Numerical Simulation of Fatigue Fracture of the Turbine Disc

This paper presents the results of the crack propagation analysis of an aircraft engine turbine disc. In the first part of the work the finite element method was used for calculation of the stress state and the stress intensity factor (SIF, K_I, K-factor) in the turbine disc with an embedded quarter-elliptical corner crack, subjected to low-cycle thermo-mechanical fatigue. To refine the K-factor calculation, specially degenerated finite elements were used. These elements provide stress singularity suitable for the linear-elastic material of the disc. The performed calculations yielded the stress intensity factor K_I for different crack sizes. Subsequently, ΔK parameter was determined as a difference of the K_I values calculated for the turbine’s speeds equal to 6373 and 14200 RPM. Based on the Paris-Erdogan equation and the obtained ΔK values, the fatigue crack growth plot for the turbine disc subjected to complex thermo-mechanical loads was determined.