The disk/blade assembly of a turbine engine is made in the shape of a dovetail type or a fir-tree type. Since disk fillet regions or contact surfaces undergo high stress concentration, fatigue cracks frequently occur in the disk/blade assembly. Therefore, it is necessary to analyze the stress distributions in the fir-tree type disk/blade assembly and predict the region of fatigue failure. The stress distributions of the disk/blade assembly were investigated by using the photoelastic method and the finite element method. Two dimensional photoelastic techniques were used to investigate the stress distributions of contact surfaces and fillet regions. The stress distributions were obtained by the shear-difference method and were compared to the results obtained by using the finite element method. It was found that maximum tensile stresses were higher in the fillet region than in the contact surfaces of the fir-tree models. The finite element results showed a good agreement with the experimental results.
