Brief note: some observations on the parametric relationships in Hertzian fretting fatigue tests

The external variables controlling the key quantities found in a Hertzian-t ype fretting fatigue test are found, and it is shown that the key surface t ractions are determined by the shearing force, while the surface displaceme nts depend strongly on the normal contact pressure. These apparently parado xical results contrast with the normally used form of the solutions and thr ow light on the interpretation of experimental results.