Friction stir welding is used to fabricate the NASA Ares I rocket upper stage fuel tank. The friction stir plug weld fills the hole left when the stir weld tool is removed. NASA engineers want to examine fracture conditions in the plug weld due to possible imperfections to assure safety and reliability. An automated and parametric crack mesh generator is needed to quickly and easily examine numerous cases. The plug weld crack meshing approach and its reliance on Abaqus for analysis is discussed, and crack mesh basics are reviewed. The choice of crack shape and 39 additional geometric and mesh control parameters, such as the plug diameter, transverse weld sizes, and plug bevel angle affect how the crack mesh is created. Using the plug bevel angle option or surface crack choice requires tied contact in Abaqus to connect some of the mesh zones. Using the through-thickness crack shape permits results comparison of tied contact versus merging coincident nodes to show that the crack front J-integral computed by Abaqus is unchanged, which gives confidence for cases where the tied contact must be used. The crack follows the plug circumference, which creates the possibility of crack face closure and the need for general contact modeling in Abaqus. The crack mesh examples used show the variety of possible geometries in the mesh zones between the plug bevel surface and the surrounding transverse welds.
Friction stir plug weld crack meshing for NASA
Ineinandergreifen der Risse bei einer Reibrührlochschweißnaht für die NASA
2010
15 Seiten, 14 Bilder, 8 Quellen
Conference paper
Storage medium
English
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