What term describes restrictions to the stress range encountered in a member subject to an anticipated number of stress range cycles?

• A. Fatigue limit state
• B. Fatigue II
• C. Fracture limit state
• D. Fatigue I

Answer: (A)

The key idea here is controlling how large the stress swings are for the number of times the member is expected to experience them. This is captured by the fatigue limit state, which specifies a maximum allowable stress range for the anticipated number of cycles so that fatigue failure is avoided within that life. In design, you ensure the actual stress range stays at or below this limit for the target cycle count, sometimes relying on an endurance limit for materials that has one, or otherwise designing to a finite life for the given number of cycles.

The other terms aren’t the standard way to describe this specific constraint. Fatigue II or Fatigue I aren’t commonly used design terms for limiting stress ranges over cycles, and a fracture limit state centers on crack initiation and propagation criteria rather than simply restricting the stress range for a planned number of cycles.