Berlin 2005 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 44: Growth and Fracture

DY 44.7: Vortrag

Dienstag, 8. März 2005, 17:15–17:30, TU H3010

Fast Crack Propagation, Martensitic Transformations and the Grinfeld Instability — •R. Spatschek, M. Hartmann, E. Brener, and H. Müller-Krumbhaar — IFF, Forschungszentrum D-52425 Jülich

Fracture is an intriguing irreversible phenomenon that plays an important role in our day-to-day-life. It is commonly believed that crack propagation is dictated by microscopic details in the vicinity of the tip. However, we present a counterintuitive and surprisingly simple continuum theory which describes crack growth only by (macroscopic) surface diffusion or phase transformations in combination with the dynamical theory of elasticity. It predicts the complicated dynamics of a fast moving crack tip, the saturation of the steady state velocity appreciably below the sound speed, blunting of the crack and a tip splitting instability for high applied tensions. Phase field calculations confirm and illustrate these generic results. They also us allow to study elastically induced martensitic (solid-solid) transformations and melting and crystallization. Also, they demonstrate the development of stressed corrugated solid surfaces in contact with their melt phases (Grinfeld instability), leading to the formation of fast moving and interacting melt fingers. In contrast to earlier theories, it contains a self-consistent selection of the tip radius and the propagation velocity.