A comparison of the state of stress at an incomplete fretting contact edge with a crack tip

The similarity in implied process zones, based on violations of the plastic yield condition, between the state of stress at the edge of an incomplete contact subject to reciprocating shear and tension and a crack suffering pure mode II loading are compared. This is done for both small and large amounts of edge slip, i.e. when the frictional slip region is either enveloped by the plastic region or envelops it. The results show that for realistic coefficients of friction strong agreement is unlikely to occur, so that attempting to analyse the nucleation of fretting cracks as a form of crack branching/turning is inappropriate and the effect of normal load on crack nucleation is an important consideration.