Torsionslast

Torsionslast, or torsional load, is a mechanical load that causes a body to experience torque about its longitudinal axis. This type of loading induces shear stresses that vary over the cross-section and produces an angular deformation or twist. Torsionslast is common in rotating components such as shafts and axles, as well as in structures or fasteners subjected to twisting torques.

For circular shafts under pure torsion, the shear stress at a distance r from the center is tau = T r / J, where T is the applied torque and J is the polar moment of area. The maximum shear stress occurs at the outer surface (r = R). For a solid circular shaft, J = pi R^4 / 2, yielding tau_max = 2T / (pi R^3). The angle of twist per unit length is phi' = T / (G J), with G the shear modulus; the total twist over length L is phi = T L / (G J). For non-circular or hollow cross-sections, the concept remains, but J is replaced by the appropriate torsional constant, and the stress distribution becomes more complex.

In design and analysis, torsionslast is treated alongside material strength, fatigue behavior, and potential interactions with bending or axial loads. The allowable torque is limited by yield or ultimate shear strength, and by safety factors. For slender or thin-walled sections, torsional buckling can also be relevant. In practice, torsion properties (J and G) are determined experimentally or from standards, and used in calculations or numerical simulations to predict twist and stresses under load.

Measurement and testing commonly involve torsion tests that record torque and resulting angle of twist to determine material and cross-sectional properties.