Parts break from repeated loading far below their breaking strength. The S-N curve predicts how many cycles a component survives — the physics of metal fatigue.
Fatigue (S-N Curve)Live
failure under cyclic load
Controls
Presets
Repeated loading well below the ultimate strength can still break a part — metal fatigue. The S-N curve plots stress amplitude against cycles to failure. Steels have an endurance limit: below it they last essentially forever, but aluminum has none and eventually fails at any stress. Cause of many catastrophic aircraft and bridge failures.
★ Sign in to save this setupSave your tuned setup, or drop this simulation into your own site, docs, or course page.
How it works
Cyclic stress accumulates microscopic damage until a crack grows and the part fails, even well below the ultimate strength. The S-N curve plots stress amplitude against cycles to failure. Steels have an endurance limit below which life is effectively infinite; aluminum and other non-ferrous metals have none. Fatigue caused many historic aircraft and bridge disasters.
✦
Ask the AI about this model
The math, the assumptions, real-world uses, or a code translation — explained for this exact simulation.
Is this fatigue S-N curve calculator tool really free?▾
Yes. Fatigue (S-N Curve) runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?▾
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?▾
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?▾
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.