Which fatigue load combination is related to finite load-induced fatigue life?

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

Answer: (D)

Finite load-induced fatigue life focuses on how many cycles a member can endure before failure under a given stress spectrum, using the finite-life S-N relationship rather than an endurance limit. This approach directly ties the loading to a finite number of cycles to failure, so the fatigue load combination that embodies this behavior is Fatigue II.

The other terms describe different fatigue concepts. The fatigue limit state relates to infinite-life behavior (endurance under a sufficiently low stress range), and the fracture limit state concerns failure by crack propagation, not the finite-cycle life calculation. Fatigue I is the infinite-life approach, not the finite-life one.