Statistical Organization Of Microscale Damage In The Vicinity Of A Dynamically Growing Crack Front: A New Equation Of Motion Of A Crack Tip.

Dynamically growing crack growth is the main vehicle of material failure. By amplifying stresses at its tip, the crack, indeed, transports remotely applied loading to the crack tip.All the dissipative damage and failure processes are confined around this tip. Linear Elastic Fracture mechanic provides the relevant framework to describe the crack front dynamics. It now addresses very well the problem of a 1D slit crack propagating in a 2D homogeneous elastic plate and there exists some extensions to describe the motion of an elastic crack line interacting with defects. Still, this framework deeply relies on the knowledge of the fracture energy, which itself seems fixed by what happen at very small scales and particularly by the near-tip damage mechanisms. In this study we focus on the statistical organization of damage at the microscale, in the very vicinity of the crack tip. We will see (i) how this organization is driven by the macroscopic quantities at stake: the loading and fracture toughness; (ii) how the existence of this microscale damage development modify the energy balance and increases drastically the radiated energy part in the budget; and (iii) how, in response, local instabilities can develop and affect deeply the large scale behavior of the crack front.