2008/07/31 by Ariel Livne, Eran Bouchbinder, Jay Fineberg · 1 citation
Physics and Astronomy · #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevlett.101.264301
published as Phys. Rev. Lett. 101, 264301 (2008) · 4 pages, 4 figures, first of a two-paper series (experiments); no change in content, minor textual revisions
arxiv created 2008/10/07 · arxiv updated 2009/12/01
We present high resolution measurements of the displacement and strain fields near the tip of a dynamic (Mode I) crack. The experiments are performed on polyacrylamide gels, brittle elastomers whose fracture dynamics mirror those of typical brittle amorphous materials. Over a wide range of propagation velocities (0.2-0.8cs), we compare linear elastic fracture mechanics (LEFM) to the measured near-tip fields. We find that, sufficiently near the tip, the measured stress intensity factor appears to be non-unique, the crack tip significantly deviates from its predicted parabolic form, and the strains ahead of the tip are more singular than the r-1/2 divergence predicted by LEFM. These results show how LEFM breaks down as the crack tip is approached.