Pure shear

In mechanics and geology, pure shear is a three-dimensional homogeneous flattening of a body. It is an example of irrotational strain in which a body is elongated in one direction while being shortened perpendicularly. For soft materials, such as rubber, a strain state of pure shear is often used for characterizing hyperelastic and fracture mechanical behavior. A rod under torsion is a practical example for a body under pure shear.

Pure shear stress, denoted ${\displaystyle \tau }$, is related to pure shear strain, denoted ${\displaystyle \gamma }$, by the following equation:

${\displaystyle \tau =\gamma G\,}$

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