TY - BOOK

T1 - Observation and modelling of the short crack growth behaviour in aluminium alloys for the designing of aircraft structures

AU - Tesch, Andreas Johannes

N1 - embargoed until null

PY - 2005

Y1 - 2005

N2 - The fatigue crack growth behaviour of long and short cracks in two aluminium alloys used in the aircraft industry was characterised in this work. The fatigue crack growth tests on long cracks showed that the alloy Al2524-T351 is more damage tolerant than Al 6013-T6. The threshold values for the propagation of long cracks are approximately 10% higher in Al 2524-T351 compared to Al 6013-T6. The fatigue crack growth tests on specimens with a short corner crack showed for both aluminium alloys that short cracks grow faster compared to long cracks at the same stress intensity factor range and at the same stress ratio. They also grow below the threshold of the stress intensity factor range for the propagation of long cracks. Below the threshold values determined with tests at high, constant Kmax-values short cracks grew but stopped after a prolongation of a few µm. Different models to predict the fatigue crack growth rates in materials were compared and their suitability to describe the short crack growth phenomenon was analysed. The applicability of the stress intensity factor to describe the short crack growth behaviour was also examined. On the basis of the fatigue crack growth data derived from constant Kmax-tests a model was developed with which it is possible to predict the short crack growth behaviour at different stress ratios. The comparison with the experimental short crack growth data showed very good agreement.

AB - The fatigue crack growth behaviour of long and short cracks in two aluminium alloys used in the aircraft industry was characterised in this work. The fatigue crack growth tests on long cracks showed that the alloy Al2524-T351 is more damage tolerant than Al 6013-T6. The threshold values for the propagation of long cracks are approximately 10% higher in Al 2524-T351 compared to Al 6013-T6. The fatigue crack growth tests on specimens with a short corner crack showed for both aluminium alloys that short cracks grow faster compared to long cracks at the same stress intensity factor range and at the same stress ratio. They also grow below the threshold of the stress intensity factor range for the propagation of long cracks. Below the threshold values determined with tests at high, constant Kmax-values short cracks grew but stopped after a prolongation of a few µm. Different models to predict the fatigue crack growth rates in materials were compared and their suitability to describe the short crack growth phenomenon was analysed. The applicability of the stress intensity factor to describe the short crack growth behaviour was also examined. On the basis of the fatigue crack growth data derived from constant Kmax-tests a model was developed with which it is possible to predict the short crack growth behaviour at different stress ratios. The comparison with the experimental short crack growth data showed very good agreement.

KW - aluminium alloys Al2524-T351 Al 6013-T6 fatigue crack growth short cracks threshold damage tolerant stress intensity factor corner crack propagation prediction models new method for the determination of fatigue crack growth curves

KW - Aluminium-Legierungen Al 2524-T351 Al 6013-T6 Ermüdung Schwellenwerte kurze Risse Ermüdungsrisswachstumskurven Vorhersage schadenstolerant Eckrisse Spannungsintensitätsfaktor Methode zur Ermittlung von Ermüdungsrisswachstumskurven

M3 - Doctoral Thesis

ER -