Partial crack closure under block loading

• Author(s): Borrego, L. P. ; Ferreira, J. M. ; Costa, J. M.
• Date: 2008
• Persistent ID: http://hdl.handle.net/10316/4171
• Origin: Estudo Geral - Universidade de Coimbra
• Subject(s): Aluminium alloy; Fatigue crack growth; Block loading; Crack closure; Partial crack closure
• Document Type: Article
• Language: English

Description

Fatigue crack propagation tests under high-low and low-high block loading sequences have been performed in aluminium alloy specimens. The tests were carried out at constant [Delta]K conditions. Two stress ratios were analysed: R = 0.05 and R = 0.4. Crack closure was monitored in all tests by the compliance technique using a pin microgauge. The observed transient post load step behaviour is discussed in terms of the load change magnitude, [Delta]K baseline levels and stress ratio. The crack closure level was obtained and compared with the crack growth transients. A good agreement between experimental and predicted crack growth rates is obtained when the partial crack closure effect is properly taken into account. Therefore, plasticity-induced crack closure plays an important role on the load interaction effects observed in aluminium alloys. http://www.sciencedirect.com/science/article/B6V35-4S01WM6-1/1/55ac18d861098dc98cd7150c4c5fa4d3