This study focuses on the behavior of brazed lap shear joints because of their importance in manufacturing aerospace structures. In Part 1, an average shear strength capability and failure modes of the single lap joints are explored. Stainless steel specimens brazed with pure silver are tested in accordance with the AWS C3.2 standard. Comparison of the failure loads and the ultimate shear strength with the finite element analysis (FEA) of the same specimens as a function of the overlap widths shows excellent correlation between the experimental and calculated values for the defect-free lap joints. A damage zone criterion is shown to work quite well in understanding the failure of the braze joints. The following conclusions can be drawn: It appears that for small overlaps (</= 0.5 T) stress distribution within the lap shear braze joint is uniform. The maximum von Mises stress calculated at failure in the 0.5T lap joint can be used as a critical or shear ultimate strength of the filler metal for the lap joint. Within the joint clearance sizes tested, 0.001 in. to 0.008 in. (25.4 mm to 203 mm), strength is not sensitive to clearance sizes. In the stainless steel lap shear joints brazed with silver metal, the failure occurs in the filler metal for overlaps up to 5T. It appears that the following damage zone criterion can be used: the lap shear braze joint fails if von Mises stress exceeds the critical value over 10 % of the overlap area. The 10 % damage zone observation checks well against other stainless steel/silver filler metal systems. The authors would encourage other researchers to apply the damage zone failure criterion to their experimental data to see if this observation holds true for other base metal/filler metal combinations. (to be continued)
Flaw tolerance in lap shear brazed joints - Part 1
Welding Journal, New York ; 83 , 1 ; 32S-38S
2004
9 Seiten, 14 Bilder, 1 Tabelle, 18 Quellen
Article (Journal)
English
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