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reliability in design and supplement the research project on ship inspection issues under Project SR-1355. In support of Goal I. reliability research goals should include: improved methods of predicting hydrodynamic loads and structural response of ships in extreme seas; details; improved methods of predicting fatigue stresses in structural components and improved descriptions of matena] properties, including fracture, corrosion, and fatigue of common marine steels; and development of structuraI-reliability theory, application to existing Resins, and development of probability-based design critena. In support of Goal 2. reliability marine activities must be based on env~ronmental- protection criteria and procedures that wall remain effective throughout the life cycle of a structure or project. In the past, inadequate criteria and procedures resulted in environmental damage and loss of natural resources, public support, and productivity. Enhanced environmental protection can be realized with improved criteria and improved procedures for designing, fabricating, operating, inspecting, and maintaining ships, offshore structures, and marine systems. Structural-research projects that wall enhance environmental protection must be pursued in the areas of: doubJe-hull technology; damage-tolerant structures; and the effect of human factors on the reliability of marine structures. Composites On September 25-26, 1990, the Manne Board of the National Research Council convened a National Conference on the Use of Composite Materials in LoacI-Beanng Manne Structures. This conference brought together leaders Tom industry, government, and academia to exchange ideas and lay the groundwork for future marine applications of composite materials by U.S. industry. The conference drew enthusiastic participation and was highly productive. Its recommendations are reported in a two volume report of the National Research Council.t As a result, the CMS adopted a thrust area in composites in its recommendations for FY 1994 so that the advantages of composites may be more fully realized in marine structures. New matenals and vanations on existing matenals offer opportunities for improving marine structures. Content emphasis is on fiber-reinforced plastics and related composites. In recent years, their use in the primary structures of vessels less than 60 meters long has increased substantially, and many navies are introducing a new class of ~ National Research Council, 1991. Conference on Use of Composite Matenal in Load-Beanng Marine Structures, September 25-27, 1990; Summary Report, Volume I, and Conference Proceedings, Volume IT. Washington, DC: National Academy Press. NTIS Report No. DTCG-23~ C-20025. s

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fiber reinforced plastic coastal minehunters. New composite matenals may have potential applications to larger marine structures, which would take advantage of their increased specific stiffness and strength and resistance to corrosion. Graphite, ceramic, and Braid composites, In addition to glass, should be evaluated for special structural components. The use of composite matenals presents a special challenge to the designer. The many matenal parameters that can be vaned, including the basic fiber and matrix matenals, require eng~neenng analysis and design evaluation to determine the most efficient design. The use of composites and their design methodoJo~es is relatively weD documented in the aerospace industry. Report SSC-360 provides a survey and assessment of the uses of fiber reinforced plastic matenals. As newer generations of matenals, such as fiber reinforced plastics, are introduced into the marine industry, new analytical techniques need to be developed to aciciress structural ~ntegnty. The structural integrity of novel matenals is strongly affected by processing. Understanding the necessary interrelationships may require matenal-property data beyond that which has been histoncally available. To expand understanding of these interrelationships requires further evaluation of expertise and design techniques used in aerospace and other irldustries and ways to adapt them to marine structures. To accomplish this, the National Conference on the Use of Composite Materials in Load-Beanng Manne Structures, which was sponsored by the SSC as project SR-133l, enabled experts to share their knowledge of and experience with the use, fabncation, and inspection of new marine matenals. The applicability of design practices used in other industnes was evaluated,.and the conference proceedings were published in 1991. The CMS prepared project descnptions in response to the recommendations of the proceedings. The first of these, "Design Guide for Marine Applications of Composites" (SR-1367), was recommended by the CMS as the initial project in this thrust area. In support of Goal I, research in composites is needed to address safety and integrity aspects with respect to corrosion, fire, and toxicity. In support of Goal 3, research in composites needs to be coordinated and advanced for the determination of performance properties of anisotropic composite matenals that wall be used increasingly by the marine industry. Producibility/Competitiveness The SSC Strategic Plan identified a decline in the U.S. merchant marine industry and developed the goad to "support the U.S. maritime industry in shipbuilding, maintenance and repair." Past recommendations of the CMS, and research projects conducted by the SSC, included projects to increase the ease of fabrication and to improve productivity. In the recommendations for FY 1994, the CMS developed a thrust area in producibili~cy/competitiveness. This thrust area seeks to improve industry competitiveness in ship design, construction, and repair. The ship design process needs to be changed to reduce design time and cost; to improve design quality, including 6

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producibility; to reduce design errors; and to produce ships that yield enhanced producibility, performance, and operability at lower life-cycle costs. Recent surveys project a steady growth in world trade during the 199Os. As a leading industna] nation, the United States win benefit from increased export arid import of raw matenals and manufactured products. At the same time, world shipbuilding costs have risen and new ship deliver dates have been extended as building berths have become filled. Increasing demand for merchant ships presents an opportunity for the United States as a shipbuilder to regain its stature as a leading maritime nation. In support of Goal 1. certain producibility/competitiveness capabilities are required: Improved design tools and information systems need to be developed, including computer-aided design, design and manufacturing information, and expert systems. Regulations need to be continuously reviewed and upgraded to reflect technological advances. Reliability-based design techniques to optimize matena] use need to be developed. Pnnciples of design for production need to be adopted. Research on design tools, producibility, production processes, reliability-based design, and damage-tolerant structures needs to be sponsored, and professional education in these fields needs to be enhanced. In support of Goal 3. the preceding as well as the follomng producibility/competitiveness items are needed: Ship repair and construction capability need to be made viable. Repair time and material costs must be reduced, and labor efficiency improved. The maritime industry needs to adopt the worldwide measurement standard System International to become competitive in the world market. Labor hours for construction and material costs for construction need to be drastically reduced to restore a viable production capability for new merchant ships. To achieve this, improvements in production technology and production processes must be developed. Examples of these improvements include laser alignment, faster welding techniques, improved accuracy control, the use of robotics, and automated material handling, automated storage equipment. inspection /Ma inten a nce The Manne Board convened a symposium and workshop on the role of design, inspection, and redundancy in marine structures on November IRIS, 1983 2 The workshop determined that consideration of the Design, Inspection, and Redundancy Triangle is necessary for reliable structural systems. To strengthen the inspection leg of the triangle, the CMS began to recommend inspection projects in its recommendations 2 National Research Council 1984. Toward an Integrated Design' Inspection, and Redundangy Research Program. Washington, DC: National Academy Press. 7

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for FY 1986 to support reliability goals. With the increasing number of aging ships and concomitant greater need for repair, life-cycle maintenance of ships grew to equal importance. As a result, the CMS incorporated a thrust area on inspectiorLlmaintenance In its recommendations for I;Y 1994. Recommended research efforts wall focus on inspection and repair strategies for aging ships. Development of improved inspection techniques for in-seIvice structural monitoring is needed, as well as analytical methods for assessing the effects of corrosion, Baws, and other strength defects. Also, development of effective localized repair methods for cntical defect areas is needed. In support of Goal I, inspection/maintenance research is needed in the areas of: determination of performance properties of coatings and other structural presentation techniques; and determination of corrosion rates for matenais under venous environmental conditions, such as bare steed in the splash zone of seawater ballast tanks filled for 10 continuous days dunug each 40-day voyage. In support of Goal 2, inspection/mainter~ance research is needed in the areas of: structural monitonug; and blasting and coating application techniques. In support of Goal 3. the following inspection/maintenance items are needed: Ship repair and construction capability must be made economically viable. Repair time and material costs must be reduced and labor efficiency improved. Better ship inspection and repair methods must be developed. Table ~ relates the recommended projects for FY 1995 to the thrust areas, and identifies the technology area under which they wall be discussed in the section on research program development. 8

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TABLE ~ Recommended Projects in Support of Thrust Areas Number Project Title Primary Technology Area RELIABILITY PROJECTS 95- 1 Symposium/Workshop: Higher Order Prediction Methods for Loads and Response Hydrodynamic Loadings and Response of Marine Structures 95- 5 Combined Load Effects for Design and Strength Assessment of Ship Loads and Response Structures (94D-J) 95- 6 Weld Detail Fatigue Life Improvement Techniques Design 95- 7 Structural Design Guide for Win Hull Vessels Loads and Response 95- 8 Fatigue and Fracture Cnteria for Double-Hulled Ships Materials Criteria 95- 9 Hull Response Monitoring System Design 95-12 Rupture Resistance of Cargo Tanks of Double Hull Tankers to Low Design Energy Impacts 95-13 Iwo-Parameter Approach to Fracture Prediction in Ship Structures Materials Criteria COMPOSITES PROJECTS 95-14 Assessment of Fire, Smoke, and Toxicity Characteristics of Composite Matenals Proposed for Marine Applications (94M-O) PRODUCIBILIlY/COMPETITIVENESS PROJECTS Materials Criteria 95-11 Alternative Stiffening Systems for Double-Skin Tankers (94-14) Design 95-15 High Productivity Welding Processes (94-13) Fabrication and Maintenance 95-16 Evaluation of Marine Structures Education in North America Design INSPEcllON/MAINTENANCE PROJECTS 95- 2 Methodology to Establish the Adequacy of Weld Repairs (94-8) Fabrication and Maintenance 95- 3 Commercial Ship Design and Fabrication for Corrosion Control Materials Criteria 95- 4 Detection Probability Assessment of Visual Inspection of Ships Fabrication and Maintenance 95-10 A Guide to Damage Tolerance Analysis of Marine Structures Materials Criteria 9

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RESEARCH PROGRAM DEVELOPMENT Technology Areas The CMS and its working groupsthe Materials Work Group and the Design Work Grou~recommend a multlyear plan that introduces new, long-range performance concerns. Long-range research guidance comes from: the working groups' thrust-development sessions held in June 1993; SSC report recommendations; the annual joint meeting of the CMS and the SSSC; the SSC fad meeting; and the expertise of the working groups, whose members were selected for their broad experience in the areas of concern. reliability are The working groups' specific concerns, activities, and common interest in structural Design Work Groupextreme wave loads, higher-order forces, and responses; ice, groundings, and collisions; large-scale structural tests; operations-onented monitoring systems; modeling errors in loads and responses; procedures for fatigue stress computations; design process improvement; producibility; and reliability-based design codes. Materials Work Grou~new marine structural materials; fracture mechanics; fatigue (incIllding corrosion fatigue); corrosion and its prevention; welding; inspection; and deep-ocean inspection and repair. To varying degrees, these specific activities and recommendations contribute knowledge and data needed for the SSC's overall objective of improving the structural reliability of vessels and other marine structures. The proposed multlyear plan addresses five technology areas that provide the underlying technical support for the thrust areas. The technology areas are I. matenals cntena; 2. loads and response; 3. design methods; 4. fabrication and maintenance techniques; and 5. reliability. Individual projects were developed by the Design Work Group and the Materials Work Group at their meeting in June 1993. Projects were prioritized as high' medium, or low pnonty. All these projects were discussed at the joint meeting of the SSSC and the CMS In September 1993. Al] these projects were then evaluated by the CMS at their September 1993 meeting. Factors taken into account during discussions were the interest 10

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shown by the agencies for individual projects, the cost and time for accomplishment' technical feasibility, t~meiiness of the project with respect to ongoing work and current needs. The projects were originally proposed by the work groups on the basis of technology area. The CMS considered their own thrust areas, the national goals of the strategic plan of the SSC, but maintained an independent attitude based upon their own professional expenence. Based on these considerations, the CMS determined an Scotia] prioritization by ballot vote. Further discussions were then held to consider the balance of the entire program, and revised priorities were assigned. At the November 1993 meeting of the CMS, project priorities were again discussed based upon the above listed factors. Final priorities for accomplishment were then assigned. Relationship Among Strategic Plan, Technology Areas, and Thrust Areas The Table ~ relationships between CMS-recommended projects and thrust areas are further expanded In Table 2 and Figure I. Table 2 relates the goals of the strategic plan to thrust areas of the CMS and to the technology areas of the multiyear research program. As Table 2 reflects, the research projects recommended for FY 1995 are heavily oriented toward the CMS's traditional emphasis on safety and integrity of structures with diverse technology areas associated with these projects. Figure ~ outlines a multiyear research program. The CMS recommendations are organized on the basis of the four thrust areas (reliability, composites, producibility/competitiveness, ant] inspection/maintenance). The proposed later year projects (see Appendix A) are included for completeness. Again, it is noted that the CMS recognizes that many recommended research projects are related to more than one strategic goal and objective. The following sections of this chapter describe the technology areas of the 5-year program plan development and the programmatic argument for the recommended FY 1995 projects. 11

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TABLE 2 Relationships Between the Strategic Plan, Thrust Areas, and Technology Areas in the Research Plan. Sheet I. Research Projects STRATEGIC PIAN: THRUST AREA TECHNOLOGY NATIONAL GOALS AREAS 95- 1 Symposium/Workshop - Higher Order Loads and Prediction Methods: Hydrodynamic Loadings and Response of Marine Structures 95- 2 Methodology to Establish the Adequacy of Weld Repairs (94-8) 95- 3 Commercial Ship Design and Fabrication for Corrosion Control 95- 4 Detection Probability Assessment of Visual Inspection of Ships 95- 5 Combined Load Effects for Design and Strength Assessment of Ship Structures (94D-J) 95- 6 Weld Detail Fatigue Life Improvement Techniques 95- 7 Structural Design Guide for Twin Hull Vessels 95- 8 Fatigue and Fracture Critena for Double-Hulled Ships Safety and Integrity Reliability Maritime Industry Support Safety and Integrity Inspection / Maintenance Maritime Industry Support Safety and Integrity Inspection / Maintenance Mantime IndustIy Support Safety and Integrity Inspection / Maintenance Environmental Risk Mitigation Safety and Integrity Reliability Loads and Response Design Fabrication and Maintenance Materials Criteria Design Reliability Loads and Response Design Safety and Integrity Reliability Materials Criteria Maritime Industry Support Safety and Integrity Reliability Design Maritime Industry Support Environmental Risk Reliability Materials Mitigation Criteria 12