What occurs when a material experiences torsion?

When a material experiences torsion, it is subjected to a twisting force or torque about its longitudinal axis. This results in the material twisting in a helical manner. The internal structure of the material attempts to resist this twisting action, leading to shear stress being generated across the cross-section. The material's response to this torsional loading is characterized by changes in shape rather than size. Because of the nature of torsion, the primary effect is the twisting action itself, which can lead to different degrees of deformation depending on the material properties, geometry, and the magnitude of the applied torque.

This twisting can affect the material's strength and performance, especially if the torsion exceeds its yield strength, potentially leading to permanent deformation or failure. However, the key takeaway is that torsion specifically refers to the twisting motion that the material undergoes under such conditions, making it the correct choice in this context.