Drejningsspænding

Drejningsspænding, also known as torsional stress, is a type of stress that occurs in a material when it is subjected to a twisting force. This force, called a torque, tends to rotate one part of the object relative to another. When a material experiences drejningsspænding, internal forces develop within it that resist this rotation.

The magnitude of drejningsspænding depends on several factors, including the amount of torque applied, the geometry of the object, and the material's properties. For a cylindrical object, the stress is greatest at the outer surface and decreases linearly towards the center. The formula for maximum shear stress in a solid cylinder is given by the torque multiplied by the radius, divided by the polar moment of inertia.

Drejningsspænding can lead to deformation, where the object twists by a certain angle. This angle of twist is also dependent on the torque, the length of the object, the material's shear modulus, and the polar moment of inertia. If the applied torque exceeds the material's yield strength, permanent deformation or failure, such as fracture, can occur.

Understanding and calculating drejningsspænding is crucial in engineering design, particularly for components like shafts, axles, and screws, which are often subjected to twisting loads. Proper material selection and geometric design are essential to ensure these components can withstand the expected drejningsspænding without failing.