FIGURE 3.
Plot of crack depth h as a function of number of cycles n in glass/polycarbonate bilayer, for (a) R-ratio fatigue; (b) uniaxial fatigue; and (c) biaxial fatigue. Indentation with WC sphere of radius r = 1.5 mm, maximum load Pm = 120 N, in water. Failure occurs when crack depth h reaches glass/polycarbonate interface (top of the vertical axis, glass thickness d = 1000 µm) at critical number of cycles nF (vertical dashed lines). Note: crack growth substantially enhanced in biaxial loading.