Torsional strain refers to the deformation that occurs in a material when it is subjected to a twisting force or torque. This strain is measured as the change in angle per unit length of the material. It is commonly observed in cylindrical objects, such as shafts and beams, where the applied torque causes the material to twist around its longitudinal axis. The amount of torsional strain a material can withstand before failing depends on its properties, including shear modulus and yield strength. Engineers must consider torsional strain when designing structures and mechanical components to ensure they can handle the expected loads without permanent deformation or failure.