SYMPOSIA PAPER Published: 01 January 1971
STP26680S

The Significance of Fatigue Crack Closure

Source

Experiments on 2024-T3 aluminum alloy sheet are described which confirm the occurrence of fatigue crack closure under cyclic tensile loading. The results show that a fatigue crack can be closed at the crack tip for up to half of the loading amplitude, leaving this portion of the cycle ineffective in propagating the crack. An expression for the crack propagation rate in terms of effective stress amplitude is proposed. This expression is fitted to existing constant amplitude crack propagation data for 2024-T3 aluminum alloy. The parameters evaluated provide a better fit to the data than other empirical expressions available. Analysis of qualitative experiments on variable amplitude loading shows that the crack closure phenomenon could account for acceleration and retardation effects in crack propagation.

Author Information

Elber, W
National Academy of Sciences, NASA Langley Research Center, National Aeronautics and Space Administration, Hampton, Va.
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Details
Developed by Committee: E08
Pages: 230–242
DOI: 10.1520/STP26680S
ISBN-EB: 978-0-8031-4595-5
ISBN-13: 978-0-8031-0031-2