Kf and effective-stress screen

Fatigue stress concentration

Inputs

Declared theoretical stress concentrationKt—User-entered elastic geometric stress-concentration factor; this workspace does not select it.

Declared notch sensitivityq—User-entered fatigue notch sensitivity from 0 through 1.

Declared nominal stressσnomOptional nominal stress to display the direct Kf-adjusted effective stress.

1.9

—

Kf-adjusted nominal stress

228

Kf = 1 + q(Kt − 1); σeffective = Kfσnom

A first-pass number, not a code check, certification, or approval. Read the method and its limits below. What this is and is not.

Calculation snapshot

Formula version 1.0.0

Declared theoretical stress concentration	2.2
Declared notch sensitivity	0.75
Declared nominal stress	120

Fatigue stress concentration	1.9 —
Kf-adjusted nominal stress	228 MPa

Kf = 1 + q(Kt − 1) · σeffective = Kfσnom

University of Illinois MechRef fatigue theory: https://www.mechref.org/mf/Fatigue/?origin=coursemenu

This printout is a record of displayed inputs and deterministic formula output. It is not an approval, certification, or engineering conclusion.

Method

Calculate fatigue stress concentration and an optional effective stress from Kt, notch sensitivity, and nominal stress.

Kf = 1 + q(Kt − 1); σeffective = Kfσnom

When

Don’t

This direct Kf relation uses user-entered Kt and notch sensitivity. It does not derive geometry, material behavior, fatigue strength, allowable stress, safety factor, life, or design approval.