Calculator · Structural Mechanics
Normal Strain Calculator
Engineering normal strain is the change in length divided by the ORIGINAL length. It is dimensionless, so it is usually quoted as a percentage or in microstrain — the unit strain gauges report.
Inputs
Positive lengthens, negative shortens.
Results
| Change in length ΔL | 0.6 mm |
|---|---|
| Original length L | 2000 mm |
| Normal strain ε = ΔL/L | 3.0000e-4 |
| Strain in microstrain | 300 µε |
| Strain as a percentage | 0.03 % |
Technical reference
ε = ΔL / L
1 µε = 1 × 10⁻⁶
- ΔL
- change in length, positive when the member lengthens[m]
- L
- ORIGINAL (undeformed) length[m]
- ε
- engineering normal strain[–]
This is ENGINEERING strain, referred to the original length. True (logarithmic) strain ln(1 + ε) differs appreciably only once strains become large; for metals in their elastic range the two agree to well within reading accuracy.
Strain is dimensionless. Microstrain is simply ε × 10⁶ and carries no extra physics — it exists because elastic strains in structural metals are of order 10⁻³ and smaller.
Assumptions
- · Uniform strain over the gauge length; a member with varying area or load has a strain that changes along its length.
- · Small-strain engineering definition, referred to the original length.
- · Both lengths are measured in the same direction, along the member axis.
Open in the Lab
The original length and the resulting strain carry over exactly. Area (500 mm²) and modulus (200 GPa) are placeholders strain does not depend on — edit them in the Lab.