Variable-Amplitude Fatigue Checklist
Review prompts for variable-amplitude fatigue — spectrum definition, cycle counting, mean stress treatment and sequence effects.
Purpose
For checking variable-amplitude fatigue analysis.
Spectrum
- Is the load spectrum representative of the actual service usage? — Based on measured data or standard spectrum
- Is the spectrum conservative enough without being excessively penalising? — Justify worst-case assumptions
- Is the spectrum cycle-counted using rainflow or range-pair counting? — Standard method
- Are sequence effects (high–low or low–high) assessed if significant? — Miner's rule ignores sequence
Damage Accumulation
- Is Miner's linear damage rule used with a critical damage value? — Typically D = 0.5–1.0, not always 1.0
- Is the damage sum reported for each critical location? — Not just the life
- Are below-knee stresses accounted for if the S-N curve does not have a fatigue limit? — Aluminium: no knee; steel: knee at 10⁶–10⁷