SBIR-STTR Award

Two central questions will be addressed in the proposed work. These are 1) For new constructions: are current Navy specifications for tolerances and structural details too stringent? Can some of them be relaxed so as to minimize ship construction costs? 2) For ships in service; how important is it to repair small damages such as dents, small cracks, initial deformations and distortions, misalignments and incorrectly built details? What criteria should be used to base a repair or replacement decision on? In both cases, the objective is to minimize cost of new constructions or repairs of in-service ships without serious degradation to structural performance. Towards this end, reliability principles will be applied in the proposed work to develop a methodology and criteria for minimizing cost, constraint by a minimum acceptable reliability level. In Phase II of the project, alternative specifications and repair/replacement criteria will be developed based on Phase I results. Both current and the proposed alternative specifications will be applied to ship structures in order to estimate the cost savings associated with the new proposed specifications.

The principal objective of the project is to reduce the initial cost of construction of new USN ships. Specific objectives are (1) Develop new tolerances and structural detailing specifications for new construction (2) using an existing ship (specified) by NAVSEA) demonstrate the differences and similarities between existing and the new proposed specifications (3) estimate the cost savings associated with the new specifications. The new specifications will be based on a careful consideration of the interaction between construction requirements and structural performance given due consideration to uncertainties in all design factors as well as the initial costs of construction costs of maintenance and the cost associated with failure. Recently developed methods of structural reliability will be employed along with elements of economic value analysis to establish tolerances and detailing specifications that will minimize the total life cycle costs of ships. A case study will be performed to demonstrate the use of the new tolerance requirements and quantify the expected cost savings by employing the new requirements. For ships in service repair of damaged members is expensive and it may not be immediately clear that the improvement in structural quality is cost effective. The use of reliability technology and decision analysis will be employed to help make the repair decision based on the life cost of the ship. The effort in connection with the in-service ships will be about 8% of the project. The principal investigator will be Alaa E. Mansour of Mansour Engineering Inc. He will be responsible for directing the project. There will be a team of consultants in reliability technology including Dr. Paul Wirsching as well as select personnel from Newport News Shipbuilding and Chevron Shipping.