Subcritical Crack Extension in 2S Aluminum and in Zinc Foils.
NAVAL RESEARCH LAB WASHINGTON D C
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The nucleation of advance fracture elements in metal foils was studied under the direction of G.R. Irwin in the years 1947 to 1949 in the Ballistics Branch of the Mechanics Division of the Naval Research Laboratory. Some heretofore unpublished results obtained on 2S aluminum and on zinc are analyzed here. The observations aid in the interpretation of fracture surface markings in other materials wherein discontinuous fracturing occurs. The spacings between nuclei were found to be larger than the Krafft d sub T, which has been successful in explaining plane strain fracturing, and the spacings were much larger than the COD. Other models for calculating the unstable ligament pinhole spacings were suggested. The work for fracturing was inconsistent with the Bluhm model but was consistent with published results by Sullivan and Freed and by Smith et al for full shear fracturing. Modified author abstract
- Metallurgy and Metallography