The National Shipbuilding Research Program, 1991 Ship Production Symposium Proceedings: Paper No. IVB-3. Recent MIT Research on Residual Stresses and Distortion in Welded Structures
The National Shipbuilding Research Program, 1991 Ship Production Symposium Proceedings: Paper No. IVB-3. Recent MIT Research on Residual Stresses and Distortion in Welded Structures

Author:

Publisher:

Published: 1991

Total Pages: 19

ISBN-13:

DOWNLOAD EBOOK

This paper presents a summary of recent efforts by the Welding Research Group at the Department of Ocean Engineering, M.I.T. The major thrust of the efforts has been to develop technologies of reducing residual stresses and distortion through in-process control. Part I discusses (a) reduction of longitudinal bending distortion of built-up beams, (b) reduction of radial distortion and residual stresses in girthwelded pipes, (c) reduction of forces acting on tack welds during butt welding, and (d) reduction of residual stresses and distortion in high-strength steel weldments. Part II presents a brief summary of other studies including (e) forming of steel plates by line heating with a high-power laser beam, (f) an intelligent system for flame straightening of panel structures, and (g) a knowledge-based system for minimizing out-of-plane distortion of welded panel structures.

The National Shipbuilding Research Program, 1991 Ship Production Symposium Proceedings: Paper No. IVB-4. Shipyard Aluminum/Steel Welded Transition Joints
The National Shipbuilding Research Program, 1991 Ship Production Symposium Proceedings: Paper No. IVB-4. Shipyard Aluminum/Steel Welded Transition Joints

Author:

Publisher:

Published: 1991

Total Pages: 10

ISBN-13:

DOWNLOAD EBOOK

Aluminum to steel explosion welded transition joints are used in shipbuilding to attach aluminum superstructures to steel hulls. This paper summarizes long term studies to determine causes of separations and describes actions to prevent separations. The aluminum/steel transition joints are manufactured by the explosion welding process and tested in accordance with MIL-J-24445. Traditional transition joints consist of alloyed aluminum bonded (by the explosion weld) to mild steel with an interlayer of low alloy aluminum. In 1989, production began using an improved transition joint product with the addition of a titanium interlayer between the steel and the low alloy aluminum. Laboratory testing showed the improved product had greater strength and temperature resistance. However, when this product was put into production, disbonding occurred at an alarming rate. As a result, it was discovered that bond notch toughness is a critical property even though it was not required to be measured by MIL-J- 24445. To improve the notch toughness while preserving earlier beneficial improvements, a ductile copper nickel (CUNI) interlayer was added between the steel and the titanium. This paper describes the study results and the development of the latest generation of aluminum steel structural transition.

The National Shipbuilding Research Program, 1990 Ship Production Symposium, Paper No. 5B-2: Shipboard Aluminum/Steel Welded Transition Joints Evaluation and Improvements
The National Shipbuilding Research Program, 1990 Ship Production Symposium, Paper No. 5B-2: Shipboard Aluminum/Steel Welded Transition Joints Evaluation and Improvements

Author:

Publisher:

Published: 1990

Total Pages: 22

ISBN-13:

DOWNLOAD EBOOK

Aluminum to steel explosion welded transition joints are used to attach aluminum superstructures to steel hulls. Transition joint bond separation sometimes occurs during ship construction. Ingalls Shipbuilding conducted a long term study to determine causes and corrective action for these separations. The aluminum/steel transition joints are manufactured by the explosion bonding process and tested in accordance with MIL-J-24445. Traditional transition joints consist of alloyed aluminum bonded to mild steel with an interlayer of low alloy aluminum. The study reviewed transition joint manufacture and quality testing required by the material specification, reviewed the adequacy of design guidelines and production practices, and considered cost effective methods for corrective action. Modifications in product design and testing, installation design and shipyard production practices can improve reliability. The most important result of this study was development of material with improved Properties. This paper relates the study procedure, findings and recommendations so that transition joint separations can be avoided on future installations. This information is useful for designers and transition joint users.

The National Shipbuilding Research Program. 1993 Ship Production Symposium. Paper No. 13: An Engineering Product Model Based on STEP Protocols
The National Shipbuilding Research Program. 1993 Ship Production Symposium. Paper No. 13: An Engineering Product Model Based on STEP Protocols

Author:

Publisher:

Published: 1993

Total Pages: 14

ISBN-13:

DOWNLOAD EBOOK

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.

The National Shipbuilding Research Program. 1997 Ship Production Symposium, Paper Number 11: Design, Fabrication, Installation, and Operation of Titanium Seawater Piping Systems
The National Shipbuilding Research Program. 1997 Ship Production Symposium, Paper Number 11: Design, Fabrication, Installation, and Operation of Titanium Seawater Piping Systems

Author:

Publisher:

Published: 1997

Total Pages: 21

ISBN-13:

DOWNLOAD EBOOK

For many years, the U.S. Navy fleet has experienced severe corrosion and erosion problems in copper nickel seawater piping systems. Since titanium is extremely resistant to corrosion and erosion, it has been viewed as a potential solution to these problems. However, certain concerns regarding shipboard use of titanium needed to be addressed: marine fouling, galvanic action with other metals, welding, system fabrication in a normal shipyard environment, testing, and life cycle costs. Over a three year period, Ingalls Shipbuilding division of Litton Industries and the Naval Surface Warfare Center, White Oak, worked with various commercial equipment suppliers to address these concerns. Partially because of the success of this project, it was decided to retrofit titanium systems aboard TARAWA Class LHAs and to specify same for the new LPD 17 Class ships.