In mechanical engineering, many terms are associated into pairs called duals. A dual of a relationship is formed by interchanging force (stress) and deformation (strain) in an expression.

Here is a partial list of mechanical dualities:

• force — deformation
• stress — strain
• stiffness method — flexibility method

• stress and strain (Hooke's law.)

${\displaystyle \sigma =E\varepsilon \iff \varepsilon ={\frac {1}{E}}\sigma \,}$

• Duality (electrical circuits)
• Hydraulic analogy
• List of dualities
• Mechanical–electrical analogies
• Series and parallel springs

• Fung, Y. C., A First Course in CONTINUUM MECHANICS, 2nd edition, Prentice-Hall, Inc. 1977