Ship Hull Plating Weld Misalignment Effects When Subjected to Tension
DEPARTMENT OF THE NAVY WASHINGTON DC
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Precision fabrication of ships is advancing. Welding is ubiquitous in ship construction and military standards have specified tolerances for joining plates in naval combatants. Precision manufacturing will allow the production of ships with smaller hull plate misalignments. A benefit from this could be improved ship survivability when subjected to underwater explosions. Slip Line Fracture Mechanics interacting with Finite Element Analysis FEA gives insight into the deformation, necking and fracture mechanisms of typical over-matched welds. The weld rotates with local necking until the plates are aligned and then shears off. FEA showed the importance of deformed geometry in promoting final fracture by slip from the toe of the weld in non-hardening material. Graphical results indicate that for a non-hardening material with an offset of 15 of the plate thickness, which is within current military standards, weld rotation of 4-6 deg and local plate thinning of 4-5 in the region next to the weld can be expected. A test specimen showed a 4 deg weld rotation but did not provide the plane-strain condition and failed by necking away from the weld. A re-design is suggested.
- Fabrication Metallurgy
- Numerical Mathematics
- Marine Engineering