SYMPOSIA PAPER Published: 01 January 1976
STP33376S

Equivalent Constant-Amplitude Concept for Crack Growth Under Spectrum Loading

Source

A concept based on the crack-closure phenomenon has been developed to replace random-load spectra with constant-amplitude loading in both analysis and tests. The maximum load and the crack-opening load in the constant-amplitude loading are chosen to be equal to those for the spectrum, so that both crack-growth mode and the crack length at failure are equivalent to those under the random-load spectra. The number of cycles of constant-amplitude loading is chosen so that the amount of crack growth is equal to that due to a given sequence or block of the random spectrum loading. The concept was tested experimentally after predicting the equivalent number of constant-amplitude cycles for six different random-load sequences. The agreement between predictions and test results was good.

Author Information

Elber, W
NASA Langley Research Center, Hampton, Va.
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Details
Developed by Committee: E08
Pages: 236–250
DOI: 10.1520/STP33376S
ISBN-EB: 978-0-8031-4672-3
ISBN-13: 978-0-8031-0344-3