This methodology provides a guide consisting of design, testing, and structural analysis steps developed to assure positive strength margins of safety (MS) in critical brazed joints used for assembly of flight and non-flight structures.

This effort was promoted by concerns expressed by industry and NASA engineers and program management that the current practices of assuring positive MS in structural brazed joints vary widely among the centers, NASA contractors, and manufacturers, making the verification of structural adequacy difficult in cases involving multiple centers, other government agencies, and their suppliers. A lack of uniform methodology of estimating MS of the brazed joints leads to increasing cost of verification structural integrity of the critical hardware fabricated by brazing.

The methodology is based on testing standard butt- and lap-brazed test specimens to establish shear and tensile allowables, developing failure criterion in the form of interaction equations consisting of the stress ratios, and verifying this failure criterion by testing realistic or geometryspecific test specimens representing the actual structure on a sub-component level.

The novelty of this methodology is that it is the first time that interactive equations were applied to the brazed joints. The methodology was verified on AlBeMet 162/AWS BAlSi-4, CRES 304/AWS Bag-8, Ti-6Al-4V/AWS Bag-8, Ticuni and Ti-6Al-4V/Al 1100 base metal/filler metal combinations.

This work was done by Yury Flom of Goddard Space Flight Center. GSC-16042-1