Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 11: Growth

MM 11.5: Vortrag

Montag, 23. März 2009, 15:45–16:00, IFW D

Crack growth by surface diffusion in viscoelastic media — Robert Spatschek, Efim Brener, and •Denis Pilipenko — Institut für Festkörperforschung, Forschungszentrum Jülich , D-52428 Jülich

Dissipation plays a central role in fracture, since typically only a small fraction on the elastic energy is used to create the surfaces of the advancing crack. Whereas in brittle materials dissipation takes place mainly close to the crack surfaces, in materials with a more viscous behavior an extended zone of bulk dissipation can form around the crack.

We discuss steady state crack growth in the spirit of a free boundary problem. It turns out that mode I and mode III situations are very different from each other: In particular, mode III exhibits a pronounced transition towards unstable crack growth at higher driving forces, and the behavior close to the Griffith point is determined entirely through crack surface dissipation, whereas in mode I the fracture energy is renormalized due to a remaining finite viscous dissipation. Intermediate mixed-mode scenarios allow steady state crack growth with higher velocities than for pure mode I.