Fatigue evaluation in Division 2 uses which of the following data or methods?

• A. Miner’s rule
• B. Paris' law
• C. S-N curves
• D. Fatigue limit concept

Answer: (C)

Fatigue evaluation in Division 2 is based on material fatigue data in the form of S-N curves, which show how many cycles a given stress amplitude can endure for a specific material and condition. In practice, you pick the appropriate S-N curve for the material, apply necessary corrections (mean-stress effects like Goodman or Gerber, and adjustments for surface finish, thickness, and temperature), and then compare the service stress to the curve to ensure the target life is achievable. While there are methods to handle variable loading (like Miner’s rule) or fracture-mechanics approaches for crack growth (Paris’ law), the standard Division 2 approach centers on using S-N data as the primary basis for estimating fatigue life. The fatigue limit concept isn’t universally applicable to all materials and isn’t the primary design basis in Division 2.