Which factor contributes to fatigue-prone details?

• A. Type of detail
• B. Weld quality
• C. All of the above
• D. Quality of fabricated detail

Answer: (C)

Fatigue-prone details come from a combination of geometry and manufacturing quality. The type of detail matters because some configurations naturally create higher stress concentrations—sharp corners, notches, holes near a load path, or abrupt changes in cross-section act as initiation points for fatigue cracks under cyclic loading. Weld quality is crucial since defects in a weld, like lack of fusion, porosity, cracks, or undercut, provide easy sites for cracks to start and propagate through repeated loading. The overall quality of the fabricated detail also influences fatigue life; precise fit-up, good workmanship, and controlled residual stresses reduce additional stress risers that can shorten the life under cycling.

Because each of these factors can worsen fatigue susceptibility, all of the above contribute to fatigue-prone details.