this is the typical frequency in Europe. In North America, the frequency is 60 Hz. The angular frequency can be calculated with the following formula: The torque carried by the shaft is related to the power by the following equation: The angular frequency is therefore 314.16 rad/s and the torque 3.1831 × 106 N·m. The maximal torque is: After substitution of the torsion constant, the following expression is obtained: The diameter is 40 cm. If one adds a factor of safety of 5 and re-calculates the radius with the maximum stress equal to the yield stress/5, the result is a diameter of 69 cm, the approximate size of a turboset shaft in a nuclear power plant. Failure mode The shear stress in the shaft may be resolved into principal stresses via Mohr's circle. If the shaft is loaded only in torsion, then one of the principal stresses will be in tension and the other in compression. These stresses are oriented at a 45-degree helical angle around the shaft. If the shaft is made of brittle material, then the shaft will fail by a crack initiating at the surface and propagating through to the core of the shaft, fracturing in a 45-degree angle helical shape. This is often demonstrated by twisting a piece of blackboard chalk between one's fingers. In the case of thin hollow shafts, a twisting buckling mode can result from excessive torsional load, with wrinkles forming at 45° to the shaft axis. See also List of area moments of inertia Saint-Venant's theorem Second moment of area Structural rigidity Torque tester Torsion siege engine Torsion spring or -bar Torsional vibration References External links Mechanics Torque Moment (physics)