About The Fatigue Life Estimator

The Fatigue Life Estimator uses two S-N curve points and an optional Goodman mean-stress correction to estimate cycle life at an alternating stress.

How to Use the Fatigue Life Estimator Online

1. Enter two stress-life points from material or test data.
2. Enter alternating stress, mean stress, and ultimate tensile strength.
3. Run the estimator to review corrected stress, Basquin exponent, life estimate, and fatigue regime.

Choosing Options Correctly

Use material-specific S-N data with matching surface finish, environment, loading mode, and reliability assumptions. Notches, size effects, residual stress, corrosion, variable amplitude loading, and safety factors are not fully modeled.

Common Use Cases

• Make preliminary cycle-life estimates.
• Compare mean-stress assumptions with Goodman correction.
• Screen whether stress sits in finite-life or high-cycle regions.

Quick FAQ

Is this a fatigue design certification?
No. It is a simplified estimate and does not replace material test data, code rules, finite-life design, or durability validation.

Why do two S-N points matter?
They define the approximate slope of the S-N curve used for interpolation or extrapolation. Poor points produce poor life estimates.

What effects are not included?
Mean stress, stress concentration, surface finish, size, corrosion, temperature, residual stress, spectrum loading, and reliability factors may need separate treatment.

Can I use it for final product release?
Use it for screening only, then verify with tested material data, load spectrum, safety factor, and physical validation where required.