Fatigue crack propagation in the threshold regime after rapid load reduction

✍ Scribed by H.R. Mayer; S.E. Stanzl; E.K. Tschegg

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 764 KB
• Volume: 40
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(91)90168-z

✦ Synopsis

Al&me

-In this work, the influence of rapid load reduction on fatigue crack growth in the threshold regime of the aluminium alloy 2024T3 has been studied. It can he shown that fatigue crack growth may be severely influenced by crack closure due to oxide formation and fracture surface roughness. After rapid load reduction, crack arrest could be observed at X;, values lO-100% above the constant amplitude threshold, depending on the environment. With measurements in different environments (humid air and vacuum), the oxide-induced crack closure effect could be recogniaed as being mainly responsible for an increase of the stress intensity threshold. Using high-frequency fatigue testing equipment, it was possible to show that after rapid load reduction in a vacuum, cracks may begin to grow again after crack arrest of more than 5 x 10' cycles.