Cyclic Load Weld Fatigue Life Estimator Calculator

Estimate fatigue life of welded joints under cyclic loading using S-N curve approach per AWS D1.1 and AISC Appendix 3

Input Parameters

Results

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Allowable Cycles (N)
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Demand Cycles
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Estimated Life
years
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Fatigue Utilization
%
Note: Uses constant amplitude S-N curves. For variable amplitude loading, apply Miner's cumulative damage rule. Stress range below FTH threshold indicates infinite life (no fatigue damage accumulation).

Reference

AWS D1.1 / AISC 360 Appendix 3 - S-N Curve Approach N = Cf / Sr^3 (number of cycles to failure) Cf = detail category constant Sr = applied stress range FTH = constant amplitude fatigue threshold Below FTH: theoretically infinite fatigue life Miner's rule for variable amplitude: Sum(ni/Ni) <= 1.0