Failure time and critical behaviour of fracture precursors in heterogeneous materials

الأصل · EN

The acoustic emission of fracture precursors, and the failure time of samples of heterogeneous materials (wood, fiberglass) are studied as a function of the load features and geometry. It is shown that in these materials the failure time is predicted with a good accuracy by a model of microcrack nucleation proposed by Pomeau. We find that the time interval % δt between events (precursors) and the energy ε are power law distributed and that the exponents of these power laws depend on the load history and on the material. In contrast, the cumulated acoustic energy E presents a critical divergency near the breaking time τ which is % E (τ-tτ) ⁻γ. The positive exponent % γ is independent, within error bars, on all the experimental parameters.