Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6444978 | Journal of Structural Geology | 2013 | 14 Pages |
Abstract
Particle size distribution (PSD) is an often used parameter to describe and quantify fragmentation of deformed rock. Our analyses of shock deformed sandstone show that dynamic fragmentation influences the PSD, expressed as fractal dimension (D-value). Image analysis was used to derive fractal dimensions from a hypervelocity impact cratering experiment (2.5Â mm steel sphere, 4.8Â km/s) and a planar shock recovery experiment (2.5Â GPa). The D-values in the cratering experiment decrease from 1.74 at the crater floor to 0.84 at a distance of 7.2Â mm to the crater floor. The D-values found in this experiment are closely related to the microstructural features found at distinct distances from the crater floor. The obtained values are in good agreement with the D-values reported for fault zones, impact sites and deformation experiments. The D-value measured in the shock recovery experiment is 2.42. Such high D-values were usually attributed to abrasive processes related to high strain. Since the strain in our experiment is only â¼23% we suggest that at highly dynamic deformation very high d-values can be reached at small strain. To quantify this, numerical impact modelling has been used to estimate strain rates for the impact experiment. This is related to the activation of more inherent flaws and fracture bifurcation at very high strain rates â¼>102Â sâ1.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Elmar Buhl, Astrid Kowitz, Dirk Elbeshausen, Frank Sommer, Georg Dresen, Michael H. Poelchau, Wolf U. Reimold, Ralf T. Schmitt, Thomas Kenkmann,