Bernhard Schrefler

Abstract:

An FEM and a novel hybrid FEM and Peridynamic modelling approach are used to predict the forerunning fracture behavior in dry and saturated porous solids. Both mechanical loading case and fluid-driven fracture case are investigated. Under the action of the applied forces or fluid injection, a forerunning fracture event is observed in the structure. It will be shown that i) in dry bodies, the forerunning increases the overall fracturing speed and is, in fact, a mechanism for a crack to move faster when a steady-state propagation is no longer supported by the body/structure due to a high level of external forces; ii) in presence of the forerunning, interaction with the waves in the fluid phase increases the average speed even further comparing to the movement in the same dry bodies; iii) the forerunning is an undeniable source of stepwise crack tip advancement of the main crack in continuum models; and iv) the forerunning phenomenon deserves further scrutiny because of its importance in geophysics as far as earthquake events are concerned.