Verification of Fatigue Life Prediction results for notched specimens with short crack propagation phase

✍ Scribed by Prof. Dr. A. Buch

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 894 KB
• Volume: 12
• Category: Article
• ISSN: 0933-5137
• DOI: 10.1002/mawe.19810120805

✦ Synopsis

Abstract

Crack initiation life estimates obtained with the local strain approach (LSA) and with the conventional nominal stress approach (NSA) were compared with experimental results obtained with stress block loading programs and flight simulation gust random loading programs. Programs with and without load peaks were used for testing internally notched 2024‐T3 sheet specimens with a very small crack propagation phase. Experimental S‐N curves obtained for the notched specimens and assumed to be linear in log σ~a~–log N coordinates were used for calculations with the NSA method. A material strain‐life curve (ϵ versus N), a cyclic stress‐strain curve and a K~f~ value calculated with a two‐parameter formula were used for life estimations with the LSA method. Calculations indicated that the life estimates obtained with the K~f~ value for R = 0 (pulsating‐tension) were more accurate than in the case of K~f~ for R = −1, for the considered loading programs of tensile type. It was also shown that the prediction accuracy can be much improved by use of a proper adjustment coefficient obtained for a sufficiently similar loading program.