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Uniform Tensile True & Engineering Stress–Strain

Convert positive engineering and true strain, with a constant-volume uniform tensile stress conversion.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Formula and method

Engineering strain 0.1 means 10% elongation and gives true strain ln(1.1), approximately 0.09531. Engineering stress of 100 Pa then gives true stress of 110 Pa under the constant-volume assumption.

True strain = ln(1 + engineering strain); true stress = engineering stress × (1 + engineering strain)

Worked example

Enter these known values and leave the other values blank.

Engineering tensile strain ratio
1
Engineering tensile stress
100 Pa
True logarithmic tensile strain
0.6931
True tensile stress
200 Pa

Assumptions and limitations

  • This retained model accepts strictly positive tensile strain and stress. Zero strain and compression are outside its input domain. Enter dimensionless strain as a ratio: 0.1 means 10%, not 10.
  • The stress conversion assumes uniform deformation and constant volume, typically used as a plastic-deformation approximation. It is not a general correction for localized necking.
  • Engineering stress uses original area; true stress uses instantaneous area. After necking, local geometry is needed. These relationships do not supply a material law, yield stress or fracture prediction.

Common questions

Should I enter 10 or 0.1 for ten percent elongation?

Enter 0.1. The strain fields use dimensionless ratios rather than percentage points.

Can these equations convert an entire tensile test past necking?

The uniform stress conversion cannot reliably do that by itself. Once strain localizes, current local area and the relevant stress state must be considered.

References

Pounds-force per square inch use the exact international pound and inch with standard gravity, replacing the rounded captured factor.

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