Very-high-cycle fatigue facture of titanium compressor disks

In the present paper there is outlined the procedure of stress state calculation for compressor disk of gas-turbine engine during flight-loading cycle (low-cycle fatigue regime – LCF) and under low-amplitude blade vibrations (very high-cycle fatigue – VHCF). The criteria and models of multiaxial fracture are studied in the case of low-cycle fatigue and in the case of very high-cycle fatigue. The model parameters are determined by using the experimental data of uniaxial fatigue tests for various asymmetry coefficients of the cycle. On the basis of the calculated stress state using multiaxial fatigue fracture criteria, the durability estimations for compressor disks are obtained for alternative mechanisms of LCF and VHCF. Two elasticity problems for circular disk are solved for confirmation of the numerical results obtained. In the first problem the centrifugal loading from the blades (analogue of LCF regime) was modeled. In the second problem loading from blade torsion (analogue of VHCF regime) was modeled. The durability estimation also shows that the fatigue fracture in LCF and VHCF regimes can take place for the same period of real time.