SYMPOSIA PAPER Published: 01 January 1976
STP33370S

Mathematical Modeling of Crack Growth Interaction Effects

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A combined analytical and experimental program was performed to obtain additional insight into the growth of cracks subjected to simple variable-amplitude loading. The experimental results were used to examine methods of mathematically modeling crack propagation behavior to enhance predictive capability for arbitrary spectrum loading.

The mathematical modeling consisted, primarily, of using the crack closure concept to correlate predicted crack propagation behavior with observed behavior for various simple loading spectra. Two analytical schemes were developed, one of which calculated the crack opening load based on residual forces acting on the crack surface, and another where empirical relationships between loading sequences and crack opening behavior were utilized. Difficulties with the Residual Force Model in correctly representing some of the experimentally observed crack opening and closing effects led to emphasizing the development of the more empirical Crack Closure Model.

The test program encompassed constant-amplitude tension loads, single and multiple tensile overloads, compression spikes, and simplified variable-amplitude load sequences applied to 2219-T851 aluminum and Ti-6Al-4V annealed titanium alloy specimens. Detailed crack-growth and crack closure measurements were obtained. These measurements were used to quantify crack closure behavior as a function of stress ratio, including negative values, and various loading sequences.

Author Information

Bell, PD
Grumman Aerospace Corporation, Bethpage, N. Y.
Wolfman, A
Grumman Aerospace Corporation, Bethpage, N. Y.
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Details
Developed by Committee: E08
Pages: 157–171
DOI: 10.1520/STP33370S
ISBN-EB: 978-0-8031-4672-3
ISBN-13: 978-0-8031-0344-3