Strain

Definition

Strain is the measure of deformation representing the displacement between particles in a material body. It is dimensionless and often expressed as a ratio of change in length to original length.

5 Must Know Facts For Your Next Test

1. Strain is calculated using the formula $\text{strain} = \frac{\Delta L}{L_0}$, where $\Delta L$ is the change in length and $L_0$ is the original length.
2. There are two main types of strain: normal strain and shear strain. Normal strain occurs due to changes in length, while shear strain results from angular distortion.
3. Strain can be positive (tensile) or negative (compressive), depending on whether the material is being stretched or compressed.
4. The unit of strain is dimensionless because it represents a ratio of lengths.
5. Hooke's Law relates stress and strain through the equation $\sigma = E \epsilon$, where $\sigma$ is stress, $E$ is Young's modulus, and $\epsilon$ is strain.

Review Questions

• What formula is used to calculate strain?
• Differentiate between normal strain and shear strain.
• In what units is strain measured?

Related terms

Stress:

Stress is the force applied per unit area within materials that arises from externally applied forces, temperature changes, or other factors.

Young's Modulus: Young's Modulus (E) measures a material's ability to withstand changes in length when under lengthwise tension or compression.

Elastic Limit:

The elastic limit is the maximum extent to which a material can be deformed without undergoing permanent deformation.