Fig.11 Amplified morphologies of the CSZ, CPZ and IFZ under DP, P=50MPa,
σe=400MPa;(a) CSZ; (b) CPZ; (c) IFZ.
Fig.12 shows the amplified morphologies of the CSZ, CPZ and IFZ under
SP; It can be found that the crack source is located at the subsurface
of fretting region from the CSZ, as shown in Fig.12(a). Similarly, the
crack is tortuous, and multiple secondary cracks are around the main
crack. In the CPZ, the steady propagation of cracks has appeared, and a
number of small secondary cracks have also extended on the main crack,
as shown in Fig.12(b). These secondary cracks have a small size due to
the large propagation resistance. The IFZ is shown in Fig.12(c), the
morphological features are significantly different from the IFZ under
DP. Under SP, a radial cross section appeared in the IFZ. Radial
cross-section is formed by the intersection of crack fronts when the
cracks rapidly expand at different heights, and there are also obvious
dimple patterns in the IFZ, as shown in Fig.13.