FATIGUE CRACK PROPAGATION IN AN AlMgSi ALLOY

Luis F. P. Borrego  José D. M. Costa  José A.M. Ferreira      

Anales de la Mecánica de la Fractura, nº 16 . 1999 . Pág. 119 -124
Ver (.pdf): Anales16-015

Resumen: Aluminium alloys of the 6000 series are largely used in structural applications. In automotive structures the type of solicitation is a random loading. However, fatigue crack growth under variable load amplitudes in this series of aluminium alloys are not so well understand as in the 7000 and 2000 series. So, in this work a fatigue crack propagation study was done in 6082 aluminium alloy using both constant and variable load amplitudes. The tests were carried out using MT specimens in a servohydraulic machine at a frequency of 25 Hz. For the constant amplitude tests four different stress ratios were analysed: R=-0.25, 0.05, 0.25 and 0.4. The threshold of the stress intensity factor range, AKth was also obtained for the four values of R. Crack closure was monitored in al! tests by the compliance technique using a pin microgauge. The crack opening loads were derived from the load-crack opening displacement records after mathematics derivation and used to calculate AKeff values from which the da/dN- AKeffcurves are obtained. The crack closure parameter U was obtained and related with AK and the stress ratio. A relationship between AKth and R was also obtained. Sorne tests of overload were a!so realised and correlation between the crack propagation rate and the effective stress intensity factor were attempted.

LocalizaciónTorremolinos, Málaga

Department of Mechanical Engineering, ISEC/IPC, 3030 Coimbra
Department of Mechanical Engineering 1 FCT, University of Coimbra- Polo II Pinhal de Marrocos, 3030 Coimbra, Portugal
Department of Mechanical Engineering 1 FCT, University of Coimbra- Polo II Pinhal de Marrocos, 3030 Coimbra, Portugal