The stressed and deformed states of the shaft are calculated by the methods of resistance of materials. So, the deformed state is described by the Mohr method, and the disclosure of static indeterminacy is performed by the force method. Static strength is evaluated by equivalent stresses obtained by the energy method. Dynamic characteristics such as natural frequencies and natural shapes are determined by the method of initial parameters.

The calculation of fatigue strength is reduced to finding the safety factor in the current section along the length of the shaft, both at a constant external load and in the case when the law of its change with time is known.