Structural Design And Optimization Of Non-circular Hole On Turbine Disks

The bolt-holes, pin-holes and eccentric holes are in many cases the most critical durabilityconcern of aero engine disk due to stress concentration. The improvement of traditional solutions (i.e.chamfering, polishing or increasing the structure size) is less satisfied. The present study proposed anon-circular hole structure, of which the contour could be converted for different structural loadconditions, to improve fatigue performance of pilot hole and that of the aero engine disk as well. Incontrast with circular bolt-holes, optimized non-circular holes could dramatically reduce stressconcentration at the hole edge. Through mathematical modeling and shape optimizing, the followingconclusions could be drawn:(1)The non-circular-holes were classified and corresponding mathematical models were derivedfor shape design and optimization. The models ensure the smooth connection of the arcs and thetangent between the contours of original hole and non-circular hole, keeping the tolerance of the boltsand holes unchanged.(2) Thermal-structural finite element analysis was conducted on high-pressure turbine disk andfront seal plate with circular bolt-hole to investigate stress/strain distribution. Simulation resultsindicate that stress concentration is significant at the circumference of bolt-hole, of which the stresslevel could be comparable or even higher than stress at turbine disk center.(3)The contours of the non-circular holes on the turbine flange and seal plate were optimizedwith appropriate methodology. The optimized non-circular hole is proved effective in reducing stressconcentration; in other words, improving fatigue performance of the structure.(4)A simplified non-circular-hole design method is proposed. Compared with3D-model basedoptimization, the simplified approach, which has higher computational efficiency, could providedesirable result in reducing stress concentration around the non-circular-hole.