implement a digital datatransfer capability between dissimilarCAD/CAM systems, several steps arerequired:

1. Models must exist or becreated

2. Data to be transferred must bedefined

3. Format of the transfer mediummust be defined or selected

4. Transfer computer softwaremust exist or be created

5. Testing must be accomplishedto validate the process

6. Transfer procedure must bedefined and implemented

When the AEGIS Destroyer Programinitiated this project in January1988, and both BIW and Ingalls alreadyhad significant 3D modelingexperience. Step 1 was completed bybuilding models of three selectedzones to use in the test phase. Steps2 through 6 represent the basic scopeof the DDT project as described below.

The management and technicalapproach for DDT includedconsideration of the followingrequirements and constraints:

Requirements.

. Transfer of engineering anddesign product modelintelligence

• Achievable and verifiabletransfer accuracy

. Configuration accounting

. Elective componentsubstitution

• User friendly translator usage• Minimized transfer file data

volume. Minimized translator

processing time. Minimized translator software

maintenance

Constraints.

• Large number of componentscontained in 3D productmodels

. Complexity of the componentrelationships definingdistributive systems

. Volume of componentnon-graphic (attribute) datacontained within the 3Dproduct models

. Similarities and differencesbetween component librariesand database constructs acrossthe two CAD/CAM systems

• Current state of the art inInitial Graphics ExchangeSpecification (IGES) andProduct Definition ExchangeSpecification (PDES)development andimplementation.

• Current state of the art indatabase management systems

• Existing manual drawingtransfer between the twoshipyards

Data Transferred

BIW and Ingalls completeddefinition of the data to betransferred for distributive systemsearly in the project. Thisdefinition was reviewed, modified, andapproved by the AEGIS DestroyerProgram, BIN and Ingalls for alldisciplines. Reference 1 provides alisting of the data transferred andcontained in the product models. Theeffort involved in the definition andconcurrence which this documentrepresents was extensive. It involveda significant review of the modelingpractices of both organizations and anin-depth understanding Of the internalarchitecture of both CAD/CAM systems.

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Neutral File

The next major step in DDT wasdefinition and selection of the formatfor the transfer. The AEGIS DestroyerProgram, BIW and Ingalls mutuallyexplored the following alternatives:

1. "Flavored" Initial GraphicExchange Specification (IGES)or Standard IGES. "Flavoring"is the term used to define theprocess of augmenting theshortcomings of theimplemented standard in orderto adapt it to the requiredtask.

2. Defer until the completion ofProduct Definition ExchangeStandard (PDES) and itscommercial implementation.

3. Development of directtranslators by a softwaredeveloper specializing in CADdirect translators.

4. Use of a neutral file thatdefines object data.

Option 1, the IGES approach wasnot selected because both shipyardswere using and developing CADapplications that were object orientedinstead of entity oriented. PDES isstill in its definition phase andselection of Option 2 would haverequired several years delay inimplementation of a productiontranslator. Option 3 would haverequired the development of directtranslators. They were not availablefor 3D product model information andwould not have met the Navy's need forflexibility in future use orexpansion. Option 4 was selected bythe AEGIS Destroyer Program forcapability, flexibility for futureexpansion, and ability to createwithin the time available.

Object Transfer

The use of an object orientedneutral file (Option 4) offeredsignificant advantages in reducing thesize of the transfer files. Moreimportantly, the object transferapproach retained the intelligencecontained in the original model. Inthis context, object (or component) isan BVAC shape, a piping valve, apiping fitting, an electrical cablewayhanger, etc. Figure 9 illustrates theobject approach versus the IGESapproach. As defined by IGES thedesired object would have beengeometrically constructed on thereceiving system as a series ofseparate lines, arc, etc., rather thanan object with associated propertiesand intelligence.

Bath Iron Works was tasked tooutline the translator specification.BIW and Ingalls divided responsibilityfor writing the specifications - eachwrote different sections and exchangedwork. The end result was the "DDG 51Class Digital Data Transfer ProjectFunctional Specifications"Reference 2. After the finalspecifications were agreed to by bothshipbuilders and approved by the Navyprogram office, each shipbuilderdeveloped or subcontracted thecomputer programs specific to hissystem.

BIW and Ingalls both use anobject modeling approach on their CADsystems and each has the capability toattach design attributes to objects,as well as a property file capability.Attributes consist of information suchas catalog number, piece/part number,fitting type, etc. Property filescontain geometric data that allow anobject to be graphically displayed,and non-geometric data such as catalognumber (link to model), description,weight, and a specification numberthat describes the object. A meanswas developed to correlate objectsbetween systems. In the case of pipeand purchased parts for BVAC andelectrical, it was determined thatcatalog numbers could define theobject. For manufactured items (HVACshapes, flanges and gaskets;penetrations; hangers; cable paths,etc.) a shape table was developed thatdefines the object. Each componentwas assigned a classification thatdefines the discipline and either thecatalog number or the shape table todefine the object. To complete theprocess a catalog cross reference filewas developed which correlates theIngalls and BIW catalogs and providesorientation normalization between theCV and CALMA systems.

Class Librarian and Parts Transfer

The testing of the translator wasbased on the transfer of a common testzone modeled at both yards. Use ofthe object oriented approach requiresthe existence of: (a) equal partlibraries at both shipyards, or, (b)development of the capability todigitally transfer library parts.Early in the project, it wasdetermined that while the librariesfor such items as piping were similar,certain DDG 51 specific equipmentitems existed only on the BIW system.

Where library parts did not existat Ingalls, the yards were tasked tocreate the necessary computer programsand procedures to transfer the partsfrom BIW. The approach chosen was tocreate a procedure file defining the

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component at BIW, and to createsoftware to read the file at Ingallsand automatically rebuild the librarypart in the CALMA system. Thecapability was based upon the use ofseven basic graphic primitives thatwere common to both CAD systems.Figure 10 represents a sampletransferred part. With the capabilityto transfer parts came the opportunityto establish a standard library forthe DDG 51 Class. BIW was tasked toact as the Class Librarian. Thelibrary parts transfer capability isin use between BIW and Ingalls. Fulltwo-way part transfer by means of theprocedure file is under development.

Life Cycle Support

The DDT project is concentratingon three aspects of CAD information toinsure its ability to support futureclass logistics: standards for zonemodel content, library part contentand the transfer process. Theseefforts are intended to be consistentwith the developing Product DefinitionExchange Standard. The contentstandards will ensure that theinformation contained in the modelsand libraries will support design,construction and life cycle supportneeds. By working with the PDESgroup, the transfer products are beingdeveloped to support data transferboth now and in the future.

Testing and Results

The translator software wasdeveloped and extensively tested byboth shipyards. The overall processis illustrated in Figure 11. Bothshipyards created a test model foreach of three disciplines (piping,HVAC and electrical) for a commonzone. First, each model of eachdiscipline was given an internal looptest. Then, these models weretransferred from their source yard tothe receiving shipyard, processed bothin and out of the receiving shipyard'stranslator, sent back to the sourceand reprocessed to create a model.This full-loop test was sufficient todetermine any deficiencies in thesoftware.

Functional software was developedand tested for intelligent 3D modelbi-directional transfer between CV andCalma for piping, HVAC and electricalobjects. The results are illustratedin Figures 12, 13, 14, and 15. Theseisometrics are representative of thetranslator capability and were createdduring the testing phase.

Status

The translator software isoperational and in use between theshipyards. An additional phase oftranslator development is ongoing toadd capability for piping and venthangars, waveguide, holes, certainfoundations, and outfit andfurnishings. When complete in late1990 the translators will be capableof moving complete product models.

STRUCTURAL DATA TRANSFER

Approach

The objective of this effort wasdigital transfer of 3D structuraldesign models generated on AUTOKON orSPADES from one system to the otherwhile retaining their topology,intelligence, and lofting capability.Ingalls Shipbuilding, Inc., a SPADESuser, and Bath Iron Works, an AUTOKONuser, were tasked by the AEGISDestroyer Program to produce a jointplan of action to develop software toaccomplish this transfer. A systemspecification was written entitled"Autokon SPADES ModelCommunication System" Reference 3.

Cali and Associates (developersand marketers of SPADES) and AutokonCIM, Inc. (developers of Autokon andpart of Kockums Computer Systems A/S)were the two firms subcontractedthrough Ingalls to develop thesoftware. The approach taken was tocreate a neutral file containing thedata elements necessary to define allrequired structural objects. Thesoftware programs which generate anduse the neutral files were calledtranslators. An overview of the linksbetween the two systems is depicted inFigures 16 and 17.

NEUTRAL FILE

The translator/neutral fileapproach was selected for structurefor the same basic reasons that it wasselected for the outfit system. Thegoal was to transfer recognizableobjects complete with intelligence andattributes. Commercially availableimplementations of IGES would havelimited the transfer to a collectionof points, lines, and arcs comprisingthe graphic representation of theobjects and would not have fulfilledthe requirements of the transfer. Byutilizing the translator/neutral fileapproach, the intelligence of theoriginal model was captured andlofting capabilities were retained.Further, it was felt that an IGES filebased on simple entities. (lines, arcs,points, etc.) would have beenprohibitively large to store and/or

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process in a timely fashion whenapplied to models the size of thosebeing considered for transfer.

TRANSLATOR COSTS

Outfit

Partial Transfers

A requirement of DDT is to beable to transfer only a portion of agiven design zone, as opposed to thepractice of transferring an entirezone with each exchange. To supportthis requirement, the concept of the"design window" was implemented ineach CAD vendors' system. Thisfeature did not exist on either systemand it provided a means of specifyingboundaries for the design zone to betransferred.

The design window is a 3D subsetof the design zone whose contents areto be transferred. It allows the userto send/receive only the desiredportion of a zone, for example, aspace where additional structure hasbeen inserted after the entire zonehas already been sent or received atthe other installation. This conceptprevents having to re-send an entirezone in order to pick up only a smallarea of change.

configuration Management

Closely related of partialtransfers is Configuration Management.The partial transfer capabilityhighlighted the need to track thestatus of previous transmittals of thestructural model of the design zone.Partial transfers must address whatdata has already been sent, what hasnot, and what has changed betweentransfers.

By means of a catalog, thetranslator keeps track of thestructural objects being transferred,bypassing objects that have alreadybeen translated and passing only thoseitems which are new or changed. Areport is generated by the translatorwith each transfer, therebydocumenting the zone's transferstatus.

Status

The translator software isoperational. There are two translatorprograms; one installed and running onthe Prime computer at BIW and theother installed and running on the IBM3090 at Ingalls. Translatorcapability is planned for inclusioninto the next formal release of thetwo CAD systems by their respectivevendors.

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The outfit translators are customsoftware packages owned by the AEGISDestroyer Program. The full cost ofdevelopment and the cost ofmaintaining the translators is theresponsibility the AEGIS Program.Unlike translators based on nationalstandards the CAD system vendors donot have any responsibility forensuring compatibility with their newsoftware releases. This was the costof acquiring a transfer capabilitysufficient to the needs of theprogram.

Structural

The structural translators weredeveloped under AEGIS DestroyerProgram funding but are theresponsibility of the CAD vendors tomaintain. Because of their uniquestructure and the lack of IGEStranslators in this area the vendorsfound it to their advantage to assumemaintenance responsibility and offerthe capability in their respective CADprograms.

ISSUES

The transition to 3D CAD designand electronic data exchange hasintroduced technical and managementchallenges. The Project hasanticipated many of the issues solvedthem by the basic approach. Othershave been solved in concept but remainto be proven in production. Four ofthe open issues are configurationmanagement, model completeness, yardpractices, and on-line inter-yard CADaccess.

Configuration management is botha technical and management issue.Technically the challenge is toestablish and maintain positivecontrol of product models and theirderived products as they are modifiedduring design development andengineering changes. For managementthe challenge is to efficientlytransition the configurationmanagement organizations from paper toelectronic data. The AEGIS DestroyerProgram is using information modelingas a basic tool in attacking thisissue.

The AEGIS Destroyer Programestablished zone model content andlibrary part content standards as thetools to solve model completenessissues. The information incorporatedin a model determines it's usefulnessfor design, engineering analysis,construction and future logistics

support. The DDG 51 Program definedthe standards on the basis of currentpractices and projected class supportneeds. As the models are placed inuse the need for more or differentinformation will surface and thestandards will be modified as needed.

Each yard has constructionpractices as well as CAD modelingpractices which are different than theother. The differences in modelingare often the result of constructionprocess differences. Shipyardmanagement and the DDG 51 Programstandards are the basic tools used inresolving the impact of thesedifferences on the data exchangeprocess. The effectiveness ofmanagement in dealing with problems inthis area will have a significantimpact on the benefits realized fromthis program.

On-line inter-yard data access isa capability which is important toefficient use of the DDT Project nowand will become more important as moreof the ship is placed in CAD. Theability to access the latest dataimmediately prior to releasing workpackages could provide significantsavings to the construction program.The principle issue is security. Eachyard is concerned with the security oftheir computer data for yardmanagement and performance. Whileaccess to CAD would not necessarilyrequire access to shipyard managementsystems, it is feared that internalnetworking could allow the competingshipyard to acquire critical businesssensitive information. This issue isa management problem currently underreview by the shipbuilders.

These issues all contribute toEngineering Data Management.Integrating the many separate datasystems which have been created withinthe shipyards over the years andtransitioning to the full use ofelectronic data for all design andconstruction support functions aresignificant management challenges.While tools to attack the problems areavailable in the form of local areanetworks, wide area networks, andEngineering Data Management SoftwareSystems implementation will requiretime and innovation.

These and other issues will bedealt with and solved by the DDG 51Program. The solutions institutedwill consider both the current andprojected needs of the AEGIS DestroyerProgram.

SUMMARY

The U.S. Navy's AEGIS DestroyerProgram established this project totake advantage CAD/CAM in shipconstruction. Accomplishments andbenefits have been significant.Twenty-six zones of the ship have beendivided between the shipbuilders formodeling and a plan is being pursuedto complete modeling for the remainderof the ship. The combat systemsengineering agent has been tasked toprovide contract level 3D models ofthe combat system spaces and libraryparts for all combat systemcomponents. These products are beingused within the shipyards to supportconstruction.

The end result of the modelingeffort will be interference-freedigital design product models. Thesewill replace the traditional designcontrol mats. The product models willalso be transferred to eachshipbuilder where manufacturinginformation will be extracted.

The DDG 51 Digital Data Transferproject has put in place a basictranslator that supports the exchangeof product models. It provides therequired path to allow full use of theproduct models for all programparticipants.

Actions taken to improve the longterm use of the product models and theDDG 51 Digital Data Translatorinclude:

. Establishing Library Part andZone Model content standards.

. Establishing configurationaccounting requirements andprocedures.

. Completing Library of Partsfor DDG 51 Class (i.e. allvalves, combat systemcomponents, pumps, motors,etc.)

. Interfacing the data transferefforts with groups involvedwith the establishment ofnational standards for IGESand PDES.

The U.S. Navy's AEGIS DestroyerProgram has established long termgoals for further development andexploitation of the technologyimplemented on this project. The DDG51 DDT translators require furtherrefinement and the use of productmodel information is just beginning tobe developed. The work remaining issignificant and the goals have beentime phased over several years. Thework done to date positions the AEGISDestroyer Program to take fulladvantage of CAD and CAM during

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construction and to realize many ofthe benefits of Computer AidedAcquisition and Logistics Support(CALS) over the life of the Class.

ACKNOWLEDGMENTS

The U.S. Navy's AEGIS DestroyerProgram could not have successfullycompleted this project without thehelp of these key contributors:

Bath Iron Works CorporationIngalls ShipbuildingGibbs and CoxGeneral Electric, GovernmentElectronics Systems DivisionCali and AssociatesKockums Computer ServicesCalma CorporationPrime/Computervision Corporation

REFERENCES

1. Naval Sea Systems command "3DCAD Model Content Standard",DDT Document #188, March 1990.

2. DDG 51 Class "Digital DataTransfer Project FunctionalSpecification", DDT Document#57, Revision C (Phase II),March 1990.

3. "Autokon SPADES ModelCommunication System", Rev 8,November 1989.

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3D CAD MODELING(INITIAL ZONES FOR MANUAL TO CAD CONVERSIONS)

FIGURE 1

3D CAD PROCESS

FIGURE 2

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OVERALL TRANSFER APPROACH (OBJECTS VS. ENTITIES)

PROPOSED APPROACH:I

DATA TRANSFERRED:

l ORIGINl ORIENTATIONl SHAPE DIMENSIONS

FEATURES :

l RECUCTICN IN TIME/SCHEDULEl DESIGN TRANSFER CAPABILITY

FIGURE 9

IGES APPROACH

ENTITY ( LINES/ARCS ) DATA

DATA TRANSFERRED:l COMPOSITE CURVE ( LINES, ARCS, .POINTS)

l EACH LINESTART . END POINTS

l EACH ARCLOCATIONORIENTATION

l EACH POINTLOCATIONDEFINITION OF CROSS-SECTION

FEATURES :

l REQUIRED FOR IGES - BUT NM SUPPORTEDl LIMITED DESIGN TRANSFER CAPABILITIESl ADEED TIM AND SCHEDULE

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DDTPROCESS TESTING FLOW CHART

FIGURE 11

P I P I N G Z O N E 2 1 5 0 C . I . C

FIGURE 12

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-20

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-22

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AUTOKON SPADESCOMMUNICATION SYSTEM

O R I G I N A T I N G S I T E :

HARDCOPY

ORIGINATINGSYSTEMMODEL

COMMUNICATIONSOFTWARE

STEP 1

TRANSFER FILE(Binary) with data

amd structures

RECEIVNG SITE: CATALOGFILE

STEP 2

UTILITY PROGRAM

.NAME TRANSLATIONINTERNAL UNIT SPEC..ESTABLISH TABLES OF

STANDARD DETAILS

Steps of Operation

FIGURE 16

AUTOKON SPADESMODEL COMMUNICATION SYSTEM

COMMUNICATIONSOFTWARE

DEVELOPED INTHIS PROJECT

COMMON SOFTWARE FORREADING AND WRITING

THE TRANSFER FILE

AUTOKON SPADES LINKFIGURE 17

Additional copies of this report can be obtained from theNational Shipbuilding Research and Documentation Center:

http://www.nsnet.com/docctr/

Documentation CenterThe University of MichiganTransportation Research InstituteMarine Systems Division2901 Baxter RoadAnn Arbor, MI 48109-2150

Phone: 734-763-2465Fax: 734-763-4862E-mail: Doc.Center@umich.edu

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