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MechanicalMay 9, 2026|3 min read

Strain

Strain is a core engineering term. Definition, usage notes, and a practical example.

Definition

Strain is the change in length divided by original length.

Why it matters

It helps identify whether a material works in the elastic or plastic region.

How it is used

In a design check, first define the relevant load, dimension, material, or flow condition. Then interpret this term by its role in the formula and compare it with limits.

Basic expression

Strain = delta L / L0

Example

A 1 m length that extends by 1 mm has strain of 0.001.

Formulas

Basic expression
Strain = delta L / L0