Design and structural engineering

Fatigue of welded joints

Fatigue is progressive crack initiation and growth under cyclic loading. A weld may have substantial static reserve and still fail at its toe or root when detail classification, load spectrum and production quality are not aligned.

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Topic overview

Fatigue is progressive crack initiation and growth under cyclic loading. A weld may have substantial static reserve and still fail at its toe or root when detail classification, load spectrum and production quality are not aligned.

Does the manufactured detail match the fatigue category used in design, including profile, root, terminations and any post-weld improvement?

Stress range and number of repetitions matter—not only a one-off maximum.

Fatigue is often governed by local toe, root or attachment-end geometry.

What the module covers

  • Fatigue-loaded welds
  • 1. Fatigue is a detail problem
  • 2. Crack initiation locations
  • 3. Assessment sequence
  • 4. Improving fatigue resistance
  • Fatigue-production checklist
  • Practical rule
Educational content does not replace current standards, approved WPS/WPQR documentation or decisions by competent welding coordination personnel.