Do I need to install anything?

No. It runs in any modern browser, free, with no account required.

For Educators · Fatigue (S-N)

Fatigue (S-N) for a foam cushion

Built for educators teaching it to a class. Drop a live demo into a lecture or assign it as a shareable link — no lab installs. Simulate a foam cushion live below — adjust the inputs and watch it respond, right in your browser.

Fatigue (S-N Curve)Live

failure under cyclic load

Controls

Presets

Ultimate strength (MPa)

Stress amplitude (MPa)

Ferrous (has endurance limit)

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.

▶ Run in Python

Data Inspector

Endurance limit250 MPa

Cycles to failure1.17e+5

Verdictfinite life

Governing equation

N = (\frac{σ _{a}}{σ _{f}^{'}})^{1/ b}, σ_{a} = 300 MPa \Rightarrow N = 1.17 e + 5 cycles

Reading this result: At 300 MPa the part fails after about 1.2e+5 cycles. Drop below the 250 MPa endurance limit to reach infinite life.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

or unlock everything with Pro →

Also for:Students Researchers Engineers Hobbyists & Makers K-12 Students First Responders General version →

More with Fatigue (S-N)

Fatigue (S-N) for a steel beam Fatigue (S-N) for an aluminum frame Fatigue (S-N) for a concrete mix Fatigue (S-N) for a carbon-fiber panel Fatigue (S-N) for a rubber seal Fatigue (S-N) for a glass pane Fatigue (S-N) for a copper wire Fatigue (S-N) for a titanium implant

Frequently asked questions

Is this good for educators?: Yes — this version of "Fatigue (S-N) for a foam cushion" is framed for educators teaching it to a class. Drop a live demo into a lecture or assign it as a shareable link — no lab installs.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.