Crack propagation in fatigue: some experiments with DTD 507A aluminium alloy sheet

Crack propagation in fatigue: some experiments with DTD 507A aluminium alloy sheet

Rooke, D.P.
Gunn, N.J.F.
Ballett, J.T.
Bradshaw, F.J.

Royal Aircraft Establishment RAE

1964-10-31

Fatigue crack propagation rates have been measured in 16 swg sheets of this aluminium alloy using stress levels of 8800 ±7200 psi, 4400 ±3600 psi and 13,200 ±10,800 psi. The scatters in crack initiation times and crack rates were determined. Varying the panel length/width ratio from 1.2 to 4.75 was found to have little effect on crack rate. A major study was made on the effect of varying panel width from 3" to 20" and various parameters were used to correlate all the results at all the three stress levels. The stress intensity factor, K, was preferred on grounds of simplicity and effectiveness, though all parameters failed to correlate stress differences adequately. Crack propagation rates in two directions at right-angles were little different. Buckling, which occurred in a few of the large panels, had little effect on crack rate. Tests on panels at the same stresses as above, with the cladding removed, showed negligible change in crack rate. Macroscopic fracture mode transitions were correlated with K values and crack rates.

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Ministry of Aviation; Royal Aircraft Establishment; RAE Farnborough

Campus only

RAE Technical Report No. 64025

Aerospace Engineering Reports

report

(c) 1964 Ministry of Aviation, Royal Aircraft Establishment