Failure Mechanisms

· The fracture surface shown is of a 2024-T3 aluminum alloy that has experienced "block" periodic stress loading as shown in the insert.
· No crack growth occurred during the low stress amplitude A-block. The applied cyclic stress is σ, and σ_max , its maximum value, is the same for each block.
· The striation spacing in the B and C blocks increases as the stress amplitude increases, as expected.

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