Marine Structures Research Recommendations Recommendations for the Interagency Ship Structure Committee's FY 1995 and Later-Years Research Program (1995) / Chapter Skim
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PROJECT RECOMMENDATIONS FOR FISCAL YEARS 1996-1997
PROJECT RECOMMENDATIONS FOR FISCAL YEARS 1996-1997
Pages 41-70
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From page 41... ...
. 96-6 Methodology for Systematic Collection of Corrosion Data Using Ultrasonic Thickness Measurements of Ship Structures (9STC-B Revisers 96-7 Workshop on Industry Standards for Integrated Ship Design Software Interfaces 50 96-8 Alternative Stiffening Systems for Double-Skin Tankers (95-11 Revised)
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From page 42... ...
SSC Strategy · Development of principles of design for production · Prevention research including damage-tolerant structure Background in general, the vessel designer assumes that the finished construction will represent accurately the configuration defined on the structural drawings, and not make allowance in the design process for certain deviations that may exist in the completed vessel. Yet it is impossible to eliminate all structural imperfections due to inherent errors in the automatic fabrication equipment and the human factors involved.
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, for mild-steel and various high-tensile steels. Duration 2,000 labor hours over 2 years 96-2 A Predictive Methodology for the Evaluation of Residual Stress and Distortion in Double Hull Ship Structures Objective Develop a predictive methodology, including the effect of the use of block welding, for evaluating residual stress and distortion in ship structures.
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Develop guidelines for residual stress and distortion modeling in ship structure that account for joint configuration and the welding processes employed. Duration 3,000 labor hours over 2 years 96-3 Failure Definition for Structural Reliability Assessment Objective Develop a method for defining failure, which is needed for structural reliability assessment of marine structures and suitable for structural reliability assessment.
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The following components of design should be included in this project: unstiffened panels, stiffened panels, hull girder, fatigue, and fracture. The load and resistance factor design methods should be presented in a code format suitable for direct use by engineers.
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· Perform code calibration of unstiffened panels for commercial and naval applications. · Present the resulting load and resistance factor design methods for unstiffened panels in a code format suitable for the direct use of engineers.
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· Present the resulting load and resistance factor design methods for hull-girder bending in a code format suitable for the direct use of engineers. The methods should be concise and complete with appendices provided that contain supporting developmental materials.
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· Improve the safety and integrity of marine structures. SSC Strategy Structural monitoring of vessels in service Background The evaluation of remaining life in structural components requires knowledge of the fatigue and fracture properties for these materials.
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SSC National Goal Improve the safety and integrity of marine structures. SSC Strategy improved structural-inspection techniques Background Presently ultrasonic inspections are performed periodically on ship structures, and extensive thickness measurement data are collected.
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Duration 1,500 labor hours over I.5 years 96-7 Workshop on Industry Standards for Integrated Ship Design Software Interfaces Objective Evaluate the status of current software developments for ship design and determine if guidelines for common interfaces can be established that would enhance the exchange of all types of data needed for the initial ship design, fabrication, life-cycle maintenance, and future design modifications to ship structures. Benefit The workshop will bring together key representatives of the shipbuilding industry, the offshore petroleum industry, military organizations, universities, standards organizations, and the software industry.
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· Prepare a written report that includes the keynote lectures, a summary of each panel session, and a list of recommendations on near-term and longer-term action items for review and distribution by the SSC. Duration 2,000 labor hours over ~ year ~ Lovdahl, R.H., P.J.
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From page 52... ...
New analytical methods are being developed and evaluated for double-hull and other configurations, with emphasis on energy-absorption capability and reduced outflow from breached tanks, in Project SR-1354, Grounding Protection of Tankers" (Massachusetts Institute of Technology Joint Industry Project) , and in the Advanced Double Hull Project by the Carderock Division of the Naval Surface Warfare Center.
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. ~ad ~ ~ A ~ ~ 1 This should include close coordination with Project SR-1354, Grounding Protection of Tankers," the British Maritime Technology computer programs for computing damage, the American Bureau of Shipping Dynamic Loading Analysis and Safohull computer programs for fatigue analysis, the related research under the shipbuilding program and the double-hull investigations at the Carderock Division of the Naval Surface Warfare Center, and the recommended Project 96-9, Rupture Resistance of Cargo Tanks of Double Hull Tankers to Low Energy Impacts." · Derive guidelines from past and current studies for maximizing the structural resistance to seaway loads.
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SSC Strategies · Research of double-hull vessel technology · Prevention research including damage-tolerant structures · Improved engineering analysis and evaluation Background To reduce the risk of environmental pollution due to grounding and collision, the Oil Pollution Act of 1990 and the International Maritime Organisation mandated that new tankers be either double hulled or, according to the organization, provide equivalent prevention of oil outflow after a collision or grounding. The doublehull design was selected as mandatory in the United States because of an assumption that the double-hull structure provides enhanced pollution protection for low-energy impacts.
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From page 55... ...
This should include close coordination with Project SR-1354, UGrounding Protection of Tankers," the British Maritime Technology computer program for computing damage, the Dynamic Load Approach and Safohull computer programs of the American Bureau of Shipping for fatigue analysis, and the related research under the shipbuilding program and the double-hull investigations at the Carderock Division of the Naval Surface Warfare Center. Using results from the first task, establish a methodology to evaluate the structural resistance and sequence of damage in tanker designs subjected to impact loads.
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design for avoiding failure and can be used in the design process to build safer double-hulled tankers and ships. SSC National Goal Reduce marine environmental risks.
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SSC National Goals · Support the North American maritime industry in shipbuilding, maintenance, and repair. · Improve the safety and integrity of marine structures.
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SSC National Goals · Reduce marine environmental risks. · Improve the safety and integrity of marine structures.
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SSC Strategy Structural reliability engineering Background Increased use of polymer-based composite materials in marine structures raises questions concerning the effects of long-term marine exposure on the degradation of composites and also the effects of these composites on the corrosion of metals. When polymer-based composites were first used in aircraft, they absorbed water, which resulted 59
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In this manner, the sensitivity of these materials to atomic oxygen was discovered and accounted for in later designs, thus preventing potential problems. In the discussion at the National Conference on the Use of Composite Materials in Load-Bearing Marine Structures (SR-1311)
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Duration 3,500 labor hours over 3 years 96-14 Crack-Arrest Toughness of Steel Weldments Objective Develop fracture mechanics test methods and analytical models for the crack-arrest assessment of marine weldments. Benefit The results of this project will enhance the durability, reliability, and safety of marine structures through a more realistic and economical fracture-mechanics approach to toughness assessment of weldments.
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Duration Phase ~ - I,000 hours over ~ year Phase I! - 2,000 hours over 2 years 96-iS Ship Bow Structural Guidance Objective Provide guidance to ship structural designers regarding bow design to improve producibility and to reduce cost, weight, and required maintenance.
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Ship structural designers with extensive experience in ship bow design are few and far between in the United States and Canada, and most of those are at or past retirement age. There is a need to capture the expertise of these individuals and upgrade it with lessons learned from state-of-the-art foreign designs to provide design guidance to the coming generation of domestic ship-structure designers.
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Duration 2,000 labor hours over ~ year 96-17 Sea-Operational Profile for Structural Reliability Assessment ~ Materials Technology Centre, 1989. Effect of Welding Process and Parameters on Weldability of Selected Primers and, by Literature Review, the Effect of Primer-Induced Porosity of Joint Performance, Report No.
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· Illustrate the developed method for selected classes. Duration 1,500 labor hours over ~ year 96- Condition Assessment and Optimal Maintenance of Existing Surface Coating System for Tankers Objective Develop guidelines to assess accurately the condition of the existing coating system and to determine an optimal coating maintenance program.
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From page 66... ...
and Canadian maritime industry in shipbuilding, maintenance, and repair. SSC Strategy Improved structural inspection techniques Background In view of the large increase in balIast-tank surface area in new double-hull tankers, the requirements by the International Association of Classification Societies to coat the ballast tanks of new tankers, and more-stringent survey and maintenance requirements by international regulatory agencies, such as the International Maritime Organisation Enhanced Survey Programme for Oil Tankers, there is an increased need to assess accurately during inspection the coating effectiveness and to determine optimal coating maintenance and replacement program.
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From page 67... ...
SSC Strategy Prevention research including damage-tolerant structures, structural monitoring, and human factors Background Much progress has been made recently in the area of design for the minimization of corrosion, and this knowledge is currently being implemented. However, corrosion detection and corrosion rate determinations for existing and inaccessible structures remain a problem.
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From page 68... ...
SSC National Goals · Improve the safety and integrity of marine structures · Support the North American maritime industry in shipbuilding, maintenance, and repair. SSC Strategies · Development of better design tools · Development of structural reliability engineering Background Reliability methods are becoming the preferred method of design over the deterministic method in many engineered structures, including marine structures.
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From page 69... ...
These areas were discussed in a recent SSC report, Uncertainty in Strength Models for Marine Structures" (SSC-375~. The report points out that insufficient data are available to determine uncertainties predicting collapse of stiffened panels.
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