Damage and Fatigue Fracture of Structural Elements in Various Cyclic Loading Modes.

On the basis of the previously suggested multimode two-criterion model of fatigue fracture, a method is proposed for calculating the origin and development of narrow localized damage zones in structural elements for various modes of cyclic loading. Such narrow zones of damage can be considered as quasi-cracks of two types, corresponding to the mechanism of normal opening and shear fracture. We consider an important example of a flight loading cycle (high-cycle fatigue) and high-frequency cyclic loading during torsion-bending vibrations of the blades (very-high-cycle fatigue) of an aircraft gas turbine engine compressor disk. The durability of this element of aircraft structures is assessed. An example of calculating fatigue fracture at high-frequency torsional vibrations of an experimental sample of a certain shape is also considered. For this sample it was possible to reproduce the observed effect of a sharp change in the growth direction and the type of quasi-crack during cyclic loading. [ABSTRACT FROM AUTHOR]