shear stress, strain and modulus

The concepts of shear stress and strain concern only solid objects or materials. Buildings and tectonic plates are examples of objects that may be subjected to shear stresses. In general, these concepts do not apply to fluids. Shear deformation occurs when two opposite parallel forces of equal magnitude are applied tangentially to opposite surfaces of a solid object. Shear deformation is characterized by a gradual shift \[\Delta x\] of layers in the direction tangent to the acting forces. Shear strain is defined by the ratio of the largest displacement \[\Delta x\] to the transverse distance \[L_{o}\].

Shear stress: \[\frac{F_{\parallel}}{A}\]
Shear strain: \[\frac{\Delta x}{L_{o}}\]
Strain modulus: \[\frac{\frac{F_{\parallel}}{A}}{\frac{\Delta x}{L_{o}}}\]