STRESS & FATIGUE
Estimate fatigue safety factor from tensile mean stress, alternating stress and a corrected endurance limit.
Values are calculated locally in your browser.
Theoretical result · verify applicability below
Schematic illustration · not to scale
Fatigue check only: peak-stress yielding must be checked separately with yield strength.
The modified Goodman line connects the corrected endurance limit on the alternating-stress axis to ultimate tensile strength on the mean-stress axis. The safety factor scales both mean and alternating stress along the current loading ray. The plotted point moves as you change the stresses.
For σa = 100 MPa, σm = 50 MPa, Se = 200 MPa and Sut = 500 MPa, utilization = 0.6 and n = 1.667. This does not establish safety against first-cycle yielding.
The initial inputs reproduce this example. Material values are illustrative inputs, not a material database or certified design values.
Uniaxial constant-amplitude high-cycle loading with nonnegative tensile mean stress. Supply an endurance limit corrected for surface finish, size, reliability, temperature and other relevant effects. Compressive mean stress, multiaxial effects, finite-life damage and yielding require separate methods.
No factor of safety or design-code allowance is applied unless explicitly stated. Read the engineering disclaimer before applying these results.
Confirm the load direction and units first. Check the schematic against your actual supports and geometry, then compare the worked example with your own independent calculation. A valid numerical result does not establish that the model is appropriate for a real component.
For background, consult the Air Force Stress Analysis Manual’s column analysis and MIT’s Mechanics of Materials learning modules. Use applicable design standards and certified material data for real designs.