Fretting fatigue is a limiting factor in blade attachment design for turbomachinery. It is potentially met e.g. at the mating surfaces of blade roots and rotor steeples. There, they are in direct neighborhood to the life-relevant notches. As they are in mutual design influence, a sole optimization of the free surface notch may lead to fretting fatigue becoming the leading failure mechanism. Shot peening is known to be a strength increasing measure against fatigue. It is applied not only to free surfaces of components under fatigue but also to contacting surfaces subject to fretting fatigue. &nbsp;The present work examines the effect of shot peening on fretting fatigue resistance in fixtures of rotor blades. The chosen integral approach allows the consideration of shot peening and subsequent fretting loading in one simulation. Thus, the residual stresses and material strengthening as well as the surface roughness of the shot peening process are included in the fretting fatigue simulation. To achieve reasonable computation times a 2D model, calibrated to a 3D unit cell model of a single shot, is employed. A comparative study on fatigue endurance limits is presented for the cases with and without shot peening. A fracture mechanical approach is used for the evaluation of the shot peened case, for the un-peened case the Sines criterion is employed.&nbsp;

Fretting Fatigue – an Integral Simulation Approach to Strengthening by Shot-Peening

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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