On Compressive Brittle Fragmentation

2016 ◽  
Vol 99 (6) ◽  
pp. 2159-2169 ◽  
Author(s):  
James David Hogan ◽  
Lukasz Farbaniec ◽  
Nitin Daphalapurkar ◽  
K.T. Ramesh
Keyword(s):  
Brittle Fragmentation

scholarly journals Dynamic Brittle Fragmentation: Probing the Byproducts of Hypervelocity Impact in Space

2015 ◽  
Vol 103 ◽  
pp. 205-212 ◽  
Author(s):  
James D. Hogan ◽  
Charles El Mir ◽  
Jeffrey B. Plescia ◽  
K.T. Ramesh
Keyword(s):  
Hypervelocity Impact ◽  
Brittle Fragmentation

scholarly journals Melting and fragmentation laws from the evolution of two large southern ocean icebergs

2017 ◽  
Author(s):  
Nicolas Bouhier ◽  
Jean Tournadre ◽  
Frédérique Rémy ◽  
Rozenn Gourves-Cousin
Keyword(s):  
Southern Ocean ◽  
Environmental Parameters ◽  
Open Water ◽  
Altimeter Data ◽  
Freshwater Flux ◽  
Realistic Representation ◽  
Modelling Studies ◽  
Visible Images ◽  
Bulk Model ◽  
Brittle Fragmentation

Abstract. The evolution of the thickness and area of two large southern ocean icebergs, having drifted in open water for more than a year, is estimated through the combined analysis of altimeter data and visible satellite images. Most of the iceberg modelling studies uses two main melting formulations that are compared with the observed thickness evolution of our two icebergs, to test their validity in case of large icebergs. The first formulation, based on a fluid dynamics approach, would tend to underestimate basal melt rates, so that using the second one (using a thermodynamic budget consideration) may be more relevant. Fragmentation is, before melting, the major decay process of large icebergs, yet it is a complex and still poorly documented mechanism. A correlation analysis between the observed volume loss of our two icebergs and environmental parameters highlights those most likely to promote fragmentation. Consequently, a bulk model of fragmentation depending on ocean temperature and iceberg velocity is established and is shown to be able to reproduce well the observed volume variations. Finally, the size distribution of the calved pieces is estimated using both altimeter data and visible images and is found to be consistent with previous studies as typical of brittle fragmentation processes. These results are valuable to account for a more realistic representation of the freshwater flux constrained by large icebergs in models.

scholarly journals Fault rheology beyond frictional melting

2015 ◽  
Vol 112 (30) ◽  
pp. 9276-9280 ◽  
Author(s):  
Yan Lavallée ◽  
Takehiro Hirose ◽  
Jackie E. Kendrick ◽  
Kai-Uwe Hess ◽  
Donald B. Dingwell
Keyword(s):  
Glass Transition ◽  
High Strain ◽  
Frictional Heating ◽  
Wall Rock ◽  
Dissipative Heating ◽  
Strain Rates ◽  
Stored Energy ◽  
Slip Resistance ◽  
Frictional Melting ◽  
Brittle Fragmentation

During earthquakes, comminution and frictional heating both contribute to the dissipation of stored energy. With sufficient dissipative heating, melting processes can ensue, yielding the production of frictional melts or “pseudotachylytes.” It is commonly assumed that the Newtonian viscosities of such melts control subsequent fault slip resistance. Rock melts, however, are viscoelastic bodies, and, at high strain rates, they exhibit evidence of a glass transition. Here, we present the results of high-velocity friction experiments on a well-characterized melt that demonstrate how slip in melt-bearing faults can be governed by brittle fragmentation phenomena encountered at the glass transition. Slip analysis using models that incorporate viscoelastic responses indicates that even in the presence of melt, slip persists in the solid state until sufficient heat is generated to reduce the viscosity and allow remobilization in the liquid state. Where a rock is present next to the melt, we note that wear of the crystalline wall rock by liquid fragmentation and agglutination also contributes to the brittle component of these experimentally generated pseudotachylytes. We conclude that in the case of pseudotachylyte generation during an earthquake, slip even beyond the onset of frictional melting is not controlled merely by viscosity but rather by an interplay of viscoelastic forces around the glass transition, which involves a response in the brittle/solid regime of these rock melts. We warn of the inadequacy of simple Newtonian viscous analyses and call for the application of more realistic rheological interpretation of pseudotachylyte-bearing fault systems in the evaluation and prediction of their slip dynamics.

BRITTLE FRAGMENTATION OF AN EXPANDING RING BY MOLECULAR DYNAMICS

2013 ◽  
Vol 02 (02) ◽  
pp. 1350010
Author(s):  
GUOWU REN ◽  
TIEGANG TANG ◽  
ZHAOLIANG GUO ◽  
YUANSHUAI YANG ◽  
QINGZHONG LI
Keyword(s):  
Strain Rate ◽  
Physical Mechanism ◽  
High Strain ◽  
Fragmentation Process ◽  
Strain Rates ◽  
Anisotropic Behavior ◽  
Wide Range ◽  
Low Strain Rate ◽  
Brittle Fragmentation ◽  
Random Defect

In this paper, the brittle fragmentation of an expanding ring is numerically studied by a simple atomistic model. We investigate the statistical distribution of fragment spanned over a wide range of strain rates when damage related to broken bond reaches a steady state. It is shown that at low strain rate limited number of heavy fragments can be generated because of anisotropic behavior while for high strain rate fragment can be well fitted with Weibull distribution. The physical mechanism of fragmentation process reveals that damage accompanying with numerous microcracks is found to initiate in the inner regime of the expanding ring. Furthermore, we discuss the effect of random defect on the fragmentation process.

Volcanic glass textures, shape characteristics and compositions of phreatomagmatic rock units from the Western Hungarian monogenetic volcanic fields and their implications for magma fragmentation

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
Karoly Németh
Keyword(s):  
Fractal Dimension ◽  
Shape Analysis ◽  
Fractal Dimensions ◽  
Volcanic Glass ◽  
Pyroclastic Deposits ◽  
Average Value ◽  
Complex Particle ◽  
Hot Melt ◽  
Brittle Fragmentation ◽  
Glass Shards

AbstractThe majority of the Mio-Pleistocene monogenetic volcanoes in Western Hungary had, at least in their initial eruptive phase, phreatomagmatic eruptions that produced pyroclastic deposits rich in volcanic glass shards. Electron microprobe studies on fresh samples of volcanic glass from the pyroclastic deposits revealed a primarily tephritic composition. A shape analysis of the volcanic glass shards indicated that the fine-ash fractions of the phreatomagmatic material fragmented in a brittle fashion. In general, the glass shards are blocky in shape, low in vesicularity, and have a low-to-moderate microlite content. The glass-shape analysis was supplemented by fractal dimension calculations of the glassy pyroclasts. The fractal dimensions of the glass shards range from 1.06802 to 1.50088, with an average value of 1.237072876, based on fractal dimension tests of 157 individual glass shards. The average and mean fractal-dimension values are similar to the theoretical Koch-flake (snowflake) value of 1.262, suggesting that the majority of the glass shards are bulky with complex boundaries. Light-microscopy and backscattered-electron-microscopy images confirm that the glass shards are typically bulky with fractured and complex particle outlines and low vesicularity; features that are observed in glass shards generated in either a laboratory setting or naturally through the interaction of hot melt and external water. Textural features identified in fine- and coarse-ash particles suggest that they were formed by brittle fragmentation both at the hot melt-water interface (forming active particles) as well as in the vicinity of the interaction interface. Brittle fragmentation may have occurred when hot melt rapidly penetrated abundant water-rich zones causing the melt to cool rapidly and rupture explosively.

Nonlinear Damage and Failure Behavior of Brittle Rock Subjected to Impact Loading

2012 ◽  
Vol 13 (1) ◽  
Author(s):  
Yi-Xian Wang ◽  
Ping Cao ◽  
Yong-Heng Huang ◽  
Rui Chen ◽  
Jiang-Teng Li
Keyword(s):  
Impact Loading ◽  
Rock Specimen ◽  
Nonlinear Problems ◽  
Brittle Rock ◽  
Failure Behavior ◽  
Underground Engineering ◽  
Damage And Failure ◽  
Dynamic Damage ◽  
Brittle Fragmentation

AbstractThe damage and fragmentation of rock induced by impact loading is one of typical nonlinear problems in underground engineering. Rock specimen such as rock plate was found to become invalid under impact loading. This paper presents brittle fragmentation for dynamic damage of rock plate based on the edge-on impact (EOI) test with varying impact velocities (10 m s

scholarly journals Fractal statistics of brittle fragmentation

2013 ◽  
Vol 7 (24) ◽  
pp. 60-68 ◽  
Author(s):  
M. Davydova ◽  
S. Uvarov
Keyword(s):  
Fractal Statistics ◽  
Brittle Fragmentation

Topological measure of brittle fragmentation

1994 ◽  
Vol 31 (3) ◽  
pp. 391-415 ◽  
Author(s):  
Z. Yong ◽  
M.T. Hanson ◽  
R. Kovacevic
Keyword(s):  
Topological Measure ◽  
Brittle Fragmentation

Exponential and power-law mass distributions in brittle fragmentation

2004 ◽  
Vol 70 (2) ◽  
Author(s):  
J. A. Åström ◽  
R. P. Linna ◽  
J. Timonen ◽  
Peder Friis Møller ◽  
Lene Oddershede
Keyword(s):  
Power Law ◽  
Mass Distributions ◽  
Brittle Fragmentation
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