Development of a dovetail fretting fatigue fixture for turbine engine materials

A unique dovetail fretting fatigue fixture was designed and evaluated for testing turbine engine materials at room or elevated temperatures. Cold section and hot section materials from military turbojet engines were chosen for testing. These included Ti-6Al-4V, Rene’88DT, and Rene’N5. The new fixture was improved over a previously used dovetail fretting fatigue fixture by including instrumentation for direct measurement of the normal contact force, alignment control, and elevated temperature capability. Measurement of the shear component of the contact force was validated through an alternative instrumentation method. Investigation of the thermal gradient in the specimen and pads was conducted. Initial test results revealed interesting variability in the behavior of the nickel based superalloy specimens at elevated temperature.