What is the Difference Between Deformation and Strain?

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The difference between deformation and strain lies in their definitions and how they are measured:

  • Deformation refers to the change in shape or size of an object due to the forces and pressure applied on it. It can be described as elastic deformation, which is temporary and reversible, or plastic deformation, which is permanent and irreversible. Deformation can be expressed in various units and is a general term that applies to any change of shape of an elastic material.
  • Strain is the force created by the elasticity of an object, and it measures the ratio between the deformation and the original length. Strain is a unitless quantity and can be classified into two types: normal strain and shear strain. Normal strain occurs when a force acts perpendicular to the surface of an object, while shear strain occurs when a force acts parallel to the surface of an object. Strain is a precise and quantifiable measurement of the change in length per unit length.

In summary, deformation refers to the actual change in shape or size of an object, while strain is a measure of the relative change in length or size of the object due to applied forces.

Comparative Table: Deformation vs Strain

Here is a table comparing deformation and strain:

Property Deformation Strain
Definition Deformation refers to the actual change in the shape or size of a material. Strain is the force created by the elasticity of an object, quantifying the change in shape or size of a material relative to its original dimensions.
Unit of Measurement Deformation is typically expressed in units like meter (m) or inch (in). Strain is a dimensionless quantity, often given units of in/in or ft/ft, and sometimes expressed as a percentage.
Cause Deformation is caused by external forces acting on a material. Strain is caused by the deformation of a material in response to stress.
Effect Deformation is the change in shape or size of a material. Strain is a measure of the deformation that a material undergoes in response to stress.

In summary, deformation refers to the actual change in the shape or size of a material, while strain quantifies this change in a specific way relative to the material's original dimensions.