A temporal averaging–based approach to toughness homogenisation in heterogeneous material

A new approach to defining the effective fracture toughness for heterogeneous materials is proposed. This temporal averaging approach is process dependent, incorporating the crack velocity and material toughness. The effectiveness of the new technique is investigated in the context of hydraulic fracture through heterogeneous rock with a periodic material toughness. The plane strain model is considered without fluid leak-off, to more easily investigate different regimes (toughness/viscosity). Numerical simulations are used to examine the effectiveness of the new homogenisation strategy, with comparison against the recently proposed maximum toughness strategy. Simulations are conducted using an extremely effective (in house-built) time–space adaptive solver. The regimes in which each strategy is effective are determined.