A simple formula for fatigue crack propagation and a new method for the determination of ΔKth

✍ Scribed by Xiulin Zheng

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 761 KB
• Volume: 27
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(87)90178-0

✦ Synopsis

In the present paper test results are given to show that a simple formula for fatigue crack propagation (FCP), the derivation of which is based on the modified static fracture model, can give a good fit to the FCP test results of metals where FCP occurs due to the striation mechanism. Additionally, this simple formula can accurately predict the stress ratio effect on FCP rates. Test results also show that the FCP coefficient can be predicted from Young's modulus and that the FCP threshold, AK,,, below or equal to which no FCP occurs, can be directly obtained by extrapolation of the test data. This is a method, believed to be new, which is simple and economical for determining the FCP threshold. Furthermore, the factors which have effect on FCP thresholds are discussed. It is tentatively thought that the FCP threshold depends mainly on the crack closure effect at small stress ratios while other factors will have a greater effect on the FCP threshold as the stress ratio increases.