Hooke's Law in Uniaxial Tension or Compression

Within the linear-elastic range, normal stress is proportional to axial strain:

$$\sigma=E\varepsilon.$$

• $\sigma$ — normal stress, Pa or MPa;
• $E$ — Young's modulus, Pa or MPa;
• $\varepsilon$ — axial strain, dimensionless.

The law applies to the linear portion of the stress–strain curve while $\sigma$ and $\varepsilon$ remain proportional.