Transient stress effects on fatigue crack growth thresholds due to testing methodology

✍ Scribed by A.K. Vasudevan; K. Sadananda

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 406 KB
• Volume: 29
• Category: Article
• ISSN: 0142-1123
• DOI: 10.1016/j.ijfatigue.2007.02.023

✦ Synopsis

It is observed that various testing methodologies used to determine DK th introduce transient stress effects. These effects give the impression that the measured values of DK th are sensitive to the test variables. However, when the same results are collectively plotted as DK vs. K max a single curve results. This is because each test method introduces its own ''internal stresses'' that affects the individual DK th that pertains to a segment of the total DK-K max curve. The implication is that any test method used to measure threshold will have history effects that cannot be avoided. Attempts can only be made to minimize such effects. It is important to recognize that threshold is not a single value, but a unique curve represented in a 2D-space by a DK-K max plot, that is independent of testing methods.