Pages 203-204
Opening displacement of a bifurcated notch is measured by means of Moire interferometry. The bifurcated notch has the same shape as a fast propagating crack just after bifurcation. Two branches of the bifurcated notch are symmetric and the angle between them is 27 degrees. The measurement results show that the opening displacement of the mother notch is proportional to the square root of distance r from the nominal tip of the mother notch. This result is in good agreement with that, after bifurcation of a fast propagating crack, crack opening displacement of the mother crack is proportional to the square root of distance r from the nominal tip of the mother crack.
