Fig. 4

Effect of polymer hardness on fatigue toughening. a Fatigue fracture energy ΓFatigue and b ΓStatic of polymer-metal-MPTMS-SiO2 stacks with a soft System Three Resins® T88 polymer (red squares), and a harder EPO-TEK 375 polymer (blue circles) at \(p_{{\mathrm{H}}_{2}{\mathrm{O}}}\) = 1.3 kPa. Each data point represents at least three tests. The width of the bands, drawn through the data points to guide the eye, connote the experimental uncertainties measured as standard deviation