PSI - Issue 18

V.N. Shlyannikov et al. / Procedia Structural Integrity 18 (2019) 322–329 Author name / Structural Integrity Procedia 00 (2019) 000–000

323

2

conditions lead to fatigue crack initiation and their propagation up to reaching a critical zone in rotating disks. Most of the critical zones are characterized by the presence of plastic deformations in which the effective stresses exceed the yield strength of the material at the corresponding temperature. These circumstances assume the application of nonlinear fracture and continuum damage mechanics approaches to aviation GTE components lifetime prediction. Prediction of fatigue crack growth from critical locations in a rotating disk, e.g., a disk-blade attachment subjected to cyclic loading conditions, is one of the parts of the tolerance damage strategy. In this regard, for correct prediction of fatigue crack propagation and life time, an advanced crack growth model needs to be developed which allows take account of nonlinear cyclic deformation and damage accumulation and growth. The findings are fundamental to the development of third-generation fatigue crack growth models that are increasingly being used as engineering tools for fatigue life prediction. It is well known that during aircraft engine operation, rotating disks are frequently subject to biaxial or multiaxial loading conditions. There is sound experimental evidence that the fatigue crack growth rate is strongly influenced by the biaxial loading conditions. The aim of this paper is to background an imitation modeling approach in order to analyze failure of a disk and blade “dovetail type” attachment in GTE compressor disk. 2. Subject for study and material properties The subject of present study is high pressure compressor disk of D-36 aircraft GTE (Fig. 1a). This compressor disk (Fig. 1b) had accumulated 3800 operation hours/cycle to failure. The failure occurred in a disk and blade dovetail type attachment. This attachment has a broach angle of 26  at the axis of rotation. Quarter-elliptical corner crack initiation zone is the slot fillet under the blade on the forward face of the disk. Further, the growing crack intersects the full thickness of the compressor disk and fracture of disk’s dovetail region is occurred (Fig. 1c).

a)

b)

c)

Fig. 1. High pressure compressor disk of D-36 GTE (a, b) and operation damages of disk and blade dovetail type attachment (c).

The compressor disk is manufactured from the two-phase titanium alloy VT3-1. The main monotonic mechanical properties of the material analysed at both room temperature and elevated temperatures are summarized in Table 1.

Table 1. Main mechanical properties of two-phase titanium alloy VT3-1.

Temperature, °C

σ 0 , MPa 1005

σ S , MPa 1073

σ u , MPa 1214

Material

α

n

E, GPa

δ, %

ψ, %

+23

1.115 0.990

12.880

100.1

21 13

46 55

VT3-1

+300

753

889

956

8.915

96.1