NJC Initiates New Projects for Distortion Control in Next Generation Surface Combatants

The Navy Joining Center (NJC) operated by Edison Welding Institute, has been awarded two new development projects from the US Navy’s ManTech office, to address distortion issues associated with manufacturing new weapons platform systems. Projects recently initiated are “Control of Thin Panel Distortion” and “Weld Distortion Control Thin Structure”. These projects are in support of the next generation aircraft carrier (CVN78) and destroyer (DDG1000) respectively.

Control of Thin Panel Distortion: Meeting operational requirements for CVN78 has placed an emphasis on reducing the weight of ship structures. Shipyard design teams are addressing this through lighter weight designs for sponsons, decks, bulkheads, and other structures. To augment the new designs, the aforementioned structures will be constructed of more lightweight plates and panels than previous aircraft carrier structures. These lightweight structures will take advantage of the strength from High Strength Low Alloy Steels (HSLA) plates to reduce the thickness of panels and stiffeners.

There is an expected 30% increase in the use of thinner plate. The objective of this project is to assess the specific needs of Northrop Grumman Newport News (NGNN) panel and final assembly fabrication equipment and processes and apply new technologies and lessons-learned from previous work to reduce distortion for CVN 78 thin structures. This project will focus primarily on current technologies and practices available and used within NGSB, while identifying potential future practices and technologies for consideration on CVN 79 and future ships. To meet the project goal of mitigating fabrication issues, the project team is researching fabrication improvements to implement for thin structure manufacture for CVN 78 to prevent increases in ship construction costs and schedules. The challenges being investigated include current fabrication practices (material handling, fitting, welding), incoming material flatness, flame straightening restrictions, and general requirements for fairness.

Distortion Control for DDG1000 Thin Structure: Distortion of thin panels makes it more difficult to fit and weld subsequent assemblies and units as well as to meet fairness and straightness requirements. As indicated in the above project the result is increased ship construction costs and schedule delays. While significant work has been done to reduce distortion, most of this work has focused on the panel line operations. There is a need to apply technology to reduce distortion for subassemblies and units as well as to support the implementation of technologies that benefit the panel line.

This ManTech project will apply lessons learned on past projects and develop new technology for DDG1000 to 1)Further improve dimensional control of cutting and handling operations 2)Develop best practices for low-distortion tandem submerged arc butt welding 3) Develop methods to reduce distortion for fabrication of sub-assemblies and units. Project activity will investigate improved submerged arc welding process (i.e. tandem SAW), assembly practices (fixtures, tooling, sequencing), and plate cutting (plasma, laser).

Distortion mitigation for both projects will reduce welding and fitting hours and move welding operations closer to first time weld quality when joining panels and units together. The result will be decreased manufacturing costs and reduced production schedules for the new surface ship platforms for the US Navy.

For more information, contact Larry Brown at 614.688.5080 or email larry_brown@ewi.org.