Yield Strength Calculator Formula
Understand the math behind the yield strength calculator. Each variable explained with a worked example.
Formulas Used
Yield Strength (0.2% offset)
yield_strength = yield_load / areaYield Strength
yield_ksi = yield_load / area * 0.145038Variables
| Variable | Description | Default |
|---|---|---|
yield_load | Load at 0.2% Offset (F)(N) | 30000 |
area | Original Cross-Sectional Area (A)(mm²) | 78.54 |
How It Works
Yield Strength (0.2% Offset Method)
Yield strength marks the transition from elastic to plastic deformation. Since many materials do not have a sharp yield point, the 0.2% offset method draws a line parallel to the elastic region, offset by 0.2% strain, and the intersection with the stress-strain curve defines yield.
Formula
sigma_y = F_yield / A_0
where F_yield is the load at the 0.2% offset intersection and A_0 is the original cross-sectional area.
Worked Example
A 10 mm diameter aluminum specimen yields at 30 kN using the 0.2% offset method.
- 01Area = pi × 5² = 78.54 mm²
- 02sigma_y = 30000 / 78.54 = 382.0 MPa
- 03In ksi: 382.0 × 0.145 = 55.4 ksi
Frequently Asked Questions
Why use 0.2% offset instead of the exact yield point?
Many metals (especially aluminum and austenitic stainless steel) exhibit a gradual transition from elastic to plastic behavior with no sharp yield point. The 0.2% offset provides a consistent, repeatable way to define yield for all materials.
What is proof stress?
Proof stress is another name for the offset yield strength. In some standards, 0.1% or 0.5% offset values are used instead of 0.2%, depending on the material and application.
How is yield strength used in design?
Engineers apply a factor of safety (typically 1.5-3) to the yield strength to determine allowable stress. The design must keep working stresses below this allowable level to prevent permanent deformation.
Learn More
Guide
Material Strength Guide: Understanding Yield, Tensile, and Fatigue
Learn the key material strength properties every engineer needs to know. Covers yield strength, ultimate tensile strength, fatigue, hardness, ductility, and how to select materials for engineering applications.
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