Intrinsic Nonlinear Scale Governs Oscillations in Rapid Fracture

 

1Tamar Goldman, 2Roi Harpaz, 2Eran Bouchbinder, and 1Jay Fineberg

 

1The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

2Chemical Physics Department, Weizmann Institute of Science, Rehovot 76100, Israel

 

When branching is suppressed, rapid cracks undergo a dynamic instability from a straight to an

oscillatory path at a critical velocity vc. In a systematic experimental study using a wide range of different

brittle materials, we first show how the opening profiles of straight cracks scale with the size lnl of the

nonlinear zone surrounding a crack’s tip. We then show, for all materials tested, that vc is both a fixed

fraction of the shear speed and, moreover, that the instability wavelength is proportional to lnl . These

findings directly verify recent theoretical predictions and suggest that the nonlinear zone is not passive,

but rather is closely linked to rapid crack instabilities.