continuum mechanics Continuum mechanics is a branch of mechanics that deals with the deformation of and transmission of forces through materials modeled as a ''continuous medium'' (also called a ''continuum'') rather than as discrete particles. Continuum mec ...

, shearing refers to the occurrence of a shear strain, which is a deformation of a material substance in which parallel internal surfaces slide past one another. It is induced by a

shear stress Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross secti ...

in the material. Shear strain is distinguished from volumetric strain. The change in a material's volume in response to stress and change of angle is called the angle of shear.

Overview

Often, the verb ''shearing'' refers more specifically to a mechanical process that causes a

plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...

shear strain in a material, rather than causing a merely

elastic Elastic is a word often used to describe or identify certain types of elastomer, Elastic (notion), elastic used in garments or stretch fabric, stretchable fabrics. Elastic may also refer to: Alternative name * Rubber band, ring-shaped band of rub ...

one. A plastic shear strain is a continuous (non-fracturing) deformation that is irreversible, such that the material does not recover its original shape. It occurs when the material is yielding. The process of shearing a material may induce a volumetric strain along with the shear strain. In

soil mechanics Soil mechanics is a branch of soil physics and applied mechanics that describes the behavior of soils. It differs from fluid mechanics and solid mechanics in the sense that soils consist of a heterogeneous mixture of fluids (usually air and ...

, the volumetric strain associated with shearing is known as Reynolds' dilation if it increases the volume, or compaction if it decreases the volume. The shear center (also known as the torsional axis) is an imaginary point on a section, where a shear force 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

metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...

s, plastics, or

granular material A granular material is a conglomeration of discrete solid, macroscopic scale, macroscopic particles characterized by a loss of energy whenever the particles interact (the most common example would be friction when granulation, grains collide). T ...

s like

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

s, the shearing motion rapidly localizes into a narrow band, known as a '' shear band''. In that case, 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 A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. ...

materials when they

fracture Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress (mechanics), stress. The fracture of a solid usually occurs due to the development of certain displacemen ...

along a narrow band. Then, all subsequent shearing occurs within the fracture.

Plate tectonics Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

, where the plates of the Earth's crust slide along fracture zones, is an example of this. Shearing in soil mechanics is measured with a

triaxial shear test In materials science, a triaxial shear test is a common method to measure the mechanical properties of many Deformation (engineering), deformable solids, especially soil (e.g., sand, clay) and Rock (geology), rock, and other granular materials or ...

or a direct shear test.

Overview

See also

Further reading