Analysis of the Size Effect in Partial-Slip Contact Fatigue

A size effect has been observed in cylinder-on-flat partial slip contact fatigue experiments (Hills et al., 1988 and 1990). The size effect in this case is defined as a discontinuous drop in the fatigue life beyond some critical value of the width of the contact region. New analysis that directly accounts for the finite substrate thickness used in the original experiments shows that both the maximum local bulk stress and maximum local bulk cyclic stress range increased systematically with contact width in the original cylinder-on-flat experiments, rather than remaining approximately constant as intended in the original experimental design.