Which of the following is NOT a type of stress?

The correct choice is that expansion is not classified as a type of stress in the context of materials and structural engineering. Instead, stress is fundamentally defined as the internal resistance offered by a material to deformation and is typically categorized into specific types based on how the load is applied.

Shear stress pertains to forces that cause parts of a material to slide past one another, often analyzed in the context of beams or materials subjected to twisting. Tension stress occurs when a material is pulled apart, causing elongation. Compression stress is the opposite, where a material is subjected to forces that push its molecules together, resulting in shortening or deformation.

Expansion, while it may occur as a result of thermal effects or physical changes in a material, does not fit the conventional classification of stress types like shear, tension, or compression. Instead, expansion refers to the physical change in dimensions or state of a material, driven by factors like temperature changes or phase transitions, rather than an internal resistance to deformation induced by an external load.