Study of size effects in fretting fatigue

Abstract The aim of this work was to carry out an experimental campaign to study the size effect on fretting fatigue. Tests were carried out on a two vertical-actuators fretting-fatigue rig at the University of Brasilia. The study of the size effect was divided into two parts. First, the influence on fretting fatigue life of the volume of material stressed under the contact was investigated. For so, the thickness of the specimens were reduced while maintaining the variation of a multiaxial fatigue parameter with the distance from the surface and the damaged area within the slip zones constant. In addition, the influence of the damaged area within the slip zones was also investigated by reducing it while maintaining all other experimental parameters constant, i.e. bulk fatigue load and tangential load per unit length. These two experimental campaigns were designed and analyzed by applying a multiaxial fatigue criterion in conjunction with the Theory of the Critical Distances (TCD). It was found that none of these two parameters seems to have a significant influence on the fretting fatigue resistance for the Ti–6Al–4V alloy here investigated.