Crack Paths 2009

a)

b)

Figure 10: Displacement fields for different crack lengths

From the displacement field data, C T O Avalues were computed from the corresponding

data points using the C T O Acalculation methodology explained in the preceding section.

The C T O Adistribution obtained is shown in Figure 11. The star symbol in the plot

pinpoints the location of the crack tip and the coordinate system in the X Ydirection is

identical to the plots in Figure 10. From the two C T O Adistribution graphs, it is clear that

the ahead of the crack tip, there is a rapid decrease in C T O Avalues. At a distance of

approximately 7.5 m mahead of the crack tip, the net displacements measured were

negligible and the corresponding C T O Avalues clearly show this.

Behind the crack tip, the resultant C T O Avalues clearly indicate that there is a

measurable angle which remains relatively unchanged until the corresponding data points approaches the crack tip where an increase in C T O Avalues is observed. This increase is

70