Finite element analysis of fir-tree region in turbine discs

Comprehensive 2D and 3D finite element analysis is undertaken of the fir-tr ee region in aeroengine turbine disc assemblies. The study examines the eff ect of the critical geometrical features, such as the number of teeth. flan k length and flank angle upon the stress field in the disc. The two-dimensi onal finite element predictions are verified using photoelastic-stress-free zing technique. The study is further extended to account for the effect of the skew angle and the interfacial friction between the disc and attached b lades upon the resulting contact stresses at the interface and through the disc thickness. The results reveal that aeroengine disc designers must trea t the two-dimensional finite element results with caution. This is due to t he fact that two-dimensional results do not account for the large stress va riations at the contact region and through the thickness due to the presenc e of skew slots in the disc. (C) 2000 Elsevier Science B.V. All rights rese rved.