Torsional

Torsional describes anything relating to torsion, the twisting of an object about its axis. The term is used across physics, engineering, chemistry, and biology to denote twisting forces, configurations, or properties.

In mechanical engineering, torsion concerns shafts and beams subjected to torque. The exterior fibers experience shear stress tau = T r / J, where T is torque, r is the radius, and J is the polar moment of inertia. The angle of twist theta = T L / (G J), where L is length and G is the shear modulus. The torsional rigidity is G J / L. Designers must limit allowable twist and shear to prevent failure, and torsion tests are used to determine material properties and behavior under twisting loads.

In materials science, torsion also relates to torsional fatigue, the wear or failure arising from cyclic torque, and to the study of how geometric and material properties influence twisting performance.

In chemistry, torsion refers to the torsion or dihedral angle between planes formed by adjacent bonds in a molecule. Torsion angles govern molecular conformation and potential energy. Rotation about a single bond is described by its dihedral angle, with common conformations such as staggered and eclipsed affecting reactivity and properties.

In biochemistry and molecular biology, torsion is relevant to DNA topology. Torsional strain from unwinding during replication and transcription can produce supercoiling, which is modulated by enzymes called topoisomerases to facilitate replication, transcription, and chromatin organization.

Measurement and units commonly involve torque in newton-meters, angles in radians, and related elastic properties derived from the shear modulus, polar moment of inertia, and geometry of the twisted element.