Stress Field Analysis And Structural Optimization Of Non-circular Hole On Flange Of Turbine Disks

The high pressure turbine (HPT) rotor assembly, which consists of the front shaft, the frontrotating air seal and the bladed disk, is an important part of the aero-engine. The turbine disk is themain load-bearing part of the HPT, and is directly bolted to other parts by an interference rabbetedbolted flange. In many cases, the bolt-holes of the forward flange of the disk are the most criticaldurability concern due to stress concentration. In this paper, the effect of the complex loads applied tothe rotor assembly connecting element on the stress level at the holes edge is researched, and thestress concentration at the hole edge is reduced by using the non-circular hole. Through stressanalyzing of the disk, sizes calculating of the flange in detail and shape optimizing of the bolt-holes,the following conclusions could be drawn:(1) The effect of the HPT loads, which consists of the centrifugal loads, axial loads, thermalloads, contact loads and torques, on the stress level at the hole edge are analyzed and calculated. Thedifferences with the stress level between circular hole and non-circular hole are compared. Thetheoretical basis for establishing a reasonable non-circular holes optimization model about HPT isprovided.(2) The effect of the chamfering parameters and the flange thickness on the stress level at thehole edge are analyzed and calculated. The results indicate that a smaller chamfering and appropriatethickness of flange could reduce the stress concentration on the holes’ edge in the case of accordingwith the assembling requirement.(3) The contours of the non-circular holes on the turbine flange and seal plate were optimized.The optimized non-circular hole is proved effective in reducing stress concentration.(4) The probabilistic sensitivity of the design variables toward σ1maxon the edge of non-circularholes is calculated through integrating Monte Carlo probabilistic design method and FEM. Therelations between design variables and the maximum first principal stress on the edge of non-circularholes are established by nonlinear data fitting and the sensitivity is influenced by the interval of thedesign variables.(5) Through the contrastive high temperature fatigue tests between the non-circular hole and thecircular hole, the rationality of using the non-circular hole is verified.