Experimental and Numerical Investigation of Circular Arc Dovetail Attachments under Fatigue Loading

Fretting fatigue is an important failure mode of dovetail attachments in gas turbine engines. One of the most difficult challenges in carrying out experiments of components with actual geometry is the design of fixtures for the dovetail attachments since it can change the stress distribution under a given load. A circular arc dovetail attachment specimen with a tenon at each end respectively was designed and machined to simulate the fatigue damage that occurs in wide-chord fan blade attachments, so it can perform two dovetail attachment simulations at each time, and its related fixture was connected with the testing machine by two pins which were orthogonal to each other so as to eliminate additional bending moment. An Instron 8802 servo-hydraulic fatigue testing system was used to provide fatigue loads. Furthermore, Finite Element (FE) analysis based on the experimental configuration was carried out to obtain the stress distribution on the contact surface, crack initiation location and number of cycles to the fretting fatigue failure were predicted based on the FE results. The results show a good agreement with the experimental counterparts.