Figure Captions
Fig. 1 FCG in PVC pipe grade material tested at 1Hz at 20oC. a) rates as a function of ΔK and b) Kmax. c) ΔK-R plots for selected crack growth rates and d) ΔK-Kmax plots showing an L-shaped type of behavior with limiting values of ΔK* and Kmax*. e). The crack growth trajectory map in terms of ΔK* and Kmax*.
Fig. 2. FCG rates in Pipe grade PVC at 10 Hz at 20oC. a) in terms of Kmax and b) in terms of ΔK. c) ΔK-R plots at low crack growth rates showing possible two mechanisms one at low R and the other at high R. d) ΔK-Kmax plots showing two L-shaped curves. e) Comparison of crack growth trajectories for PVC-PIPE GRADE material.
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.
Fig. 4 FCG for Epoxy at different R-ratios. a) in terms of ΔK and b) in terms of Kmax. c) ΔK-R plots at low crack growth rates. d) corresponding ΔK-Kmax plots with limiting ΔK and Kmax values. e) The trajectory showing deviation from the pure fatigue line.
Fig. 5 Comparison of crack growth trajectories of three polymer materials tested by Osorio, 1981. PVC and DARVIC show two mechanisms while Epoxy shows one.
Fig. 6. FCG behavior of commercial PMMA plastics a) as a function of ΔK with three R-ratios and one Kmean and one Kmax constant tests. b) The data in terms of Kmax. c) ΔK-R plots at selected crack growth rates close to the threshold value. d) The ΔK-Kmax plot showing L-shaped curves. e) The FCG trajectory showing its deviation from the pure-fatigue line.
Fig. 7 Crack growth rates in rubber toughened epoxy resin. a) in terms of ΔK and b) in terms of Kmax. c) ΔK –R plots for selected crack growth rates showing two mechanisms. d) ΔK-Kmax plots showing two L-shaped curves. e) Crack growth trajectory maps for the two mechanisms. The results are compared with the trajectory of Epoxy material tested by Osorio.
Fig 8. The FCG rates in Rice Husk composite. a) in terms of amplitude, √ΔG. b) the √ΔG versus R plots for selected crack growth rates. c) √ΔG vs √Gmax plots at selected crack growth rates showing the L-shaped curve with limiting √ΔG and √Gmax values. d) shows the cack growth trajectory deviating from the pure fatigue line.