Definition of the damage ratio in case of incremental loading of machines parts
Many parts and assemblies of the drilling equipment operate in different modes, and the operating loads vary with time. The magnitude of the stresses is usually below the endurance limit, but in some operating modes of stresses, assemblies and machine parts it can be higher than the endurance limit. However, the formation of damages of the machines details is associated with the stress spectra, the level of which is lower than the endurance limit.