What Is the Goodman & Söderberg Fatigue Factor of Safety Calculator?
Tensile mean stress accelerates fatigue crack initiation and reduces cyclic endurance, while compressive mean stress is beneficial.
Fatigue failure diagrams plot alternating stress σa on the vertical axis against mean stress σm on the horizontal axis.
How Does the Goodman & Söderberg Fatigue Factor of Safety Calculator Work?
The Modified Goodman relation connects the fatigue limit Se to the ultimate tensile strength Sut via a straight line.
Söderberg uses yield strength Sy, providing a conservative lower bound that guards against both fatigue and gross yielding.
Goodman & Söderberg Fatigue Factor of Safety Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Modified Goodman and Söderberg fatigue failure criteria for fluctuating stresses.
How to Use the Goodman & Söderberg Fatigue Factor of Safety Calculator
- Input alternating stress, mean stress, yield strength, UTS, and endurance limit.
- Review Goodman, Söderberg, Gerber, and static yield factors of safety.
Step-by-Step Example Calculation
Drive Shaft Alternating Bending with Mean Torque
Input Values:
Understanding Your Result
n ≥ 1.0 indicates infinite fatigue life predicted.
n < 1.0 predicts finite life failure.
Factors That Affect the Result
- Surface finish, size factor, and corrosion pitting degrade endurance limit Se significantly.
When Should You Use This Calculator?
- Mechanical shaft design, pressure vessel cyclic stress verification, connecting rod sizing, and gear tooth fatigue.
Assumptions & Limitations
- Applies to ductile metals under proportional uniaxial or equivalent von Mises multiaxial loading.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard Shigley / ASME mechanical design methodology.