Abstract
Fretting fatigue tests on leaf springs and small axial-loading specimens were carried out under constant loading and random loading simulating field load spectra. The results of leaf springs were compared with the literature data for similar springs. The behavior of fretting fatigue crack initiation and propagation in the leaf springs was found to be almost the same as those in the small laboratory specimen. No significant differences between their fretted surfaces or between their fatigue fractured surfaces were observed. Random loading reduced the fretting fatigue lives by a factor of 1.5. The effects of shot peening on fretting fatigue were also investigated. Shot peening improved the fretting fatigue strength in both specimens by a factor of two. The residual compressive stress induced by the shot peening process was attributed as being the controlling factor to the improvement. It was suggested that the fretting fatigue life of leaf springs can be estimated from that of laboratory specimens, if the clamping pressures and the relative slip amplitudes of both the specimens have the same magnitudes.
