Experimental and Computational Investigations on Fretting Fatigue Crack Growth in Dovetail Joints

Fretting fatigue is a significant damage mode for turbine engine blade/disk components. In the present work, fretting fatigue crack growth of a nickel-based superalloy was experimentally and computationally investigated. Fretting fatigue experiments of dovetail joints were conducted under loading ratio , and the results revealed that the fretting fatigue cracks nucleated in multiple sites on the contact edge, which was accompanied by oxide wear debris and propagated with a single through-thickness crack. The crack growth rate was determined based on the variation of applied loading ratio in the experiments. With the help of the maximum tensile stress criterion, the friction coefficient of the fretting pair was determined from simulations of the fretting fatigue crack propagation. With the increasing friction coefficient, the kinking angle of the fretting crack approaches a stable value. The stress was verified to have significant effects on the short crack kinking and implemented in the maximum tensile stress criterion. A methodology based on fracture mechanics was proposed to identify the friction coefficient on the fretting surfaces.