Materials, Properties and Design

· Aerodynamic loads subject the Fan blades to fluctuating stresses. Material performance is reduced in this Fatigue environment.
· The diagram shows the number of cycles to failure for a 7075-T6 aluminum alloy as a function of the periodic stress amplitude. The P values represent probabilities of failure. The alloy yield stress is 505 MPa. Fatigue failure occurs at stress levels well below this value.
· Understanding fluctuating stress response and stress concentration effects is essential in component design.

From: Callister,
"Materials Science and Engineering,"
Wiley (2000)