Pages 15-18
The stress and displacement fields near the bonding edge, sharp notch, and contact edge show singularity behaviors, so methods of evaluating the strength of these points using maximum stresses calculated by a numerical stress analysis, such as the finite element method, are generally not valid. We have previously presented a new method of evaluating the strength of these singular points using two stress singularity parameters H and λ. The difficulty with this method was in obtaining the critical value of the intensity of the stress singularity parameter Hc for each order of stress singularity λ. We therefore present in this paper methods of formularizing Hc by λ based on typical strength parameters such as the fatigue limit σ_<w0> and the threshold stress intensity factor range ΔK_<th>. These critical value Hc (λ) agreed well with the experimental results. Using these easily obtained formularized critical value Hc (λ), we can estimate the fretting fatigue crack initiation criteria for each contact edge angle, and thus optimize the contact edge geometry. Finally, we discuss the development of these strength criteria in terms of stress singularity fields for general stress concentration fields.
