The integration of production planning within design has had a positive impact on both the design process and the design products. To effectively accomplish the integration, it is necessary to have a single 3-D product model of the ship, by which all design disciplines and construction planning personnel can effectively communicate. The authors will address the significant changes this new approach has upon the design community and its deliverables. They will provide an overview of the enabling technologies and methods which facilitate construction-oriented feedback in the design phase. They will review additional benefits derived from the product model, such as eliminating physical mock-ups.
Draft STEP application protocols, developed by the Navy Industry Digital Data Exchange Standards Committee (NIDDESC), have been issued to define the information content of a product model for a ship. The work reported in this paper combines the existing CAD models of the DDG51 Class design with a newly developed non-graphic database so that the overall information content complies with the STEP protocols. This work represents the first-time implementation of the application protocols and is a significant step in the Navy's plan to do the design of variants of the DDG51 Class totally in CAD. The combined graphic/non-graphic database is referred to as the DDG51 engineering product model. Emphasis has been placed on populating the non-graphic database with the information necessary to perform all required engineering analyses. The basic schema described in this paper may be extended to support other areas of interest, such as logistics support. technology. As a cost saving initiative and quality improvement measure, the Navy has implemented the use of 3-D Computer Aided Design (CAD). This effort required the development of leading edge CAD technology and the achievement of a cooperative (rather than competitive) success story by the two DDG51 Class shipbuilders and other industry participants. Over 2,500 drawings, many of which contain over 30 sheets per drawing, are required to build an AEGIS destroyer. Maintaining an error free design baseline defined by these drawings has proven to be a challenge in a 2-D manual environment. To improve efficiency, the entire design is being converted to 3-D CAD. The DDG51 design consists of 77 design zones. A 3-D computer generated representation of each of these zones is being developed. These models contain library parts defining equipment and machinery arrangements, structure, ventilation, electrical, and piping distributive systems.
This is a brief introduction to the present status of the AUTOMODL development- effort (AUTOKON) and an indepth description of the first module of an AUTOMODL named PARTGEN. PARTGEN works on a topological model of the ship and is stored in the database. PARTGEN uses extensively interactive graphics and will virtually eliminate 90 percent of what today is called partcoding in the production phase. In addition to performing part generation, PARTGEN also has other valuable functions. It can do fairing of lines, interactively, to establish a preliminary hull form for building up the design model in the database, It has a report generator whereby the user can make extensive reports from the database and inake user formulated layouts on the reports. PARTGEN also includes extensive automatic updating procedures due to changes. This is a benefit of having parts for production stored as topological data instead of as geometry.
In the current severely competitive climate that is challenging shipbuilders everywhere, how information is managed is taking on extraordinary importance. Existing computer aided design (CAD) systems have not been focused on the most critical information needs, for example, information to serve marketing. This limitation is the result of concentrating primarily on aspects of design and manufacturing without regard for impact on an overall manufacturing system. In this paper the need to extend CAD systems is identified so that they would more fully provide critical-data to everyone who has to have understanding of a manufacturing system's capability and availability.
A computer graphics based advisory system has been developed to aid in the design and manufacture of submarine hulls. The design and manufacture advisor incorporates models of the materials (steel) and processes (bump forming roll bending. welding and fixturing) used for the manufacture of the hulls and allows the user to explore the effect of different material qualities (described in terms of variances of thickness and yield strength) and different manufacturing parameters (punch penetration punch spacing and number of fixtures for example) on the resulting quality (circuliuity) of the hull section. By Designing through Manufacture in this way the resulting design of the submarine hull section is not just a geometric representation of the desired shape of the hull but incorporates explicit information about the materials and processes used to create the shape and of the quality that results from the designer!5 choice of materials and processes.
In a shipbuilding CAD/CAM system a product model is successively built up during the design process, with geometric as well as non-geometric information. In parallel with the design process, the model is further extended with work preparation (in some countries called production engineering) information e.g. definition of building strategy and definition of the assembly structure. Information needed for part fabrication can be derived from the model, such as drawings, parts lists and information for numerically controlled (NC) equipment. When work preparation definitions are combined with a product model, the information needed for assembly parts lists, assembly drawings, etc. can be derived from the product model instead of being created manually. Use of the product model concept, systems based upon it and procedures implementing it in an organization will allow a reduction of costs and an increase in productivity and competitiveness.
This paper reports on the on-going development of an object-oriented CAD system at the Advanced Computer Laboratory for Shipbuilding at the University of New Orleans. It describes: the reasons for object-oriented (yard specific) development; the computer-aided software development environment; the developing class structure of the ship structures design application; and the planned developments within the CAD system and integration of packages to support visualization, planning and enterprise management and electronic data interchange.
With their ongoing reentry into the international shipbuilding market, U.S. shipyards are focusing on the strengths and potential of computer-aided design/computer-aided manufacturing/computer-integrated manufacturing, or CAD/CAM/CIM. World-class commercial shipyards and software suppliers in Europe and Japan have advanced the state of the art of CAD/CAM/CIM and offer much for U.S. yards to learn. Indeed, they have proven generous in sharing their knowledge with the U.S., as evidenced during the conduct of the recent National Shipbuilding Research Program "Evaluate the Shipbuilding CAD/CAM Systems" Project. The primary goal of Phase I of the Project was to identify key features of CAD/CAM/CIM implementations at world-class shipyards that most significantly contribute to the success of those shipyards in commercial shipbuilding and deliver this information to U.S. shipyards. That goal has been accomplished and the results presented at a CAD/CAM/CIM workshop at the 1996 Ship Production Symposium. This paper reports on Phase II of the CAD/CAM/CIM project, which built upon the knowledge gained in Phase I. In Phase II, the Project Team developed a set of 70 technical requirements for a world-class ship design and production CAD/CAM/CIM system that is future-oriented. In addition, the Team described links between the technical side of shipbuilding and the business side, illustrating the business value of the technical requirements in particular and advanced CAD/CAM/CIM in general. It is hoped that the technical requirements and business links will provide U.S. yards with guide posts which will help those yards not only catch up with, but leapfrog, world-class technology and establish a competitive presence in the international shipbuilding market.
