4 Effective toughness of heterogeneous brittle materials
نویسندگان
چکیده
A heterogeneous brittle material characterized by a random field of local toughness K c (x) can be represented by an equivalent homogeneous medium of toughness, K eff. Homogenization refers to a process of estimating K eff from the local field K c (x). An approach based on a perturbative expansion of the stress intensity factor along a rough crack front shows the occurrence of different regimes depending on the correlation length of the local toughness field in the direction of crack propagation. A " weak pinning " regime takes place for long correlation lengths, where the effective toughness is the average of the local toughness. For shorter correlation lengths, a transition to " strong pinning " occurs leading to a much higher effective toughness, and characterized by a propagation regime consisting in jumps between pinning configurations.
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