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

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...