Definition - What does Shear mean?

Shear is a type of strain produced by pressure in the structure of a substance, when its layers are laterally shifted in relation to each other.

In engineering, the strength of a material or component depends on the type of yield or structural failure where the material or component fails in shear. A shear load is a force that tends to produce a sliding failure on a material along a plane that is parallel to the direction of the force.

Corrosionpedia explains Shear

When a material is subjected to forces which cause it to twist or one face to slide relative to another, this material is said to be in shear. Compared to tensile and compressive stress and strain, the shear forces act over an area which is in line with the forces.

There is an imaginary point on a section is known as the shear center (also known as the elastic axis or torsional axis), where shear forces can be applied without inducing any torsion. In general, the shear center is not the centroid. For cross-sectional areas having one axis of symmetry, the shear center is located on the axis of symmetry. For those having two axes of symmetry, the shear center lies on the centroid of the cross-section.

In some materials such as metals, plastics, or granular materials like sand or soils, a shearing motion rapidly localizes into a narrow band, known as a shear band. When that happens, all the sliding occurs within the band while the blocks of material on either side of the band simply slide past one another without internal deformation. A special case of shear localization occurs in brittle materials when they fracture along a narrow band. Then, all subsequent shearing occurs within the fracture.

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