Strain-rate effects on the strength and fragmentation size of rocks

Qi, Chengzhi; Wang, Mingyang; Qi, Qian

doi:10.1016/j.ijimpeng.2009.04.008

Cited by 125 publications

(33 citation statements)

References 14 publications

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“…During the low rate loading, the stress distribution at the micro level is constant throughout the material, and the crack propagation focuses on the weakest areas of the sample. At higher strain rates, however, the stress increases very rapidly and exceeds the material fracture strength in several locations, not only at the weakest point [29]. This leads to simultaneous initiation and propagation of multiple cracks and finally complete pulverization of the sample, as well as a fast release of elastic strain energy as kinetic energy of the rock particles, acoustic emission, and generation of frictional heat.…”

Section: Analysis Of Resultsmentioning

confidence: 99%

Effects of strain rate and confining pressure on the compressive behavior of Kuru granite

Hokka

Black

Tkalich

et al. 2016

International Journal of Impact Engineering

153

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Section: Analysis Of Resultsmentioning

confidence: 99%

Effects of strain rate and confining pressure on the compressive behavior of Kuru granite

Hokka

Black

Tkalich

et al. 2016

International Journal of Impact Engineering

153

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“…An objective of this study is to provide further insights into some salient features of the deformation dynamics of brittle solids, specifically the ceramic materials with the inferior grain boundary strength and low fracture energy. With these materials in mind, the strain rate range of these virtual idealized experiments (10 s À1 , 1 Â 10 9 s À1 ]) tentatively labeled medium-to-high reaches the theoretical limit, _ " 0 ¼ " 0 = 0 %10 9 s À1 ; defined by the assumed limit failure strain, " 0 ¼ 0.001, and a temporal parameter of the order of Debye's atomic vibration period, 0 ¼ 10 À12 s (Qi et al, 2009). The lower and upper ends of the range investigated herein are customarily explored by the split Hopkinson bar (below 10 4 s À1 ) and the planar impact tests (up to 10 8 s À1 ), respectively (Field et al, 2004).…”

Section: Introductionmentioning

confidence: 96%

Further Remarks on Stochastic Damage Evolution of Brittle Solids Under Dynamic Tensile Loading

Mastilović

2010

International Journal of Damage Mechanics

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This article illuminates some general features and provides elementary interpretations of the deformation, damage, and failure of brittle solids characterized by very low fracture energy. The dynamic response of these materials is determined to a large extent by stochastic and random factors. The investigation emphasis is on the moderate-to-extremely high rate range (10 s À1 , 1 Â 10 9 s À1 ), explored under practically identical in-plane stress conditions. The statistical approach is based on repeated particle dynamics simulations for different physical realizations of micromechanical disorder of a 2D brittle discrete system. The proposed strategy is computationally intensive, which necessitates simplicity of the laws governing the interparticular interaction. Based on the simulation results, an expression is proposed to model the mean tensile strength dependence on the strain rate. The linearity of the rate dependence of the stress-peak macroscopic response parameters is observed and discussed.KEY WORDS: brittle systems, dynamic strength, damage energy rate, time to failure, disorder.

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“…In addition, in DEM, cracks form, interact, and coalesce into macroscopic fractures as a consequence of bond breakage between particles. This ensures that the numerical model can simulate the dynamic crushing failure of rock effectively (Hazzard et al 2000;Qi et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Rock SHPB Test with a Special Shape Striker Based on the Discrete Element Method

2013

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A split Hopkinson pressure bar (SHPB) system with a special shape striker has been suggested as the test method by the International Society for Rock Mechanics (ISRM) to determine the dynamic characteristics of rock materials. In order to further verify this testing technique and microscopically reveal the dynamic responses of specimens in SHPB tests, a numerical SHPB test system was established based on particle flow code (PFC). Numerical dynamic tests under different impact velocities were conducted. Investigation of the stresses at the ends of a specimen showed that the specimen could reach stress equilibrium after several wave reverberations, and this balance could be maintained well for a certain time period after the peak stress. In addition, analyses of the reflected waves showed that there was a clear relationship between the variation of the reflected wave and the stress equilibrium state in the specimen, and the turning point of the reflected wave corresponded well with the peak stress in the specimen. Furthermore, the reflected waves can be classified into three types according to their patterns. Under certain impact velocities, the specimen deforms at a constant strain rate during the whole loading process. Finally, the influence of the micro-strength ratio (s c =r c ) and distribution pattern on the dynamic increase factor (DIF) of the strength DIF were studied, and the lateral inertia confinement and heterogeneity were found to be two important factors causing the strain rate effect for rock materials.Keywords SHPB Á Special shape striker Á Discrete element method Á Strain rate effect Micro-strength ratio (ratio of contact-bond shear to normal strength) n Time-step N Current time-step DTðnÞ Interval time under time-step n(s) l Frictional coefficient at the specimen/bar interface

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Strain-rate effects on the strength and fragmentation size of rocks

Cited by 125 publications

References 14 publications

Effects of strain rate and confining pressure on the compressive behavior of Kuru granite

Effects of strain rate and confining pressure on the compressive behavior of Kuru granite

Further Remarks on Stochastic Damage Evolution of Brittle Solids Under Dynamic Tensile Loading

Numerical Simulation of the Rock SHPB Test with a Special Shape Striker Based on the Discrete Element Method

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