SYMPOSIA PAPER Published: 01 January 1980
STP27481S

Time Dependent Changes in Notch Stress/Notch Strain and Their Effects on Crack Initiation

Source

An analytical and experimental program was conducted to evaluate the time-dependent changes in the stress-strain state at stress concentrations. Load-time interaction effects on creep and stress relaxation were evaluated utilizing simple coupon, super-scale, and simplified stress concentration test specimens. Periods of sustained compression loads included in a load sequence or spectrum were shown to affect a reduction in specimen fatigue life due to creep and stress relaxation occurring during the hold period. Experiments were designed such that a quantitative assessment of time-dependent changes in both notch stress and notch strain was possible. Resulting data were used to formulate a creep and stress relaxation module for inclusion in an automated hysteresis fatigue analysis program. Agreement between experimental and predicted lives using the hysteresis analysis is significantly better than predictions using a linear analysis method.

Author Information

Carroll, JR
Advanced Structures Department, Lockheed-Georgia Company, Marietta, Ga.
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Details
Developed by Committee: E08
Pages: 24–40
DOI: 10.1520/STP27481S
ISBN-EB: 978-0-8031-4782-9
ISBN-13: 978-0-8031-0720-5