2017/08/06 by Itamar Kolvin, Gil Cohen, Jay Fineberg · 46 citations
Engineering · Physics and Astronomy · #Adhesion, Friction, and Surface Interactions #Amorphous solid #Composite material #Crystallography #Facet (psychology) #Fracture (geology) #Fracture mechanics #Front (military) #Geometry #Geophysical Methods and Applications #Materials science #Mechanics #Physics #Rock Mechanics and Modeling #cond-mat.mtrl-sci #cond-mat.soft #nlin.PS
paper · pdf · doi:10.1038/nmat5008
published in Nature Materials 17(2), 140-144 (Nature Portfolio) · 14 pages, 6 figures
arxiv created 2017/08/06 · openalex publication_date 2017/10/16 · arxiv updated 2018/02/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Patterns on broken surfaces are well-known from everyday experience, but surprisingly, how and why they form are very much open questions. Well-defined facets are commonly observed1-4 along fracture surfaces which are created by slow tensile cracks. As facets appear in amorphous materials5-7, their formation does not reflect microscopic order. Fracture mechanics, however, predict that slow crack fronts should be straight, creating mirror-like surfaces8-13. In contrast, facet-forming fronts propagate simultaneously within different planes separated by steps. It is therefore unclear why steps are stable, what determines their path and how they couple to crack front dynamics. Here we show, by integrating real-time imaging of propagating crack fronts with surface measurements, that steps are topological defects of crack fronts; crack front separation into discontinuous overlapping segments provides the condition for step stability. Steps drift at a constant angle to the local front propagation direction and the increased local dissipation due to step formation couples to the long-range deformation of the surrounding crack fronts. Slow crack front dynamics are enslaved to changes in step heights and positions. These observations show how 3D topology couples to 2D fracture dynamics to provide a fundamental picture of how patterned surfaces are generated.