INVESTIGATING POSSIBILITIES OF CRACK INITIATION LIFE EXTENSION IN JET ENGINES COMPRESSOR DISKS

This paper deals with jet engines compressor disks which have dovetail joints with blades. A compressor disk with reduced fatigue resistance was taken as an example. Two simplified conceptual solutions of the dovetail joint with blades were devised. Based on the low cycle fatigue theory, the crack initiation life of their critical parts with newly-proposed transition rounding at the bottom of dovetail grooves was estimated. Two different flank angles in the dovetail grooves (60° in the critical part that belongs to the first dovetail joint conceptual solution and 55° in the critical part that belongs to the second dovetail joint conceptual solution), two different aviation steels selected for workmanship (13H11N2V2MF and AISI 304 steel) and two load histories (load history LH1 and load history LH2), were taken into account. By load history LH2 an overload of the critical parts was simulated. The results of crack initiation life estimation of the critical parts in the dovetail joint conceptual solutions show that there is a possibility for the crack initiation life extension of the observed compressor disk. In all analyzed variants, it has been shown that the critical part in the second dovetail joint conceptual solution has longer crack initiation life than the critical part in the first dovetail joint conceptual solution. For example, the critical part in the second dovetail joint conceptual solution made of AISI 304 steel, in the case of load history LH1 has 141.55% longer crack initiation life than the critical part in the first dovetail joint conceptual solution made of 13H11N2V2MF steel. In the case of load history LH2 (an overload case) that percent is greater and amounts to 173.15%.