Shear stress and bearing stress are two different types of stresses that occur in materials and structures, and they are characterized by the way the forces act on the material.
Shear Stress: Shear stress is a stress that occurs when two forces act parallel to each other but in opposite directions, trying to slide one part of a material relative to another along a plane. It is a measure of the intensity of the internal forces within the material that resist the sliding. Shear stress is typically denoted by the Greek letter tau (τ) and is expressed in force per unit area (N/m^2 or Pa). It is commonly encountered in applications like cutting, bending, or when a structure is subject to lateral forces.
Bearing Stress: Bearing stress, also known as contact stress, occurs when two objects are in contact with each other, and a force is applied perpendicular to the surface of contact. Bearing stress is the pressure that develops at the point of contact between the two objects. It is a measure of how much force is distributed over the area of contact between the objects. Bearing stress is expressed in force per unit area (N/m^2 or Pa) as well.
The key difference between shear stress and bearing stress lies in the direction of the forces they resist:
- Shear stress resists forces applied parallel to the material's surface, trying to slide one part of the material relative to another along a plane.
- Bearing stress resists forces applied perpendicular to the material's surface, where two objects are in contact.
To illustrate the difference, imagine a bolt connecting two metal plates. When a force is applied to the bolt head to compress the plates together, the bolt experiences a bearing stress where it contacts the plates. On the other hand, if a force is applied laterally to try to slide the plates relative to each other, the bolt experiences a shear stress along its shank.