torsjonen

Torsjonen, often translated as torsion, is a concept used across several disciplines to describe twisting around an axis caused by a twisting force or torque. In general usage it denotes the state or process of twisting, bending, or winding something so that its orientation changes relative to its original position.

In engineering and materials science, torsion refers to the deformation of an object when it is twisted about its longitudinal axis. The torque applied, T, produces a twist angle φ over a length L. For many shafts with circular cross-sections, the relationship is described by φ = TL/(GJ), where G is the shear modulus and J is the polar moment of area. Torsional stiffness is often expressed as GJ/L. Torsion tests measure shear properties and assess fatigue and failure modes, which typically occur due to shear stresses on cross sections.

In mathematics and theoretical physics, torsion has different meanings. In group theory, a torsion element is one with finite order. In differential geometry and gravitation, torsion refers to the torsion tensor associated with a connection, capturing a twisting of space-time that is distinct from curvature. Some theories of gravity extend general relativity to include torsion as a geometric property of space-time.

In biology and medicine, torsion describes the twisting of tissues or organs. Examples include testicular torsion and ovarian torsion, conditions that can compromise blood supply and require urgent attention.

The term derives from Latin torquere, to twist, and appears in many languages to denote twisting or torsion in various scientific contexts. See also torque, twist, and torsion tensor.