Shear strain

Shear strain is a strain that acts parallel to the face of a material that it is acting on. Normal strain acts perpendicular to the face of that it is acting on. There are two ways to interpret shear strain: the average shear strain and the engineering shear strain. The variable used to denote average shear strain is $epsilon\; ,$ while $gamma\; ,$ denotes engineering shear strain.

Consider an infinitesimal rectangle in the xy plane subject to shear strain. The rectangle becomes a parallelogram where $alpha\; ,$ is the displacement from the y axis in the x direction and $delta\; ,$ is the displacement from the x axis in the y direction. The average shear strain is

:$epsilon\_\{xy\}\; =\; 0.5\; (alpha\; +\; delta\; )\; =\; epsilon\_\{yx\}\; ,$

Definition of engineering shear strain

:$gamma\; =\; epsilon\_\{xy\}\; +\; epsilon\_\{yx\}\; =\; 2\; epsilon\_\{xy\}\; ,$:

where:$heta\; ,$ is the angle before deformation and : is the angle at that same point after deformation.

Therefore $gamma\; ,$ describes the total deformation.

See also

* Shear modulus
* Moiré pattern (the Moiré effect can be used to measure strain)
* Shear stress
* Shear strength