Loading-rate-dependent progressive fracturing of cracked chevron-notched Brazilian disc specimens in split Hopkinson pressure bar tests

Dai, Feng; Xu, Yongbin; Zhao, Tao; Xu, Nuwen; Liu, Yi

doi:10.1016/j.ijrmms.2016.07.003

Cited by 123 publications

(35 citation statements)

References 30 publications

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“…Chevron bending (CB) method 16,17 Three-point bending Chevron-notched short rod (SR) method 16,17 Direct tension Cracked chevron notched Brazilian disc (CCNBD) method [18][19][20][21][22][23][24][25] Brazilian-type compression Cracked straight-through Brazilian disc method [26][27][28][29][30][31] Brazilian-type compression Modified ring method 32 Brazilian-type compression Hollow centre cracked disc method 33 Brazilian-type compression Cracked chevron notched semicircular bending (CCNSCB) method [34][35][36] Three-point bending Straight-crack semicircular bending (SCB) method [37][38][39][40] Three-point bending Flattened Brazilian disc method 41 Brazilian-type compression Edge-cracked triangular method 42 Three-point bending Four point bend rectangular beam method 5…”

Section: Test Methods Loading Typementioning

confidence: 99%

An experimental and theoretical comparison of CCNBD and CCNSCB specimens for determining mode I fracture toughness of rocks

Wei

Dai

Liu

et al. 2017

Fatigue Fract Eng Mat Struct

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The cracked chevron notched Brazilian disc (CCNBD) specimen, suggested by the International Society for Rock Mechanics for testing mode I fracture toughness of rocks, usually yields rather conservative toughness measurements, and the reasons have not been fully explored. In this study, the CCNBD method is compared with the cracked chevron notched semicircular bending (CCNSCB) method in the fracture process zone (FPZ) and its influence on the fracture toughness measurement. Theoretical analysis reveals that the FPZ is longer in the CCNBD specimen than in the CCNSCB specimen using a relatively large support span, the toughness measurement using the former is affected more seriously by the presence of FPZ, and thus the CCNBD method is usually, more or less, conservative compared with the CCNSCB method. These inferences are further validated by experimental results, which indicate that the CCNBD test indeed produces much lower fracture toughness values and even the results of 75‐mm radius CCNBD specimens are still lower than those of 25‐mm radius CCNSCB specimens. Consequently, due to smaller FPZ, the CCNSCB specimen with a relatively large span is more likely to produce comparably accurate or representative toughness value, and it may be more suitable than the CCNBD specimen for the engineering applications that require more representative or less conservative fracture toughness.

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Section: Test Methods Loading Typementioning

confidence: 99%

An experimental and theoretical comparison of CCNBD and CCNSCB specimens for determining mode I fracture toughness of rocks

Wei

Dai

Liu

et al. 2017

Fatigue Fract Eng Mat Struct

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“…When the diurnal temperature is high, the water in joints will undergo periodic freezingthawing cycles. e periodic frost heaving force generated by freezing-thawing cycles causes the joint cracks to expand continuously, which will lead to be failure of the rock mass [11][12][13]. Many scholars have conducted numerous theoretical explorations and experimental research on freezingthawing mechanical characteristics at present [14], which can be categorized into two parts.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cyclic Freezing-Thawing on the Shear Mechanical Characteristics of Nonpersistent Joints

Lei

Lin

Chen

et al. 2019

Advances in Materials Science and Engineering

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The effects of freezing-thawing cycles and persistency differences have a significant impact on the shear mechanical properties of joints. In this paper, a series of joints direct shear tests were performed on freezing-thawing treated joints to investigate the effect of freezing-thawing cycles and the persistency on the shear strength deterioration of joints. Shear strength and residual strength decrease with the freezing-thawing cycle increase and joint persistency increase. Shear strength damage mainly generates in the initial stage of the freezing-thawing cycle, and the shear strength decreases slightly in the late freezing-thawing cycle stage. The freeze-thaw cycle has a minimal effect on the shear strength of joints with low persistency, yet has a great effect on joints with high persistency. The damage of joint roughness caused by freezing-thawing cycles increases with joint persistency increases. When the joint persistency is constant, the shear strength parameter decreases with the freezing-thawing cycle at first and then tends to be stable. Cohesion is the dominant factor that controls shear strength. When freezing-thawing cycles are constant, the friction angle decreases slowly with persistency at first and then decreases rapidly, and the friction angle is the dominant factor that controls shear strength.

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“…The split Hopkinson pressure bar (SHPB) system has been widely recognized to apply highly controlled dynamic loads (Dai et al 2010;Dai et al 2016;Zhang and Zhao 2014); the strain rate of the tested rock specimen generally surpasses 10 1 s -1…”

Section: Introductionmentioning

confidence: 99%

Effects of coupled static and dynamic strain rates on mechanical behaviors of rock-like specimens containing pre-existing fissures under uniaxial compression

et al. 2018

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Rocks containing preexisting fissures in underground engineering are likely to be subjected to static pre-stress and dynamic loads simultaneously. Understanding the deformation and failure mechanism of fissured rocks under coupled static and dynamic strain rates is beneficial for the stability assessment of rock engineering structures. This study experimentally investigates the mechanical behaviors of fissured specimens under coupled static and dynamic loads with different loading parameters. Our experiments reveal that the coupled static-dynamic strain rates significantly affect the strength, deformation, energy characteristics and failure mode of fissured specimens.For each dynamic strain rate, the strength and elastic modulus of specimens feature an increase first as the static pre-stress increases up to half of the uniaxial compression strength, and then a decrease. However, for each static pre-stress of coupled loads, the strength and elastic modulus obviously increase with increasing dynamic strain rate.From the perspective of energy partition, for each static pre-stress, the higher dynamic strain rate induces the greater energy dissipation of the specimens during the coupled loading, and more elastic energy is released at the end of loading. Moreover, for each dynamic strain rate, the pre-stress of half uniaxial compression strength induces the highest released elastic energy.

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Loading-rate-dependent progressive fracturing of cracked chevron-notched Brazilian disc specimens in split Hopkinson pressure bar tests

Cited by 123 publications

References 30 publications

An experimental and theoretical comparison of CCNBD and CCNSCB specimens for determining mode I fracture toughness of rocks

An experimental and theoretical comparison of CCNBD and CCNSCB specimens for determining mode I fracture toughness of rocks

Effect of Cyclic Freezing-Thawing on the Shear Mechanical Characteristics of Nonpersistent Joints

Effects of coupled static and dynamic strain rates on mechanical behaviors of rock-like specimens containing pre-existing fissures under uniaxial compression

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