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. has been extended to allow for a more generalized stress state and to incorporate an experimentally motivated new crack growth (damage evolution) law that is valid over a wide range of loading rates. This law is sensitive to both the crack tip stress field and its time derivative. Incorporating this feature produces additional strain-rate sensitivity in the constitutive response. The model is also experimentally verified by predicting the failure strength of Dionysus-Pentelicon marble over strain rates ranging from $10 À 6 to 10 3 s À 1 . Model parameters determined from quasistatic experiments were used to predict the failure strength at higher loading rates. Agreement with experimental results was excellent.

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“…However, the damage evolution law, Eq. (38), depends on the size of the penny crack a. We thus use this length-scale to discretize our model.…”

Section: Numericalmentioning

confidence: 99%

A Micromechanics Based Constitutive Model for Brittle Failure at High Strain Rates

Bhat

Rosakis

Sammis

2012

Journal of Applied Mechanics

124

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“…THE conventional Hopkinson bar has been modified to study the fracture behavior of materials under both tensile [1][2][3] and compressive loading conditions (stress wave loading). Among Hopkinson bar loaded fracture tests, the compressive stress wave is more commonly employed compared to the tensile stress wave, because it is straightforward to perform and the bend specimen employed is easier to prepare (fabrication and fatigue precrack).…”

Section: Introductionmentioning

confidence: 99%

“…In the one single incident bar setup, the load and load-point displacement can be determined by onepoint [5,8,9] and two-point strain measurement techniques. [10,12] In the 2-bar compression pulse fracture test, the specimenÕs displacement and load are measured independently via strain gages attached to the incident and transmission bars, [3,[15][16][17][18][19][20][21][22][23][24][25][26][27] respectively.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, a stress-state equilibrium condition (quasi-static stress state) is critical. Because the dynamic loads applied on the specimen and the specimenÕs displacements are determined by individually transmitted and reflected stress pulses, [17][18][19][20][21][22][23][24][25][26][27][28] respectively, calculation of dynamic fracture toughness, by a static fracture mechanics theory, [3,20,21,[24][25][26][27] must be validated. All these calculations must be based on the assumption that the fracture specimen is in an equilibrium state of quasi-static stress, prior to crack initiation and throughout crack propagation.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it is essential to achieve stress-state equilibrium in the cracked fracture specimen for a valid Hopkinson fracture test. However, only a few authors [3,22,23,26,32] have considered the effect of stress-state equilibrium in the Hopkinson bar loaded fracture test. Corran et al [22,23] have investigated the time required for stress equilibrium in 2-bar/wedge-loaded compact tension fracture test and demonstrated that quasi-static equilibrium across the nonuniform section of the loading bars is achieved after 60 to 70 ls.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dynamic Effects in Hopkinson Bar Four-Point Bend Fracture

Jiang

Vecchio

2007

Metall Mater Trans A

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Hopkinson bar techniques have played an important role in the study of high-rate deformation and fracture behavior of materials. In the current work, a split Hopkinson pressure bar was developed for dynamic four-point bend fracture testing, referred to as a ''two-bar (incident and transmitted bars)/four-point'' (2-bar/4-pt) bend test. To further understand some fundamental issues regarding stress wave propagation in this 2-bar/4-pt bend testing system, dynamic fracture tests were performed in pulse-shaped and unshaped pulse testing conditions. The effect of the pulse shaper on the incident pulse characteristics (rise time and duration), specimenÕs dynamic response (load and loading point displacement), crack initiation time and stress-state equilibrium were investigated experimentally in the current work. The present results show that stress state equilibrium can be achieved prior to fracture initiation in notched and precracked specimens. In the pulse-shaped bending test, the specimen is more likely to attain stress-state equilibrium than in an unshaped incident pulse test. The crack initiation time was extended and the time required for attaining stress equilibrium was reduced by pulse shaping due to the tailored incident pulse having a longer rise time, which ensures that stress equilibrium is achieved prior to crack initiation.

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Split Hopkinson Bars for Dynamic Structural Testing

Syn¹,

Chen²

2007

Advanced Ultrasonic Methods for Material and Structure Inspection

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Cited by 111 publications

References 25 publications

A Micromechanics Based Constitutive Model for Brittle Failure at High Strain Rates

A Micromechanics Based Constitutive Model for Brittle Failure at High Strain Rates

Dynamic Effects in Hopkinson Bar Four-Point Bend Fracture

Split Hopkinson Bars for Dynamic Structural Testing

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