Fig. 3 FCG in DARVIC 110 material plotted in terms of a) ΔK and b) Kmax. c) ΔK-R curves for crack growth rate near thresholds showing two possible mechanisms. d) The corresponding two L-shaped ΔK-Kmax curves with limiting values. e)FCG trajectory for the two mechanisms.
corresponding two L-shaped ΔK-Kmax curves are shown in Fig.3d, with limiting values at each crack growth rate. The FCG trajectories for the material are shown in Fig.3e. Both mechanisms deviate from the pure fatigue line, with mechanism two operating at high R-ratios, deviating more towards the Kmax-axis.
Osorio has determined FCG for somewhat brittle Epoxy(828/959) material also at many R-ratios. Fig. 4a shows the crack growth rates in terms of ΔK and Fig. 4b in terms of Kmax. In contrast to PVC material, the data for Epoxy seem to spread out in terms of both parameters. Fig. 4c shows the plot of ΔK-R curves at low crack growth rates, which follows a typical trend. Fig. 4