What Is the Basquin High-Cycle Fatigue Life Calculator?
O.H. Basquin proposed in 1910 that high-cycle fatigue test data forms a linear relationship on a log-log plot of stress versus cycles to failure.
It applies whenever macro-scale plastic deformation is negligible and stress remains below monotonic yield.
How Does the Basquin High-Cycle Fatigue Life Calculator Work?
The fatigue strength coefficient σf’ represents the stress intercept at 1 reversal (2Nf = 1).
The negative exponent b dictates the slope; steeper slopes indicate materials that tolerate stress increases more poorly.
Basquin High-Cycle Fatigue Life Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Basquin empirical power-law for high-cycle fatigue life.
How to Use the Basquin High-Cycle Fatigue Life Calculator
- Input stress amplitude, fatigue strength coefficient, and Basquin exponent b.
- Check predicted cycles to failure Nf, reversals, and log10(Nf).
Step-by-Step Example Calculation
High-Strength Steel Crankshaft
Input Values:
Understanding Your Result
For steels, if stress is below the endurance limit, life is practically infinite (>10⁷ cycles).
Factors That Affect the Result
- Surface treatments like shot peening impart compressive residual stresses that dramatically extend Basquin life.
When Should You Use This Calculator?
- Automotive engine rotating parts, transmission gears, bridge girders, and turbine blades in HCF.
Assumptions & Limitations
- Valid only in the elastic high-cycle fatigue regime (Nf > 10⁴ cycles).
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard ASTM E739 statistical analysis of linear fatigue S-N data.