SHEAR STRESS Meaning and
Definition
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Shear stress refers to the force per unit area that acts parallel to a surface, causing one layer of a solid or fluid substance to move relative to an adjacent layer of the same substance. It is commonly denoted by the Greek letter "tau" (τ) and is typically expressed in units of force per unit area (such as pascals or newtons per square meter).
In a solid material, shear stress occurs when external forces are applied in opposite or tangential directions to different portions of the material. This results in the deformation and displacement of one layer of the material relative to another. Shear stress can cause the material to undergo shearing, twisting, bending, or torsional motion. The magnitude of the shear stress depends on the applied force, the area over which it is distributed, and the resistance of the material to deformation, known as its shear modulus.
In a fluid, shear stress arises due to the frictional forces between layers of the liquid or gas as they move relative to each other. This phenomenon is known as viscosity. Shear stress in a fluid is responsible for the development of velocity gradients known as shear rates, with faster moving layers of the fluid near a surface experiencing higher shear stresses compared to slower-moving layers.
Understanding shear stress is crucial in various engineering fields, such as civil engineering, mechanical engineering, and material science. It is crucial for analyzing the behavior and stability of structures, designing and evaluating materials, and predicting how fluids flow and deform in pipes, channels, and other systems.
Etymology of SHEAR STRESS
The word "shear" comes from the Old English word "scearian", which means to cut or sever. It has Germanic roots and is related to the Middle High German "scheren" and Old Norse "skera". The term "stress" is derived from the Old French word "estrece", meaning narrowness, oppression, or affliction. It traces back to the Latin word "strictus", which means tight or drawn. In the context of engineering and physics, "shear stress" refers to the force or stress that acts parallel to the face of a material, causing it to deform or shear.
