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TRANSIENT ANALYSIS IN FRACTURING ALUMINUM PLATE.
Technical rept., Apr 66-May 67,
WASHINGTON UNIV SEATTLE DEPT OF MECHANICAL ENGINEERING
Pagination or Media Count:
Transient displacement distributions in centrally notched aluminum plates with propagating cracks were determined by using the Moire fringe technique. Specimens used were 7075-T6 and 7178-T6 aluminum alloy 4 inches wide, 116 inch thick with half crack lengths of 0.12 to 0.25 inches. The transient Moire patterns were recorded with a Beckman and Whitley Model 501A image converter camera. Crack velocities and crack accelerations were determined by utilizing crack wires. Crack velocities in 7178-T6 specimens were higher than those in 7075-T6 specimens. It was also found that the static and transient normal strain distributions in the region immediately ahead of the crack tip were similar. Also with increasing crack velocities, the order of strain singularity approached the order of r to the -0.5 power as found in a previous investigation see AD-624 168. It was concluded that for this series of experiments, Craggs model of a moving crack agreed with the experimental results. Author
APPROVED FOR PUBLIC RELEASE