Alizée Dubois (ENS Lyon) Roughness properties and normal modes of a dynamic crack front

Dynamic crack propagation drives catastrophic material failures. Elastodynamic and continuum fracture theory a priori provide the relevant tools to describe dynamic crack growth. Still, at high enough speed several instabilities are observed. Since the pioneering work of Gao and Rice, 1986, it has been proposed to model crack propagation in a 3D solid as an elastic line moving through obstacles. The distortion in the crack front, in turn, increases locally the stress intensity factor. Such model gained momentum when the first statistical studies of crack surfaces revealed self-affine features for the roughness. The elastic line model meet great success in the quasi static crack front modeling. In this context, it is now timely to understand how crack surfaces roughness is organized in the dynamic case. 

The main point here is to use a model experiment, and a numerical simulation, to systematically study the roughness properties and dynamic properties, of a fast crack front. Fractography is a promising method to probe the fracture history and to measure the fracture toughness of materials. How could the method be applied to dynamic crack surfaces? What kind of information would it bring on material properties and crack