Shearing Stress State

When a material is subjected to external forces, it develops internal resistance called stress. Stress can be normal (perpendicular to the surface) or tangential (parallel to the surface). Tangential stress is also known as shearing stress.

Simple Shear Definition

A material is said to be in a state of simple shear when it is subjected only to shearing stress, and there are no normal stresses acting on the same planes. This is a specific type of deformation where layers of the material slide past each other without changing volume significantly under ideal conditions.

Consider a block fixed at its base. If a tangential force is applied to the top surface, causing it to deform by shearing without any force pushing down or pulling up (normal stress), this is a state of simple shear.

Comparing Options

• Bending Shear: This occurs in beams subjected to bending loads. While shearing stresses are present, normal stresses (due to bending) are also simultaneously present and vary across the beam's cross-section. It's not *only* shearing stress.
• Simple Shear: This is the state where *only* shearing stress exists on the planes being considered, with no normal stress on those planes. This directly matches the condition given in the question.
• Maximum Shear: This refers to the maximum value of shearing stress that occurs in a material under a given loading condition. It's a magnitude, not necessarily a specific state defined by *only* shearing stress (a material might have maximum shear stress occurring alongside normal stresses).
• Torsional Force: This is a type of force (or torque) that causes twisting in a member. Torsion induces shearing stresses within the material, but the term "torsional force" itself describes the cause (the load), not the resulting state of stress within the material. While pure torsion can lead to a state of pure shear (a specific case closely related to simple shear) in some geometries, the question asks about the *state* of the material when subjected to *only* shearing stress, which is most accurately described as simple shear.

Conclusion

Based on the definitions, when a material experiences only shearing stress without accompanying normal stress on the relevant planes, it is in a state of simple shear. This state isolates the effect of tangential forces causing deformation by sliding.