Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 49: Topical Session: Fundamentals of Fracture - Novel Experimental Techniques I

MM 49.1: Topical Talk

Donnerstag, 14. März 2013, 10:15–10:45, H4

How crystals break - crack initiation and propagation, experiments and atomistic calculations — •Dov Sherman — Technion, Haifa, Israel

The fine details of the way brittle crystals break are still not well understood. Continuum elastodynamics based Freund energy-speed relationship suggests crack initiation at Griffith energy and propagation speed that ranges 0<V<CR. Massive atomistic computer calculations have been employed in the last two decades to resolve the fundamentals of crack initiation and propagation in brittle crystals. New effects were suggested which are not in accord with the continuum approach. The lack of sufficient experimental evidences for the theory and described effects prevent the final approval of both.

Our cleavage fracture experiments of silicon crystal show crack propagation at low speed with energy-speed relationship that apparently obeys Freund equation of motion. These findings, in addition to the fine details of the crack front, have yielded a new type of atomistic computer calculations that were able to ascertain the experimental results.

We will describe the past and present theories and phenomena associated with fracture in brittle crystals, present the fine details of the experimental results and the new atomistic calculations, and suggest a new paradigm for crack propagation sequence and energy consumption mechanisms not consider before.