Stiffness is a property that describes how resistant a material or component is to elastic deformation when subjected to a force. It is directly proportional to the modulus of elasticity and depends on geometry and material.

The mathematical expression for stiffness is:

k = F / δ


Where:

k = stiffness

F = applied force

δ = extension (change in length)

A higher stiffness value means the material requires more force to stretch or compress.