High-cycle mean-stress arithmetic

Goodman fatigue

Inputs

Declared nominal alternating stressσa,nomUser-entered high-cycle alternating stress before the declared Kf multiplier.

Declared nominal mean stressσm,nomUser-entered mean stress before the declared Kf multiplier.

Declared fatigue stress concentrationKf—User-entered fatigue concentration factor; no geometry or material inference is made.

Declared endurance limitSnUser-entered corrected endurance limit for the specific stated condition.

Declared ultimate strengthSuUser-entered ultimate tensile strength used in the Goodman denominator.

Kf-adjusted alternating stress

128

Kf-adjusted mean stress

Linear Goodman utilizationU

0.87111

—

σa = Kfσa,nom; σm = Kfσm,nom; U = σa/Sn + σm/Su

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 nominal alternating stress	80
Declared nominal mean stress	60
Declared fatigue stress concentration	1.6
Declared endurance limit	180
Declared ultimate strength	600

Kf-adjusted alternating stress	128 MPa
Kf-adjusted mean stress	96 MPa
Linear Goodman utilization	0.87111 —

σa = Kfσa,nom · σm = Kfσm,nom · U = σa/Sn + σm/Su

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 Kf-adjusted stresses and a linear Goodman utilization from nominal stresses and fatigue strengths.

σa = Kfσa,nom; σm = Kfσm,nom; U = σa/Sn + σm/Su

When

Don’t

This high-cycle linear Goodman screen does not establish a pass/fail criterion or model endurance modifiers, yield, low-cycle fatigue, multiaxial loading, reliability, life, or design approval.