13th International Conference on Fracture June 16–21, 2013, Beijing, China -8- on a rigid pin through the hole. Figure 5. (a) Finite element mesh for the tensile specimen. (b) Comparison of the predicted and experimental load-displacement curves. Figure 6 shows the comparison between the model predicted load versus crack growth curve with the experimental measurements (two sets of experimental data) for different choices of α and β, where the lines represent model predictions and the symbols denote experimental measurements. Here aΔ represent the amount of crack growth measured at the free surface. In the numerical model, the propagating crack front is defined by the elements which have reached the failure strain Ec. From Figure 6, it can be seen that the choice of α = 0.93 and β = -1.45 (solid line) results in a best fit to the experimental data. Therefore, these values are the calibrated values for α and β and will be used to predict crack growth in other fracture specimens. Δa (mm) 0 1020304050607080 Load (N) 0 2000 4000 6000 8000 10000 12000 14000 Εc = 0.1261(T) -0.3342 Εc = 0.1(T) -0.5451 Εc = 0.0824(T) -0.7211 Figure 6. Comparison of the model predicted load versus crack growth curve with the experimental measured data (symbols) showing the choice of α = 0.93 and β = -1.45 (solid line) results in a best fit to the experimental data. (a) (b) Ec=0.8e-1.15T Ec=0.93e-1.45T Ec=e-1.598T 0 1000 2000 3000 4000 5000 6000 7000 8000 0 1 2 3 4 5 6 Load (N) Displacement (mm) EXP FEA
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