Failure Mechanisms

· The fractograph, a scanning electron micrograph of the fatigue striations in the 2024-T42 bulkhead skin 3.05 mm from the rivet in hole 34 are shown. The striation spacing of about 1.5 µm indicates a stress intensity factor range ΔK = 10 to 15 MPa m^0.5.
· Closer to the rivet hole (0.28 mm) the spacing was 0.23 μm, indicating that the crack growth rate increased with the number of times the fuselage was pressurized.

From: Suresh, "Fatigue of Materials," Cambridge (1991)