True Stress and True Strain Calculator: Convert Engineering Values from a Tensile Test
Engineering and true stress and strain.
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How this calculator works
Choose which way to convert.
Enter the stress and the strain.
The calculator gives the converted values.
Formulas used
- \sigma_t = \sigma(1 + e)
- \epsilon_t = \ln(1 + e)
- e = e^{\epsilon_t} - 1
Worked example
With the default numbers in the calculator above:
- True stress: 330 MPa
- True strain: 9.531 %
Change the numbers in the calculator to see the full working, every step, for your own case.
A second worked example
A different case, with these numbers: What do you want to do? True values to engineering values.
- Engineering strain: 10 %
- Engineering stress: 300 MPa
Common questions
What is the difference between true and engineering stress?
Engineering stress uses the original area. True stress uses the actual area at that instant, which gets smaller as the bar stretches.
When are the formulas valid?
Up to the start of necking, because they assume the strain is the same along the whole bar.
Why use true strain?
True strains add up correctly over a series of steps, and plastic flow follows them.
Related calculators
Got a question about this? Ask an engineering question and get a plain-language answer with references.
Further reading: Any materials or strength of materials text (true stress and true strain).
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